###### Abstract

In this article, we discuss the state of “AGN feedback” in radio-quiet (RQ)
AGN. This study involves heterogeneous samples of nearby Seyfert and LINER
galaxies as well as quasi-stellar objects (QSOs) that have been observed at
low radio frequencies (few $\sim$100 MHz) with the upgraded Giant Meterwave
Radio Telescope (GMRT) and $\sim$GHz frequencies with the Karl G. Jansky Very
Large Array (VLA) and Very Long Baseline Array (VLBA). These multi-frequency,
multi-resolution observations detect a range of arcsecond-scale radio spectral
indices that are consistent with the presence of multiple contributors
including starburst winds and AGN jets or winds; steep spectrum “relic”
emission is observed as well. Polarization-sensitive data from the VLA and
GMRT suggest that the radio outflows are stratified (e.g., in IIIZw2, Mrk231);
distinct polarization signatures suggest that there could either be a “spine +
sheath” structure in the radio outflow, or there could be a “jet + wind”
structure. Similar nested biconical outflows can also explain the VLBA and
SDSS emission-line data in the KISSR sample of double-peaked emission-line
Seyfert and LINER galaxies. Furthermore, the modeling of the emission-lines
with plasma modeling codes such as MAPPINGS indicates that parsec-scale jets
and winds in these sources can disturb or move the narrow-line region (NLR)
gas clouds via the “shock + precursor” mechanism. Apart from the presence of
“relic” emission, several Seyfert and LINER galaxies show clear morphological
signatures of episodic jet activity. In one such source, NGC2639, at least
four distinct episodes of jets are observed, the largest one of which was only
detectable at 735 MHz with the GMRT. Additionally, a $\sim$6 kpc hole in the
CO molecular gas along with a dearth of young stars in the center of its host
galaxy is observed. Multiple jet episodes on the 10–100 parsec scales and a
$\sim$10 parsec hole in the molecular gas is also observed in the Seyfert
galaxy NGC4051. This suggests a link between episodic jet activity in RQ AGN
and “AGN feedback” influencing the evolution of their host galaxies. However,
a similar simple relationship between radio outflows and molecular gas mass is
not observed in the Palomar–Green (PG) QSO sample, indicating that “AGN
feedback” is a complex phenomenon in RQ AGN. “AGN feedback” must occur through
the local impact of recurring multi-component outflows in RQ AGN. However,
global feedback signatures on their host galaxy properties are not always
readily evident.

###### keywords:

quasars; Seyfert galaxies; LINER galaxies; radio continuum emission;
polarimetry; very long baseline interferometry

11 1 27 Academic Editors: Stefi Baum and Christopher P. O’Dea 15 December 2022
21 January 2023 2 February 2023 8 February 2023
https://doi.org/10.3390/galaxies11010027 Looking for Signatures of AGN
Feedback in Radio-Quiet AGN Looking for Signatures of AGN Feedback in Radio-
Quiet AGN Preeti Kharb *,† and Sasikumar Silpa †Preeti Kharb and Sasikumar
Silpa Kharb, P.; Silpa, S. Correspondence<EMAIL_ADDRESS>These
authors contributed equally to this work.

##  1 Introduction

Galaxy evolution is one of the leading open questions in astrophysics (e.g.,
(Gardner et al., 2006)). The observational findings of a close link between
the galaxy properties, such as bulge mass and stellar velocity dispersion, and
its central supermassive black hole (SMBH) have led astronomers to believe
that the SMBH with its parsec-scale sphere of influence can affect the kpc-
scale galaxy bulge through the process of “Active Galactic Nuclei (AGN)
feedback” (Fabian, 2012; King and Pounds, 2015). AGN are believed to regulate
galaxy growth by injecting energy into the surrounding gas, which has the
effect of either heating and/or expelling star-forming gas (“negative
feedback”) or facilitating localized star-formation (“positive feedback”)
(Alexander and Hickox, 2012; Fabian, 2012; Morganti, 2017; Harrison, 2017).
“AGN feedback” can occur through radiative power (“quasar mode”, e.g.,
(Faucher-Giguère and Quataert, 2012; Costa et al., 2018)) or mechanical power
fed back into the galaxy through AGN winds and jets (“maintenance/jet mode”,
e.g., (McNamara and Nulsen, 2012; Mahony et al., 2013; Morganti, 2017;
Hardcastle and Croston, 2020)). The observational and energetic signatures of
this “AGN feedback” are, however, still far from being unambiguous (King and
Pounds, 2015; Harrison et al., 2018). While highly collimated jets cannot be
efficient agents of “AGN feedback”, presumably due to the smaller working
surfaces at their advancing ends, relatively isotropic impacts via changes in
jet direction can be highly effective, as can broader AGN outflows and winds
(King and Pounds, 2015).

Radio-quiet (RQ) AGN that comprise greater than 80% of the AGN population,
however, have small-scale jets on the parsec to hundreds of parsec scales (de
Bruyn and Wilson, 1976; Ulvestad and Wilson, 1984; Roy et al., 1994; Thean et
al., 2001), but typically not extending beyond $\sim$10 kpc (Gallimore et al.,
2006; Singh et al., 2015); their total radio luminosities do not overwhelm
their optical luminosities (Kellermann et al., 1989). Recent work using 6 GHz
Very Large Array (VLA) data of SDSS quasi-stellar objects (QSOs) by Kellermann
et al. (2016) has suggested that RQ AGN have
$21\leq\mathrm{log[L_{6}(W~{}Hz^{-1})]\leq 23}$. RQ AGN also tend to be low
luminosity AGN (LLAGN) and comprise Seyfert nuclei and LINER galaxies
(Heckman, 1980; Ho, 2008). Ho (1999) have identified LLAGN as those with
H$\alpha$ line luminosities ranging from $10^{37}$ to $10^{41}$ erg s-1 or
with bolometric luminosities in the range L${}_{bol}\lesssim 10^{37}-10^{44}$
erg s-1 and Eddington ratios in the range Lbol/L${}_{Edd}\sim 10^{-9}-10^{-1}$
(Ho, 2009). In this article, we use LLAGN and RQ AGN interchangeably when
referring to Seyferts, LINERs, and RQ quasars (which we use in lieu of QSOs).

Jet–interstellar medium (ISM) interaction has been inferred or observed in
several RQ AGN in the literature. For example, in IC5063, NGC5643, NGC1068,
and NGC1386 (as part of the Measuring Active Galactic Nuclei Under MUSE
Microscope (MAGNUM) Survey; (Venturi et al., 2021)), IC5063 (Morganti, 2017;
Tadhunter et al., 2014; Dasyra et al., 2022), NGC1266 (Alatalo et al., 2011),
HE 0040-1105 from the Close AGN Reference Survey (CARS) survey (Singha, 2022),
and subset of sources from the Quasar Feedback Survey (Jarvis et al., 2019;
Girdhar et al., 2022; Girdhar, 2022; Silpa et al., 2022). Evidence for an
interaction between the AGN-driven winds and ISM has also been reported for RQ
AGN in the literature (e.g., (Feruglio et al., 2010; Rupke and Veilleux, 2011;
Liu et al., 2013; Zakamska and Greene, 2014; McElroy et al., 2015; Wylezalek
and Zakamska, 2016)). Therefore, despite the lack of large and powerful radio
outflows in RQ AGN, they can be effective agents for AGN feedback.

In this review, we discuss the radio observations at multiple spatial
resolutions of samples of Seyferts, LINERs, and RQ quasars. We review the
results from multi-frequency as well as multi-scale observations going from
arcsecond scales with the upgraded Giant Meterwave Radio Telescope (GMRT) and
the Karl G. Jansky Very Large Array (VLA) in Sections 2–4, to milli-arcsec
scales with the Very Long Baseline Array (VLBA), of nearby low luminosity or
radio-quiet AGN in Section 5, and we discuss the state of “AGN feedback” in
them. All sources lie at redshifts $<$0.1, which correspond to spatial scales
smaller than $\sim$2 parsec on milli-arcsec and $\sim$2 kpc on arsec scales.
We assume a cosmology with H0 = 73 km s-1 Mpc-1, $\Omega_{mat}$ = 0.27,
$\Omega_{vac}$ = 0.73. Spectral index $\alpha$ is defined such that the flux
density at frequency $\nu$ is $S_{\nu}\propto\nu^{\alpha}$.

##  2 Low Radio Frequency Observations of RQ AGN

Low-frequency radio (few $\sim$100 MHz) observations with the GMRT have
typically detected radio emissions from both the AGN as well as stellar-
related activity from the host galaxies of Seyferts or LINERs (e.g., (Singh et
al., 2013, 2015; Hota and Saikia, 2006; Kharb et al., 2016)). In these data,
radio emission from the Seyferts/LINERs is lobe-like or bubble-like but often
simply in the form of extended diffuse emission without distinct morphological
features. The radio spectral index images cannot distinguish between the AGN
and stellar-related emission either. While the stellar-related emission is
typically steep ($\alpha\leq-0.7$), the AGN emission even in the unresolved
“cores” can be either flat ($\alpha\geq-0.5$) or steep. Steep spectrum “cores”
are likely to be due to the large beam of the GMRT including optically thin
jet or lobe emission on sub-arcsec scales. The presence of additional lobes on
arcsec scales has been indicated in the GMRT 325 and 610 MHz observations of
the Seyfert galaxies, NGC3516, NGC5506, NGC5548, NGC5695 (Rubinur et al. in
prep.).

GMRT observations can probe additional activity episodes as large steep-
spectrum diffuse lobes/bubbles or as “relic” lobe emission that is no longer
being supplied with particles and fields from the AGN (e.g., (Kharb et al.,
2016; Silpa et al., 2020, 2021; Rao et al., 2023)). The lobes of the Seyfert
galaxy NGC4235 with abruptly changing spectral indices between two sets of
lobes represent one such case (see Figure 1; (Kharb et al., 2016)). Both the
610 MHz image and the 325–610 MHz spectral index image of NGC4235 hinted at
diffuse steep-spectrum radio emission just beyond the well-defined western
lobe and enveloping it. While the average spectral index is $-0.29\pm 0.19$ in
the western lobe and $-0.56\pm 0.24$ in the eastern lobe, the average spectral
index is $-1.82\pm 0.17$ in this extended region. The average spectral index
errors come from a spectral index noise image. The robustness of the steep
spectrum emission is discussed in greater detail by Kharb et al. (2016). This
surrounding steep-spectrum emission is reminiscent of “relic” radio emission,
as observed in the lobes of the radio galaxy 3C388 by Roettiger et al. (1994),
where a lobe with an average spectral index of $\sim$$-$0.8 was surrounded by
the steep-spectrum emission of spectral index $\sim$$-$1.5 from a previous AGN
activity episode. Based on a simple spectral aging analysis in NGC4235, the
relic outer lobe appeared to be at least two times older than the present
lobe. This implied that the AGN in NGC4235 was switched “off” for the same
time that it has been “on” for the current episode (Kharb et al., 2016).

