11institutetext: Department of Experimental Physics, Maynooth University,
Maynooth, Co. Kildare, Ireland
11email<EMAIL_ADDRESS>22institutetext: Univ. Grenoble Alpes, CNRS,
IPAG, 38000 Grenoble, France 33institutetext: INAF – Osservatorio Astronomico
di Roma, Via di Frascati 3300074, Monte Porzio Catone, Italy 44institutetext:
PSL University, Sorbonne Université, Observatoire de Paris, LERMA, CNRS UMR
8112, 75014 Paris, France 55institutetext: Department of Astronomy, Shanghai
Jiao Tong University, 800 Dongchuan Rd., Minhang, Shanghai 200240, China

# A kinematical study of the launching region of the blueshifted
HH 46/47 outflow with SINFONI K-band observations††thanks: Based on
observations collected with the VLT operated by the European Southern
Observatory under ESO program ID 0102.C-0615(A).

M. Birney A kinematical study of the launching region of the blueshifted HH
46/47 outflow with SINFONI K-band observations††thanks: Based on observations
collected with the VLT operated by the European Southern Observatory under ESO
program ID 0102.C-0615(A).A kinematical study of the launching region of the
blueshifted HH 46/47 outflow with SINFONI K-band observations††thanks: Based
on observations collected with the VLT operated by the European Southern
Observatory under ESO program ID 0102.C-0615(A). C. Dougados A kinematical
study of the launching region of the blueshifted HH 46/47 outflow with SINFONI
K-band observations††thanks: Based on observations collected with the VLT
operated by the European Southern Observatory under ESO program ID
0102.C-0615(A).A kinematical study of the launching region of the blueshifted
HH 46/47 outflow with SINFONI K-band observations††thanks: Based on
observations collected with the VLT operated by the European Southern
Observatory under ESO program ID 0102.C-0615(A). E. T. Whelan A kinematical
study of the launching region of the blueshifted HH 46/47 outflow with SINFONI
K-band observations††thanks: Based on observations collected with the VLT
operated by the European Southern Observatory under ESO program ID
0102.C-0615(A).A kinematical study of the launching region of the blueshifted
HH 46/47 outflow with SINFONI K-band observations††thanks: Based on
observations collected with the VLT operated by the European Southern
Observatory under ESO program ID 0102.C-0615(A). B. Nisini A kinematical study
of the launching region of the blueshifted HH 46/47 outflow with SINFONI
K-band observations††thanks: Based on observations collected with the VLT
operated by the European Southern Observatory under ESO program ID
0102.C-0615(A).A kinematical study of the launching region of the blueshifted
HH 46/47 outflow with SINFONI K-band observations††thanks: Based on
observations collected with the VLT operated by the European Southern
Observatory under ESO program ID 0102.C-0615(A). S. Cabrit A kinematical study
of the launching region of the blueshifted HH 46/47 outflow with SINFONI
K-band observations††thanks: Based on observations collected with the VLT
operated by the European Southern Observatory under ESO program ID
0102.C-0615(A).A kinematical study of the launching region of the blueshifted
HH 46/47 outflow with SINFONI K-band observations††thanks: Based on
observations collected with the VLT operated by the European Southern
Observatory under ESO program ID 0102.C-0615(A). Y. Zhang , A kinematical
study of the launching region of the blueshifted HH 46/47 outflow with SINFONI
K-band observations††thanks: Based on observations collected with the VLT
operated by the European Southern Observatory under ESO program ID
0102.C-0615(A).A kinematical study of the launching region of the blueshifted
HH 46/47 outflow with SINFONI K-band observations††thanks: Based on
observations collected with the VLT operated by the European Southern
Observatory under ESO program ID 0102.C-0615(A).

(Received –; accepted –)

###### Abstract

Context. Studying outflows is important as they may significantly contribute
to angular momentum removal from the star/disk system, affecting disk
evolution and planet formation.

Aims. To investigate the different outflow components; the collimated jet,
wide-angled molecular outflow, and outflow cavity, of the Class I HH 46/47
outflow system. We focus on their kinematics.

Methods. We present Near Infrared (NIR) K-band integral field observations of
the blue-shifted HH 46/47 outflow base obtained using VLT/SINFONI with an
angular resolution of 0$\aas@@fstack{\prime\prime}$81\. Our analysis focuses
on [Fe ii], H2 1–0 S(1), and Br-$\gamma$ emission. We employ a wavelength
recalibration technique based on OH telluric lines to probe the kinematics of
the wide-angled flow with an accuracy of $\sim$ 1 km s-1 \- 3 km s-1.

Results. A velocity gradient of $\sim$ 10 km s-1 transverse to the outflow
direction is confirmed in the wide-angled H2 outflow cavity. The H2 cavity
peaks at radial velocities of $\sim$ $-$15 km s-1 to $-$30 km s-1, and the
atomic jet at $v_{\mathrm{rad}}$ $\sim$ $-$210 km s-1. The outflow exhibits a
layered structure; the high-velocity [Fe ii] and Br-$\gamma$ jet is surrounded
by a wide-angled H2 outflow cavity, which is in turn nested within the
continuum emission and CO molecular outflow. The continuum emission and H2
outflow cavity are asymmetric with respect to the jet axis.

Conclusions. We propose that the origin of the asymmetries and the velocity
gradient detected in the wide-angled H2 cavity, is due to a wide-angled
outflow or successive jet bowshocks expanding into an inhomogeneous ambient
medium, or the presence of a secondary outflow. We eliminate outflow rotation
as an exclusive origin of this velocity gradient due to large specific angular
momenta values, $J(r)$ $\approx$ 3000 - 4000 km s${}^{-1}\,$au calculated from
1″ to 2″ along the outflow. The observations reveal the complexities inherent
in outflow systems, and the risk of attributing transverse velocity gradients
solely to rotation.

###### Key Words.:

Herbig-Haro objects – ISM: individual objects (HH 46, HH 47) – ISM: jets and
outflows – Stars: formation – Stars: winds, outflows – Stars: jets

##  1 Introduction

Outflows (jets and winds) from young stellar objects (YSOs) are ubiquitous,
but their origin is a major open question in star formation (Frank et al.
2014; Pascucci et al. 2023). They are launched very early in the star
formation process perpendicularly to the accretion disk surrounding the YSO,
and can persist for several million years (Whelan 2014). Ejection in YSOs is
intrinsically linked with accretion and the outflows interact with the
surrounding envelope of quiescent material creating shocked regions (Hartigan
2003; Arce et al. 2007). Studying YSO outflows is important as they may
significantly contribute to the angular momentum removal from the star/disk
system, which is an unsolved dilemma in star formation (Pudritz & Ray 2019).
Angular momentum transport plays a central role in the star formation process
as the initial angular momentum present in dense star forming cores needs to
be reduced by several orders of magnitude in order to permit a star or a
multiple star system to form (Belloche 2013). Outflows also influence disk
evolution and likely affect planet formation and migration as they may
interact with the planet forming regions of the disk (Pascucci et al. 2023).

Observing protostars is essential to gain insights on the most active period
of accretion and ejection from the forming star and Class 0/I low mass sources
have been much studied to date (Ray & Ferreira 2021). However, protostars are
challenging to observe due to their heavily embedded nature. Their dusty and
gaseous envelopes cause strong extinction, making it difficult to probe the
inner regions of the disks where accretion occurs and where the earliest
instances of planet formation are beginning. We can however learn about the
ejection, and indirectly the inner disk properties, of these YSOs by studying
their powerful outflows, once we select the most suitable tracers.
Protostellar outflows from Class 0/I YSOs consist of high-velocity ($v$ $\sim$
100 km s-1 \- 400 km s-1), collimated jets launched from the innermost region
of the disks, lower velocity ($v$ $\sim$ 1 km s-1 \- 30 km s-1), wide-angled
winds launched from larger disk radii (Frank et al. 2014; Pascucci et al.
2023) and entrained material from the surrounding envelope (Arce et al. 2013).
Lower-velocity, wider outflow components surrounding the bases of class I jets
were first discovered by Davis (2002) using NIR narrow-band H2 imaging.
Cavities, which are defined as hollow, low-density regions created by the
outflow, surrounding atomic jets are well documented phenomena (Habel et al.
2021), and Class I protostars are regularly seen with such cavities. The
origin of these outflow cavities is currently debated. They may be directly or
partly tracing intrinsic wide-angled disk winds originating from the disk
surface (de Valon et al. 2022; López-Vázquez et al. 2024). They may be tracing
an interaction region between some kind of wide-angled disk wind, either by
magnetic (MHD) processes or thermal (photo-evaporative) processes, and the
surrounding medium, be it static or an infalling envelope. They may also be
produced by the stacking of successive jet bowshocks from a collimated,
variable inner jet propogating into a density-stratified surrounding medium
(Rabenanahary et al. 2022).

MHD (magnetohydrodynamic) processes in the rotating star-disk system, where
magnetic field lines anchored in the accretion disk magneto-centrifugally
launch material from the disk plane, are theorised to give rise to outflows
(Ray & Ferreira 2021). Current models predict that MHD outflows emanate from a
range of disk radii (the Disk wind model) or from a single narrow radial
region (the X-wind model) (Ferreira 1997; Bai et al. 2016). In the disk wind
model (Pudritz & Norman 1983; Konigl & Pudritz 2000; Pudritz et al. 2007), the
high-velocity, collimated jet component is launched from the innermost regions
of the disk, whilst the launching region of the lower-velocity, wide-angled
outflow component is more radially extended along the disk and distributed
over a larger range of disk radii. This is significant for both disk evolution
and later, planet formation as wide-angled winds may affect these
substantially. An alternative model for launching an outflow magneto-
centrifugally is the X-wind model (Shu et al. 2000). In this model, the
outflow is launched from a narrow radial region at the interface region
between the inner disk edge and the stellar magnetosphere, the so called co-
rotation radius. High-velocity, collimated jets and slower moving, wide-angled
winds are also predicted with this model (Shang et al. 2020), however in
contrast with the disk wind model, the wide-angled wind component in the
X-wind model flows at much higher velocities as all of the magnetic outflow
streamlines originate at the same disk radius.

Disk wind models predict a greater fraction of angular momentum removal from
the star disk system as the outflow driving region extends further radially
along the disk from the driving source, and specific angular momentum
increases with disk radii (Anderson et al. 2003; Ferreira et al. 2006; Pudritz
& Ray 2019; Lee et al. 2021). Therefore, measurements of outflow rotation
which lead to estimates of specific angular momentum are critical for
constraining the two MHD models and to date have tended to support the disk
wind model (Coffey 2017). Wide-angled winds can offer information about
angular momentum transport. As we can more readily spatially resolve the
lateral component of these wide-angled winds, it is more promptly achievable
to perform outflow rotation measurements (Tabone et al. 2017; Zhang et al.
2018). Measuring outflow rotation signatures using only the high-velocity jet
counterparts is more challenging and requires more specialised observations
(Coffey et al. 2004, 2007; Lee et al. 2017).

