# A GMOS/IFU Study of Jellyfish Galaxies in Massive Clusters

Jeong Hwan Lee Astronomy Program, Department of Physics and Astronomy, SNUARC,
Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of
Korea  Myung Gyoon Lee Astronomy Program, Department of Physics and Astronomy,
SNUARC, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826,
Republic of Korea  Jae Yeon Mun Research School of Astronomy and Astrophysics,
Australian National University, Canberra, ACT 2611, Australia  Brian S. Cho
Astronomy Program, Department of Physics and Astronomy, SNUARC, Seoul National
University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea  Jisu Kang
Astronomy Program, Department of Physics and Astronomy, SNUARC, Seoul National
University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea Myung Gyoon
Lee<EMAIL_ADDRESS><EMAIL_ADDRESS>
###### Abstract

Jellyfish galaxies are an intriguing snapshot of galaxies undergoing ram-
pressure stripping (RPS) in dense environments, showing spectacular star-
forming knots in their disks and tails. We study the ionized gas properties of
five jellyfish galaxies in massive clusters with Gemini GMOS/IFU observations:
MACSJ0916-JFG1 ($z=0.330$), MACSJ1752-JFG2 ($z=0.353$), A2744-F0083
($z=0.303$), MACSJ1258-JFG1 ($z=0.342$), and MACSJ1720-JFG1 ($z=0.383$). BPT
diagrams show that various mechanisms (star formation, AGN, or mixed effects)
are ionizing gas in these galaxies. Radial velocity distributions of ionized
gas seem to follow disk rotation of galaxies, with the appearance of a few
high-velocity components in the tails as a sign of RPS. Mean gas velocity
dispersion is lower than 50 ${\rm km~{}s^{-1}}$ in most star-forming regions
except near AGNs or shock-heated regions, indicating that the ionized gas is
dynamically cold. Integrated star formation rates (SFRs) of these galaxies
range from $7~{}{\rm M_{\odot}~{}{\rm yr^{-1}}}$ to $35~{}{\rm
M_{\odot}~{}{\rm yr^{-1}}}$ and the tail SFRs are from $0.6~{}{\rm
M_{\odot}~{}{\rm yr^{-1}}}$ to $16~{}{\rm M_{\odot}~{}{\rm yr^{-1}}}$, which
are much higher than those of other jellyfish galaxies in the local universe.
These high SFR values imply that RPS triggers intense star formation activity
in these extreme jellyfish galaxies. The phase-space diagrams demonstrate that
the jellyfish galaxies with higher stellar masses and higher host cluster
velocity dispersion are likely to have more enhanced star formation activity.
The jellyfish galaxies in this study have similar gas kinematics and dynamical
states to those in the local universe, but they show a much higher SFR.

Galaxy environments (2029) — Galaxy clusters (584) — Ram pressure stripped
tails (2126) — Intracluster medium (858) — Starburst galaxies (1570) — Galaxy
spectroscopy (2171)

††software: Numpy (Harris et al., 2020), Matplotlib (Hunter, 2007), Scipy
(Virtanen et al., 2020), Astropy (Astropy Collaboration et al., 2013, 2018),
PyRAF (Science Software Branch at STScI, 2012), Vorbin (Cappellari & Copin,
2003), Emcee (Foreman-Mackey et al., 2013), Photutils (Bradley et al., 2021),
and SExtractor (Bertin & Arnouts, 1996)

##  1 Introduction

Environmental effects play an important role in galaxy transformation
associated with high-density environments. Most gas-rich galaxies in galaxy
groups or clusters evolve by losing their gas content due to various
mechanisms: galaxy mergers (Toomre & Toomre, 1972), ram-pressure stripping
(RPS; Gunn & Gott, 1972), galaxy harassment (Moore et al., 1996), and
starvation (Larson et al., 1980). These external processes remove the gas
ingredients for star formation from galaxies and transform late-type galaxies
into early-type galaxies in dense environments.

Among these mechanisms, RPS is the interaction between the intracluster medium
(ICM) and the interstellar medium (ISM) in galaxies. It has been known as the
most efficient mechanism of gas removal from galaxies in cluster environments.
When a galaxy moves through the intergalactic space that is filled with hot
and diffuse gas, ram pressure applies a force to the gas component in the
galaxy towards the direction opposite of the galaxy motion. RPS eventually
quenches star formation activity by sweeping out the gas content in galaxies.
Since diffuse ICM gas with X-ray emission is frequently observed in galaxy
clusters, RPS seems to significantly contribute to the passive evolution of
cluster galaxies (Dressler, 1980).

However, some late-type galaxies undergoing RPS are not quiescent but rather
show local star-forming regions. Several late-type galaxies under the effect
of RPS in Virgo and Coma were found to have a large number of blue and UV-
emitting knots or “spur clusters” throughout their disks (Hester et al., 2010;
Smith et al., 2010; Yoshida et al., 2012; Lee & Jang, 2016). Interestingly, a
post-merger elliptical galaxy in Abell 2670 was revealed to be undergoing RPS
and exhibits compact star-forming blobs outside the main body of the galaxy
(Sheen et al., 2017). Cluster galaxies with remarkable RPS features like one-
sided tails and bright star-forming knots are often called “jellyfish
galaxies” (Bekki, 2009; Chung et al., 2009). The presence of young stellar
systems in jellyfish galaxies implies that RPS can locally boost the star
formation activity in gas-rich galaxies before removing gas completely. Thus,
jellyfish galaxies are very interesting and useful targets to investigate the
relationship between star formation activity and RPS.