Figure 1: The 325–610 MHz spectral index image from the GMRT in color overlaid
with the 610 MHz radio contours for the Seyfert galaxy NGC4235. The average
spectral index is $\sim$$-$0.6 in the lobes and $\leq$$-$1.8 in the “relic”
lobe (emission between the red dotted lines). The contour levels are in
percentage of the peak intensity and increase by factors of two. The peak
intensity and lowest contour levels are $2.3\times 10^{-2}$ Jy beam-1 and
$\pm$0.3% of the peak intensity, respectively. The contour image is convolved
with a circular beam of size 8 arcsec. Image reproduced from Kharb et al.
(2016).

##  3 Jet Driven Feedback: The Case of NGC2639

Sanders (1984) had predicted that Seyfert activity must be episodic on
timescales of $10^{4}$–$10^{5}$ years during its statistical lifetime of 3–7
$\times$ $10^{8}$ years. They had arrived at these numbers based on the
typical extent of the radio outflows as well as the NLR in Seyfert galaxies. A
Seyfert galaxy must therefore undergo $\sim$100 activity episodes during its
lifetime. Clear examples of episodic jet activity in Seyfert and LINER
galaxies have been identified in only a couple of sources, viz., Mrk6 (Kharb
et al., 2006), NGC2992 (Irwin et al., 2016), and NGC2639 (Sebastian et al.,
2019). Sebastian et al. (2020) had found tentative signatures for multiple jet
episodes in a majority ($\sim$55%) of their small Seyfert galaxy sample of
nine sources. This fraction appeared to be higher than that has been reported
in radio-loud (RL) AGN ($\sim$10–15% in radio galaxies (Jurlin et al., 2020))
(see also the 3D GRMHD jet simulations of Lalakos et al. (2022) that reproduce
these low fractions). However, signatures of $\sim$100 episodes are almost
never observed in Seyferts or LINERs, at least in the radio outflows. This
might not be due to their true absence but rather due to the difficulty in
their identification due to the low surface brightness of Seyfert/LINER lobes,
their small spatial extents, lack of collimated jets, and confusion with the
radio emission from stellar-related activity (star-formation, supernovae, and
starburst winds) arising in the host galaxy.

Sebastian et al. (2019) had noted the presence of at least three episodes in
NGC2639 with two sets of bipolar radio lobes detected with the VLA and
oriented nearly perpendicular to each other, similar to what was observed in
Mrk6, as well as a parsec-scale core–jet structure detected with the Very Long
Baseline Array (VLBA) and oriented at least 30 degrees from the sub-kpc
east–west oriented radio lobes. GMRT observations at 325 and 735 MHz showed
the presence of an additional pair of radio lobes, oriented nearly 45 degrees
from the previously known north–south lobes (see Figure 2; (Rao et al.,
2023)). It is worth pointing out that there is no continuous connecting radio
emission between different jet episodes. Rather, the jets and lobes in each
episode have clearly defined hotspots or edges distinguishing them as
independent events, making a single precessing jet model fitting all of the
radio emission improbable.

Figure 2: The four AGN jet episodes of NGC2639. (Left) 735 MHz GMRT total
intensity image. The $\sim$9 kpc radio lobes are seen in this image. Contour
levels: $(-2,-1,1,2,4,8,16,32,64,128,256)\times 0.6$ mJy beam-1. The beam at
the bottom left corner is of size: 5.48 arcsec $\times$ 3.0 arcsec at PA =
$54.6$ degrees. (Top) 5.5 GHz VLA total intensity image. Contour levels:
$(-2,-1,1,2,4,8,16,32,64,128,256,512)\times 0.03$ mJy beam-1. The $\sim$1.5
kpc north-south radio jets are seen here. Beam size: 1.02 arcsec $\times$ 0.89
arcsec at PA = $-5.8$ degrees. (Right) 5 GHz VLA radio image. Contour levels:
$(-2,-1,1,2,4,8,16,32,64,128)\times 0.164$ mJy beam-1. The $\sim$360 parsec
east-west lobes are seen in this image. Beam size: 0.43 arcsec $\times$ 0.30
arcsec at PA = $-85.4$ degrees. (Bottom) 8.3 GHz VLBA image showing a $\sim$3
parsec jet at PA = 130 degrees. Contour levels:
$(-2,-1,1,2,4,8,16,32,64)\times 0.239$ mJy beam-1. Beam size: 7.7 mas $\times$
6.2 mas at PA = $-$4.9 degrees. Figure reproduced from Rao et al. (2023). A
$\sim$6 kpc hole in the molecular gas distribution is observed in the central
regions of NGC2639.

Ages of the three pairs of lobes were derived using the spectral aging
software BRATS, which stands for Broadband Radio Astronomy Tools (Harwood et
al., 2015), and they turned out to be, respectively, $34^{+4}_{-6}$ million
years, $11.8^{+1.7}_{-1.4}$ million years, and $2.8^{+0.7}_{-0.5}$ million
years, with the GMRT lobes being the oldest. Using the “on” and “off” times of
these jets or lobes (using the spectral age of a given set of lobes and the
spectral age difference between two sets of lobes, respectively), the AGN jet
duty cycle in NGC2639 turns out to be $\sim$60%. Based on the molecular gas
data from the EDGE (Bolatto et al., 2017)—Calar Alto Legacy Integral Field
Area (CALIFA (Sánchez et al., 2012)) survey, Ellison et al. (2021) have found
that the gas fraction in the central region of NGC2639 is a factor of a few
lower than in star-forming regions, suggesting that the AGN has partially
depleted the central molecular gas reservoir. Like the CO (1-0) molecular gas
image, which shows a hole with a diameter of $\sim$6 kpc, the GALEX NUV image
also shows a deficiency of star formation in the last 200 million years in the
inner $\sim$6 kpc region of NGC2639. These results point to star-formation
quenching taking place in the central regions of NGC2639.

If the CO (1-0) molecular gas ring is a result of push-back from the jet in
NGC2639, the $PV$ (pressure times volume) amount of work done on the molecular
gas by the jet to create a cavity can be estimated. Rao et al. (2023) have
shown that for the CO gas ring radius of 3 kpc, the volume of the disk-like
cavity is $1.25\times 10^{66}$ cm3, and the $PV$ work done is $>$3.44 $\times$
$10^{54}$ erg. Using the lobe flux densities at 5 GHz, the time-averaged power
(e.g., using the relations in (Merloni and Heinz, 2007)) for a spectral age of
2.8 million years is $6.8\times 10^{56}$ erg. Therefore, only $\sim$0.5% of
the east–west jet power is sufficient to push back the CO gas in NGC2639.
Similarly small fractions are needed from the north–south jets and the
north–east–south–west jets. However, the creation of a hole in the molecular
gas in the galactic center likely required several jet episodes to occur,
given that each jet episode is collimated and therefore highly directional
(Rao et al., 2023).

NGC2639 or Mrk6 are not unique in showing signatures of radio jets or lobes
that have different sky orientations when looked at with multiple spatial
resolutions. Another case is the famous Seyfert galaxy, NGC4051. Multi-
resolution images of NGC4051 from Jones et al. (2011) and Giroletti and
Panessa (2009) show at least three sets of radio lobes or jets. At a
resolution of $\sim$2 arcsec, there lies a double-lobed radio structure of
extent $\sim$830 parsec at a PA of 30 degrees (at its redshift of 0.002336, 1
arcsec corresponds to 61 parsecs). At a resolution of $\sim$0.5 arcsec, there
is a jet–core–jet structure of extent $\sim$90 parsec at a PA of 60 degrees.
Finally, on the 100 mas scale as probed by the European VLBI Network (EVN),
the parsec-scale core–jet structure shows a faint extension toward the south
(See Figure 3). Interestingly, NGC4051 also appears to have a hole with a
diameter of $\sim$10 parsecs in its molecular gas distribution, as observed
from Gemini North (data from Riffel et al. (2008) reanalyzed by D. May et al.
https://webarchive.gemini.edu/20210427-gsm12/gsm2012_poster_may-daniel.pdf
(accessed on 1 January 2023).). Overall, NGC2639 and NGC4051 could be
candidates for the presence of jet-driven “negative AGN feedback” in RQ AGN.

Figure 3: The three radio lobes or jets at different position angles in the
Seyfert galaxy NGC4051. The leftmost panel (VLA 1.4 GHz) image shows the
galactic emission surrounding the 1 kpc-sized radio AGN. The middle panel
shows $\sim$830 parsec lobes at a PA of 30 degrees. The rightmost panel shows
a $\sim$90 parsec lobes at a PA of 60 degrees. The bottom panel shows the EVN
image with a parsec-scale core–jet structure, showing a faint extension toward
the south. Figure reproduced from Giroletti and Panessa (2009). A $\sim$10
parsec hole in the molecular gas distribution is observed in the central
regions of NGC4051.

##  4 Jet + Wind Driven Feedback

###  4.1 The Palomar–Green Radio-Quiet Quasar Study on Kpc-Scales

We now discuss the case of the Palomar–Green (PG; (Boroson and Green, 1992))
sample of RQ quasars, which has extensive multi-resolution radio jet and
multi-phase gas outflow data, in the literature. Silpa et al. (2020) carried
out a 685 MHz GMRT study of the PG RQ quasar sample and found that the two-
frequency radio spectral indices (using the GMRT and VLA) were ultra-steep
($\alpha\leq-1.0$) in few of the sources. Other than a correlation between the
total GMRT 685 MHz luminosity and Eddington ratios, other radio properties of
the sample such as radio core sizes and radio spectral indices did not
correlate with BH properties such as their masses or Eddington ratios. This
suggested either that the radio emission was stellar-related or was due to
previous jet episodes (i.e., “relic” emission) in them (see Section 3). A
combined GMRT–VLA study of the PG RQ sample has shown evidence for the
presence of small-scale, bent, and low-powered jets in a couple of sources
(see Section 5 ahead), while for the rest, it was difficult to unambiguously
determine the origin of radio emission (whether via jet or wind or stellar
processes; (S. et al., 2023)). Multi-frequency, multi-resolution radio
polarization observations have detected a stratified radio outflow in PG
0007+106 (a.k.a. IIIZw2 (Silpa et al., 2021)). The stratified radio outflow
could either be a “spine + sheath” structure in the jet or a “jet + wind”
composite structure (see Figure 4). Each component of the stratified outflow
is observed to have a characteristic magnetic (B) field geometry (e.g.,
(Mehdipour and Costantini, 2019; Miller et al., 2012)). B fields are aligned
with the jet direction in the case of a jet or jet “spine” while they are
transverse in the case of a wind or jet “sheath”. The parallel B fields could
represent the poloidal component of a large-scale helical B field, while the
transverse B fields could either represent the toroidal component of the
helical field or a series of transverse shocks that order B fields by
compression. Alternately, they could represent toroidal B fields threading an
AGN wind or jet “sheath”, which is sampled in the lower-resolution images. The
bow-shock-like feature at the termination point of the VLA jet (see Figure 5
of (Silpa et al., 2021)), and the presence of a misaligned “sputtering” lobe
in the GMRT image (annotated as ML in Figure 4), are consistent with restarted
jet activity in IIIZw2.