Outflows emission arises primarily from the cooling regions of the shocks
generated when higher velocity material catches up with and impacts material
ahead of it (Tsukamoto et al. 2023). While outflows are observed in all
wavelength regimes, Class 0/I outflows are best observed with IR and sub-mm
observations, as these wavelengths allow us to peer through the dusty envelope
(Yang et al. 2022; Harsono et al. 2023; Beuther et al. 2023; Ray et al. 2023;
Nisini et al. 2024; Delabrosse et al. 2024). In particular, these outflows can
be studied using IR Fe forbidden and H2 ro-vibrational emission lines as these
lines are brightly emitting near their bases and interestingly these two
species trace different outflow components (Davis et al. 2011). [Fe ii]
emission traces hot, dense, partially-ionised, and high-velocity gas ($T$
$\sim$ 10,000 K; $n_{\mathrm{e}}$ $\sim$ 105 cm-3; $v$ $\sim$ 100 km s-1 \-
400 km s-1) (Nisini et al. 2002; Davis et al. 2003), while H2 traces a
molecular hydrogen emission line (MHEL) region associated with lower
excitation, shocked molecular gas, or UV fluoresced gas, at much lower
velocities ($T$ $\sim$ 2,000 K; $n_{\mathrm{e}}$ $\sim$ 103 cm-3; $v$ $\sim$
10 km s-1 \- 50 km s-1) (Davis 2002; Caratti o Garatti et al. 2006; Frank et
al. 2014). Therefore [Fe ii] emission is a well established atomic jet tracer
(Davis et al. 2003) and shocked H2 emission is an important means of tracing
molecular winds and cavities (Nisini et al. 2024). CO rotational emission
lines at sub-mm wavelengths are also found in outflows from Class 0/I YSOs.
The component of the outflow that CO likely maps is the resulting ambient gas
after it has been swept up and entrained by some wide-angled wind and later
left to cool (Arce et al. 2013), however in some cases it is thought to trace
the disk wind itself (Louvet et al. 2018; de Valon et al. 2022). The CO
emission traces molecular gas at low velocities also and is cooler than the H2
emission ($T$ $\sim$ 100 K; $n_{\mathrm{e}}$ $\sim$ 103 cm-3). Therefore, CO
emission complements snapshots of current shock interactions obtained with H2
and [Fe ii] observations by providing us with an insight into the outflow
history of the protostar (Richer et al. 2000).

Here SINFONI IFS observations of the HH 46/47 outflow system in the K-band
(1.95 - 2.45 $\mu$m) are presented with a resolving power of R = 4000 (Fig.
1). HH 46/47 is an excellent prototype system for isolated star formation,
located in the Bok Globule ESO 210-6A in the Gum nebula. See Sect. 2.1 for
more details on the target. The field of view (FOV) chosen was
8$\aas@@fstack{\prime\prime}$0 $\times$ 8$\aas@@fstack{\prime\prime}$0
resulting in an observation of the base of the blue-shifted outflow. These
observations allow us to investigate both the base of the fast axial jet and
the wide-angled outflow component in near-infrared (NIR) [Fe ii] and H2
emission, and then comparison can be made with previous CO sub-millimeter
observations. In particular, we wished to use a wavelength recalibration
technique based on OH lines to search for a rotation signature in the HH 46/47
outflow. The target, observations, data reduction and data calibration are
discussed in Sect. 2. In Sect. 3 we present the results of our observations,
namely the morphologies and kinematics of the continuum emission, the wide-
angled H2 outflow cavity, and the base of the atomic jet. We also present a
velocity gradient transverse to the outflow axis observed in the H2 outflow
cavity. In Sect. 4 we discuss our results. Included in our discussion is the
observed layering of different emission tracers and the the origin of the
velocity gradient associated with the H2 outflow cavity. We summarise our
conclusions in Sect. 5.

##  2 Target, observations, data reduction and calibration

###  2.1 HH 46/47

Figure 1: Integrated intensity maps displaying the morphologies of the outflow
in different emission tracers. The source position is marked with a red plus.
Contour levels for all begin at 3$\sigma$ of the background emission and
increase by factors of 1.5. The vertical axis is aligned with centre axis of
CO outflow (PA = 60°). Top: Continuum emission displaying a wide,
approximately parabolic shape. Average jet PA of 52.3° indicated by a green
arrow. Centre: Continuum subtracted and scattered light subtracted, integrated
H2 emission displaying a V-shaped outflow cavity. Bottom: Continuum
subtracted, integrated [Fe ii] emission displaying collimated atomic jet
emission.

HH 46/47, discovered by Schwartz (1977), is a well studied complex of Herbig-
Haro (HH) objects, series’ of internal working surfaces or shock fronts in a
larger outflow. The driving source of the outflow system (HH 46 IRS, HH 47
IRS, IRAS 08242-5050, 2MASS J08254384-5100326) is an embedded (AV ¿ 35), low-
mass, Class I YSO binary system of $\sim$ 0$\aas@@fstack{\prime\prime}$26
separation or 117 au (Reipurth et al. 2000; Nisini et al. 2024), taking a
distance to the system of 450 pc (Graham & Heyer 1989). The source has a mass
of approximately 1.2 M⊙ and bolometric luminosity of ¡ 15 L⊙ (Antoniucci et
al. 2008), and is located at the north-eastern edge of the Bok globule, ESO
210-6A, in the Gum nebula. The bipolar outflow system consist of wide-angled,
low-velocity, molecular outflows accompanied by highly-collimated, high-
velocity, mainly atomic jets. The blueshifted side of the jet emanates north-
easterly from the Bok Globule, making it easily visible at optical wavelengths
(Heathcote et al. 1996; Hartigan et al. 2011). The redshifted side of the jet
penetrates south-westerly, deep into the cloud, making it, and the driving
source itself, visible at only infrared wavelengths (Eisloeffel & Mundt 1994;
Reipurth et al. 2000; Noriega-Crespo et al. 2004; Erkal et al. 2021b).

The blueshifted jet displays a screw-like structure that spirals counter-
clockwise towards the observer with an angle of inclination of 37° with
respect to the plane of the sky (Hartigan et al. 2005). Proper motions at the
base of the jet are approximately 270 km s-1 and increases to 300 km s-1
(Hartigan et al. 2005; Erkal et al. 2021b). Wide-field images reveal that HH
46/47 extends at least 2.6 pc from the driving source, setting a lower limit
to the dynamical age of the outflow of $10^{4}$ – $10^{5}$ years old (Stanke
et al. 1999). The jets display a prominent ‘wiggling’. It was postulated that
the orbital motion of an unresolved tertiary component caused the meandering
of the jet (Reipurth et al. 2000) as the separation of the binary system was
too large to explain the short wiggling period of $\sim$ 200 yr of the jet
seen at large scales. The jet also displays a highly structured morphology,
with knots seen along the outflow implying episodic ejection of material from
the driving source.

The wide-angled molecular outflows have been well studied using ALMA CO (1-0)
observations (Arce et al. 2013; Zhang et al. 2016) and CO (2-1) observations
(Zhang et al. 2019). The low-velocity, wide-angled CO outflow is highly
asymmetric, with the redshifted lobe extending four times further than
blueshifted lobe, a lack of dense material in the path of the blueshifted flow
is responsible for this. This wide-angled component displays multiple shell-
like structures and these shells trace the ejection variability just like the
collimated component of the outflow (Zhang et al. 2019). The variability
timescales of the multiple outbursts seen in the wide-angle wind is consistent
with episodic knots along the jet of HH 46/47. This suggests that the multiple
shell structure seen in wide-angle component may arise from the same high
accretion rate episodes that is reflected in the knots in the jets.

H2 emission was first detected in the HH 46/47 system by Schwartz (1983) with
the identification of six fluorescent UV emission lines produced by
Ly-$\alpha$ pumping of H2. These molecules had to be first warmed to the
second vibrational state of the electronic ground state. Later, NIR H2
quadrupole emission in HH 46/47 was detected by Wilking et al. (1990).
Eisloeffel & Mundt (1994) first presented the H2 morphology of the HH 46/47
system using the IRAC2 instrument on the ESO/MPI 2.2 m telescope. Noriega-
Crespo et al. (2004) imaged the system in the near to mid-infrared using the
Spitzer Space Telescope revealing the optically invisible redshifted jet
propagating southwesterly revealing a loop-like morphology, with both outflow
lobes being narrower than those observed in CO emission. Garcia Lopez et al.
(2010) used long-slit NIR spectroscopic observations of the system using ISAAC
and investigated the kinematics of the atomic and molecular emission, namely
H2 and [Fe ii] emission, along the jet.

Erkal et al. (2021b) mapped the HH 46/47 system with HST with, at the time,
unprecedented detail and recently, the HH 46/47 driving source and outflow
were mapped at higher angular resolution of $\sim$
0$\aas@@fstack{\prime\prime}$2 with JWST using the NIRSpec IFU and MIRI MRS as
part of the PROJECT-J program (ID 1706, P: B. Nisini) (Nisini et al. 2024).
These observations provide unprecedented detail of the structure of the jet,
the associated molecular outflow, and the cavity. Emission in H2 reveals a
complex molecular outflow, where the bright outflow cavity, expanding
molecular shells and jet-driven bow-shocks interact with, and are influenced
by ambient conditions. The superior spectral resolution provided by our
SINFONI observations with respect to JWST (R = 4000 vs 2700), allows the
outflow kinematics to be studied with unprecedented detail.

###  2.2 VLT SINFONI

Observations of the HH 46/47 outflow were obtained with the Spectrograph for
INtegral Field Observations in the Near Infrared (SINFONI) on the 27th of
November 2018 under ESO Program ID 0102.C-0615(A) (PI: C. Dougados). The NIR
observations were obtained using the K-band grating (1.95 - 2.45 $\mu$m) with
a resolving power of R = 4000. The FOV chosen was
8$\aas@@fstack{\prime\prime}$0 $\times$ 8$\aas@@fstack{\prime\prime}$0
providing a spatial sampling of 0$\aas@@fstack{\prime\prime}$125 $\times$
0$\aas@@fstack{\prime\prime}$250 (Eisenhauer et al. 2003). This FOV was chosen
as it was well suited to encompass the base of the outflow. The detector was
rotated 60° so that the vertical axis of the detector was parallel to the
approximate CO outflow position angle (PA) (Zhang et al. 2019). The
observations consisted of ten exposures of 150 s each providing an on target
exposure time of 1500 s. The average seeing of the science observation was
0$\aas@@fstack{\prime\prime}$81\. It was not possible to use the instruments
AO correction due to a lack of a suitable bright point source nearby. Three
exposures of 300 s were also taken for sky exposures. Two standard stars, HD
67954 (HIP 039774) and HD 73105 (HIP 042038), were also observed for flux
calibration and telluric correction. The goal of the observations was to
extract the 2-Dimensional (2D) spatial and kinematic distribution of atomic
and H2 emission lines at the base of the blueshifted outflow cavity.

###  2.3 Data reduction

The data was reduced using ESO’s SINFONI data reduction pipeline (Version
3.3.0) and run with ESOReflex (Freudling et al. 2013). Standard calibration
files were used. The datacube was corrected for bad pixels, flat-fielding,
bias and dark signal, sky emission and a first order wavelength calibration
was done using arc lamp wavelength solutions. All emission line velocities
discussed throughout are corrected for the Barycentric Earth Radial Velocity
(BERV) and the Local Standard of Rest (LSR) velocity of the cloud that the
outflow emanates from, which is +5.3 km s-1 (van Kempen et al. 2009). The
kinematical measurements presented here are therefore expressed with respect
to the frame of the central source.

###  2.4 Wavelength recalibration

The spectral resolution of SINFONI in the K-band is approximately R = 4000 or
2.45 Å, which translates to a velocity resolution of 75 km s-1. The spectral
sampling size in terms of velocity is 38 km s-1 at 1.95 $\mu$m and 30 km s-1
at 2.45 $\mu$m. The wavelength calibration was performed using the standard
procedure with the SINFONI data reduction pipeline. Wavelength calibration
errors of approximately $\pm$ 30 km s-1 were observed, by fitting OH telluric
emission lines from Earth’s upper atmosphere, in the final datacube after data
reduction using the SINFONI pipeline, which are not optimal for kinematical
analysis. In order to increase the velocity calibration accuracy, a more
rigorous wavelength calibration technique was employed. The data was run
through the data reduction pipleine again, but the sky subtraction step was
omitted from the process. This resulted in a datacube that contained the OH
telluric emission lines. As these lines have a radial velocity of 0 km s-1
with respect to Earth’s surface, they serve as a valuable tool for wavelength
calibration. A 2D wavelength correction map could be produced using these OH
lines as a velocity reference point, accounting for possible wavelength drifts
across the FOV of the observation.