Table 1: Examples of Jellyfish Galaxies (JFGs) at $z>0.1$

Reference | JFGs (Host System) | Redshift | Observing Instruments
---|---|---|---
Owen et al. (2006) | C153 (A2125) | $z=0.253$ |  HST/WFPC2, KPNO 4m,
|  |  | Gemini/GMOS longslit
|  |  | VLA, Chandra
Cortese et al. (2007) | 131124$-$012040 (A1689) | $z=0.187$ |  HST/WFPC2, HST/ACS,
| 235144$-$260358 (A2667) | $z=0.227$ | VLT/ISAAC, Spitzer/IRAC,
|  |  |  Spitzer/MIPS, VLA,
|  |  | VLT/VIMOS, Keck/LRIS
Owers et al. (2012) | 4 JFGs (A2744) | $z=0.29-0.31$ |  HST/ACS
|  |  | AAT/AAOmega
Ebeling et al. (2014) | 6 JFGs | $z=0.3-0.5$ |  HST/ACS
| (37 MACS clusters) |  |
McPartland et al. (2016) | 16 JFGs | $z=0.3-0.5$ |  HST/ACS,
| (63 MACS clusters) |  | Keck/DEIMOS
Ebeling et al. (2017) | MACSJ0553-JFG1 | $z=0.442$ |  HST/ACS, HST/WFC3,
| (MACSJ0553$-$3342) |  | Keck/LRIS, Keck/DEIMOS,
|  |  |  Chandra, GMRT
Boselli et al. (2019) | ID 345 and ID 473 (CGr32) | $z=0.73$ |  VLT/MUSEaaIntegral field spectroscopic (IFS) observations., XMM-Newton,
|  |  |  HST/ACS, Subaru/Suprime-Cam
Kalita & Ebeling (2019) | A1758N_JFG1 (A1758N) | $z=0.273$ |  Keck/KCWIaaIntegral field spectroscopic (IFS) observations., Keck/DEIMOS,
|  |  |  HST/ACS, Chandra
Roman-Oliveira et al. (2019) | 70 JFGs (A901/2) | $z=0.165$ | GTC/OSIRIS (the OMEGA survey),
|  |  |  HST/ACS, XMM-Newton
Castignani et al. (2020) | The southern companion of BCG | $z=1.71$ | IRAM/NOEMA, HST/ACS
| (SpARCS1049+56) |  |
Durret et al. (2021) | 81 JFGs (MACS0717.5$+$3745) | $z=0.546$ |  HST/ACS
| 97 JFGs (22 clusters) | $z=0.2-0.9$ | NASA/IPAC Extragalactic Database
Moretti et al. (2022) | 13 JFGs (A2744 and A370) | $z=0.3-0.4$ |  HST/ACS, VLT/MUSEaaIntegral field spectroscopic (IFS) observations.

††footnotetext: Note.

Recently, observational studies on jellyfish galaxies have utilized integral
field spectroscopy (IFS). IFS observations provide both spatial and spectral
information, so they are optimal to investigate various physical properties of
jellyfish galaxies. For instance, the GAs Stripping Phenomena (GASP) survey
observed a large sample of jellyfish galaxies in nearby galaxy clusters using
the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT)
(Poggianti et al., 2017). Studies from the GASP survey found that star-forming
knots in jellyfish galaxies are formed in situ with stellar ages younger than
10 Myr, are dynamically cold ($\sigma_{v,{\rm gas}}<40~{}{\rm km~{}s^{-1}}$),
and are mostly ionized by photons emitted from young massive stars (Bellhouse
et al., 2017, 2019). They obtained a mean star formation rate (SFR) of $\sim
1.8$ $M_{\odot}~{}{\rm yr^{-1}}$ in the disks and $\sim 0.13$
$M_{\odot}~{}{\rm yr^{-1}}$ in the tails of the jellyfish galaxies (Poggianti
et al., 2019; Gullieuszik et al., 2020). As a result, the GASP survey has
successfully provided a comprehensive view of the star formation activity of
jellyfish galaxies in the local universe ($z<0.1$).

However, most IFS studies have been limited to jellyfish galaxies in low-mass
clusters ($\sigma_{v,{\rm cl}}\lesssim 1000$ ${\rm km~{}s^{-1}}$) in the local
universe ($z<0.1$). Since massive clusters are rare in the nearby universe,
jellyfish galaxies in massive clusters have been mostly found at intermediate
redshift $(z>0.1)$ and were studied using deep images from the Hubble Space
Telescope (HST).  Table 1 lists the jellyfish galaxies that have been mainly
observed at $z>0.1$ so far. All the observations used HST optical images
because such high-resolution images show the dramatic features of jellyfish
galaxies very well. Owen et al. (2006) and Cortese et al. (2007) found three
disturbed jellyfish galaxies with blue star-forming knots in the multi-band
HST optical images and radio images: C153 (Abell 2125; $z=0.253$),
131124-012040 (Abell 1689; $z=0.187$), and 235144-260358 (Abell 2667;
$z=0.227$). Owers et al. (2012) studied four jellyfish galaxies with highly
asymmetric tails and very bright star-forming knots in the merging cluster
Abell 2744, using the HST optical images and AAOmega spectra. Ebeling et al.
(2014) and McPartland et al. (2016) performed a systematic search of jellyfish
galaxies using the HST images of the Massive Cluster Survey (MACS; Ebeling et
al., 2001, 2010) and provided a catalog of 16 jellyfish galaxies in the MACS
cluster samples at $z>0.3$ ($\langle M_{\rm tot}\rangle\sim 1.3\times
10^{15}~{}M_{\odot}$). Roman-Oliveira et al. (2019) presented the
characteristics of 70 jellyfish galaxies using the OMEGA-OSIRIS survey of a
multi-cluster system A901/2. Similarly, Durret et al. (2021) found a total of
178 jellyfish galaxy candidates in 23 clusters from the DAFT/FADA and CLASH
surveys.

Among the studies described in  Table 1, the IFS observations of jellyfish
galaxies at $z>0.1$ are rare except for the three cases. Boselli et al. (2019)
detected two massive star-forming galaxies with long gaseous tails in the
COSMOS cluster CGr32 ($z=0.73$) using VLT/MUSE. Kalita & Ebeling (2019)
studied an extreme jellyfish galaxy, A1758N-JFG1, in the colliding galaxy
cluster Abell 1758N ($z=0.28)$ with the Keck Cosmic Web Imager (KCWI). These
two studies focused on the resolved kinematics of jellyfish galaxies based on
the [O II]$\lambda\lambda 3727,3729$ doublet emission line because their IFS
data did not cover the ${\rm H\alpha}$ emission line. Recently, Moretti et al.
(2022) presented the properties of 13 jellyfish galaxies in the inner regions
of Abell 2744 ($z=0.306$) and Abell 370 ($z=0.375$) using the emission lines
of ${\rm H\alpha}$ and [O II]$\lambda\lambda 3727,3729$. Their study suggested
that the [O II]/${\rm H\alpha}$ ratio in the tails of their sample galaxies is
much higher than those of local jellyfish galaxies, which implies that the
stripped gas might have low gas density or interact with the ICM.

In this study, we investigate the physical properties of jellyfish galaxies in
massive clusters using the integral field unit (IFU) instrument on the Gemini
Multi-Object Spectrograph (GMOS). The 8-m Gemini telescope is suitable for
observing jellyfish galaxies at intermediate redshift in terms of its light-
gathering power and field of view (FOV). We carry out emission line analyses
of the GMOS/IFU data of jellyfish galaxies, which includes the ${\rm H\alpha}$
line. Using the ${\rm H\alpha}$-derived SFRs of jellyfish galaxies in this
study, Lee et al. (2022) presented a relation between the star formation
activity of the jellyfish galaxies and the host cluster properties. In this
paper, we present the detailed methods and analyses of emission lines of the
jellyfish galaxies.