Figure 4: The GMRT 685 MHz total intensity contour image of IIIZw2
superimposed with red fractional polarization vectors, with 2 arcsec length of
the vector corresponding to 6.25% fractional polarization. The inset on the
right presents the VLA 5 GHz total intensity contour image of the south-
western jet–lobe region, superimposed with red fractional polarization
vectors, with 1 arcsec length of the vector corresponding to 25% fractional
polarization. The smallest inset on the top right presents the VLA 5 GHz total
intensity contour image of the radio core with red polarized intensity
vectors, with 1 arcsec length of the vector corresponding to 0.031 mJy beam-1
polarized intensity. The peak contour surface brightness is x mJy beam-1 and
the levels are y $\times$ ($-$1, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512) mJy
beam-1, where (x ; y) are (35, 0.21) and (124, 0.05) for the GMRT and VLA
images respectively. Figure reproduced from Silpa et al. (2021).

The 5 GHz jet kinetic power of a subset of the PG RQ quasars estimated using
the empirical relation of Merloni and Heinz (2007) is within the range
1042–$10^{43}$ erg s-1 (S. et al., 2023). For these jet powers, either
stellar-mass loading (e.g., (Komissarov, 1994; Bowman et al., 1996)) or the
growth of Kelvin–Helmholtz (KH) instabilities triggered by recollimation
shocks/jet–medium interactions can effectively decelerate and decollimate the
jets (e.g., (Perucho and Martí, 2007; Perucho et al., 2014)). As the jets
propagate through the host galaxy, they would encounter numerous stars, which
inject matter into the jets via stellar winds. The mixing of the injected
stellar material with the jet plasma causes the jets to decelerate. Using a
small sample of RQ quasars, Silpa et al. (2022) found that the polarized radio
emission and [O III] emission did not always spatially overlap. This was
suggested to arise from the depolarization of radio emission by either an
irregular Faraday screen of clumpy emission-line gas or by the emission-line
gas that had entrained and mixed with the synchrotron plasma in the lobes.
While modeling the former scenario, the fluctuation scales of the electron
density (or, equivalently the sizes of the emission-line gas clumps or clouds,
or filaments) were considered and estimated. This value was also assumed to
represent the fluctuation scales of the random B-field component while
modeling the latter scenario. Interestingly, the lower limit on the size value
($\sim$$10^{-5}$ parsec) matches the sizes of red giant stars. KH
instabilities also promote entrainment and mixing between the surrounding gas
and the jet plasma, resulting in the deceleration and decollimation of the
jets. KH instabilities can also cause jet bending (e.g., (Hardee, 1987;
Savolainen et al., 2006)). Signatures of KH instabilities include knotty
polarization structures and the presence of poloidal magnetic fields (e.g.,
(Mukherjee et al., 2020)). Both of these signatures are observed in the few RQ
quasars that are detected in polarized light. Overall, therefore, there is
evidence for small (arcsec) scale jet–medium interaction taking place in these
sources.

Shangguan et al. (2020) have found that the molecular gas masses and
kinematics of the PG quasars were similar to those of the star-forming
galaxies. Additionally, no molecular gas outflows were detected in these
sources. Their host galaxies were found to be following the “Kennicutt–Schmidt
law” (Kennicutt, 1998), suggesting that no star formation quenching was taking
place in them. In the recent work of Molina et al. (2022), the molecular gas
kinematics of the PG quasar host galaxies also suggest that the “negative AGN
feedback” is ineffective in them. In general, there appears to be no immediate
significant impact on the global molecular gas reservoirs by jets or outflows
in the PG sources. However, the possibility that the AGN might be impacting
the ISM locally cannot be ruled out (e.g., (Jarvis et al., 2020)). As
discussed above, we infer the presence of localized jet–medium interaction
from the jet kinetic power argument as well as the polarization data in the PG
RQ quasar sample. Localized impact on the gas by AGN or jets could in
principle be captured by spatially resolved observations of multiple and
higher CO transitions (e.g., (van der Werf et al., 2010; Mashian et al., 2015;
Carniani et al., 2019; Dasyra et al., 2016; Zhang et al., 2019; Salomé et al.,
2017; Rosario et al., 2018; Fotopoulou et al., 2019; Ramakrishnan et al.,
2019; Shin et al., 2019; Lutz et al., 2020)).

One of the plausible mechanisms for star-formation quenching as proposed in
the literature includes galaxy major and minor mergers (along with “AGN
feedback” in most cases (Di Matteo et al., 2005; Springel et al., 2005; Cox et
al., 2006; Hopkins et al., 2008; Khalatyan et al., 2008; Cheung et al., 2012;
Barro et al., 2013; Smethurst et al., 2015)). The galaxy major merger
simulations by Springel et al. (2005) show that the presence of accreting BHs
can significantly impact the merger dynamics. Galaxy mergers can also cause
enhanced star-forming activity (Sanders and Mirabel, 1996; Mihos and
Hernquist, 1996; Lin et al., 2007) just as a “positive AGN feedback” process
(Mahoro et al., 2017, 2019). On the other hand, Weigel et al. (2017) suggest
that the major merger quenching cannot fully explain the slow evolution of
galaxies from blue to red; alternative quenching mechanisms (“AGN feedback”
being a potential candidate) are needed. The host galaxies of a large fraction
of the PG RQ quasars show signatures of ongoing galactic mergers (Silpa et
al., 2020). Therefore, the merger scenario can also have an influence on the
overall interpretation of AGN feedback.

###  4.2 The Jet and Wind in Mrk231

We now discuss the case of the quintessential AGN that clearly hosts both a
jet and wind component and is routinely considered in “AGN feedback”
scenarios, viz., Mrk231. Mrk231 is a Seyfert galaxy that hosts multi-phase
multi-scale gas outflows, such as a nuclear ultra-fast outflow (UFO; (Feruglio
et al., 2015)), a sub-kpc scale HI outflow (Morganti et al., 2016), a kpc-
scale molecular CO outflow (Feruglio et al., 2010, 2015), and a $\sim$3 kpc
scale outflow seen in the Na I doublet lines (Rupke and Veilleux, 2011, 2013).
A massive molecular OH outflow has also been detected in Mrk231 (Fischer et
al., 2010; Sturm et al., 2011; Morganti, 2017). In VLA observations, Mrk231
reveals a one-sided radio outflow to the south, comprising a weakly collimated
jet or jet “spine” embedded inside a broader magnetized wind component (Silpa
et al., 2021), resembling the stratified radio outflow in IIIZw2 (see Section
4.1). The composite outflow in Mrk231 is curved, low-powered, and oriented at
a small angle to our line of sight. The wind component may comprise both a
nuclear starburst and AGN wind, where the former may be the primary
contributor close to the core, while the latter may dominate further away.
Moving away from the core, the wind component could also be the outer layers
of a widened jet like a jet “sheath”. The 10-kpc-scale radio structure in
Mrk231 is “self-similar” to the radio structure observed on the 10-parsec-
scale in the literature (see Figure 1 in (Morganti et al., 2016)), resembling
the lobes observed in Mrk6 (Kharb et al., 2006). The radio structures on the
two scales in Mrk231 are not as clearly delineated, however, which may be a
result of the low inclination angle. However, the presence of two distinct
structures is consistent with episodic jet activity in Mrk231, similar to the
case of Mrk6 (see Section 3).

Silpa et al. (2021) obtained first-order estimates of the relative
contributions of the different components (jet/AGN wind/starburst wind) to the
overall budget of the radio emission. While the starburst-driven wind
accounted for $\sim$10–20% of the total radio emission, both jet and AGN wind
contributed significantly to the rest of the emission. To estimate the
contribution of starburst-driven wind, two different models were used: one
assumed that 10% of the supernova kinetic energy was carried away by the winds
(Thornton et al., 1998; Leitherer et al., 1999), and the other assumed 40%
(Dalla Vecchia and Schaye, 2008). The latter analysis has also been carried
out assuming two different initial mass functions (IMFs; (Salpeter, 1955;
Chabrier, 2003)). The contribution of the starburst-driven wind remained the
same for the different assumed models. The contribution of AGN wind was
estimated assuming two different coupling efficiencies (5%; (Di Matteo et al.,
2005)) and (0.5%; (Hopkins and Elvis, 2010)). For a 0.5% coupling efficiency,
the radio contribution of the jet estimated using Leitherer et al. (1999)
model, as well as Dalla Vecchia and Schaye (2008) model with Chabrier (2003)
IMF, turned out to be more than of the wind. Although such a first-order
analysis cannot provide a one-to-one correspondence between the dominant
driver (between jet or AGN wind) and the outflowing gas phase (HI or Na I D or
CO or OH), it still indicates that the multi-phase gas outflow in Mrk231 is
likely to be driven by both a jet and a wind.

##  5 Signatures of Jet + Wind Feedback on Parsec-Scales

We now turn our attention to much smaller spatial scales than probed by the
GMRT and VLA observations. We focus on the KPNO Internal Spectroscopic Survey
Red (KISSR; (Wegner et al., 2003)) sample of Seyfert and LINER galaxies (Kharb
et al., 2021). This sample was chosen based on the presence of double-peaked
emission lines in their SDSS spectra as well as a radio detection in the VLA
FIRST survey (Kharb et al., 2015). Phase-referenced observations of this
sample with the Very Long Baseline Array (VLBA) have revealed the presence of
elongated jet-like features, similar to other Very Long Baseline
Interferometry (VLBI) studies of RQ AGN in the literature (e.g., (Falcke et
al., 2000; Middelberg et al., 2004; Nagar et al., 2005; Kharb et al., 2010;
Orienti and Prieto, 2010; Baldi et al., 2018; Kharb et al., 2021)).
Interestingly, these jets are one-sided, similar to the one-sided parsec-scale
jets observed in RL AGN. VLBI imaging also reveals one-sided jets in narrow-
line Seyfert 1 galaxies (Doi et al., 2011; Richards and Lister, 2015; Richards
et al., 2015). A $\sim$60 parsec long radio source (jet–core–counterjet) was
imaged in the Seyfert 2 galaxy Mrk348 using VLBI by Neff and de Bruyn (1983);
the counterjet emission was detected more than 40 parsecs away from the radio
core. In RL AGN, one-sidedness is typically understood to be a consequence of
Doppler-boosting effects (Blandford and Königl, 1979). It is not clear if the
one-sidedness in Seyfert or LINER jets is a result of Doppler-boosting effects
or due to free-free absorption; multi-frequency and spectral index
observations could help to disentangle these two scenarios (e.g., (Baczko et
al., 2019, 2022)). If Doppler-boosting is responsible for the jet one-
sidedness in the KISSR sources, for instance, then lower limits to jet speeds
would range from $0.003c$ to $0.75c$ (Kharb et al., 2021) assuming jet
inclinations to be $\geq$50 degrees, consistent with their type 2
classification, and the expected torus half-opening angles being $\sim$50
degrees (e.g., (Simpson et al., 1996)).