A cross-correlation method was employed to produce this 2D wavelength
correction array by comparing the OH emission lines present in the science
cube spectra with a theoretical night-sky spectrum. The cross-correlation
routine used was from the Toolkit for Exoplanet deTection and chaRacterization
with IfS (TExTRIS) (Bonnefoy et al. 2014; Petrus et al. 2021; Palma-Bifani et
al. 2023; Demars et al. 2023). The ESO SKYCALC tool (Noll et al. 2012; Jones
et al. 2013) was used to generate a synthetic night-sky spectrum that matched
the night of observation and observatory location. The synthetic spectrum had
a spectral resolution of R = 100,000 and was convolved with a Gaussian in
order to downscale the spectral resolution to match that of the SINFONI K-band
observations.

The cross-correlation procedure compares the spectral positions of the OH
lines in the science cube with the theoretical positions in the synthetic
night sky spectrum, and calculates the wavelength offset between the two
around a desired spectral region. The cross-correlation method was run in a
spectral region centred on the the H2 2.12 $\mu$m emission line with care
taken to avoid large telluric absorption bands within the spectral window. A
2D wavelength correction map was produced, where each pixel in the map
corresponded to a wavelength offset between the OH lines in the science
spectra and theoretical spectrum. A linear trend was observed in the each of
the horizontal rows of pixels in the 2D map. This trend is in accordance with
the orientation of the horizontal slicing mirrors of the beam splitter present
in the SINFONI Integral Field Unit (IFU). Each horizontal row of pixels in the
2D wavelength correction map was isolated and a linear fit was applied to the
data points. Each linear fit was compiled into a 2D wavelength correction map.
This wavelength correction map is shown in the appendix in the central panel
of Fig. 9. This method of precise wavelength calibration was also performed on
SINFONI observations in Delabrosse et al. (2024).

This final wavelength correction map was applied to the SINFONI datacube,
effectively obtaining a more accurate wavelength calibration than that offered
with the standard arc lamp wavelength calibration. The relative uncertainty
associated with this wavelength correction map, calculated from the standard
deviations of the residuals of the horizontal linear fits, is $\pm$ 0.55 km
s-1. The absolute error associated with the map is estimated to be $\pm$ 0.62
km s-1, calculated by by computing the wavelength correction map in several
narrow wavelength intervals throughout the spectral axis, allowing us to
estimate the variation in wavelength (velocity) correction values as a
function of the central wavelength. Summing the absolute and relative error in
quadrature we retrieve the total uncertainty of the wavelength calibration
procedure to be $\pm$ 0.83 km s-1. Note that this value is not the final
uncertainty on individual line centroid velocities.

There are also systematic errors that arise when using this wavelength
calibration method that must be considered, as a single average wavelength
correction value is derived for each spaxel over a wavelength range.
Delabrosse et al. (2024) noticed when applying the 2D wavelength correction
map to single OH lines in the vicinity of the H2 2.12 $\mu$m emission line,
there existed systematic offsets from the OH line’s actual wavelength. These
systematic uncertainties produce absolute errors of the order of 0.4 km s-1,
retrieved from Gaussian centroid offsets from the OH lines’ known wavelengths,
and relative uncertainties of the order of 0.9 km s-1, retrieved from the
standard deviation of wavelength correction values in the 2D wavelength
correction map applied to the OH lines. We adopt the same values as we find
similar results, as expected using the same wavelength calibration method. We
therefore estimate a 1$\sigma$ uncertainty associated with the wavelength
calibration of $\pm$ 1.0 km s-1.

###  2.5 Uneven slit effect correction

The uneven slit effect is an instrumental limitation associated with
spectrometers due to the non-uniform illumination of the slit, or an
illumination gradient within the slit. In the case of IFUs, the slicing
mirrors, which individually behave like long-slit spectrographs, are
illuminated non-uniformly, introducing a spurious wavelength shift in the
spectral axis between on-axis and off-axis light. Incoming light that enters
the slicing mirror or slitlet at a point above the slitlet centre will have an
opposite wavelength bias when compared with incoming light entering the slit
at a point below the slitlet centre (Whelan & Garcia 2008). In the case of
these observations, the effect arises due to the slope of the PSF creating a
non-uniform brightness gradient within the slit. The resulting spurious
wavelength shift depends on how strong the local brightness gradient is across
the slit.

The generation of a further 2D wavelength correction map was necessary in
order to correct for these illusory wavelength shifts due to uneven slit
illumination. In our case, we endeavored to generate a wavelength correction
map for the H2 2.12 $\mu$m emission line as we required optimal confidence in
the radial velocity measurements of the molecular outflow. In the case of
SINFONI, the horizontal slicing mirrors can introduce spurious wavelength
shifts up to a few km s-1 (Agra-Amboage et al. 2014). The wavelength
correction map due to uneven slit illumination was generated following the
formulation developed by Marconi et al. (2003). This method is used
successfully in Erkal et al. (2021a) and Agra-Amboage et al. (2014). The
correction for the uneven slit effect is explained further in Sect. B of the
appendix. Figure 10 displays the resulting 2D wavelength correction map to
amend for uneven slit illumination, generated for the H2 2.12 $\mu$m emission
line, was applied to the datacube around this emission line of interest.

###  2.6 Flux calibration and telluric correction

Flux calibration was performed on the SINFONI datacube using the two standard
star observations that were part of the same observation run. The standard
star observations, HD 67954 (HIP 39774) & HD 73105 (HIP 42038), were reduced
with the SINFONI data reduction pipeline in the same fashion as the science
cube. Apertures, slightly larger in size than the seeing disc radius, were
placed over the standard star’s stellar positions and integrated to obtain the
total flux with a high S/N. Annuli were used to estimate the contribution from
the local background, which was subsequently subtracted from the aperture
integration. Integrated stellar spectra were extracted using this method. The
standard star’s known magnitudes in J, H and K were obtained from the 2MASS
catalogue (Skrutskie et al. 2006) and these magnitudes were converted to flux
densities. Using the Rayleigh-Jeans approximation of Planck’s radiation law a
flux vs. wavelength plot could be produced in order to calibrate the stellar
spectra. The average calibration curve obtained independently from both of the
standard star observations was used to flux calibrate the science data cube.
The telluric contamination present in the observation was also corrected using
the standard star observations. Each spectrum present in the science
observation was divided by a normalised telluric correction spectrum obtained
from the standard star HD 73105.

###  2.7 Continuum subtraction and scattered emission removal

Figure 2: Line-to-continuum ratio plots of H2, [Fe ii], and Br-$\gamma$
emission. Intrinsic emission appears bright in these images, whereas scattered
light is represented by a constant ratio close to unity. The source position
is represented with a red plus symbol. A signal-to-noise threshold, set at 3
times the background noise, is implemented in these images to reject
background emission, meaning the morphologies we see in these figures is due
to a combination of the continuum and the intrinsic line emission. Top left:
Integrated H2 emission between $-$140 km s-1 and +60 km s-1, divided by nearby
continuum. Intrinsic line emission here is coming from the cavity walls and a
H2 knot at the base of the left cavity wall (A1). Top right: Integrated [Fe
ii] emission between $-$310 km s-1 and $-$100 km s-1, divided by nearby
continuum. Intrinsic line emission we see here traces the high velocity atomic
jet. Bottom left: Integrated high-velocity Br-$\gamma$ emission between $-$230
km s-1 and $-$130 km s-1, divided by nearby continuum. Intrinsic line emission
we see here, again, traces the high velocity atomic jet. Bottom right:
Integrated low-velocity Br-$\gamma$ emission between $-$100 km s-1 and +100 km
s-1, divided by nearby continuum. There is no spatially extended intrinsic
emission detected here.

The top panel of Fig. 1 in Sect. 2.1 displays a continuum image, integrated
over $\lambda$2.190 $\mu$m - $\lambda$2.191 $\mu$m, which represents the same
number of datacube slices as the integrated H2 and [Fe ii] images displayed in
the central and bottom panels. The continuum emission is tracing a reflection
nebula with an approximate parabolic shape that is asymmetric in intensity
about the average jet PA of 52.3° from Erkal et al. (2021b) indicated by a
green arrow in the top panel of Fig. 1. This reflection nebula is light from
the driving source of the outflow scattered off the walls of the cavity,
revealing the extent of the scattered light component present in these images,
this contribution is present at all wavelengths.

As we endeavoured to investigate spectro-images of the outflow in intrinsic
line emission, the scattered emission first needed to be removed. As the
cavity was fully illuminated in continuum emission, an assumption was made
that the scattered light component was entirely light from the unresolved
central binary reflecting off the cavity. A spectrum was extracted from the
continuum peak position (or the source position) to best represent the
scattered emission contribution. A polynomial fit was applied to this source
spectrum in order to rescale the source spectrum to the same level as the
continuum at each spatial-pixel (spaxel) in the datacube. Subsequently, the
rescaled source spectrum was subtracted locally in wavelength around each
emission line of interest from the spectra at each each spaxel. This
effectively removed the scattered light component and continuum emission from
the emission line of interest, leaving only the intrinsic line emission. This
scattered emission removal routine was performed locally in the spectral
region around each emission line of interest to ensure an accurate subtraction
of scattered light. See Fig. 11 in the appendix for a before and after of the
scattered emission removal routine applied to H2 emission.

Line to continuum ratio plots are an effective tool for investigating the
contribution of scattered emission and for checking the effectiveness of any
process for removing it. These plots display the result of calculating the
ratio between an integrated line image and an integrated continuum image,
taken spectrally nearby to the line of interest. The contribution from
scattered light to the integrated line images will be represented by a
constant ratio in these plots, as the scattered light follows the same spatial
distribution as the continuum emission. In contrast, the real, intrinsic local
emission will appear bright in these images, exceeding the constant ratio that
represents the contribution from scattered light. The top left panel of Fig. 2
displays the result for H2 emission. It is seen that the intrinsic line
emission here is coming from the cavity walls and the H2 knots at the bases of
the cavity walls, in agreement with the central panel of Fig. 1. Intrinsic
emission appears brighter as offset from the source increases as the
contribution from scattered light decreases with distance from the source.
This is why the tips of the northern and eastern cavity walls have
significantly larger ratio values.

As the scattered emission subtraction process samples the representative
scattered emission spectrum from the continuum peak, the base of the jet,
traced in forbidden iron emission and Br-$\gamma$ emission, is removed as a
unavoidable byproduct of the process, as jet emission is more compact and
closer to the source position. This implies that some intrinsic atomic jet
emission is present in the representative scattered emission spectrum or
source spectrum due to the diameter of the aperture used to sample the
spectrum, and also the angular resolution of the observation. As we were
sacrificing the ability to trace the jet back to the source when applying this
process to the jet tracing emission lines, we chose to not perform the
scattered emission removal process from the jet tracing lines.111This is also
true for the H2 emission originating on or near the source position. However,
we recover very little to no intrinsic H2 emission on or near source in our
data and so we could proceed with the scattered emission removal routine for
molecular hydrogen. The low emission on or near the source position is
confirmed by the line to continuum plot shown in Fig. 2. Regions immediately
in the vicinity of the source position here display little to no intrinsic H2
emission.