This paper is organized as follows. In  Section 2.1, we explain our target
selection and their properties. Then, we describe our GMOS/IFU observations
and data reduction in  Section 2.2, and we describe the multi-wavelength
archival images in  Section 2.3. We explain our analysis of the GMOS/IFU data
cube to derive the physical quantities in  Section 3. In  Section 4, we
illustrate the maps of the gas ionization mechanisms, the kinematics, the star
formation activity, and the dynamical states for our targets. In  Section 5,
we discuss the star formation activity of jellyfish galaxies in this study in
comparison with those in the literature using phase-space diagrams. Finally,
we summarize primary results in  Section 6. We adopt the cosmological
parameters with $H_{0}=70~{}{\rm km~{}s^{-1}~{}Mpc^{-1}}$, $\Omega_{M}=0.3$,
and $\Omega_{\Lambda}=0.7$ in this study.

Figure 1:  HST color images of the host clusters of the jellyfish galaxies in
this study. These images were prepared by combining the two band images of
HST/ACS $F606W$ and $F814W$. Cyan circles denote the location of each
jellyfish galaxy. Magenta circles denote the brightest cluster galaxy (BCG),
which is set to be the center of each cluster. The orientations and the
angular scales are marked.

##  2 Sample and Data

###  2.1 Jellyfish Galaxy Sample

Table 2: Properties of the Host Clusters of the Jellyfish Galaxies

Cluster NameaaMACSJ0916.1$-$0023 (M0916), MACSJ1752.0$+$4440 (M1752), Abell 2744 (A2744), MACSJ1258.0$+$4702 (M1258), and MACSJ1720.2$+$3536 (M1720). | M0916 | M1752 | A2744 | M1258 | M1720
---|---|---|---|---|---
R.A. (J2000)bbNASA/IPAC Extragalactic Database (NED). | 09:16:13.9 | 17:52:01.5 | 00:14:18.9 | 12:58:02.1 | 17:20:16.8
Decl. (J2000)bbNASA/IPAC Extragalactic Database (NED). |  $-$00:24:42 |  $+$44:40:46 |  $-$30:23:22 |  $+$47:02:54 |  $+$35:36:26
Redshift ($z$)ccRepp & Ebeling (2018) for MACSJ0916.1$-$0023 and MACSJ1258.0$+$4702, Golovich et al. (2019) for MACSJ1752$+$4440, Owers et al. (2011) for Abell 2744, and Ebeling et al. (2010) for MACSJ1720.2$+$3536. | 0.320 | 0.365 | 0.306 | 0.331 | 0.387
Luminosity distance (Mpc)ddBased on the cosmological parameters of $H_{0}=70~{}{\rm km~{}s^{-1}~{}Mpc^{-1}}$, $\Omega_{M}=0.3$, $\Omega_{\rm\Lambda}=0.7$, and $T_{\rm CMB}=2.73~{}{\rm K}$. | 1673.0 | 1949.1 | 1591.0 | 1740.0 | 2089.1
Angular scale (${\rm kpc~{}arcsec^{-1}}$)ddBased on the cosmological parameters of $H_{0}=70~{}{\rm km~{}s^{-1}~{}Mpc^{-1}}$, $\Omega_{M}=0.3$, $\Omega_{\rm\Lambda}=0.7$, and $T_{\rm CMB}=2.73~{}{\rm K}$. | 4.655 | 5.073 | 4.519 | 4.762 | 5.265
Age at redshift (Gyr)ddBased on the cosmological parameters of $H_{0}=70~{}{\rm km~{}s^{-1}~{}Mpc^{-1}}$, $\Omega_{M}=0.3$, $\Omega_{\rm\Lambda}=0.7$, and $T_{\rm CMB}=2.73~{}{\rm K}$. | 9.86 | 9.47 | 9.98 | 9.76 | 9.29
$E(B-V)$ (mag)eeForeground reddening from Schlafly & Finkbeiner (2011). | 0.027 | 0.027 | 0.012 | 0.012 | 0.034
Velocity dispersion (${\rm km~{}s^{-1}}$)ffGolovich et al. (2019) for MACSJ1752$+$4440, Boschin et al. (2006) for the main clump of Abell 2744, and ∗ marks the velocity dispersion estimated from the scaling relation of Evrard et al. (2008). | $1066^{\ast}$ | 1186 | 1301 | $872^{\ast}$ | $1068^{\ast}$
Virial mass ($10^{14}~{}M_{\odot}$)ggVirial mass ($M_{200}$) and virial radius ($r_{200}$) are from the following literature: Medezinski et al. (2018) and Osato et al. (2020) for MACSJ0916$-$0023, Golovich et al. (2019) for MACSJ1752.0$+$4440, and Boschin et al. (2006) for Abell 2744, Sereno & Ettori (2017) for MACSJ1258.0$+$4702, and Umetsu et al. (2018) for MACSJ1720.2$+$3536\. Asterisks mark the virial mass estimated from the scaling relation of Evrard et al. (2008). | 11.6 | $15.5^{\ast}$ | 22.0 | 6.3 | 11.2
Virial radius (Mpc)ggVirial mass ($M_{200}$) and virial radius ($r_{200}$) are from the following literature: Medezinski et al. (2018) and Osato et al. (2020) for MACSJ0916$-$0023, Golovich et al. (2019) for MACSJ1752.0$+$4440, and Boschin et al. (2006) for Abell 2744, Sereno & Ettori (2017) for MACSJ1258.0$+$4702, and Umetsu et al. (2018) for MACSJ1720.2$+$3536\. Asterisks mark the virial mass estimated from the scaling relation of Evrard et al. (2008). | 1.9 | 2.1 | 2.4 | 1.6 | 1.9
X-ray luminosity (${\rm erg~{}s^{-1}}$)hhThe ROSAT all-sky survey ($0.1-2.4~{}{\rm keV}$; Voges et al., 1999). | $5.9\times 10^{44}$ | $6.3\times 10^{44}$ | $1.6\times 10^{45}$ | $3.5\times 10^{44}$ | $1.6\times 10^{45}$

††footnotetext: Notes.

Figure 2:  The zoom-in HST images of the five jellyfish galaxies with the size
of $12^{\prime\prime}\times 12^{\prime\prime}$. Green boxes show the field-of-
view of the GMOS/IFU 2-slit mode ($5^{\prime\prime}\times 7^{\prime\prime}$).
Magenta arrows represent the directions to the cluster center (BCGs). The
orientations are same as in  Figure 1.