On the other hand, if the missing counterjet emission was a result of
free–free absorption, the required electron densities of the ionized gas could
be estimated using $EM=3.05\times 10^{6}~{}\tau~{}T^{1.35}~{}\nu^{2.1}$, and
$n_{e}=\sqrt{EM/l}$ (Mezger and Henderson, 1967), where $EM$ is the emission
measure in pc cm-6, $\tau$ is the optical depth at frequency $\nu$ in GHz, $T$
is the gas temperature in units of $10^{4}$ K, $n_{e}$ is the electron density
in cm-3, and $l$ is the path length in parsecs. In order to account for the
observed jet-to-counterjet surface brightness ratios ($R_{J}$) of $\sim$20 on
parsec scales (as in the case of KISSR434; (Kharb et al., 2019)), the optical
depth at 1.5 GHz would need to be at least $\sim$1.0 using
$\exp(-\tau)=1/R_{J}$ (Ulvestad et al., 1999). For a gas temperature of
$10^{4}$ K and a jet path length of 1 parsec, an $EM$ of $\approx$7.1 $\times$
$10^{6}$ pc cm-6 and $n_{e}$ of $\approx$2700 cm-3 are required for free–free
absorption on parsec scales. Such ionized gas densities can be found in NLR
gas clouds. However, their volume filling factor is of the order of $10^{-4}$
(e.g., (Alexander et al., 1999)), making them unlikely candidates for
absorbers for the $\sim$100-parsec-scale (counter-)jets observed in a couple
of the KISSR sources (Kharb et al., 2019, 2021). Ionized gas in giant HII
regions with $n_{e}\sim$100–1000 cm-3 could in principle also be the candidate
media for free–free absorption (Clemens et al., 2010) but also has a low
volume filling factor ($\geq$0.2, e.g., (Walterbos and Braun, 1994)).

Multi-epoch VLBI observations are therefore necessary to check for proper
motions and obtain accurate jet speeds to verify the Doppler-boosting picture
in Seyferts and LINERs. This has recently become possible for eight KISSR
sources. Preliminary results suggest the detection of superluminal jet motion
in at least one source (Kharb et al. in prep.). With these new observations,
the jet detection rate in the KISSR sample becomes $\sim$75%. Jet detection
rates in larger samples of Seyferts and LINERs range between $\sim$30% and
$\sim$50% (e.g., (Baldi et al., 2018, 2021)). The higher jet detection rate in
the KISSR sample is consistent with a selection bias that comes from selecting
double-peaked emission-line AGN (DPAGN) and jet–NLR interaction being the
primary cause of the double-peaked emission lines in them.

Furthermore, it was found that the double peaks of the emission lines were
typically separated by velocities of $\sim$100–300 km s-1 for most sources,
and the widths of the lines corresponded to velocities of $\sim$100–200 km s-1
(Kharb et al., 2015, 2017, 2019, 2021). These velocities are much smaller, by
factors of several hundred, than the expected jet speeds. This, therefore,
suggests that the emission line gas could be pushed in a direction lateral to
the jet (e.g., (Kharb et al., 2017; Girdhar et al., 2022)) or could arise in
wider, slower-moving winds around the jets (see for example Figure 5). Indeed,
nested biconical outflows have been invoked to explain the origin of double-
peaked emission lines in low luminosity AGN by Nevin et al. (2016, 2018).
Importantly, wide wind-like outflows can be efficient agents of “AGN feedback”
(see the review by (Harrison et al., 2018)). Indeed, from the MAPPINGS III
modeling of emission lines such as H$\alpha$, H$\beta$, H$\gamma$, [S II], [O
III], and [O II], it appears that in sources possessing parsec-scale jets, the
“shock + precursor” model can explain the observed line ratios, consistent
with the idea of jet–NLR interaction. The “shock + precursor” model comes into
play when ionizing radiation (i.e., extreme UV and soft X-ray photons)
generated by the cooling of hot gas behind a shock front creates a strong
radiation field leading to significant photoionization (Allen et al., 2008).
The spatial scales sampled by the SDSS optical fiber with a diameter of 3
arcsecs, corresponding to $\sim$3–6 kpc at the distance of the KISSR sources,
are much larger than the $\sim$100 parsec-scale VLBA jets. However, as Schmitt
et al. (2003a, b) have noted, the NLR ranges from a few 100 parsecs to a few
kpcs in Seyfert galaxies. The emission-line modeling is consistent with the
idea that RQ AGN are energetically capable of influencing their parsec and
kpc-scale environments, making them agents of “radio AGN feedback”.

Figure 5: Cartoon showing a nested biconical structure in the outflow (that is
blue-shifted when approaching and redshifted when receding as denoted by the
colors) in order to reproduce the double-peaked emission line AGN
spectroscopic observations. The host galaxy (red ellipse) and accretion disk
(blue ellipse) as shown here are not to scale. The outer layers of a jet or a
wind could be driving the NLR gas clouds.

##  6 Summary

Radio-quiet AGN make up the vast majority of all AGN. While they lack the 100
kpc radio jets and lobes that are observed in the more spectacular looking and
rarer radio-loud AGN, the smaller outflows in RQ AGN have profound though
subtle effects on their host galaxies. Multi-frequency polarization-sensitive
observations of the PG RQ quasars and other Seyfert galaxies with the VLA and
GMRT indicate that the radio outflows are layered or stratified. The multi-
component outflows could either be spine + sheath structures or jets with
winds. While the “sheath” layers around the “spines” of jets could come about
due to jet–medium interaction, they continue to entrain the surrounding gas,
create instabilities between layers, and further impact both the jet and the
medium itself. Small (arcsec) scale jet–medium interaction is also implied by
their polarimetric and jet kinetic power data. The picture of nested biconical
outflows also emerges from a completely different study, namely, the VLBI
study of a sample of Seyfert and LINER galaxies that exhibit double-peaked
emission lines in their SDSS optical spectra. Two separate results point to
jet–medium interaction in these sources. First, the high incidence of one-
sided radio jets, several of which are $\sim$100 parsec in extent, points to a
selection bias when choosing a DPAGN sample as the double-peaked emission
lines appear to be the result of jet–NLR gas cloud interaction. Second, plasma
modeling codes on the optical emission lines from SDSS indicate that the NLR
gas clouds are affected through the “shock + precursor” mechanism and that the
jets are likely stratified with a faster moving “spine” and a slower moving
“sheath” or wind. Finally, multi-frequency arcsec-scale observations detect
the signatures of multiple jet episodes in RQ AGN through the presence of
additional steep-spectrum radio lobes. Episodic AGN activity in fact appears
to be the norm in RQ AGN, signatures of which are seen in the radio spectra as
well as morphological features like bow-shocks. In the case of the Seyfert
galaxies NGC2639 and NGC4051, and others, these multiple jet episodes appear
to excavate holes in the molecular gas in the central regions of their host
galaxies, consistent with “negative AGN feedback”. However, in many cases,
like the PG RQ quasars, there appears to be no currently observable depletion
of molecular gas in their host galaxies. “AGN feedback”, therefore, appears to
be a complex phenomenon in the case of RQ AGN. It cannot be ruled out on small
spatial scales as implied by the signatures of jet–medium interaction.
However, global impact signatures on the host galaxies are often difficult to
see.

This paper has contributions from projects lead by both P.K. and S.S. Projects
lead by S.S. are a part of her Ph.D. thesis currently being supervised by P.K.
All authors have read and agreed to the published version of the manuscript.

This research received no external funding.

Informed consent was obtained from all subjects involved in the study.

The data underlying this article will be shared on reasonable request to the
corresponding author.

###### Acknowledgements.

We thank the anonymous reviewers for their suggestions that have significantly
improved this paper. We thank the staff of the GMRT that made these
observations possible. GMRT is run by the National Center for Radio
Astrophysics of the Tata Institute of Fundamental Research. P.K. and S.S.
acknowledge the support of the Department of Atomic Energy, Government of
India, under the project 12-R&D-TFR-5.02-0700. The National Radio Astronomy
Observatory is a facility of the National Science Foundation operated under
cooperative agreement by Associated Universities, Inc. The authors declare no
conflict of interest. [custom] References