The top right panel of Fig. 2 presents the line to continuum plot for the [Fe
ii] emission. There is little contribution from the scattered emission to the
integrated line emission image of the jet, seen in Fig. 1 as the morphologies
are similar, supporting our decision to not perform scattered emission
subtraction on this emission line. The high-velocity ($-$230 km s-1 to $-$130
km s-1) Br-$\gamma$ emission line to continuum plot is displayed in the bottom
left panel of Fig. 2, and is seen to trace the jet also. Therefore scattered
emission subtraction was not performed on this emission line either. A
baseline continuum subtraction routine was instead implemented by performing
local polynomial fitting to the continuum around the emission lines. This
polynomial fit continuum subtraction was performed at every spaxel in the
datacube, for each emission line, with care taken to exclude the line emission
region from the baseline fit.

In the bottom right panel of Fig. 2, we present a line to continuum map of low
velocity Br-$\gamma$ emission, integrated from $-$100 km s-1 to +100 km s-1.
In this line to continuum map, the ratio of integrated line emission to
continuum is approximately constant across the morphology of the cavity, and
equal to the ratio located at the continuum peak position. We can infer from
this that any spatially extended Br-$\gamma$ emission we see in the low
velocity interval follows the same spatial distribution as the scattered light
seen in continuum. This implies that any extended, low velocity Br-$\gamma$
emission is not intrinsic emission and is instead dominated by scattering of
the central source spectrum off of the dusty, nebulous cavity material traced
by the continuum.

##  3 Results

Figure 3: Spectrum extracted using a circular aperture of radius
0$\aas@@fstack{\prime\prime}$41 from the continuum peak. The jet emission is
identified in the FELs of [Fe ii], and in Br-$\gamma$ emission. The outflow is
detected in the H2 emission lines. In addition, CO overtone bandhead emission
at 2.29-2.36 $\mu$m, which traces the inner gaseous disk, is also seen. A
characteristic reddening slope is evident in this spectrum as expected as the
source is heavily extincted and only visible at infrared wavelengths. Stellar
absorption lines were not identified in this spectrum, it was concluded that
the central source is too heavily extincted to study these lines.

The SINFONI observation of HH 46/47 reveals emission lines tracing outflow and
accretion activity, in agreement with previous spectroscopic studies
(Antoniucci et al. 2008; Garcia Lopez et al. 2010). In this paper we discuss
the morphology and kinematics of the jet and wide-angled outflow with a
particular focus on the kinematics. Figure 1 presents integrated intensity
maps which showcase the morphology of the HH 46/47 blue-shifted outflow. Maps
of the continuum emission, molecular hydrogen (H2) emission at 2.12 $\mu$m,
and forbidden iron emission at [Fe ii] $\lambda$2.047 $\mu$m are shown. The H2
emission line at 2.12 $\mu$m, hereafter referred to as H2, is the brightest
MHEL in the dataset that does not suffer any negative effects due to closeness
to the spectral edge of the detector. The forbidden iron emission line at
2.047 $\mu$m, hereafter referred to as [Fe ii], is the brightest iron emission
line in the dataset. The source is partially embedded at these wavelengths but
we detect a point source at the apex of the cavity in continuum emission. We
fit a 2D Gaussian profile to this continuum peak and use this as our driving
source position throughout. This continuum peak is not necessarily coincident
with the position of the HH 46 IRS millimeter position derived by Arce et al.
(2013) as in the IR, it is possible that the significant contribution of
scattered light could shift the barycentre of the source continuum peak. A
spectrum extracted from the source position is presented in Fig. 3. Atomic jet
emission is identified in the FELs of [Fe ii], and in Br-$\gamma$ emission.
Several H2 ro-vibrational emission lines ($v$ = 1-0 & 2-1) are detected,
likely due to a wide-angled outflow cavity (see Sect. 3.1). In addition, CO
overtone bandhead emission at 2.29 - 2.36 $\mu$m, which traces the inner
gaseous disk is also seen222Spectra extracted from an atomic jet knot at
1$\aas@@fstack{\prime\prime}$0 (450 au) offset from the source position, and
from both emission peaks (A1 & A2) either side of the V-shaped cavity traced
by molecular hydrogen (H2) are also presented in Fig. 12 of the appendix.

###  3.1 Morphology

The top panel of Fig. 1 as discussed in Sect. 2.7 displays a continuum image,
integrated over $\lambda$2.190 $\mu$m - $\lambda$2.191 $\mu$m, which
represents the same number of datacube slices as the integrated H2 and [Fe ii]
images displayed in the central and bottom panels. The morphology of the
reflection nebula is approximately parabolic, and asymmetric in intensity
about the average jet PA of 52.3° from Erkal et al. (2021b), indicated by a
green arrow. The scattered light in the continuum image delineates the
boundary region between the outflow and the ambient material, sweeping out a
wide-angled hollow cavity in the quiescent material. The boundary region we
see is essentially the cavity walls. The structure of the cavity as traced by
continuum emission, CO emission and H2 emission is discussed further in Sect.
4.2. The northern arm of the cavity extends further from the source than the
eastern arm, suggesting a dissymmetry in the distribution of ambient material
surrounding the outflow. The position of the driving source of the outflow is
marked with a red plus symbol.

The central panel displays the continuum subtracted and scattered emission
subtracted H2 1-0 S(1) emission, integrated over radial velocities of $v$ =
$-$95 km s-1 to +110 km s-1. As also shown by the JWST NIRSpec H2 2.12 $\mu$m
image in Nisini et al. (2024), the integrated H2 emission has a striking
V-shaped morphology tracing the limb-brightened cavity walls of the outflow.
The shocked northern cavity wall traced by H2 emission lies within the cavity
structure seen in the continuum image, meaning the H2 emission is confined
within the outflow cavity seen in scattered light. This narrowing of the
cavity walls suggests that the H2 emission is probing deeper into the outflow
cavity, allowing us to see within the cavity walls traced in scattered light.
The H2 cavity is again asymmetric about the jet PA with the northern wall
appearing significantly brighter and extending further than the eastern wall.
There is also some faint emission present within the cavity, especially
apparent close to the interior of northern cavity wall. This emission within
the cavity walls signifies that the cavity structure we see has a
3-Dimensional inverted-conical shape extending from the source and surrounding
the atomic jet. The jet is not detected in H2. A bright H2 knot of emission is
also seen at the base of the eastern cavity wall at a distance of
approximately 1$\aas@@fstack{\prime\prime}$0 (450 au) from the source
position. We label this bright H2 peak A1 following Nisini et al. (2024). We
also label the dimmer H2 peak at the base of the northern cavity wall at
approximately 1$\aas@@fstack{\prime\prime}$4 from the source position A2, and
the arc-like structure extending from the northern cavity wall, curling
towards the jet axis A3, again, following Nisini et al. (2024).

The bottom panel of Fig. 1 is the continuum subtracted, but not scattered
emission subtracted, [Fe ii] emission at 2.047 $\mu$m, integrated over radial
velocities of $v$ = $-$280 km s-1 to $-$65 km s-1. [Fe ii] forbidden emission
lines are well established atomic jet tracers. The [Fe ii] emission traces the
base of the high-velocity, collimated jet, culminating in a bright knot or bow
shock approximately 1$\aas@@fstack{\prime\prime}$0 (450 au) from the source
position. The jet bends slightly, tending towards the northern cavity wall as
the jet PA (52.3°) and CO outflow PA (60°) are different from one another. An
interesting observation is that the jet knot we trace with [Fe ii] does not
coincide with the bright knot, A1, seen in H2 emission, as seen in Nisini et
al. (2024). There is a horizontal offset of approximately
0$\aas@@fstack{\prime\prime}$53 (240 au) between the centres of these outflow
emission knots. This offset between the jet knot seen in [Fe ii] and the
outflow knot, A1, seen in H2 suggests that the atomic jet emanates within the
H2 cavity, extending between the bases of the cavity walls seen in H2. Again,
this indicates that the conical outflow cavity traced by molecular hydrogen
surrounds the more collimated and faster moving atomic jet. The morphology of
the high-velocity ($-$230 km s-1 to $-$130 km s-1) Br-$\gamma$ emission is
almost identical to that traced by [Fe ii], displaying the base of the jet and
the same knot at 1$\aas@@fstack{\prime\prime}$0 from the source position. This
is shown in the bottom left panel of Fig. 2. The Br-$\gamma$ emission is
discussed further in Sect. 3.2.

###  3.2 Kinematics

Position velocity (PV) diagrams can be extracted from integral-field
spectroscopic data. A pseudo-slit is placed along the desired emission region,
the spatial information within the slit is collapsed and represented by one
axis and the wavelength information is converted into a radial velocity using
Doppler shift and represented on the other axis. Figure 4 displays two PV
diagrams, taken along the outflow axis, with a PA of 60°, from Zhang et al.
(2019), and a pseudo-slit width of 1″.

Figure 4: Upper: PV diagram of the [Fe ii] emission line region. The emission
is traced from the source at 0″ and culminates in a bow shock at $\sim$
1$\aas@@fstack{\prime\prime}$0 (450 au). The radial velocity of the jet
emission traced in this line peaks at approximately $-$200 km s-1, in
agreement with previous observations. Lower: PV diagram of the
Brackett-$\gamma$ emission line region. The emission is again traced from the
source and culminates in a bow shock at $\sim$ 1$\aas@@fstack{\prime\prime}$0
(450 au). The radial velocity of the jet emission traced in this line peaks at
approximately $-$200 km s-1. The spatially extended low velocity Br-$\gamma$
emission here, i.e. the emission centred around 0 km s-1 and having a full
width extending to approximately $\pm$ 180 km s-1, is not intrinsic emission,
it is instead light scattered off of the nebulous cavity material. Contour
levels for both begin at 3$\sigma$ of the background emission and increase by
factors of 1.2. Velocities are expressed with respect to the LSR. Figure 5:
Transverse PV diagram of the H2 emission line region extracted at a projected
z of 1$\aas@@fstack{\prime\prime}$2 and with a pseudo slit width of
0$\aas@@fstack{\prime\prime}$5\. The radial velocity of the molecular emission
is much lower than that of the atomic emission. Two emission peaks are seen
either side of the source position, labelled A1 and A2. The emission peak on
the left side of the cavity (A1) has a slightly higher radial velocity of
$-$33.9 km s-1 than the emission peak on the right side of the cavity (A2) at
$-$16.9 km s-1. This hints at the presence of a velocity gradient transverse
to the outflow direction in the cavity. Contour levels begin at 3$\sigma$ of
the background emission and increase by factors of 1.2.

The top image in Fig. 4 displays a PV diagram extracted along the PA of the CO
outflow axis in [Fe ii] emission. Here we see emission traced from the source
position at 0″ culminating in a knot at $\sim$ 1$\aas@@fstack{\prime\prime}$0
or 450 au. The radial velocity of the emission peaks at approximately $-$200
km s-1, as is expected for a collimated atomic jet. A Gaussian profile was fit
to the emission peak at offset 1$\aas@@fstack{\prime\prime}$0, along the
velocity axis, and a Gaussian centroid velocity of $v_{\mathrm{LSR}}$ =
$-$208.7 $\pm$ 3.6 km s-1 was retrieved. These radial velocities are
consistent with previous observations (Garcia Lopez et al. 2010; Nisini et al.
2024). In the bottom image of Fig. 4 a PV diagram, again taken along the PA of
the CO outflow axis is shown, traced by Brackett-$\gamma$. The high velocity
emission ($\sim$ $-$200 km s-1) in this PV diagram is almost identical to that
traced by [Fe ii] implying that they are both tracing the jet. The high
velocity emission again culminates in a knot at $\sim$
1$\aas@@fstack{\prime\prime}$0 or 450 au. Again, a Gaussian profile was fit to
the emission peak at offset 1$\aas@@fstack{\prime\prime}$0, along the velocity
axis, and a Gaussian centroid velocity of $v_{\mathrm{LSR}}$ = $-$211.9 $\pm$
3.5 km s-1 was retrieved. A strong low velocity component at $\sim$ 0 km s-1
with a full width extending to approximately $\pm$ 180 km s-1 is also evident.
As discussed in Sect. 2.7 the line to continuum map of this low velocity
Br-$\gamma$ emission, displayed in Fig. 2, implies that all of the extended,
low velocity Br-$\gamma$ emission is not intrinsic emission and is instead
dominated by scattering. The intrinsic emission traced at approximately 0 km
s-1 and having a full width extending to approximately $\pm$ 180 km s-1, is
very compact, spatially unresolved emission entirely collocated at the source
position, possibly tracing accretion processes and compact disk winds.