We selected five jellyfish galaxies in the MACS clusters (McPartland et al.,
2016) and Abell 2744 (Owers et al., 2012) for our IFS observations:
MACSJ0916-JFG1 ($z=0.330$), MACSJ1752-JFG2 ($z=0.353$), A2744-F0083
($z=0.303$), MACSJ1258-JFG1 ($z=0.342$), and MACSJ1720-JFG1 ($z=0.383$). Among
these five galaxies, A2744-F0083 and MACSJ1258-JFG1 host type I active
galactic nuclei (AGN) in their center. We will describe this again with the
Baldwin, Phillips & Terlevich (BPT) diagrams (Baldwin et al., 1981) in
Section 4.1. The properties of the host clusters are summarized in  Table 2.

Figure 1 shows the HST/ACS color composite images of the selected jellyfish
galaxies and their host clusters. We display the locations of the brightest
cluster galaxies (BCGs) and jellyfish galaxies in the host clusters. In this
study, we set the marked BCGs as the center of each cluster.  Figure 2 shows
the zoom-in thumbnail images of the five jellyfish galaxies. We mark the FOV
of the GMOS/IFU 2-slit mode (green boxes; $5\arcsec\times 7\arcsec$) and the
direction to the cluster center (magenta arrows). In these HST optical images,
all the jellyfish galaxies show disturbed and asymmetric morphology with blue
tails and bright star-forming knots. MACSJ0916-JFG1 has a short ($\sim
5~{}{\rm kpc}$) tail at the eastern side of the galactic center and a few
star-forming knots in the disk and tail. MACSJ1752-JFG2 shows not only an
extended ($\sim 25~{}{\rm kpc}$) tail towards the southern direction, but also
large bright knots with ongoing star formation around the disk. A2744-F0083 is
the most spectacular object exhibiting large and bright star-forming knots and
multiple stripped tails. MACSJ1258-JFG1 has a bright tail towards the northern
direction with a length of $\sim 10~{}{\rm kpc}$ and small blue extraplanar
knots outside the disk. MACSJ1720-JFG1 is the most distant galaxy in this
study. This galaxy shows a star-forming tail in the northern region and a
bright compressed region at its head. The FOV of the GMOS/IFU is wide enough
to cover the substructures of the jellyfish galaxies except for a few faint
tails at the western side of A2744-F0083.

For these jellyfish galaxies, there seems to be no clear trend between the
direction of the tails and their direction towards the cluster center. Tails
of MACSJ0916-JFG1 and MACSJ1752-JFG2 are extended in a direction nearly
tangential to the cluster center. In contrast, tails of MACSJ1258-JFG1 and
MACSJ1720-JFG1 are extended towards the opposite direction to the cluster
center. Interestingly, A2744-F0083 has multiple tails extending towards the
BCGs in the cluster center. This misalignment of the direction of tails and
the direction to the cluster center has been also shown by the jellyfish
galaxies in the GASP survey (Poggianti et al., 2016) and those in the
IllustrisTNG simulation (Yun et al., 2019). This indicates that these
jellyfish galaxies travel in various orbital trajectories within their host
clusters, and do not necessarily travel in a radial direction.

Figure 3: Color-magnitude diagrams of galaxies detected in the HST images of
the host clusters. All colors and magnitudes are de-reddened by the foreground
extinction magnitudes. Red star symbols show the data of the five jellyfish
galaxies. Gray circles show the data of all extended sources with half-light
radii larger than $0\farcs 2$ in the angular scale and $\gtrsim 1~{}{\rm kpc}$
in the physical scale.

Figure 3 shows the color-magnitude diagrams of galaxies in the HST fields of
the host clusters. We ran SExtractor (Bertin & Arnouts, 1996) to detect
sources in the HST images and measure their colors and magnitudes. For the
color-magnitude diagrams, we plot the data of the extended sources (gray
circles) with a half-light radius (FLUX_RADIUS) larger than 4 pixels ($0\farcs
2$ in the angular scale and $\gtrsim 1~{}{\rm kpc}$ in the physical scale).
These diagrams clearly show the red sequence of cluster members in each HST
field. The jellyfish galaxies in this study (red star symbols) have much bluer
colors than the galaxies in the red sequence. This indicates that young
stellar populations are more dominant in these jellyfish galaxies than in
other cluster members.

Table 3: GMOS/IFU Observations of the Jellyfish Galaxies

Galaxy Name | MACSJ0916-JFG1 | MACSJ1752-JFG2 | A2744-F0083 | MACSJ1258-JFG1 | MACSJ1720-JFG1
---|---|---|---|---|---
Program ID | GS-2019A-Q-214 | GN-2019A-Q-215 | GS-2019B-Q-219 | GN-2021A-Q-205 | GN-2021A-Q-205
Instrument | GMOS-S | GMOS-N | GMOS-S | GMOS-N | GMOS-N
Observing mode | IFU two-slit | IFU two-slit | IFU two-slit | IFU two-slit | IFU two-slit
Grating & Filter | R150+GG455 | R150+GG455 | R400+CaT | R150+GG455 | R150+GG455
$\lambda_{\rm obs}~{}({\rm\AA})$ | $4550-9550$ | $4690-9590$ | $7820-9260$ | $4690-9280$ | $4700-9700$
$\lambda_{\rm rest}~{}({\rm\AA})$ | $3420-7180$ | $3470-7090$ | $6000-7110$ | $3490-6910$ | $3430-7080$
Spectral resolutionaaSpectral resolution is derived from $R=\lambda/\Delta\lambda_{\rm FWHM}$ in the ${\rm H\alpha}$ emission line. | 1230 | 1260 | 2440 | 1200 | 1270
Total exposure (sec) | 4320 | 15040 | 10320 | 9900 | 14400
Observing date (UT) | 2019-03-04 | 2019-06-11 | 2019-08-09 | 2021-05-17 | 2021-06-21
Mean airmass | 1.29 | 1.25 | 1.19 | 1.23 | 1.18
Standard star | GD108 | Wolf1346 | VMa2 | Feige34 | Feige34
Seeing FWHMbbSeeing values are derived from the median FWHMs of stars detected in the following GMOS acquisition images: MACSJ0916-JFG1 ($r$-band, 60 sec), MACSJ1752-JFG2 ($r$-band, 15 sec), A2744-F0083 ($i$-band, 30 sec), MACSJ1258-JFG1 ($r$-band, 15 sec), and MACSJ1720-JFG1 ($r$-band, 15 sec). | 0.88″ | 0.50″ | 1.14″ | 0.71″ | 0.56″
Surface brightness limitccThe $3\sigma$ surface brightness level measured at the ${\rm H\alpha}$+[N II] regions. | $4.9\times 10^{-20}$ | $1.8\times 10^{-19}$ | $2.7\times 10^{-19}$ | $4.5\times 10^{-19}$ | $2.1\times 10^{-20}$
(${\rm erg~{}s^{-1}~{}cm^{-2}~{}arcsec^{-2}}$)

††footnotetext: Notes.