## References

  * Gardner et al. (2006) Gardner, J.P.; Mather, J.C.; Clampin, M.; Doyon, R.; Greenhouse, M.A.; Hammel, H.B.; Hutchings, J.B.; Jakobsen, P.; Lilly, S.J.; Long, K.S.; et al.  The James Webb Space Telescope.  Space Sci. Rev. 2006, 123, 485–606. [CrossRef]
  * Fabian (2012) Fabian, A.C.  Observational Evidence of Active Galactic Nuclei Feedback.  Annu. Rev. Astron. Astrophys. 2012, 50, 455–489. [CrossRef]
  * King and Pounds (2015) King, A.; Pounds, K.  Powerful Outflows and Feedback from Active Galactic Nuclei.  Annu. Rev. Astron. Astrophys. 2015, 53, 115–154. [CrossRef]
  * Alexander and Hickox (2012) Alexander, D.M.; Hickox, R.C.  What drives the growth of black holes?  New Astron. Rev. 2012, 56, 93–121. [CrossRef]
  * Morganti (2017) Morganti, R.  The many routes to AGN feedback.  Front. Astron. Space Sci. 2017, 4, 42. [CrossRef]
  * Harrison (2017) Harrison, C.M.  Impact of supermassive black hole growth on star formation.  Nat. Astron. 2017, 1, 0165. [CrossRef]
  * Faucher-Giguère and Quataert (2012) Faucher-Giguère, C.A.; Quataert, E.  The physics of galactic winds driven by active galactic nuclei.  Mon. Not. R. Astron. Soc. 2012, 425, 605–622. [CrossRef]
  * Costa et al. (2018) Costa, T.; Rosdahl, J.; Sijacki, D.; Haehnelt, M.G.  Quenching star formation with quasar outflows launched by trapped IR radiation.  Mon. Not. R. Astron. Soc. 2018, 479, 2079–2111. [CrossRef]
  * McNamara and Nulsen (2012) McNamara, B.R.; Nulsen, P.E.J.  Mechanical feedback from active galactic nuclei in galaxies, groups and clusters.  New J. Phys. 2012, 14, 055023. [CrossRef]
  * Mahony et al. (2013) Mahony, E.K.; Morganti, R.; Emonts, B.H.C.; Oosterloo, T.A.; Tadhunter, C.  The location and impact of jet-driven outflows of cold gas: The case of 3C 293.  Mon. Not. R. Astron. Soc. 2013, 435, L58–L62. [CrossRef]
  * Hardcastle and Croston (2020) Hardcastle, M.J.; Croston, J.H.  Radio galaxies and feedback from AGN jets.  New Astron. Rev. 2020, 88, 101539. [CrossRef]
  * Harrison et al. (2018) Harrison, C.M.; Costa, T.; Tadhunter, C.N.; Flütsch, A.; Kakkad, D.; Perna, M.; Vietri, G.  AGN outflows and feedback twenty years on.  Nat. Astron. 2018, 2, 198–205. [CrossRef]
  * de Bruyn and Wilson (1976) de Bruyn, A.G.; Wilson, A.S.  A 1415 MHz Survey of Seyfert and Related Galaxies.  Astron. Astrophys. 1976, 53, 93.
  * Ulvestad and Wilson (1984) Ulvestad, J.S.; Wilson, A.S.  Radio structures of Seyfert galaxies. VI. VLA observations of a nearby sample.  Astrophys. J. 1984, 285, 439–452. [CrossRef]
  * Roy et al. (1994) Roy, A.L.; Norris, R.P.; Kesteven, M.J.; Troup, E.R.; Reynolds, J.E.  Compact Radio Cores in Seyfert Galaxies.  Astrophys. J. 1994, 432, 496. [CrossRef]
  * Thean et al. (2001) Thean, A.; Pedlar, A.; Kukula, M.J.; Baum, S.A.; O’Dea, C.P.  High-resolution radio observations of Seyfert galaxies in the extended 12-$\mu$m sample—II. The properties of compact radio components.  Mon. Not. R. Astron. Soc. 2001, 325, 737–760. [CrossRef]
  * Gallimore et al. (2006) Gallimore, J.F.; Axon, D.J.; O’Dea, C.P.; Baum, S.A.; Pedlar, A.  A Survey of Kiloparsec-Scale Radio Outflows in Radio-Quiet Active Galactic Nuclei.  Astron. J. 2006, 132, 546–569. [CrossRef]
  * Singh et al. (2015) Singh, V.; Ishwara-Chandra, C.H.; Wadadekar, Y.; Beelen, A.; Kharb, P.  Kiloparsec-scale radio emission in Seyfert and LINER galaxies.  Mon. Not. R. Astron. Soc. 2015, 446, 599–612. [CrossRef]
  * Kellermann et al. (1989) Kellermann, K.I.; Sramek, R.; Schmidt, M.; Shaffer, D.B.; Green, R.  VLA Observations of Objects in the Palomar Bright Quasar Survey.  Astron. J. 1989, 98, 1195. [CrossRef]
  * Kellermann et al. (2016) Kellermann, K.I.; Condon, J.J.; Kimball, A.E.; Perley, R.A.; Ivezić, Ž.  Radio-loud and Radio-quiet QSOs.  Astrophys. J. 2016, 831, 168. [CrossRef]
  * Heckman (1980) Heckman, T.M.  An Optical and Radio Survey of the Nuclei of Bright Galaxies - Activity in the Normal Galactic Nuclei.  Astron. Astrophys. 1980, 87, 152.
  * Ho (2008) Ho, L.C.  Nuclear Activity in Nearby Galaxies.  Annu. Rev. Astron. Astrophys. 2008, 46, 475–539. [CrossRef]
  * Ho (1999) Ho, L.C.  LINERs as low-luminosity active galactic nuclei.  Adv. Space Res. 1999, 23, 813–822. [CrossRef]
  * Ho (2009) Ho, L.C.  Radiatively Inefficient Accretion in Nearby Galaxies.  Astrophys. J. 2009, 699, 626–637. [CrossRef]
  * Venturi et al. (2021) Venturi, G.; Cresci, G.; Marconi, A.; Mingozzi, M.; Nardini, E.; Carniani, S.; Mannucci, F.; Marasco, A.; Maiolino, R.; Perna, M.; et al.  MAGNUM survey: Compact jets causing large turmoil in galaxies. Enhanced line widths perpendicular to radio jets as tracers of jet-ISM interaction.  Astron. Astrophys. 2021, 648, A17. [CrossRef]
  * Tadhunter et al. (2014) Tadhunter, C.; Morganti, R.; Rose, M.; Oonk, J.B.R.; Oosterloo, T.  Jet acceleration of the fast molecular outflows in the Seyfert galaxy IC 5063.  Nature 2014, 511, 440–443. [CrossRef]
  * Dasyra et al. (2022) Dasyra, K.M.; Paraschos, G.F.; Bisbas, T.G.; Combes, F.; Fernández-Ontiveros, J.A.  Insights into the collapse and expansion of molecular clouds in outflows from observable pressure gradients.  Nat. Astron. 2022, 6, 1077–1084. [CrossRef]
  * Alatalo et al. (2011) Alatalo, K.; Blitz, L.; Young, L.M.; Davis, T.A.; Bureau, M.; Lopez, L.A.; Cappellari, M.; Scott, N.; Shapiro, K.L.; Crocker, A.F.; et al.  Discovery of an Active Galactic Nucleus Driven Molecular Outflow in the Local Early-type Galaxy NGC 1266.  Astrophys. J. 2011, 735, 88. [CrossRef]
  * Singha (2022) Singha, M.  The Curious Case of a Radio Quiet AGN: Jet-Outflow Connection Unveiled by the Close AGN Reference Survey (CARS).  In Proceedings of the Multiphase AGN Feeding & Feedback II, Sexten, Italy, 20–24 June 2022; p. 59.
  * Jarvis et al. (2019) Jarvis, M.E.; Harrison, C.M.; Thomson, A.P.; Circosta, C.; Mainieri, V.; Alexander, D.M.; Edge, A.C.; Lansbury, G.B.; Molyneux, S.J.; Mullaney, J.R.  Prevalence of radio jets associated with galactic outflows and feedback from quasars.  Mon. Not. R. Astron. Soc. 2019, 485, 2710–2730. [CrossRef]
  * Girdhar (2022) Girdhar, A.  The Important Role of Low Power Radio Jets in Driving Multiphase Outflows in Quasar Host Galaxies.  In Proceedings of the Multiphase AGN Feeding & Feedback II, Sexten, Italy, 20–24 June 2022; p. 20.
  * Silpa et al. (2022) Silpa, S.; Kharb, P.; Harrison, C.M.; Girdhar, A.; Mukherjee, D.; Mainieri, V.; Jarvis, M.E.  The Quasar Feedback Survey: Revealing the interplay of jets, winds, and emission-line gas in type 2 quasars with radio polarization.  Mon. Not. R. Astron. Soc. 2022, 513, 4208–4223. [CrossRef]
  * Girdhar et al. (2022) Girdhar, A.; Harrison, C.M.; Mainieri, V.; Bittner, A.; Costa, T.; Kharb, P.; Mukherjee, D.; Arrigoni Battaia, F.; Alexander, D.M.; Calistro Rivera, G.; et al.  Quasar feedback survey: Multiphase outflows, turbulence, and evidence for feedback caused by low power radio jets inclined into the galaxy disc.  Mon. Not. R. Astron. Soc. 2022, 512, 1608–1628. [CrossRef]
  * Feruglio et al. (2010) Feruglio, C.; Maiolino, R.; Piconcelli, E.; Menci, N.; Aussel, H.; Lamastra, A.; Fiore, F.  Quasar feedback revealed by giant molecular outflows.  Astron. Astrophys. 2010, 518, L155. [CrossRef]
  * Rupke and Veilleux (2011) Rupke, D.S.N.; Veilleux, S.  Integral Field Spectroscopy of Massive, Kiloparsec-scale Outflows in the Infrared-luminous QSO Mrk 231.  Astrophys. J. Lett. 2011, 729, L27. [CrossRef]
  * Liu et al. (2013) Liu, G.; Zakamska, N.L.; Greene, J.E.; Nesvadba, N.P.H.; Liu, X.  Observations of feedback from radio-quiet quasars—II. Kinematics of ionized gas nebulae.  Mon. Not. R. Astron. Soc. 2013, 436, 2576–2597. [CrossRef]
  * Zakamska and Greene (2014) Zakamska, N.L.; Greene, J.E.  Quasar feedback and the origin of radio emission in radio-quiet quasars.  Mon. Not. R. Astron. Soc. 2014, 442, 784–804. [CrossRef]
  * McElroy et al. (2015) McElroy, R.; Croom, S.M.; Pracy, M.; Sharp, R.; Ho, I.T.; Medling, A.M.  IFU observations of luminous type II AGN—I. Evidence for ubiquitous winds.  Mon. Not. R. Astron. Soc. 2015, 446, 2186–2204. [CrossRef]
  * Wylezalek and Zakamska (2016) Wylezalek, D.; Zakamska, N.L.  Evidence of suppression of star formation by quasar-driven winds in gas-rich host galaxies at z < 1?  Mon. Not. R. Astron. Soc. 2016, 461, 3724–3739. [CrossRef]
  * Kharb et al. (2016) Kharb, P.; Srivastava, S.; Singh, V.; Gallimore, J.F.; Ishwara-Chandra, C.H.; Ananda, H.  A GMRT study of Seyfert galaxies NGC 4235 and NGC 4594: Evidence of episodic activity?  Mon. Not. R. Astron. Soc. 2016, 459, 1310–1326. [CrossRef]