In Fig. 5 a PV diagram taken transverse to the outflow direction at a PA of
150° and at a distance of 1$\aas@@fstack{\prime\prime}$2 above the source
position is shown, traced by H2 emission after scattered emission removal.
This PA is perpendicular to the PA of the CO outflow axis. The width of the
pseudo-slit used to extract this PV diagram is
0$\aas@@fstack{\prime\prime}$5\. The pseudo-slits position on the H2 cavity is
shown in the right panel of Fig. 11, in the appendix. Notice that the radial
velocity of material traced by H2 is much lower than that traced by [Fe ii]
emission and Br-$\gamma$. Two emission peaks are seen either side of the
source position, labelled A1 and A2. These emission peaks are the bases of
each outflow cavity wall seen in H2 emission in Fig. 1. We see that the
emission peak from the eastern cavity wall (A1) peaks at a slightly higher
radial velocity than the emission from the northern cavity wall (A2). A
Gaussian fit was applied to both emission peaks in the velocity axis to
retrieve the Gaussian centre of the emission. The Gaussian centroid velocity
($v_{\mathrm{LSR}}$) of the emission peak A1 is $-$33.9 $\pm$ 1.4 km s-1. The
Gaussian centroid velocity of the emission peak A2 is $-$16.9 $\pm$ 1.5 km
s-1. These are highlighted on the figure. This difference in centroid velocity
between the two sides of the cavity walls hints at the presence of a velocity
gradient in the molecular cavity, transverse to the outflow direction.

###  3.3 H2 velocity centroid map

The transverse PV diagram in H2 emission hinting that both sides of the
V-shaped outflow cavity had different radial velocities prompted the
production of a 2D radial velocity map of the H2 emission after scattered
emission removal. The H2 emission line at 2.122 $\mu$m is chosen here as it
possesses the highest S/N of all of the H2 emission lines in our observation
and does not suffer any erroneous effects that are common near the spectral
edges of IFU observations. The production of a 2D radial velocity map of the
H2 emission was achieved by fitting Gaussian profiles to each H2 emission line
at every spaxel in the data cube and rejecting fits with a S/N below a certain
threshold. The centres of each of the Gaussian profiles were taken as the
centroid radial velocities of the emission line. This resulted in a
2-Dimension velocity centroid map of the H2 2.12 $\mu$m emission region shown
in Fig. 6. The velocities in this map are expressed with respect to the LSR
velocity of the cloud that the outflow emanates from. The error associated
with the velocity centroid map is a combination of the uncertainty associated
with the Gaussian fitting, namely the accuracy of the Gaussian centroid
measurement and the uncertainty involved with the OH emission line wavelength
recalibration. Thus, summing the relative and absolute errors in quadrature,
we derive a 1$\sigma$ uncertainty associated with the velocity centroid map of
$\pm$ 1.0 km s-1 to $\pm$ 3.0 km s-1 depending on the brightness of the H2
line.

We see the V-shaped cavity morphology reproduced in velocity centroid maps.
The left image in the figure displays the integrated H2 emission intensity map
overplotted in black contour lines. The source position is marked with a black
plus symbol. Here, $-$20 km s-1 was chosen as the centre point for the radial
velocity gradient map. We see that the left outflow cavity wall has, on
average, higher radial velocity peaks when compared to the right wall of the
cavity. The velocity difference between both sides of the cavity is $\sim$ 10
km s-1. In order to recover a more quantitative value for the radial velocity
difference between both sides of the H2 cavity, transverse PV cuts, similar to
that presented in Fig 5, were taken at different heights ($z$) along the
outflow. PV cuts of width 0$\aas@@fstack{\prime\prime}$25 were taken at $z$ =
1$\aas@@fstack{\prime\prime}$0, 1$\aas@@fstack{\prime\prime}$5,
2$\aas@@fstack{\prime\prime}$0, 2$\aas@@fstack{\prime\prime}$5, and
3$\aas@@fstack{\prime\prime}$0\. The emission peaks corresponding to each side
of the H2 cavity in each PV plot were fit with Gaussian profiles along the
velocity axis to retrieve the centroid velocity, in the same way the Gaussian
centroid velocities were retrieved in Fig. 5. The difference in radial
velocity centroid measurements ($\Delta v_{\mathrm{rad}}$) between the left
side of the H2 cavity ($v_{\mathrm{rad,\ left}}$) and the right side
($v_{\mathrm{rad,\ right}}$), at each height ($z$) along the outflow, is
presented in Table 1. The uncertainties associated with the centroid
velocities are quadrature summations of the Gaussian centroid error and the
uncertainty obtained with wavelength recalibration as discussed in Sect. 2.4.

Table 1: Velocity difference between eastern and northern pointing H2 cavity walls at various heights along the outflow. $z$ (″) |  $v_{\mathrm{rad,\ left}}$ (km s-1) |  $v_{\mathrm{rad,\ right}}$ (km s-1) |  $\Delta v_{\mathrm{rad}}$ (km s-1)
---|---|---|---
1.0 | 31.3 $\pm$ 1.5 | 17.3 $\pm$ 2.5 | 14.0 $\pm$ 2.9
1.5 | 25.1 $\pm$ 2.0 | 13.4 $\pm$ 1.4 | 11.7 $\pm$ 2.4
2.0 | 24.0 $\pm$ 2.1 | 15.2 $\pm$ 1.4 | 8.8 $\pm$ 2.5
2.5 | 22.0 $\pm$ 2.3 | 16.6 $\pm$ 2.9 | 5.4 $\pm$ 3.7
3.0 | 22.8 $\pm$ 2.5 | 14.5 $\pm$ 2.0 | 8.3 $\pm$ 3.2

The right image in Fig. 6 presents the same H2 velocity centroid map, but
integrated jet emission traced by [Fe ii] in orange contours, and integrated
Br-$\gamma$ emission in green contours are overplotted instead. These emission
lines are tracing the base of the jet. We see that the jet emission flows in-
between either side of the H2 cavity walls. This further illustrates that the
H2 low velocity gas is surrounding the high velocity jet in a conical
morphology. This velocity gradient pattern observed between the eastern and
northern pointing walls of the outflow cavity is also seen in the other
molecular hydrogen emission lines present in our observation.

Figure 6: Scattered light corrected H2 emission radial velocity centroid maps.
The source position is marked by a black plus symbol. The radial velocity
centroid maps display a clear velocity gradient between both sides of V-shaped
cavity. The left side of the cavity has, on average, a greater radial velocity
when compared with the right side. The difference in velocity between both
sides is $\sim$ 10 km s-1. Contour levels for both begin at 3$\sigma$ of the
background emission and increase by factors of 1.5. Left: H2 velocity centroid
map with integrated H2 emission overplotted in black contour lines. Right: The
same H2 velocity centroid map with jet-tracing integrated [Fe ii] emission in
orange contours, and integrated Br-$\gamma$ emission in green contours
overplotted. The jet flows between both sides of the cavity traced by H2.

##  4 Discussion

Nisini et al. (2024) present spectacular JWST NIRSpec and MIRI observations of
the HH 46/47 molecular outflow, cavity and atomic jet. Their NIRSpec 6″
$\times$ 6″ FOV encompasses a similar region to the SINFONI observations
presented here but they have the advantage of the superior angular resolution
of JWST. They suggest that A1 is a expanding bubble ejected by the secondary
component of the binary system, as the A1 knot has a shell-like morphology
revealed by the higher NIRSpec resolution and additional NIRCam images. They
associate both A2 and A3 with material entrained by the primary jet. The
morphology of the H2 emission obtained with SINFONI and seen in Fig. 1 further
supports these conclusions. However, we cannot rule out with the SINFONI data
alone that A1 and A2 instead trace the base of the cavity walls surrounding
the jet. The spectral resolution of the Nisini et al. (2024) observations is R
$\sim$ 2700 which translates to $\sim$ 110 km s-1 of velocity resolution. The
spectral resolution provided with SINFONI in the K-band (R $\sim$ 4000) is
superior, and the significant advantage of being able to perform a wavelength
recalibration with OH lines (as described in Sect. 2.4) means that we can
extract important kinematical information about the molecular emission and
atomic jet which is not possible from the JWST observations.

###  4.1 Importance of removing scattered emission

The SINFONI observations presented here probe the launching region of an
outflow, close to the embedded driving source. We were therefore conscious
that our observations of various emission lines of interest would contain
strong contributions of scattered light from the central engine. In order to
study the emission lines of interest it was necessary to attempt to remove
this contribution from scattered light and leave only intrinsic line emission.
The contribution of scattered light to the intensity maps of various emission
lines is clear in the line to continuum ratio plots in Fig. 2.

In this case, a simple baseline continuum subtraction method was sufficient in
removing the continuum emission, however a different method, as described in
Sect. 2.7, was required to produce a clean observation free from scattered
line photons emitted close to the central source. The line to continuum map of
H2 emission shown in the top left panel of Fig. 2 displays ratio values
approximately between 1 and 2 in the inner region of the cavity and along the
outer side of the northern pointing cavity wall. Here, the contribution from
scattered light is strongest. Figure 11 displays the integrated intensity map
of the H2 $\lambda$2.122 $\mu$m emission line before and after the scattered
emission removal routine was implemented. When comparing between these two
images, it is clear that after the scattered light is subtracted there is a
steeper intensity gradient associated with the intrinsic H2 emission, which is
most readily observable in the closeness of contour lines surrounding bright
H2 emission, such as the features labelled A1 & A2. Nebulous emission close
the apex of the cavity has also been diminished after scattered light
subtraction, which is in agreement with H2 line to continuum map predicting a
strong contribution from scattered photons in this region.

The work presented in this paper clearly highlights that for similar studies
of outflows from embedded sources, it is critical to consider the contribution
of scattered light to the emission line profiles and to acknowledge that
removing the continuum emission using a baseline subtraction may not be
optimal.