###  2.2 Gemini GMOS/IFU Data

####  2.2.1 Observation

Table 3 summarizes our GMOS/IFU observation programs. The five jellyfish
galaxies were observed in the 2019A/B and 2021A seasons (PI: Jeong Hwan Lee):
MACSJ0916-JFG1, MACSJ1752-JFG2, A2744-F0083, MACSJ1258-JFG1, and
MACSJ1720-JFG1. (PID: GN-2021A-Q-205). We obtained the IFU data of three
galaxies (MACSJ1752-JFG2, MACSJ1258-JFG1, and MACSJ1720-JFG1) from the site of
GMOS-North (GMOS-N) and two other targets (MACSJ0916-JFG1 and A2744-F0083)
from GMOS-South (GMOS-S). All the observations used the GMOS/IFU 2-slit mode
with an FOV of $5\arcsec\times 7\arcsec$.

We observed all galaxies with the exception of A2744-F0083 with the R150
grating and GG455 blocking filter, which securely covers a wide range of
wavelengths from 4700Å to 9200Å in the observer frame ($\sim 3500-6900$Å in
the rest frame). This coverage includes strong emission lines from [O
II]$\lambda\lambda 3727,3729$ to [S II]$\lambda\lambda 6717,6731$. We derived
the spectral resolution of the spectra from the telluric emission lines
obtained by the sky fibers. The configuration of R150$+$GG455 has a low
spectral resolution of $R\sim 1200$ at the wavelength of the ${\rm H\alpha}$
line. For A2744-F0083, the R400 grating and CaT filter were applied with the
central wavelength of 8600Å. This combination had a limited wavelength
coverage from 7820Å to 9260Å (6000-7110Å in the rest frame) but had better
spectral resolution ($R\sim 2400$). As a result, the data of A2744-F0083 only
covered emission lines from [O I]$\lambda 6300$ to [S II]$\lambda\lambda
6717,6731$.

MACSJ0916-JFG1 was observed at the GMOS-South with an exposure time of
$4\times 1080~{}{\rm s}$ (total 1.2 hr) on the 2019-03-04 (UT). MACSJ1752-JFG2
was observed with the exposure time of $16\times 900~{}{\rm s}+640~{}{\rm s}$
(total 4.2 hr) during three nights starting from 2019-06-11 (UT). A2744-F0083
was observed with $12\times 860~{}{\rm s}$ (total 2.9 hr) on the UT dates from
2019-08-09 to 2019-08-30. In the 2021A season, MACSJ1258-JFG1 and
MACSJ1720-JFG1 were observed with $11\times 900~{}{\rm s}$ (total 2.8 hr) and
$16\times 900~{}{\rm s}$ (total 4.0 hr), respectively. The mean airmass of the
data ranged from 1.2 to 1.3 for all targets. The median full widths at half
maximum (FWHMs) of the seeing in our observations were measured from the
acquisition images, ranging about $0\farcs 5-0\farcs 7$ at the GMOS-N and
$0\farcs 9-1\farcs 2$ at the GMOS-S.

####  2.2.2 Data Reduction

We reduced the GMOS/IFU data using the GEMINI package in PyRAF. We used the
tasks of GBIAS, GFREDUCE, and GFRESPONSE for bias subtraction and flat
fielding with the Gemini Facility Calibration Unit (GCAL) flat. Since there
were some missing fibers that the PyRAF/Gemini tasks could not find, we
developed our own codes111https://github.com/joungh93/PyRAF_GMOS_IFU to
correct the IFU mask definition file (MDF) for proper flat fielding. We
performed the interactive tasks of GSWAVELENGTH to obtain the wavelength
solution from the CuAr arcs. The scattered light interfering in the fiber gaps
was removed by the 2-D surface model with the order of 3 in the GFSCATSUB
task. After the preprocessing of the science frames, the cosmic rays and the
sky lines were removed by GEMCRSPEC and GFSKYSUB tasks. Four standard stars
were used for flux calibrations of our sample: GD108 (MACSJ0916-JFG1),
Wolf1346 (MACSJ1752-JFG2), VMa2 (A2744-F0083), and Feige34 (MACSJ1258-JFG1 and
MACSJ1720-JFG1). We carried out the flux calibrations by using GSCALIBRATE
with the Chebyshev polynomials with an order of 11. These reduction processes
created individual IFU data cubes with dispersions of
$1.95{\rm~{}\AA~{}pixel^{-1}}$ for the R150 grating and
$0.75{\rm~{}\AA~{}pixel^{-1}}$ for the R400. The spatial pixel scale of all
cubes is $0\farcs 1~{}{\rm pixel^{-1}}$. We then carried out the spectral and
spatial alignments of the cubes and combined them into one final cube for each
target. We used these final data cubes for the analysis of the five jellyfish
galaxies in this study.

Table 4: Optical and Near-infrared Archival Images of the Jellyfish Galaxies

Galaxy Name | Instrument | Filters | SurveyaaHST \- PIs: H. Ebeling (PID 10491, 12166, 12884), D. Wittmann (PID 13343), B. Siana (PID 13389), J. Lotz (PID 13495), C. Steinhardt (PID 15117), and M. Postman (PID 12455), Spitzer \- PIs: E. Egami (PID 545, 12095), G. Rieke (PID 83), T. Soifer (PID 90257), R. Bouwens (PID 90213), C.Lawrence (PID 90233)
---|---|---|---
MACSJ0916-JFG1 |  HST/ACS |  $F606W$, $F814W$ | PID: 10491, 12166
| WISE | W1 (3.4 $\mu$m), W2 (4.6 $\mu$m) | All-Sky Data Release
MACSJ1752-JFG2 |  HST/ACS |  $F435W$, $F606W$, $F814W$ | PID: 12166, 12884, 13343
|  Spitzer/IRAC | 3.6 $\mu$m, 4.5 $\mu$m | PID: 12095
A2744-F0083 |  HST/ACS |  $F435W$, $F606W$, $F814W$ | PID: 13495, 15117
|  Spitzer/IRAC | 3.6 $\mu$m, 4.5 $\mu$m | PID: 83, 90257
MACSJ1258-JFG1 |  HST/ACS |  $F606W$, $F814W$ | PID: 10491, 12166
|  Spitzer/IRAC | 3.6 $\mu$m, 4.5 $\mu$m | PID: 12095
MACSJ1720-JFG1 |  HST/ACS |  $F435W$, $F606W$, $F814W$ | PID: 12455
|  Spitzer/IRAC | 3.6 $\mu$m, 4.5 $\mu$m | PID: 545, 90213, 90233

††footnotetext: Note.