  * Singh et al. (2013) Singh, V.; Shastri, P.; Ishwara-Chandra, C.H.; Athreya, R.  Low-frequency radio observations of Seyfert galaxies: A test of the unification scheme.  Astron. Astrophys. 2013, 554, A85. [CrossRef]
  * Hota and Saikia (2006) Hota, A.; Saikia, D.J.  Radio bubbles in the composite AGN-starburst galaxy NGC6764.  Mon. Not. R. Astron. Soc. 2006, 371, 945–956. [CrossRef]
  * Silpa et al. (2020) Silpa, S.; Kharb, P.; Ho, L.C.; Ishwara-Chandra, C.H.; Jarvis, M.E.; Harrison, C.  Probing the origin of low-frequency radio emission in PG quasars with the uGMRT—I.  Mon. Not. R. Astron. Soc. 2020, 499, 5826–5839. [CrossRef]
  * Silpa et al. (2021) Silpa, S.; Kharb, P.; Harrison, C.M.; Ho, L.C.; Jarvis, M.E.; Ishwara-Chandra, C.H.; Sebastian, B.  Outflows in the radio-intermediate quasar III Zw 2: A polarization study with the EVLA and uGMRT.  Mon. Not. R. Astron. Soc. 2021, 507, 991–1001. [CrossRef]
  * Rao et al. (2023) Rao, V.V.; Kharb, P.; Rubinur, K.; Silpa, S.; Roy, N.; Sebastian, B.; Singh, V.; Baghel, J.; Manna, S.; Ishwara-Chandra, C.H.  AGN Feedback Through Multiple Jet Cycles in the Seyfert Galaxy NGC 2639\.  arXiv 2023, arXiv:2301.01610.
  * Roettiger et al. (1994) Roettiger, K.; Burns, J.O.; Clarke, D.A.; Christiansen, W.A.  Relic radio emission in 3C 388.  Astrophys. J. 1994, 421, L23–L26. [CrossRef]
  * Sanders (1984) Sanders, R.H.  Seyfert nuclei as short-lived stochastic accretion events.  Astron. Astrophys. 1984, 140, 52–54.
  * Kharb et al. (2006) Kharb, P.; O’Dea, C.P.; Baum, S.A.; Colbert, E.J.M.; Xu, C.  A Radio Study of the Seyfert Galaxy Markarian 6: Implications for Seyfert Life Cycles.  Astrophys. J. 2006, 652, 177–188. [CrossRef]
  * Irwin et al. (2016) Irwin, J.A.; Schmidt, P.; Damas-Segovia, A.; Beck, R.; English, J.; Heald, G.; Henriksen, R.N.; Krause, M.; Li, J.T.; Rand, R.J.; et al.  CHANG-ES—VIII. Uncovering hidden AGN activity in radio polarization.  Mon. Not. R. Astron. Soc. 2016, 464, 1333–1346. [CrossRef]
  * Sebastian et al. (2019) Sebastian, B.; Kharb, P.; O’Dea, C.P.; Gallimore, J.F.; Baum, S.A.  The discovery of secondary lobes in the Seyfert galaxy NGC 2639.  Mon. Not. R. Astron. Soc. 2019, 490, L26–L31. [CrossRef]
  * Sebastian et al. (2020) Sebastian, B.; Kharb, P.; O’Dea, C.P.; Gallimore, J.F.; Baum, S.A.  A radio polarimetric study to disentangle AGN activity and star formation in Seyfert galaxies.  Mon. Not. R. Astron. Soc. 2020, 499, 334–354. [CrossRef]
  * Jurlin et al. (2020) Jurlin, N.; Morganti, R.; Brienza, M.; Mandal, S.; Maddox, N.; Duncan, K.J.; Shabala, S.S.; Hardcastle, M.J.; Prandoni, I.; Röttgering, H.J.A.; et al.  The life cycle of radio galaxies in the LOFAR Lockman Hole field.  Astron. Astrophys. 2020, 638, A34. [CrossRef]
  * Lalakos et al. (2022) Lalakos, A.; Gottlieb, O.; Kaaz, N.; Chatterjee, K.; Liska, M.; Christie, I.M.; Tchekhovskoy, A.; Zhuravleva, I.; Nokhrina, E.  Bridging the Bondi and Event Horizon Scales: 3D GRMHD Simulations Reveal X-shaped Radio Galaxy Morphology.  Astrophys. J. 2022, 936, L5. [CrossRef]
  * Harwood et al. (2015) Harwood, J.J.; Hardcastle, M.J.; Croston, J.H.  Spectral ageing in the lobes of cluster-centre FR II radio galaxies.  Mon. Not. R. Astron. Soc. 2015, 454, 3403–3422. [CrossRef]
  * Bolatto et al. (2017) Bolatto, A.D.; Wong, T.; Utomo, D.; Blitz, L.; Vogel, S.N.; Sánchez, S.F.; Barrera-Ballesteros, J.; Cao, Y.; Colombo, D.; Dannerbauer, H.; et al.  The EDGE-CALIFA Survey: Interferometric Observations of 126 Galaxies with CARMA.  Astrophys. J. 2017, 846, 159. [CrossRef]
  * Sánchez et al. (2012) Sánchez, S.F.; Kennicutt, R.C.; Gil de Paz, A.; van de Ven, G.; Vílchez, J.M.; Wisotzki, L.; Walcher, C.J.; Mast, D.; Aguerri, J.A.L.; Albiol-Pérez, S.; et al.  CALIFA, the Calar Alto Legacy Integral Field Area survey. I. Survey presentation.  Astron. Astrophys. 2012, 538, A8. [CrossRef]
  * Ellison et al. (2021) Ellison, S.L.; Wong, T.; Sánchez, S.F.; Colombo, D.; Bolatto, A.; Barrera-Ballesteros, J.; García-Benito, R.; Kalinova, V.; Luo, Y.; Rubio, M.; et al.  The EDGE-CALIFA survey: Central molecular gas depletion in AGN host galaxies—A smoking gun for quenching?  Mon. Not. R. Astron. Soc. 2021, 505, L46–L51. [CrossRef]
  * Merloni and Heinz (2007) Merloni, A.; Heinz, S.  Measuring the kinetic power of active galactic nuclei in the radio mode.  Mon. Not. R. Astron. Soc. 2007, 381, 589–601. [CrossRef]
  * Jones et al. (2011) Jones, S.; McHardy, I.; Moss, D.; Seymour, N.; Breedt, E.; Uttley, P.; Körding, E.; Tudose, V.  Radio and X-ray variability in the Seyfert galaxy NGC 4051.  Mon. Not. R. Astron. Soc. 2011, 412, 2641–2652. [CrossRef]
  * Giroletti and Panessa (2009) Giroletti, M.; Panessa, F.  The Faintest Seyfert Radio Cores Revealed by VLBI.  Astrophys. J. 2009, 706, L260–L264. [CrossRef]
  * Riffel et al. (2008) Riffel, R.A.; Storchi-Bergmann, T.; Winge, C.; McGregor, P.J.; Beck, T.; Schmitt, H.  Mapping of molecular gas inflow towards the Seyfert nucleus of NGC4051 using Gemini NIFS.  Mon. Not. R. Astron. Soc. 2008, 385, 1129–1142. [CrossRef]
  * Boroson and Green (1992) Boroson, T.A.; Green, R.F.  The Emission-Line Properties of Low-Redshift Quasi-stellar Objects.  Astrophys. J. Suppl. Ser. 1992, 80, 109. [CrossRef]
  * S. et al. (2023) Silpa, S.; Kharb, P.; Ho, L.C.; Harrison, C.M.  A Radio-Gas Study of 11 Radio-quiet PG Quasars.  arXiv 2023, arXiv:2301.07929.
  * Mehdipour and Costantini (2019) Mehdipour, M.; Costantini, E.  Relation between winds and jets in radio-loud AGN.  Astron. Astrophys. 2019, 625, A25. [CrossRef]
  * Miller et al. (2012) Miller, J.M.; Raymond, J.; Fabian, A.C.; Reynolds, C.S.; King, A.L.; Kallman, T.R.; Cackett, E.M.; van der Klis, M.; Steeghs, D.T.H.  The Disk-wind-Jet Connection in the Black Hole H 1743-322.  Astrophys. J. 2012, 759, L6. [CrossRef]
  * Komissarov (1994) Komissarov, S.S.  Mass-Loaded Relativistic Jets.  Mon. Not. R. Astron. Soc. 1994, 269, 394. [CrossRef]
  * Bowman et al. (1996) Bowman, M.; Leahy, J.P.; Komissarov, S.S.  The deceleration of relativistic jets by entrainment.  Mon. Not. R. Astron. Soc. 1996, 279, 899. [CrossRef]
  * Perucho and Martí (2007) Perucho, M.; Martí, J.M.  A numerical simulation of the evolution and fate of a Fanaroff-Riley type I jet. The case of 3C 31.  Mon. Not. R. Astron. Soc. 2007, 382, 526–542. [CrossRef]
  * Perucho et al. (2014) Perucho, M.; Martí, J.M.; Laing, R.A.; Hardee, P.E.  On the deceleration of Fanaroff-Riley Class I jets: Mass loading by stellar winds.  Mon. Not. R. Astron. Soc. 2014, 441, 1488–1503. [CrossRef]
  * Hardee (1987) Hardee, P.E.  Spatial Stability of Relativistic Jets: Application to 3C 345.  Astrophys. J. 1987, 318, 78. [CrossRef]
  * Savolainen et al. (2006) Savolainen, T.; Wiik, K.; Valtaoja, E.; Kadler, M.; Ros, E.; Tornikoski, M.; Aller, M.F.; Aller, H.D.  An Extremely Curved Relativistic Jet in PKS 2136+141.  Astrophys. J. 2006, 647, 172–184. [CrossRef]
  * Mukherjee et al. (2020) Mukherjee, D.; Bodo, G.; Mignone, A.; Rossi, P.; Vaidya, B.  Simulating the dynamics and non-thermal emission of relativistic magnetized jets I. Dynamics.  Mon. Not. R. Astron. Soc. 2020, 499, 681–701. [CrossRef]
  * Shangguan et al. (2020) Shangguan, J.; Ho, L.C.; Bauer, F.E.; Wang, R.; Treister, E.  AGN Feedback and Star Formation of Quasar Host Galaxies: Insights from the Molecular Gas.  Astrophys. J. 2020, 899, 112. [CrossRef]
  * Kennicutt (1998) Kennicutt, R.C., Jr.  The Global Schmidt Law in Star-forming Galaxies.  Astrophys. J. 1998, 498, 541–552. [CrossRef]
  * Molina et al. (2022) Molina, J.; Ho, L.C.; Wang, R.; Shangguan, J.; Bauer, F.E.; Treister, E.; Zhuang, M.Y.; Ricci, C.; Bian, F.  Ionized Outflows in Nearby Quasars Are Poorly Coupled to Their Host Galaxies.  Astrophys. J. 2022, 935, 72. [CrossRef]
  * Jarvis et al. (2020) Jarvis, M.E.; Harrison, C.M.; Mainieri, V.; Calistro Rivera, G.; Jethwa, P.; Zhang, Z.Y.; Alexander, D.M.; Circosta, C.; Costa, T.; De Breuck, C.; et al.  High molecular gas content and star formation rates in local galaxies that host quasars, outflows, and jets.  Mon. Not. R. Astron. Soc. 2020, 498, 1560–1575. [CrossRef]
  * van der Werf et al. (2010) van der Werf, P.P.; Isaak, K.G.; Meijerink, R.; Spaans, M.; Rykala, A.; Fulton, T.; Loenen, A.F.; Walter, F.; Weiß, A.; Armus, L.; et al.  Black hole accretion and star formation as drivers of gas excitation and chemistry in Markarian 231.  Astron. Astrophys. 2010, 518, L42. [CrossRef]