###  4.2 Layering of emission and axial asymmetries

The cavity seen in continuum emission surrounds the cavity traced by H2
emission which in turn encompasses the collimated jet revealing a layered
asymmetric outflow structure. To investigate this further we compared our
SINFONI observations with HST and ALMA observations. Figure 7 displays the
continuum subtracted [Fe ii] $\lambda$1.64 $\mu$m emission image of HH 46/47,
obtained using HST WFC3 with the narrowband filter, F164N (Program ID: 15178,
PI: B. Nisini) (Erkal et al. 2021b). The blueshifted jet extends north-
easterly and the redshifted jet, south-westerly. The inset shows a 3-colour
image made from the SINFONI observation of the outflow cavity and jet.
Integrated continuum, or scattered light from the outflow driving source, is
traced here in red. The continuum and scattered light subtracted, integrated
H2 emission is traced here in green. The SINFONI [Fe ii] continuum subtracted
emission, tracing the collimated atomic jet is displayed here in blue.
Finally, the inner part of the HST [Fe ii] $\lambda$1.64 $\mu$m is overplotted
in orange contours. For the inset, the HST contours have been rotated to match
the 60° clockwise rotation that our SINFONI observations underwent. The HST
image was aligned with the SINFONI image by coinciding the continuum peak
positions, retrieved using 2D Gaussian fitting, located at the apex of the
cavity in each image. Figure 8 displays an adapted figure from Zhang et al.
(2019) of the blue and red-shifted molecular outflows from the HH 46/47 system
in 12CO (2-1) as observed with ALMA. Here, blue traces integrated CO emission
from $-$35 km s-1 to $-$10 km s-1, green traces the 1.3 mm dust continuum
emission and, red traces integrated CO emission from +10 km s-1 to +50 km s-1.
The blue-shifted cavity seen in H2 emission is overplotted. The H2 cavity has
been rotated anticlockwise by 90° with respect to the SINFONI results
presented earlier so that the outflow cavity axis points along the horizontal
axis. The continuum peak position in the SINFONI image, marked with a red plus
symbol, was aligned with the centre of the 1.3 mm dust continuum in the ALMA
image. An inset displays a zoomed image of the H2 emission overplotted on the
blueshifted CO outflow to better illustrate that the H2 emission is nested
within the CO outflow. This inset has been rotated clockwise by 90° to match
the convention of figures presented in this paper, where the outflow axis is
aligned with the vertical axis.

The comparison between SINFONI and HST shows that both sets of observations
are consistent. The bending towards the northern cavity wall does not just
occur for the $\sim$ 675 au long SINFONI jet but continues out to $>$ 1000 au
in the HST jet. Also, the bright knot seen in [Fe ii] $\lambda$2.047 $\mu$m
emission in the SINFONI dataset coincides with a knot traced by the [Fe ii]
$\lambda$1.64 $\mu$m emission from the HST dataset. This is expected as the
SINFONI observations took place in November 2018 and HST observations took
place in March 2019, just four months later. As the jet knot radial velocity
traced by [Fe ii] $\lambda$2.047 $\mu$m emission is $\sim$
$-$200$\leavevmode\nobreak\ km\leavevmode\nobreak\ s^{-1}$, the jet velocity
in the plane of the sky is $\sim$ 265$\leavevmode\nobreak\
km\leavevmode\nobreak\ s^{-1}$, or 56 $\leavevmode\nobreak\
au\leavevmode\nobreak\ yr^{-1}$, using a jet inclination value of 37° from
Hartigan et al. (2005). We therefore expect the jet knot to have moved by just
14 au between observations. The pixel scale of the SINFONI observations is
$\sim$ 56 au, meaning the expected offset would not be measurable. The [Fe ii]
$\lambda$1.64 $\mu$m emission displayed in orange contours appears to possess
an additional knot coinciding with the H2 knot A1 seen here in green,
suggesting that the knot may also be traced in [Fe ii] emission. However, due
the the low S/N, and the observation that this knot is not traced by any of
the other [Fe ii] emission lines, we instead attribute this emission to
residual unsubtracted continuum emission or scattered light.

The layered structure we see clearly in Figs. 7 and 8 is a radial
stratification, not only morphological in nature but also in temperature,
between hot gas (T${}_{H_{2}}$ $\sim$ $10^{3}$ K) and the bulk of the
surrounding colder material (TCO $\sim$ $10^{1}$ K). Not only do we see that
the H2 emission lies within the continuum emission, but we also see that the
H2 outflow cavity is nested within the blue-shifted 12CO (2-1) cavity. The H2
outflow cavity existing within the CO molecular outflow has been observed in
HH 46/47 in Noriega-Crespo et al. (2004), with different emission lines than
those presented here, and more recently in Nisini et al. (2024), showing that
the mid-IR H2 emission is nested within the CO cavity in both the blue and
red-shifted outflow lobes. At $\sim$ 4″ along the outflow axis, the northern
H2 cavity wall begins to curl inwards towards the jet axis. This curling of
the H2 cavity is also seen in Nisini et al. (2024), that they interpret as
material entrained by the expanding primary jet. Similarly, the eastern cavity
wall lies within the CO molecular outflow and appears to possess a narrower
opening angle. However, we note that CO opening angle close to the base is
narrower than the CO cone farther away from the source, indicating that there
is some sudden increase of the CO opening angle, especially evident in the
east side at some distance. The inner, narrower CO cone has a morphology more
consistent with the H2 emission morphology. This comparison of the different
emission tracers reveals a stratification between continuum emission, CO
emission, H2 emission, and the jet implying that outflowing material from the
star/disk system is spatially layered as radial distance from the jet axis
increases. The highest velocity, highest temperature, and most strongly
collimated emission is located at the centre of the outflow axis and
surrounding it is the slower moving, cooler, wide-angled molecular component
of the outflow. This onion-like layered flow structure with stratification of
emission in velocity, temperature, and chemistry has been observed in some
cases (Delabrosse et al. 2024), and is predicted by MHD disk wind models
(Ferreira 1997; Panoglou et al. 2012; Bai et al. 2016; Zhu & Stone 2018; Wang
et al. 2019). In these models, material is accelerated along flow streamlines,
poloidal magnetic field lines anchored in the rotating disk. Hot, high-
velocity emission travel along streamlines originating in the very inner disk
region, whilst cooler, lower velocity emission travel along streamlines
originating further out in the disk. This stratified structure can be
identified observationally when tracing the disk wind directly or tracing the
winds interaction with surrounding ambient material. In this case, the CO is
thought to be entrained material, tracing material located outside the cavity
wall, whilst the H2 emission is likely tracing the interaction region that put
the entrained material into motion. The origin of such an interaction can be
explained by an MHD disk wind, but can also be produced by the jet alone.
Consequently, we cannot conclusively attribute the onion-like stratified
structure exclusively to an MHD disk wind.

Figure 7:  Background: Continuum subtracted [Fe ii] $\lambda$1.64 $\mu$m
emission image of HH 46/47. Observation obtained using HST WFC3 with
narrowband filter F164N (Program ID: 15178, PI: B. Nisini) (Erkal et al.
2021b). Inset: SINFONI 3-colour image displaying the outflow cavity and jet.
Red emission traces integrated continuum emission or scattered light from the
outflow driving source. Green emission traces continuum subtracted integrated
molecular hydrogen (H2) emission displaying the V-shaped outflow cavity. The
shocked cavity walls lie within the cavity structure seen in scattered light
in continuum emission. There is a bright outflow knot at the base of the left
cavity wall. Blue emission traces [Fe ii] emission, displaying collimated
atomic jet emission. The jet culminates in a bright knot or bow shock
approximately 1$\aas@@fstack{\prime\prime}$0 (450 au) from the source
position. This knot does not spatially coincide with the outflow knot seen in
H2 emission. The inner part of the HST [Fe ii] $\lambda$1.64 $\mu$m is
overplotted in orange contours. Figure 8: SINFONI H2 emission overplotted on
the blueshifted molecular outflow traced by 12CO (2-1) as observed by ALMA
(Zhang et al. 2019). Blue traces integrated CO emission from $-$35 km s-1 to
$-$10 km s-1. Green traces the 1.3 mm dust continuum. Red traces integrated CO
emission from +10 km s-1 to +50 km s-1. The shocked cavity walls traced by H2
lie within the cavity structure seen CO emission. The red plus indicates the
continuum peak position in the SINFONI data. An inset displays a zoomed image
of the H2 emission overplotted on the blueshifted CO outflow to better
illustrate that the H2 emission is nested within the CO outflow. This inset
has been rotated clockwise by 90° to match the convention of figures presented
in this paper, where the outflow axis is aligned with the vertical axis.
Figure adapted from Zhang et al. (2019).

The H2 cavity is likely an interaction region between some wide-angled
component of the outflow, be it an uncollimated or poorly collimated wind, or
an expanding shell of material produced by a wide-angled wind, and the
surrounding ambient material, or by the stacking of successive jet bowshocks
from a collimated, variable inner jet propagating into a density-stratified
surrounding medium (Rabenanahary et al. 2022). It is possible that we are
seeing nested cavities traced in H2 similar to those seen in cooler CO
emission caused by multiple expanding shells. These expanding shells of
material have been observed in the blue-shifted and red-shifted outflows of HH
46/47, traced by 12CO emission (Zhang et al. 2019). These shells, which are
highly coherent in space and velocity, have an parabolic morphology. The
origin of these outflowing shells can be explained by entrainment of ambient
material by an episodic wide-angle wind (Li & Shu 1996; Lee et al. 2000) which
produces radially expanding parabolic shells, or by successive jet bowshocks.
The general morphology of the H2 cavity which lies within the cavity traced by
continuum emission could be produced by expanding shells of material, interior
to the shells identified in CO by Zhang et al. (2019). Furthermore, the
emission peaks labelled A1 and A2 could potentially be tracing shocked
interaction regions between a more evolved shell, traced by the outer cavity
walls, and a smaller scale, asymmetric H2 shell nested within, produced by a
subsequent outburst of the wide-angled wind or a successive jet bowshock. The
arc-shaped morphological component labelled A3 could also be associated with a
cavity or shocked region created by an expanding shell.

It is clear that both the outflow cavity traced by H2 emission and the atomic
jet traced by [Fe ii] and Br-$\gamma$ emission are asymmetric about the CO
outflow direction. The emission region of the left side of the cavity, that
is, the eastern cavity wall, traced by H2 is spatially more compact when
compared to the right side, the northern cavity wall. The right side of the
cavity also extends further from the driving source, both vertically and
laterally. If the surrounding medium on the right side of the cavity side is
denser than that of the left side, then this would naturally lead to brighter
shocked wall regions on the right side of the cavity. The suggestion that the
surrounding ambient material is denser on the right side of the cavity is
further supported by the morphology of the scattered light emission seen in
Fig. 1. Here, the cavity as seen in scattered light is highly asymmetric about
the CO outflow axis with the northern arm extending much further from the
driving source than the eastern arm. This further suggests a dissymmetry in
the distribution of the surrounding ambient material. This inhomogeneous
ambient material is further testified by the general morphology of the
reflection nebula seen at optical wavelengths that extends mostly in the
northern direction (Heathcote et al. 1996). Furthermore, in Fig. 8, the 1.3 mm
dust continuum is clearly brighter on the northern side, supporting this
argument. As mentioned before, there is some sudden increase of the CO opening
angle, especially evident in the east side at between 2″ and 3″ additionally
reinforcing this argument. The northern side of the outflow is facing the
cloud edge that the blueshifted outflow is emanating from, which may be shaped
or compressed by radiation from outside the cloud. This may provide a
rationale for why the ambient material on the northern side appears denser.
There also exists and offset between the average PA of the atomic jet, 52.3°
from Erkal et al. (2021b), and the central axis of the wide-angled CO outflow,
$\sim$ 60° from Zhang et al. (2019). This difference between the jet PA and
molecular outflow PA can be interpreted as being due to an inhomogeneous
surrounding medium, with the eastern cavity wall expanding quicker than the
northern cavity wall and therefore shifting the central axis of the CO outflow
to a larger PA than the jet PA.

We see that the atomic jet is deflected away from the left side of the cavity,
tending towards the northern wall. Also, the jet knot traced by [Fe ii] and
Br-$\gamma$ emission does not coincide with either peak traced at the bases of
the cavity walls seen in H2 labelled A1 and A2. The bending of the atomic jet
towards the northern cavity wall is consistent with the [Fe ii] $\lambda$1.64
$\mu$m emission from the HST observations. This bending of the atomic jet is
indicative of jet wiggling, that is clearly seen in large scale observations
of the jet (Reipurth et al. 2000; Erkal et al. 2021b). Jet wiggling can be
induced by an orbiting companion to the outflow driving source (Murphy et al.
2021). These axial asymmetries seen in the blueshifted outflow, both in the
atomic jet and the wide-angled outflow and cavity may also arise due to the
influence of two outflows being driven by each of the components of the binary
system (Nisini et al. 2024). The difference between the jet PA and molecular
outflow PA can also be interpreted as being due to the secondary jet pushing
on the eastern cavity wall, again shifting the central axis of the CO outflow
to a different PA when compared to the jet PA.