###  2.3 Archival Images

We used optical and near-infrared (NIR) images of our targets to estimate
their stellar mass. This is because the signal-to-noise ratios (S/N) of the
GMOS/IFU spectra were not high enough to derive their stellar mass from
spectral continuum fitting. We collected the images from archives of the HST
for optical views and Wide-field Infrared Survey Explorer (WISE) and Spitzer
for NIR views. With these multi-wavelength images, we compared the morphology
of the stellar emission with that of the gas emission observed by the GMOS/IFU
spectral maps. In addition, we derived stellar masses of the jellyfish
galaxies using these images.  Table 4 lists the information of the archival
images we used for analysis.

####  2.3.1 HST Optical Images

We retrieved the HST/ACS images of the five jellyfish galaxies from the
Mikulski Archive for Space Telescopes (MAST). We obtained the individual
calibrated images (*_flc.fits or *_flc.fits) and drizzled them by using the
TweakReg and AstroDrizzle tasks in DrizzlePac. We combined all the images with
a pixel scale of $0\farcs 05~{}{\rm pixel^{-1}}$.

MACSJ0916-JFG1 and MACSJ1258-JFG1 were covered with two optical bands of
ACS/$F606W$ and ACS/$F814W$. Both bands were observed during the HST program
of the snapshot survey of the massive galaxy clusters (PI: H. Ebeling). The
drizzled HST images had exposure times of 1200 sec for $F606W$ and 1440 sec
for $F814W$.

For MACSJ1752-JFG2, we utilized three ACS optical bands ($F435W$, $F606W$, and
$F814W$). These images were obtained through a snapshot survey (PI: H.
Ebeling) and a program for weak lensing analysis (PI: D. Wittmann). The
exposure times of the final images were 2526 sec ($F435W$), 3734 sec
($F606W$), and 6273 sec ($F814W$).

A2744-F0083 was covered in the HFF (Lotz et al., 2017) and the Buffalo HST
survey (Steinhardt et al., 2020). We utilized three ACS optical bands
($F435W$, $F606W$, and $F814W$) from the surveys. These drizzled images had
the longest exposure times among our targets: 45747 sec ($F435W$), 26258 sec
($F606W$), and 108984 sec ($F814W$).

MACSJ1720-JFG1 was observed by a multi-wavelength observation program for the
lensing analysis of massive clusters (PI: M. Postman). We utilized three ACS
optical bands ($F435W$, $F606W$, and $F814W$). The images had exposure times
of 2040 sec ($F435W$), 2020 sec ($F606W$), and 3988 sec ($F814W$),
respectively.

####  2.3.2 Spitzer and WISE NIR Images

We obtained archival NIR images taken with Spitzer/IRAC from the Spitzer
Heritage Archive (SHA) for all galaxies with the exception of MACSJ0916-JFG1,
which was not observed by Spitzer. For MACSJ0916-JFG1, we retrieved the WISE
images from the NASA/IPAC Infrared Science Archive (IRSA). The images were
taken from the WISE All-Sky Data Release and had exposure times of 7.7 sec for
W1 ($3.4~{}{\rm\mu m}$) and W2 ($4.6~{}{\rm\mu m}$) bands. As the sensitivity
of the W3 ($12~{}{\rm\mu m}$) and W4 ($22~{}{\rm\mu m}$) bands are too low, we
only used the W1 and W2 images for our analysis. MACSJ1752-JFG2 and
MACSJ1258-JFG1 were observed through an IRAC snapshot imaging survey of
massive clusters (PID: 12095, PI: Egami) with exposure times of 94 sec
($3.6~{}{\rm\mu m}$) and 97 sec ($4.5~{}{\rm\mu m}$). As for A2744-F0083, we
combined a total of 20 IRAC exposures from two science programs: PID 83 (2
exposures; PI: Rieke) and PID 90257 (18 exposures; PI: Soifer). The exposure
times of the combined images were 1878 sec ($3.6~{}{\rm\mu m}$) and 1936 sec
($4.5~{}{\rm\mu m}$). MACSJ1720-JFG1 had 6 IRAC exposures from three programs:
PID 545 (2 exposures), PID 90213 (3 exposures), and PID 90233 (1 exposure).
After combining these images, we obtained the final images with exposure times
of 374 sec ($3.6~{}{\rm\mu m}$) and 387 sec ($4.5~{}{\rm\mu m}$).

##  3 Analysis

###  3.1 Emission Line Fitting

In this study, we focused on analyzing strong emission lines such as ${\rm
H\alpha}$, ${\rm H\beta}$, [O III], [N II], and [S II] given the low S/N of
the spectral continuum in the GMOS/IFU data. First, we removed the background
spectral noise from the combined IFU cubes. We took the median value of the
spaxels at the edge of the cubes, which has no object signal, as background
noise in each cube. We subtracted these noise patterns from all the pixels in
the IFU cubes. This process cleaned the unnecessary instrumental noise pattern
of the spectra. Next, we carried out Voronoi binning with the Python vorbin
package (Cappellari & Copin, 2003) to obtain high S/N for emission line
analysis in each bin. The S/N in the Voronoi bins ranged from 30 to 60 at the
${\rm H\alpha}$+[N II] regions for the jellyfish galaxies, depending on the
exposure time and the quality of the data. The numbers of the final Voronoi
bins in the IFU cubes were 42 (MACSJ0916-JFG1), 147 (MACSJ1752-JFG2), 175
(A2744-F0083), 215 (MACSJ1258-JFG1), and 166 (MACSJ1720-JFG1). Then, we
subtracted the continuum from the spectra of all the Voronoi bins. We
performed the Gaussian smoothing for continuum subtraction because it was
difficult to carry out the spectral continuum fitting (e.g., pPXF) for the
Voronoi bins with low S/N in the outer region. For the Gaussian smoothing of
the continuum, we applied a kernel width of 10Å after masking the emission
lines.