  * Mashian et al. (2015) Mashian, N.; Sturm, E.; Sternberg, A.; Janssen, A.; Hailey-Dunsheath, S.; Fischer, J.; Contursi, A.; González-Alfonso, E.; Graciá-Carpio, J.; Poglitsch, A.; et al.  High-J CO Sleds in Nearby Infrared Bright Galaxies Observed By Herschel/PACS.  Astrophys. J. 2015, 802, 81. [CrossRef]
  * Carniani et al. (2019) Carniani, S.; Gallerani, S.; Vallini, L.; Pallottini, A.; Tazzari, M.; Ferrara, A.; Maiolino, R.; Cicone, C.; Feruglio, C.; Neri, R.; et al.  Constraints on high-J CO emission lines in z $\sim$ 6 quasars.  Mon. Not. R. Astron. Soc. 2019, 489, 3939–3952. [CrossRef]
  * Dasyra et al. (2016) Dasyra, K.M.; Combes, F.; Oosterloo, T.; Oonk, J.B.R.; Morganti, R.; Salomé, P.; Vlahakis, N.  ALMA reveals optically thin, highly excited CO gas in the jet-driven winds of the galaxy IC 5063.  Astron. Astrophys. 2016, 595, L7. [CrossRef]
  * Zhang et al. (2019) Zhang, C.P.; Li, G.X.; Zhou, C.; Yuan, L.; Zhu, M.  Using CO line ratios to trace compressed areas in bubble N131.  Astron. Astrophys. 2019, 631, A110. [CrossRef]
  * Salomé et al. (2017) Salomé, Q.; Salomé, P.; Miville-Deschênes, M.A.; Combes, F.; Hamer, S.  Inefficient jet-induced star formation in Centaurus A. High resolution ALMA observations of the northern filaments.  Astron. Astrophys. 2017, 608, A98. [CrossRef]
  * Rosario et al. (2018) Rosario, D.J.; Burtscher, L.; Davies, R.I.; Koss, M.; Ricci, C.; Lutz, D.; Riffel, R.; Alexander, D.M.; Genzel, R.; Hicks, E.H.; et al.  LLAMA: Normal star formation efficiencies of molecular gas in the centres of luminous Seyfert galaxies.  Mon. Not. R. Astron. Soc. 2018, 473, 5658–5679. [CrossRef]
  * Fotopoulou et al. (2019) Fotopoulou, C.M.; Dasyra, K.M.; Combes, F.; Salomé, P.; Papachristou, M.  Complex molecular gas kinematics in the inner 5 kpc of 4C12.50 as seen by ALMA.  Astron. Astrophys. 2019, 629, A30. [CrossRef]
  * Ramakrishnan et al. (2019) Ramakrishnan, V.; Nagar, N.M.; Finlez, C.; Storchi-Bergmann, T.; Slater, R.; Schnorr-Müller, A.; Riffel, R.A.; Mundell, C.G.; Robinson, A.  Nuclear kinematics in nearby AGN—I. An ALMA perspective on the morphology and kinematics of the molecular CO(2-1) emission.  Mon. Not. R. Astron. Soc. 2019, 487, 444–455. [CrossRef]
  * Shin et al. (2019) Shin, J.; Woo, J.H.; Chung, A.; Baek, J.; Cho, K.; Kang, D.; Bae, H.J.  Positive and Negative Feedback of AGN Outflows in NGC 5728.  Astrophys. J. 2019, 881, 147. [CrossRef]
  * Lutz et al. (2020) Lutz, D.; Sturm, E.; Janssen, A.; Veilleux, S.; Aalto, S.; Cicone, C.; Contursi, A.; Davies, R.I.; Feruglio, C.; Fischer, J.; et al.  Molecular outflows in local galaxies: Method comparison and a role of intermittent AGN driving.  Astron. Astrophys. 2020, 633, A134. [CrossRef]
  * Di Matteo et al. (2005) Di Matteo, T.; Springel, V.; Hernquist, L.  Energy input from quasars regulates the growth and activity of black holes and their host galaxies.  Nature 2005, 433, 604–607. [CrossRef]
  * Springel et al. (2005) Springel, V.; Di Matteo, T.; Hernquist, L.  Black Holes in Galaxy Mergers: The Formation of Red Elliptical Galaxies.  Astrophys. J. 2005, 620, L79–L82. [CrossRef]
  * Cox et al. (2006) Cox, T.J.; Jonsson, P.; Primack, J.R.; Somerville, R.S.  Feedback in simulations of disc-galaxy major mergers.  Mon. Not. R. Astron. Soc. 2006, 373, 1013–1038. [CrossRef]
  * Hopkins et al. (2008) Hopkins, P.F.; Cox, T.J.; Kereš, D.; Hernquist, L.  A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies. II. Formation of Red Ellipticals.  Astrophys. J. Suppl. Ser. 2008, 175, 390–422. [CrossRef]
  * Khalatyan et al. (2008) Khalatyan, A.; Cattaneo, A.; Schramm, M.; Gottlöber, S.; Steinmetz, M.; Wisotzki, L.  Is AGN feedback necessary to form red elliptical galaxies?  Mon. Not. R. Astron. Soc. 2008, 387, 13–30. [CrossRef]
  * Cheung et al. (2012) Cheung, E.; Faber, S.M.; Koo, D.C.; Dutton, A.A.; Simard, L.; McGrath, E.J.; Huang, J.S.; Bell, E.F.; Dekel, A.; Fang, J.J.; et al.  The Dependence of Quenching upon the Inner Structure of Galaxies at 0.5 <= z < 0.8 in the DEEP2/AEGIS Survey.  Astrophys. J. 2012, 760, 131. [CrossRef]
  * Barro et al. (2013) Barro, G.; Faber, S.M.; Pérez-González, P.G.; Koo, D.C.; Williams, C.C.; Kocevski, D.D.; Trump, J.R.; Mozena, M.; McGrath, E.; van der Wel, A.; et al.  CANDELS: The Progenitors of Compact Quiescent Galaxies at z ~2\.  Astrophys. J. 2013, 765, 104. [CrossRef]
  * Smethurst et al. (2015) Smethurst, R.J.; Lintott, C.J.; Simmons, B.D.; Schawinski, K.; Marshall, P.J.; Bamford, S.; Fortson, L.; Kaviraj, S.; Masters, K.L.; Melvin, T.; et al.  Galaxy Zoo: Evidence for diverse star formation histories through the green valley.  Mon. Not. R. Astron. Soc. 2015, 450, 435–453. [CrossRef]
  * Springel et al. (2005) Springel, V.; Di Matteo, T.; Hernquist, L.  Modelling feedback from stars and black holes in galaxy mergers.  Mon. Not. R. Astron. Soc. 2005, 361, 776–794. [CrossRef]
  * Sanders and Mirabel (1996) Sanders, D.B.; Mirabel, I.F.  Luminous Infrared Galaxies.  Annu. Rev. Astron. Astrophys. 1996, 34, 749. [CrossRef]
  * Mihos and Hernquist (1996) Mihos, J.C.; Hernquist, L.  Gasdynamics and Starbursts in Major Mergers.  Astrophys. J. 1996, 464, 641. [CrossRef]
  * Lin et al. (2007) Lin, L.; Koo, D.C.; Weiner, B.J.; Chiueh, T.; Coil, A.L.; Lotz, J.; Conselice, C.J.; Willner, S.P.; Smith, H.A.; Guhathakurta, P.; et al.  AEGIS: Enhancement of Dust-enshrouded Star Formation in Close Galaxy Pairs and Merging Galaxies up to z ~1\.  Astrophys. J. 2007, 660, L51–L54. [CrossRef]
  * Mahoro et al. (2017) Mahoro, A.; Pović, M.; Nkundabakura, P.  Star formation of far-IR AGN and non-AGN galaxies in the green valley: Possible implication of AGN positive feedback.  Mon. Not. R. Astron. Soc. 2017, 471, 3226–3233. [CrossRef]
  * Mahoro et al. (2019) Mahoro, A.; Pović, M.; Nkundabakura, P.; Nyiransengiyumva, B.; Väisänen, P.  Star formation in far-IR AGN and non-AGN galaxies in the green valley—II. Morphological analysis.  Mon. Not. R. Astron. Soc. 2019, 485, 452–463. [CrossRef]
  * Weigel et al. (2017) Weigel, A.K.; Schawinski, K.; Caplar, N.; Carpineti, A.; Hart, R.E.; Kaviraj, S.; Keel, W.C.; Kruk, S.J.; Lintott, C.J.; Nichol, R.C.; et al.  Galaxy Zoo: Major Galaxy Mergers Are Not a Significant Quenching Pathway.  Astrophys. J. 2017, 845, 145. [CrossRef]
  * Feruglio et al. (2015) Feruglio, C.; Fiore, F.; Carniani, S.; Piconcelli, E.; Zappacosta, L.; Bongiorno, A.; Cicone, C.; Maiolino, R.; Marconi, A.; Menci, N.; et al.  The multi-phase winds of Markarian 231: From the hot, nuclear, ultra-fast wind to the galaxy-scale, molecular outflow.  Astron. Astrophys. 2015, 583, A99. [CrossRef]
  * Morganti et al. (2016) Morganti, R.; Veilleux, S.; Oosterloo, T.; Teng, S.H.; Rupke, D.  Another piece of the puzzle: The fast H I outflow in Mrk 231.  Astron. Astrophys. 2016, 593, A30. [CrossRef]
  * Rupke and Veilleux (2013) Rupke, D.S.N.; Veilleux, S.  The Multiphase Structure and Power Sources of Galactic Winds in Major Mergers.  Astrophys. J. 2013, 768, 75. [CrossRef]
  * Fischer et al. (2010) Fischer, J.; Sturm, E.; González-Alfonso, E.; Graciá-Carpio, J.; Hailey-Dunsheath, S.; Poglitsch, A.; Contursi, A.; Lutz, D.; Genzel, R.; Sternberg, A.; et al.  Herschel-PACS spectroscopic diagnostics of local ULIRGs: Conditions and kinematics in Markarian 231.  Astron. Astrophys. 2010, 518, L41. [CrossRef]
  * Sturm et al. (2011) Sturm, E.; González-Alfonso, E.; Veilleux, S.; Fischer, J.; Graciá-Carpio, J.; Hailey-Dunsheath, S.; Contursi, A.; Poglitsch, A.; Sternberg, A.; Davies, R.; et al.  Massive Molecular Outflows and Negative Feedback in ULIRGs Observed by Herschel-PACS.  Astrophys. J. 2011, 733, L16. [CrossRef]
  * Silpa et al. (2021) Silpa, S.; Kharb, P.; O’Dea, C.P.; Baum, S.A.; Sebastian, B.; Mukherjee, D.; Harrison, C.M.  AGN jets and winds in polarized light: The case of Mrk 231.  Mon. Not. R. Astron. Soc. 2021, 507, 2550–2561. [CrossRef]
  * Thornton et al. (1998) Thornton, K.; Gaudlitz, M.; Janka, H.T.; Steinmetz, M.  Energy Input and Mass Redistribution by Supernovae in the Interstellar Medium.  Astrophys. J. 1998, 500, 95–119. [CrossRef]
  * Leitherer et al. (1999) Leitherer, C.; Schaerer, D.; Goldader, J.D.; Delgado, R.M.G.; Robert, C.; Kune, D.F.; de Mello, D.F.; Devost, D.; Heckman, T.M.  Starburst99: Synthesis Models for Galaxies with Active Star Formation.  Astrophys. J. Suppl. Ser. 1999, 123, 3–40. [CrossRef]
  * Dalla Vecchia and Schaye (2008) Dalla Vecchia, C.; Schaye, J.  Simulating galactic outflows with kinetic supernova feedback.  Mon. Not. R. Astron. Soc. 2008, 387, 1431–1444. [CrossRef]
  * Salpeter (1955) Salpeter, E.E.  The Luminosity Function and Stellar Evolution.  Astrophys. J. 1955, 121, 161. [CrossRef]