###  4.3 Origin of the H2 transverse velocity gradient

The V-shaped, parabolic cavity observed in the integrated H2 emission in Fig.
6 displays a clear transverse velocity gradient of approximately $\sim$ 10 km
s-1 between the eastern and northern pointing cavity walls, see Table 1. A
transverse velocity difference, lower in magnitude, is also present in 12CO
emission in the same sense as the velocity difference presented here (2024,
priv. comm Y. Zhang). Whilst the spectral resolution of the SINFONI dataset is
R = 4000 or 2.45 Å, which translates to a spectral sampling of 38 km s-1 at
1.95 $\mu$m and 30 km s-1 at 2.45 $\mu$m, we can be confident in a velocity
difference of $\sim$ 10 km s-1 between either side of the cavity due to our
wavelength recalibration performed using the OH lines from the upper
atmosphere and discussed in Sect. 2.4. We obtained a 1$\sigma$ uncertainty of
$\pm$ 1.0 km s-1 to $\pm$ 3.0 km s-1 associated with this velocity centroid
map, which encompasses absolute and relative errors associated with Gaussian
centroid accuracy and the OH wavelength calibration.

Initially it may appear that this velocity gradient we see is due to the
anticlockwise rotation of the H2 cavity, with the eastern cavity wall
approaching at a higher velocity with respect to the northern cavity wall.
This apparent rotation may be tracing a rotating disk wind directly (Zhang et
al. 2016), or tracing the rotation of entrained material, where the angular
momentum present in the envelope is provided for by the jet (Gaudel et al.
2020). This rotation would support the MHD driven wind model as we expect a
rotation of the outflow if the wind is removing angular momentum from the
star/disk system. Rotating cavities have been observed in early to late stages
of low mass star formation (Bjerkeli et al. 2016; Tabone et al. 2017; Zhang et
al. 2018; Louvet et al. 2018; de Valon et al. 2022; Launhardt et al. 2023). In
order to investigate the plausibility of this velocity gradient being caused
by a rotation of the cavity, we assumed that the velocity gradient was purely
due to rotational motion and calculated the specific angular momentum of this
apparent rotation at different heights along the outflow. We derive the
velocity differentials from the H2 velocity centroid map provided in Fig. 6,
by extracting a transverse PV cut at a specific height along the outflow.
Gaussian profiles are then fit along the velocity axis to both of the emission
peaks corresponding to each side of the H2 cavity, retrieving the centroid
velocity of each side of the H2 cavity, as described in Sect. 3.3. The
rotational radius r is estimated, assuming the rotation is axisymmetric, as
half of the distance between the two emission peaks corresponding to each side
of the H2 cavity. The uncertainties associated with the centroid velocities
are quadrature summations of the Gaussian centroid error and the uncertainty
obtained with wavelength recalibration as discussed in Sect. 2.4. The specific
angular momentum ($J=r\times v_{rot}$) of a rotation or orbit is defined as
the angular momentum associated with the rotation divided by the systems mass,
in other words, the angular momentum per unit mass. Assuming that the flow is
axisymmetric we can calculate the specific angular momentum as follows:

$J(r)\ =\ r\times v_{\mathrm{rot}}(r)\ =\
r\times\frac{v_{\mathrm{left}}\>-\>v_{\mathrm{right}}}{2\,\mathrm{sin}(i)}$
(1)

Where $v_{rot}(r)$ is the rotational velocity and $i$ is the angle of
inclination of the flow with respect to the line of sight, $i$ = 53°. Using
Equation 1, we calculated the specific angular momentum of the apparent cavity
rotation at heights along the outflow in the plane of the sky, of $z$ = 450
au, 675 au, and 900 au ($z$ = 1$\aas@@fstack{\prime\prime}$0,
1$\aas@@fstack{\prime\prime}$5, 2$\aas@@fstack{\prime\prime}$0). The specific
angular momentum results are presented in Table 2. We calculate specific
angular momenta values of $J(r)$ = 3217 $J(r)$ = $\pm$ 658 km s-1au, at 1″
offset from the central source, to 3867 $\pm$ 1125 km s-1au, at 2″ offset.

Table 2: Specific angular momenta calculations of H2 cavity rotation at various heights along the outflow. $z$ (au) |  $v_{\mathrm{left}}$ (km s-1) |  $v_{\mathrm{right}}$ (km s-1) |  $v_{\mathrm{rot}}$ (km s-1) |  $r$ (au) |  $r$ (10-3 pc) |  $J(r)$ (km s-1au) |  $J(r)$ (10-2 km s-1pc)
---|---|---|---|---|---|---|---
450 | 31.3 $\pm$ 1.5 | 17.3 $\pm$ 2.5 | 8.8 $\pm$ 1.8 | 365.6 | 1.8 | 3217 $\pm$ 658 | 1.6 $\pm$ 0.3
675 | 25.1 $\pm$ 2.0 | 13.4 $\pm$ 1.4 | 7.3 $\pm$ 1.5 | 506.3 | 2.5 | 3696 $\pm$ 759 | 1.8 $\pm$ 0.4
900 | 24.0 $\pm$ 2.1 | 15.2 $\pm$ 1.4 | 5.5 $\pm$ 1.6 | 703.1 | 3.4 | 3867 $\pm$ 1125 | 1.9 $\pm$ 0.6

In the case that the H2 velocity gradient is directly tracing an outflow
rotation we can compare to previous outflow rotation observations. Bjerkeli et
al. (2016) measure the specific angular momentum, in 12CO emission, of the
rotating outflow associated with the TMC1A protostellar system to be less than
200 km s-1au, using r values an order of magnitude lower than those used here.
Zhang et al. (2018) measure the mean specific angular momentum, in C18O
emission, in the rotating NGC 1333 IRAS 4C outflow to be 100 km s-1au. Louvet
et al. (2018) measure the specific angular momentum, in 12CO emission, of the
rotating HH 30 outflow to be $\sim$ 40 km s-1au. In de Valon et al. (2022),
they measure the specific angular momentum, in 12CO emission, of the rotating
outflow from DG Tauri B to be $\sim$ 65 km s-1au. Launhardt et al. (2023)
measure the specific angular momentum, in 12CO emission, of the rotating
outflow from a young T Tauri star in the CB 26 Bok globule to be less than 200
km s-1au. Zhang et al. (2016) estimated the specific angular momentum in the
equatorial plane of the envelope surrounding HH 46/47 in 13CO and C18O
emission. They found specific angular momentum values for the rotation of $J$
= 450 - 540 km s-1au ($J$ = 2.2 $\times$ 10-3 to 2.6 $\times$ 10-3 km s-1pc),
an order of magnitude lower than the specific angular momenta estimated here.
As this rotation is measured in the equatorial plane, it is indicative of an
upper limit for the specific angular momentum in this system. In the case that
the H2 velocity gradient is instead tracing the rotation of entrained
material, where the angular momentum present in the envelope is provided for
by the jet we can compare with Gaudel et al. (2020). They measure the specific
angular momentum of the midplanes of circumstellar environments of a sample of
class 0/1 protostellar envelopes. In their sample, the maximum specific
angular momenta values, at similar r values presented here, are 2 $\times$
10-3 km s-1pc ($\sim$ 400 km s-1au), an order of magnitude below what we
measure here.

The specific angular momenta calculated here at various heights along the
outflow cavity are significantly larger than that seen before for rotating
outflow cavities, either rotational motion traced directly by the outflow or
by rotating entrained material. Furthermore, the apparent anticlockwise
rotation we see here is opposite to the clockwise rotation of the flattened
structure around the central source perpendicular to the outflow axis traced
by 13CO and C18O from Zhang et al. (2016). Whilst this flattened structure has
a size of approximately 10″ (4500 au) across, which is much larger than what
is expected for a rotationally supported Keplerian disk, it is indicative of
the disk rotation direction as the sense of rotation remains consistent as the
beam size, in 13CO and C18O, is scaled down to its smallest size,
1$\aas@@fstack{\prime\prime}$5 (675 au). They conclude that the structure is a
rotating envelope that feeds the accretion disk. Although some jets present
transverse velocity gradients in the opposite sense to the disk rotation
(Cabrit et al. 2006; Louvet et al. 2016), it is unclear if these gradients (of
a few km s-1 and variable in time) truly trace counter-rotation of the jet, or
if they are contaminated by other effects such as jet precession or shock
asymmetries. The large specific angular momenta calculated here and the fact
that the apparent rotation is opposite to the sense of the disk rotation lead
us to rule out the interpretation that the velocity gradient observed in the
H2 cavity is entirely tracing a rotation signature and other effects must be
considered.

Another possible explanation for the velocity gradient could be ascertained
from the observation that the cavity seen in H2 is clearly asymmetric about
the outflow direction. If the surrounding medium in the region of the northern
cavity wall is denser than that in the region around the eastern cavity wall,
as discussed in 4.2, then the outflowing material, or expanding shells of
material rather than a wide-angled wind, would encounter and impact denser
quiescent material in the region of the northern cavity wall causing the
outflow or shells to decelerate more quickly. This could explain why the
northern wall of the cavity displays lower radial velocities when compared to
that seen in the eastern wall. The denser quiescent material at the right side
of the cavity could naturally explain the velocity gradient we see in the H2
emission. The production of transverse velocity gradients due to dissymetry in
density of surrounding ambient material has been discussed by De Colle et al.
(2016).

Lastly, the velocity gradient seen in the cavity traced by H2 emission could
be that the dominating outflow driver for the northern and eastern cavity
walls originate from different sources. The driving source of the HH 46/47
outflow system is known to be a binary source (Reipurth et al. 2000). Nisini
et al. (2024) suggest that the bright H2 knot seen at the base of the eastern
cavity wall, A1, is a expanding bubble ejected by the secondary component of
the binary system. This could imply that the emission we see in the eastern
wall of the H2 cavity could have been strongly influenced by this secondary
outflow driver. The outflow from this secondary source in the binary system
could be strongly contributing to the shocked H2 emission in the eastern wall
of the cavity, potentially increasing it’s radial velocity in comparison to
the northern wall. This is further testified by the H2 knot A1 possessing the
highest blueshifted radial velocity in the velocity centroid maps provided in
Fig. 6.

We would like to emphasise that velocity gradient signatures observed
transverse to the outflow direction can easily be misinterpreted as being due
to rotational motion, and this interpretation is further motivated by current
MHD disk wind models. However, other effects, such as ambient material density
variations and the presence of multiple outflows, as discussed above can
produce transverse velocity gradient signals. In addition, further effects
such as kink instabilities (Staff et al. 2014) and twin-jet structures (Soker
et al. 2022), to name a few, can reproduce transverse velocity gradients. We
investigated other interpretations of the observed velocity gradient due to
our specific angular momentum values being significantly larger than that seen
before for rotating outflow cavities, and due to the apparent counter-rotation
of the outflow with respect to the conjectured disk rotation direction.
However, other effects that can produce similar velocity gradient signatures
must be considered in cases where specific angular momentum estimates are as
expected and apparent rotation direction is in the same sense as the disk.