We then fitted strong emission lines (${\rm H\beta}$, [O III]$\lambda\lambda
4959,5007$, ${\rm H\alpha}$, [N II]$\lambda\lambda 6548,6584$, and [S
II]$\lambda\lambda 6717,6731$) with the Markov chain Monte Carlo (MCMC) method
using the Python emcee package (Foreman-Mackey et al., 2013). For A2744-F0083,
we fitted only the ${\rm H\alpha}$+[N II] doublet and [S II] doublet lines. We
applied multiple Gaussian functions for fitting the line profiles. For the
narrow components of the emission lines, we used three Gaussian profiles for
the ${\rm H\beta}$+[O III] and ${\rm H\alpha}$+[N II] regions and two for the
[S II] doublet. In the case of AGN host galaxies (A2744-F0083 and
MACSJ1258-JFG1), more profiles were added for fitting the broad components of
the ${\rm H\beta}$+[O III] and ${\rm H\alpha}$+[N II] regions.

We initially fitted the emission lines from the central Voronoi bins with high
S/N. We then used the initial solutions to run the MCMC process for all the
bins. We defined the prior distributions of parameters as Gaussian functions
centered on the initial solutions. We implemented the MCMC process in emcee
with 50 walkers and 2000 steps. After finishing all the MCMC steps of walkers,
we measured the skewness and kurtosis of the posterior distributions of
parameters to check the reliability of our parameter estimation. We rejected
solutions from Voronoi bins with values of skewness and kurtosis higher than
0.5 or lower than $-0.5$. We took the median values of the posterior
distributions as the burn-in solutions of the MCMC process.

In  Figure 4, we plot the GMOS/IFU spectra in the central regions (within a
radius of $0\farcs$4) of our targets. We used these integrated spectra for
obtaining the initial solutions of the line fitting in all the Voronoi bins.
We plot the original spectra and the continuum subtracted spectra in the left
and middle panels, respectively. The right panels show the zoom-in spectra at
the ${\rm H\alpha}$+[N II] regions overlaid with the best-fit models (pink
solid lines). For the AGN host galaxies, we added two more profiles (red
dashed lines) for broad components of this region. Residuals (green solid
lines) show that the best-fit models represent the spectra well.

Figure 4:  The integrated spectra within a radius of within a radius of
$0\farcs 4$ from the galactic center of jellyfish galaxies in this study. The
left panels show the original spectra before continuum subtraction, and the
middle panels show the continuum subtracted spectra. In the middle panels,
several strong emission lines are marked in each spectrum. The right zoom-in
panels show the ${\rm H\alpha}$+[N II] region of each galaxy. We plot the
observed spectra (blue solid lines), our best-fit models (pink solid lines),
and residuals (green solid lines). In the case of AGN host galaxies, we plot
narrow and broad components of the emission lines with orange solid lines and
red dashed lines, respectively.

###  3.2 Measurements of SFRs, Gas Velocity Dispersion, and Stellar Masses

####  3.2.1 $H\alpha$-derived SFRs

In this section, we describe how we estimated the SFRs based on the emission
line analysis. We derived the SFRs of jellyfish galaxies from their ${\rm
H\alpha}$ luminosity that was corrected for stellar absorption, extinction,
and AGN contamination.

Stellar absorption affects the observed fluxes of the Balmer lines such as
${\rm H\alpha}$ and ${\rm H\beta}$. Since the S/N of stellar continuum in our
GMOS/IFU data is too low to do the full spectrum fitting, we took a simple
approach for absorption correction by assuming constant equivalent widths
(EWs) of the Balmer absorption lines (Hopkins et al., 2003; Gunawardhana et
al., 2011). We used the following formula for the absorption correction,

$S_{\rm H\alpha}=F_{\rm H\alpha}\times\frac{{\rm EW_{H\alpha}}+{\rm
EW}_{c}}{\rm EW_{H\alpha}},$ (1)

where $S_{\rm H\alpha}$ is the absorption-corrected ${\rm H\alpha}$ flux,
$F_{\rm H\alpha}$ is the observed ${\rm H\alpha}$ flux, ${\rm EW_{H\alpha}}$
is the observed ${\rm H\alpha}$ EW, and ${\rm EW}_{c}$ is the EW for stellar
absorption. Hopkins et al. (2003) suggested that the median intrinsic value of
${\rm EW}_{c}$ is 2.6Å for the SDSS sample of star-forming galaxies but this
value would be reduced to 1.3Å in the real SDSS spectra. This is because SDSS
spectra have sufficient spectral resolution ($R\sim 2000$) to resolve broad
stellar absorption profiles (see Figure 7 in Hopkins et al. (2003)).
Therefore, we adopted ${\rm EW}_{c}=1.3{\rm\AA}$ for A2744-F0083 observed by
the R400 grating with a similar resolution ($R\sim 2400$) to the SDSS and
${\rm EW}_{c}=2.6{\rm\AA}$ for the remaining targets observed with the R150
grating ($R\sim 1200$). We applied the same EWs to correct the absorption of
${\rm H\beta}$ line.

We subsequently corrected for internal dust extinction and foreground
extinction. For the dust extinction correction, we used the absorption-
corrected flux ratio of the ${\rm H\alpha}$ and ${\rm H\beta}$ lines,
otherwise known as the Balmer decrement. We assumed an intrinsic ${\rm
H\alpha}$ to ${\rm H\beta}$ flux ratio of 2.86 for the case B recombination
with $T_{e}=10000~{}{\rm K}$ and adopted the Cardelli et al. (1989) extinction
law. The equations for extinction correction are given as below,

$A_{\rm H\alpha}=k_{\rm H\alpha}\times E(B-V),$ (2)

where $A_{\rm H\alpha}$ is the extinction magnitude of the ${\rm H\alpha}$
flux, $k_{\rm H\alpha}$ is the extinction coefficient for ${\rm H\alpha}$, and
$E(B-V)$ is the color excess. We adopted $k_{\rm H\alpha}=2.53$ from Cardelli
et al. (1989). The color excess can be derived from the equation (3).

$E(B-V)=2.33\times\log\left[\frac{S_{\rm H\alpha}/S_{\rm
H\beta}}{2.86}\right],$ (3)

where $S_{\rm H\alpha}/S_{\rm H\beta}$ is the absorption-corrected ${\rm
H\alpha}$ to ${\rm H\beta}$ flux ratio. We also corrected for foreground
extinction using the reddening magnitudes from Schlafly & Finkbeiner (2011)
(see  Table 2).