  * Chabrier (2003) Chabrier, G.  Galactic Stellar and Substellar Initial Mass Function.  Publ. Astron. Soc. Pac. 2003, 115, 763–795. [CrossRef]
  * Hopkins and Elvis (2010) Hopkins, P.F.; Elvis, M.  Quasar feedback: More bang for your buck.  Mon. Not. R. Astron. Soc. 2010, 401, 7–14. [CrossRef]
  * Wegner et al. (2003) Wegner, G.; Salzer, J.J.; Jangren, A.; Gronwall, C.; Melbourne, J.  Spectroscopy of KISS Emission-Line Galaxy Candidates. I. MDM Observations.  Astron. J. 2003, 125, 2373–2392. [CrossRef]
  * Kharb et al. (2021) Kharb, P.; Subramanian, S.; Das, M.; Vaddi, S.; Paragi, Z.  The Nature of Jets in Double-peaked Emission-line AGN in the KISSR Sample.  Astrophys. J. 2021, 919, 108. [CrossRef]
  * Kharb et al. (2015) Kharb, P.; Das, M.; Paragi, Z.; Subramanian, S.; Chitta, L.P.  VLBI Imaging of the Double Peaked Emission Line Seyfert KISSR 1494.  Astrophys. J. 2015, 799, 161. [CrossRef]
  * Falcke et al. (2000) Falcke, H.; Nagar, N.M.; Wilson, A.S.; Ulvestad, J.S.  Radio Sources in Low-Luminosity Active Galactic Nuclei. II. Very Long Baseline Interferometry Detections of Compact Radio Cores and Jets in a Sample of LINERs.  Astrophys. J. 2000, 542, 197–200. [CrossRef]
  * Middelberg et al. (2004) Middelberg, E.; Roy, A.L.; Nagar, N.M.; Krichbaum, T.P.; Norris, R.P.; Wilson, A.S.; Falcke, H.; Colbert, E.J.M.; Witzel, A.; Fricke, K.J.  Motion and properties of nuclear radio components in Seyfert galaxies seen with VLBI.  Astron. Astrophys. 2004, 417, 925–944. [CrossRef]
  * Nagar et al. (2005) Nagar, N.M.; Falcke, H.; Wilson, A.S.  Radio sources in low-luminosity active galactic nuclei. IV. Radio luminosity function, importance of jet power, and radio properties of the complete Palomar sample.  Astron. Astrophys. 2005, 435, 521–543. [CrossRef]
  * Kharb et al. (2010) Kharb, P.; Hota, A.; Croston, J.H.; Hardcastle, M.J.; O’Dea, C.P.; Kraft, R.P.; Axon, D.J.; Robinson, A.  Parsec-scale Imaging of the Radio-bubble Seyfert Galaxy NGC 6764.  Astrophys. J. 2010, 723, 580–586. [CrossRef]
  * Orienti and Prieto (2010) Orienti, M.; Prieto, M.A.  Radio structures of the nuclei of nearby Seyfert galaxies and the nature of the missing diffuse emission.  Mon. Not. R. Astron. Soc. 2010, 401, 2599–2610. [CrossRef]
  * Baldi et al. (2018) Baldi, R.D.; Williams, D.R.A.; McHardy, I.M.; Beswick, R.J.; Argo, M.K.; Dullo, B.T.; Knapen, J.H.; Brinks, E.; Muxlow, T.W.B.; Aalto, S.; et al.  LeMMINGs—I. The eMERLIN legacy survey of nearby galaxies. 1.5-GHz parsec-scale radio structures and cores.  Mon. Not. R. Astron. Soc. 2018, 476, 3478–3522. [CrossRef]
  * Doi et al. (2011) Doi, A.; Asada, K.; Nagai, H.  Very Long Baseline Array Imaging of Parsec-scale Jet Structures in Radio-loud Narrow-line Seyfert 1 Galaxies.  Astrophys. J. 2011, 738, 126. [CrossRef]
  * Richards and Lister (2015) Richards, J.L.; Lister, M.L.  Kiloparsec-Scale Jets in Three Radio-Loud Narrow-Line Seyfert 1 Galaxies.  Astrophys. J. 2015, 800, L8. [CrossRef]
  * Richards et al. (2015) Richards, J.L.; Lister, M.L.; Savolainen, T.; Homan, D.C.; Kadler, M.; Hovatta, T.; Readhead, A.C.S.; Arshakian, T.G.; Chavushyan, V.  The parsec-scale structure, kinematics, and polarization of radio-loud narrow-line Seyfert 1 galaxies.  In Proceedings of the Extragalactic Jets from Every Angle, Galapagos Islands, Ecuador, 15–19 September 2014; Massaro, F., Cheung, C.C., Lopez, E., Siemiginowska, A., Eds.; Cambridge University Press: Cambridge, UK, 2015; Volume 313, pp. 139–142. [CrossRef]
  * Neff and de Bruyn (1983) Neff, S.G.; de Bruyn, A.G.  The compact radio core of MKN 348: Evidence for directed outflow in a type 2 Seyfert galaxy.  Astron. Astrophys. 1983, 128, 318–324.
  * Blandford and Königl (1979) Blandford, R.D.; Königl, A.  Relativistic jets as compact radio sources.  Astrophys. J. 1979, 232, 34–48. [CrossRef]
  * Baczko et al. (2019) Baczko, A.K.; Schulz, R.; Kadler, M.; Ros, E.; Perucho, M.; Fromm, C.M.; Wilms, J.  Asymmetric jet production in the active galactic nucleus of NGC 1052\.  Astron. Astrophys. 2019, 623, A27. [CrossRef]
  * Baczko et al. (2022) Baczko, A.K.; Ros, E.; Kadler, M.; Fromm, C.M.; Boccardi, B.; Perucho, M.; Krichbaum, T.P.; Burd, P.R.; Zensus, J.A.  Ambilateral collimation study of the twin-jets in NGC 1052.  Astron. Astrophys. 2022, 658, A119. [CrossRef]
  * Simpson et al. (1996) Simpson, C.; Mulchaey, J.S.; Wilson, A.S.; Ward, M.J.; Alonso-Herrero, A.  An Ionization Cone and Dusty Disk in Markarian 348: The Obscuring Torus Revealed?  Astrophys. J. 1996, 457, L19. [CrossRef]
  * Mezger and Henderson (1967) Mezger, P.G.; Henderson, A.P.  Galactic H II Regions. I. Observations of Their Continuum Radiation at the Frequency 5 GHz.  Astrophys. J. 1967, 147, 471. [CrossRef]
  * Kharb et al. (2019) Kharb, P.; Vaddi, S.; Sebastian, B.; Subramanian, S.; Das, M.; Paragi, Z.  A Curved 150 pc Long Jet in the Double-peaked Emission-line AGN KISSR 434.  Astrophys. J. 2019, 871, 249. [CrossRef]
  * Ulvestad et al. (1999) Ulvestad, J.S.; Wrobel, J.M.; Roy, A.L.; Wilson, A.S.; Falcke, H.; Krichbaum, T.P.  Subrelativistic Radio Jets and Parsec-Scale Absorption in Two Seyfert Galaxies.  Astrophys. J. 1999, 517, L81–L84. [CrossRef]
  * Alexander et al. (1999) Alexander, T.; Sturm, E.; Lutz, D.; Sternberg, A.; Netzer, H.; Genzel, R.  Infrared Spectroscopy of NGC 4151: Probing the Obscured Ionizing Active Galactic Nucleus Continuum.  Astrophys. J. 1999, 512, 204–223. [CrossRef]
  * Clemens et al. (2010) Clemens, M.S.; Scaife, A.; Vega, O.; Bressan, A.  Starburst evolution: Free-free absorption in the radio spectra of luminous IRAS galaxies.  Mon. Not. R. Astron. Soc. 2010, 405, 887–897. [CrossRef]
  * Walterbos and Braun (1994) Walterbos, R.A.M.; Braun, R.  Diffused ionized gas in the spiral galaxy M31.  Astrophys. J. 1994, 431, 156–171. [CrossRef]
  * Baldi et al. (2021) Baldi, R.D.; Williams, D.R.A.; McHardy, I.M.; Beswick, R.J.; Brinks, E.; Dullo, B.T.; Knapen, J.H.; Argo, M.K.; Aalto, S.; Alberdi, A.; et al.  LeMMINGs—II. The e-MERLIN legacy survey of nearby galaxies. The deepest radio view of the Palomar sample on parsec scale.  Mon. Not. R. Astron. Soc. 2021, 500, 4749–4767. [CrossRef]
  * Kharb et al. (2017) Kharb, P.; Subramanian, S.; Vaddi, S.; Das, M.; Paragi, Z.  Double-peaked Emission Lines Due to a Radio Outflow in KISSR 1219.  Astrophys. J. 2017, 846, 12. [CrossRef]
  * Nevin et al. (2016) Nevin, R.; Comerford, J.; Müller-Sánchez, F.; Barrows, R.; Cooper, M.  The Origin of Double-peaked Narrow Lines in Active Galactic Nuclei. II. Kinematic Classifications for the Population at z < 0.1.  Astrophys. J. 2016, 832, 67. [CrossRef]
  * Nevin et al. (2018) Nevin, R.; Comerford, J.M.; Müller-Sánchez, F.; Barrows, R.; Cooper, M.C.  The origin of double-peaked narrow lines in active galactic nuclei—III. Feedback from biconical AGN outflows.  Mon. Not. R. Astron. Soc. 2018, 473, 2160–2187. [CrossRef]
  * Allen et al. (2008) Allen, M.G.; Groves, B.A.; Dopita, M.A.; Sutherland, R.S.; Kewley, L.J.  The MAPPINGS III Library of Fast Radiative Shock Models.  Astrophys. J. Suppl. Ser. 2008, 178, 20–55. [CrossRef]
  * Schmitt et al. (2003a) Schmitt, H.R.; Donley, J.L.; Antonucci, R.R.J.; Hutchings, J.B.; Kinney, A.L.  A Hubble Space Telescope Survey of Extended [O III] $\lambda$5007 Emission in a Far-Infrared Selected Sample of Seyfert Galaxies: Observations.  Astrophys. J. Suppl. Ser. 2003, 148, 327–352. [CrossRef]
  * Schmitt et al. (2003b) Schmitt, H.R.; Donley, J.L.; Antonucci, R.R.J.; Hutchings, J.B.; Kinney, A.L.; Pringle, J.E.  A Hubble Space Telescope Survey of Extended [O III] $\lambda$5007 Å Emission in a Far-Infrared-Selected Sample of Seyfert Galaxies: Results.  Astrophys. J. 2003, 597, 768–779. [CrossRef]