##  5 Summary and conclusions

We have investigated the morphology and kinematics of the launching region of
the blueshifted HH 46/47 outflow, emanating from the Class I binary system HH
46 IRS, with SINFONI K-band observations. We achieve an angular resolution of
0$\aas@@fstack{\prime\prime}$81 and a precision in velocity centroids (in H2
1-0 S(1) emission) of $\pm$ 1 to 3 km s-1. These observations allow us to
study both the base of the atomic jet traced by [Fe ii] and Br-$\gamma$
emission and the wide-angled molecular hydrogen outflow. We summarise our main
results as follows:

  * –

We use PV diagrams, as seen in Sect. 3.2, to investigate the kinematics of the
atomic jet and the H2 outflow cavity. The radial velocity of the atomic jet
emission traced by [Fe ii] and Br-$\gamma$ peaks at $\sim$ $-$210 km s-1,
which is consistent with previous measurements. The Gaussian centroid velocity
of the atomic jet knot at an offset of 1″ from the source position is
$v_{\mathrm{LSR}}$ = $-$208.7 $\pm$ 3.6 km s-1 in [Fe ii] emission and
$v_{\mathrm{LSR}}$ = $-$211.9 $\pm$ 3.5 km s-1 in Br-$\gamma$ emission. A PV
diagram taken transverse to the outflow axis was taken to investigate the
kinematics of the H2 emission. The radial velocity of the H2 emission is
significantly lower than that of the atomic jet emission, peaking around
$\sim$ $-$15 km s-1 to $-$30 km s-1. Two emission peaks located at the base of
each cavity wall are seen either side of the source position, labelled A1 and
A2. The emission peak from the base of the eastern cavity wall (A1) peaks at a
slightly higher radial velocity ($-$33.9 $\pm$ 1.4 km s-1) than the emission
peak (A2) from the base of the northern cavity wall ($-$16.9 $\pm$ 1.5 km
s-1).

  * –

We confirm the presence of a velocity gradient in the outflow cavity,
transverse to the outflow axis, traced in H2. We generate a velocity centroid
map to probe this observed velocity gradient. The magnitude of this velocity
difference is $\sim$ 10 km s-1 and exists between the northern and eastern
pointing cavity walls, see Table 1. We discuss some possible explanations for
the origin of this velocity gradient in Sect. 4.3. We rule out outflow
rotation as the sole origin due to large specific angular momenta values,
$J(r)$ = 3217 $\pm$ 658 to 3867 $\pm$ 1125 km s-1au calculated from 1″ to 2″
offset from the central source. We instead favour a dissymmetry in the ambient
material surrounding the outflow or the presence of multiple outflows.

  * –

The morphology of the NIR continuum, H2 1-0 S(1), [Fe ii] $\lambda$2.047
$\mu$m and Br-$\gamma$ emission is presented. The continuum emission displays
an approximately parabolic and asymmetric reflection nebula, that we interpret
as a boundary region between the outflow and the ambient material, sweeping
out a wide-angled cavity in the quiescent material. We recover a point source
at the apex of this cavity which we establish as the source position. The H2
emission displays a striking V-shaped morphology tracing the limb-brightened
cavity walls of the outflow. We infer that the cavity structure we see has a
3-Dimensional inverted-conical shape, surrounding the atomic jet. The forging
of this outflow cavity, which we determine to be an interaction region between
the outflow and the surrounding quiescent material, may be due to some wide-
angled wind, or expanding shells of material produced by and episodic wide-
angled wind, or by the stacking of successive jet bowshocks from a collimated,
variable inner jet propagating into a density-stratified surrounding medium.
The morphological components labelled A1, A2 and A3 may arise due to multiple
expanding shells, with a smaller scale shell, associated with the shocked
emission peaks A1 and A2, expanding within a slightly larger scale shell
associated with the outer cavity walls produced by an earlier outburst of the
wide-angled wind, or by a successive jet bowshock. The high-velocity [Fe ii]
and Br-$\gamma$ emission traces the base of the atomic jet that culminates in
a jet knot at approximately 1$\aas@@fstack{\prime\prime}$0 or 450 au from the
source position.

  * –

We find radial stratification of the outflow in different emission tracers
which produces an onion-like flow structure as discussed in Sect. 4.2. The
slow-moving, wide-angled molecular outflow cavity traced in H2 emission
surrounds the base of the hotter, high-velocity atomic jet traced in [Fe ii]
and Br-$\gamma$ emission. The H2 outflow cavity lies within the reflection
nebula seen in continuum emission, extending less laterally and having a
narrower opening angle. The H2 outflow cavity is also nested withing the
molecular outflow traced in 12CO (2-1), and appears to curl inward towards the
outflow axis at a distance along the outflow of approximately 4″.

  * –

The reflection nebula seen in continuum emission, the H2 outflow cavity and,
the atomic jet traced in [Fe ii] and Br-$\gamma$, are all asymmetric about the
outflow direction. This is discussed in Sect. 4.2. We provide explanations for
the origin of the H2 outflow cavity asymmetries including density variations
in the surrounding ambient material, and the influence of multiple outflows,
it is plausible that both components of the binary source are driving
outflows. We observe bending of the atomic jet, which emanates from the source
position and tends towards the northern cavity wall, which is indicative of
jet wiggling that we observe in this jet at larger scales.

This paper displays the wealth of information that can be extracted from IFU
observations of protostellar outflows on intermediate scales in the NIR, and
also highlights the morphological and kinematical complexity that needs to be
considered when interpreting various aspects of outflows on these scales. In
particular, we want to emphasise that radial velocity gradients observed
transverse to the outflow axis can be misinterpreted as rotation signatures,
when other effects, as discussed, can produce equivalent transverse velocity
gradients.

###### Acknowledgements.

This work supported by the John & Pat Hume Doctoral Scholarship at Maynooth
University (MU) and the Travelling Doctoral Studentship from the National
University of Ireland (NUI).

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##  Appendix A OH wavelength calibration map

Figure 9 illustrates the effect of the OH line wavelength recalibration on the
H2 emission velocity centroid maps. The magnitude of the wavelength/velocity
correction, shown in the central panel, varies between $\sim$ $-$26 km s-1 and
$-$30 km s-1 and varies most significantly in the vertical direction. This
wavelength correction map was applied to the SINFONI datacube around the H2
1–0 S(1) emission line at 2.12 $\mu$m, effectively obtaining a more accurate
wavelength calibration than that offered with the standard arc lamp wavelength
calibration.

Figure 9: Velocity centroid maps of H2 emission before (top), and after
(bottom), the wavelength recalibration map (centre), derived from the OH
emission lines, is applied. Notice the change in velocity scales used for the
velocity centroid maps. The source position is represented with a black plus
symbol in the velocity centroid maps. Contour levels for both begin at
3$\sigma$ of the background emission and increase by factors of 1.5.

##  Appendix B Uneven slit effect correction

In order to correct for uneven slit illumination, we follow the method
outlined in (Agra-Amboage et al. 2014; Erkal et al. 2021a). First, we model
the distribution of incoming light by spectrally integrating the emission line
of interest and the local continuum emission either side of the emission line.
We then estimate the brightness centroid and its displacement with respect to
the centre of the slitlet at each spaxel in the datacube. The spurious
wavelength shift, expressed in terms of a velocity shift, is calculated using
the adapted formula, derived by Marconi et al. (2003), shown below:

$\Delta v(x_{0},y_{0})=\frac{\delta u}{\delta y}\times\frac{\iint
I_{\mathrm{mod}}(u,v)\times(v-y_{0})\leavevmode\nobreak\
\mathrm{d}u\leavevmode\nobreak\ \mathrm{d}v}{\iint
I_{\mathrm{mod}}(u,v)\leavevmode\nobreak\ \mathrm{d}u\leavevmode\nobreak\
\mathrm{d}v}$ (2)

Here, $\delta u$ is the spectral pixel sampling, $\delta y$ is the width of
the slitlet, and $I_{mod}$ is the modelled light intensity integrated over a
single spaxel of detector coordinates $(x_{0},y_{0})$. Figure 10 displays the
2D wavelength correction map computed around the H2 $\lambda$2.122 $\mu$m
emission line. Velocity corrections here vary from $-$5 km s-1 to +10 km s-1.
As expected, the velocity corrections have a strong variation in the vertical,
or dispersion direction due to the nature of the horizontal slicing mirrors
present in the SINFONI instrument. The effect due to uneven slit illumination
is more prominent in brighter emission and more compact emission.

Figure 10: Velocity centroid maps of H2 emission before (top), and after
(bottom), the wavelength correction map required to amend illusory
wavelength/velocity shifts due to uneven slit illumination (centre), is
applied. In the central figure H2 emission is overplotted in white contours.
The continuum peak position is marked with a red plus symbol. Contour levels
for the 3 panels begin at 3$\sigma$ of the background emission and increase by
factors of 1.5.

##  Appendix C Effect of scattered emission removal

Figure 11 displays the integrated H2 1-0 S(1) line emission before (top), and
after (bottom), the scattered emission removal routine is preformed. It is
clear that the after the scattered light is subtracted, there is a steeper
intensity gradient associated with the intrinsic H2 emission, which is most
readily observable in the closeness of contour lines surrounding bright H2
emission, such as the features labelled A1 & A2. Nebulous emission close the
apex of the cavity has also been diminished after scattered light subtraction.
The bottom panel also displays, with a red rectangular region, the position
and width of the pseudo-slit used to extract the transverse PV diagram seen in
Fig. 5.

Figure 11: Figure displaying integrated H2 line emission before (top) and
after (bottom) the scattered emission removal routine is preformed. The source
position is represented with a red plus symbol. Contour levels for both begin
at 3$\sigma$ of the background emission and increase by factors of 1.5. The
red rectangle in the bottom panel displays the position and width of the
pseudo-slit used to extract the transverse PV diagram seen in Fig. 5.

##  Appendix D Supplementary spectra

Figure 12 displays three integrated spectra extracted from various spatial
positions on the object. Molecular hydrogen emission lines (H2), forbidden
iron emission ([Fe ii]), Br-$\gamma$ emission and CO emission are common to
all spectra.

The top spectrum in Fig. 12 was extracted using a circular aperture of radius
0.$\aas@@fstack{\prime\prime}$4 from the atomic jet knot located approximately
450 au, or 1$\aas@@fstack{\prime\prime}$0, from the source position. This knot
allows us to study the jet close to the base of the outflow. Atomic forbidden
emission lines are identified in this spectrum tracing the collimated jet
emanating from the source. Br-$\gamma$ is also identified here with a double
peaked structure displaying strong emission in the blueshifted peak. This
implies that Br-$\gamma$ here is tracing not only accretion processes onto the
star but also ejection, namely the base of the atomic jet. Molecular hydrogen
(H2) emission lines also tracing the outflow are identified.

The central spectrum in Fig. 12 displays a spectrum extracted using a circular
aperture of radius 0$\aas@@fstack{\prime\prime}$4 from the H2 knot labelled A1
on the left side of the limb-brightened V-shaped cavity traced by molecular
hydrogen. The H2 emission lines here are very bright. Comparatively, the
spectrum in the bottom of Fig. 12 extracted using a circular aperture of
radius 0$\aas@@fstack{\prime\prime}$4, but from the H2 knot labelled A2 on the
right side of the V-shaped cavity traced by molecular hydrogen. The H2
emission lines here are not as strong as they appear on the left side of the
V-shaped cavity. This is expected as the left knot of the cavity has a
significantly greater intensity when compared with the knot on the right side.

Figure 12: Top: Integrated spectrum extracted using a circular aperture of
radius 0$\aas@@fstack{\prime\prime}$4 from atomic jet knot located at 1″
offset from source position. Centre: Integrated spectrum extracted using a
circular aperture of radius 0$\aas@@fstack{\prime\prime}$4 from base of left
cavity wall traced in H2, position A1. Bottom: Integrated spectrum extracted
using a circular aperture of radius 0$\aas@@fstack{\prime\prime}$4 from base
of cavity wall, position A2.