From the corrected ${\rm H\alpha}$ flux, we derived the SFRs using the
following relation given by Kennicutt (1998) assuming the Chabrier (2003)
initial mass function (IMF),

${\rm SFR_{H\alpha}}=4.6\times 10^{-42}L_{\rm H\alpha},$ (4)

where ${\rm SFR_{H\alpha}}$ is the ${\rm H\alpha}$-based SFR with unit of
$M_{\odot}~{}{\rm yr^{-1}}$ and $L_{\rm H\alpha}$ is the ${\rm H\alpha}$
luminosity corrected for stellar absorption and extinction. The extinction law
and IMF adopted in this paper are consistent with those in the GASP studies.

Throughout these processes, we rejected the Voronoi bins with S/N (${\rm
H\alpha}$) lower than 3. In addition, we excluded the Voronoi bins classified
as AGN and low-ionization nuclear emission-line regions (LINERs) in the BPT
diagram, as shown in  Figures 5 and  6 (see  Section 4.1). For the Voronoi
bins with $\rm S/N<3$ in ${\rm H\beta}$ and [O III], we used the [N
II]$\lambda 6584/{\rm H\alpha}$ ratio for the classification instead. We
classified the Voronoi bins with log([N II]$\lambda 6584/{\rm H\alpha})>-0.4$
as AGN and excluded them from consideration. We also included the Voronoi bins
with ${\rm S/N~{}(H\alpha)>3}$ but weak S/N ($<3$) of ${\rm H\beta}$ and the
BPT forbidden lines ([O III] and [N II]) for computing the SFR, as done in
Medling et al. (2018).

As a result, total SFR values in each correction step (continuum subtraction,
absorption correction, and extinction correction) for the five jellyfish
galaxies are listed in  Table 5. This table shows that dust extinction
correction takes much more effect on the SFR values than the two other
correction steps.

Table 5: Total SFR Calculations of the Jellyfish Galaxies in Each Step

Galaxy Name | Initial SFR | Continuum subtraction | Absorption correction | Extinction correction
---|---|---|---|---
| ($M_{\odot}~{}{\rm yr^{-1}}$) | ($M_{\odot}~{}{\rm yr^{-1}}$) | ($M_{\odot}~{}{\rm yr^{-1}}$) | ($M_{\odot}~{}{\rm yr^{-1}}$)
(1) | (2) | (3) | (4) | (5)
MACSJ0916-JFG1 | 7.21 | 5.47 | 5.64 | 7.12
MACSJ1752-JFG2 | 11.43 | 8.79 | 9.03 | 30.43
A2744-F0083∗ | 12.76 | 9.08 | 9.17 | 22.00
MACSJ1258-JFG1∗ | 17.89 | 10.37 | 11.37 | 35.71
MACSJ1720-JFG1 | 13.75 | 7.14 | 7.62 | 17.37

††footnotetext: Notes.

††footnotetext: Columns are: (1) Name of jellyfish galaxy; (2) Total SFR
values from the original spectra; (3) Total SFR values from the spectra after
continuum subtraction; (4) Total SFR values from the spectra after continuum
subtraction and stellar absorption correction; (5) Final SFR values from the
spectra after continuum subtraction, stellar absorption correction, and dust
extinction correction.

††footnotetext: Asterisks (∗) mark AGN host galaxies.

####  3.2.2 Gas Velocity Dispersion

We derived the gas velocity dispersion ($\sigma_{v,{\rm gas}}$) using the
standard deviation of ${\rm H\alpha}$ emission line corrected for beam-
smearing and instrumental dispersion. Beam-smearing occurs when the observed
line in a IFU spaxel is blended with the lines from the neighboring spaxels,
which makes a broader line profile. Since the seeing FWHM in our observations
ranged from $0\farcs 5$ to $1\farcs 1$, which corresponds from 5 to 11 spaxels
for the GMOS/IFU, this effect significantly contributes to the velocity
dispersion. To correct for beam-smearing, we followed the method described in
Appendix A in Stott et al. (2016). Using the artificial VLT/KMOS data cube
with similar seeing and pixel scale to our GMOS/IFU data, they suggested that
a linear subtraction of velocity gradient ($\Delta v/\Delta r$) from the
observed velocity dispersion can effectively correct for beam-smearing. This
method is described with the equation below,

$\sigma_{v,{\rm cor}}=\sigma_{v,{\rm obs}}-\frac{\Delta v}{\Delta r},$ (5)

where $\sigma_{v,{\rm cor}}$ is the beam-smearing corrected velocity
dispersion, $\sigma_{v,{\rm obs}}$ is the observed velocity dispersion, and
$\Delta v/\Delta r$ is the maximum velocity gradient at a distance equivalent
to the seeing FWHM from the center of a galaxy. Our data cubes showed maximum
velocity gradients of $\Delta v/\Delta r=4.9~{}{\rm
km~{}s^{-1}~{}spaxel^{-1}}$ (MACSJ0916-JFG1), $8.2~{}{\rm
km~{}s^{-1}~{}spaxel^{-1}}$ (MACSJ1752-JFG2), $10.6~{}{\rm
km~{}s^{-1}~{}spaxel^{-1}}$ (A2744-F0083), $10.5~{}{\rm
km~{}s^{-1}~{}spaxel^{-1}}$ (MACSJ1258-JFG1), and $14.8~{}{\rm
km~{}s^{-1}~{}spaxel^{-1}}$ (MACSJ1720-JFG1). For comparison, Stott et al.
(2016) measured $\Delta v/\Delta r=13.4~{}{\rm km~{}s^{-1}~{}spaxel^{-1}}$.

Then, we subtracted the GMOS/IFU instrumental dispersion from the beam-
smearing corrected dispersion. The instrumental velocity dispersion was
derived from a single Gaussian fitting of the sky emission lines which were
extracted during the data reduction process. We obtained the instrumental
velocity dispersion at the wavelength of ${\rm H\alpha}$ for our GMOS/IFU
data: $\sigma_{v,{\rm inst}}=103.1~{}{\rm km~{}s^{-1}}$ (MACSJ0916-JFG1),
$101.4~{}{\rm km~{}s^{-1}}$ (MACSJ1752-JFG2), $52.2~{}{\rm km~{}s^{-1}}$
(A2744-F0083), $106.1~{}{\rm km~{}s^{-1}}$ (MACSJ1258-JFG1), and $100.1~{}{\rm
km~{}s^{-1}}$ (MACSJ1720-JFG1). We used a quadrature removal of instrumental
dispersion,

$\sigma_{v,{\rm gas}}^{2}=\sigma_{v,{\rm cor}}^{2}-\sigma_{v,{\rm inst}}^{2},$
(6)

where $\sigma_{v,{\rm gas}}$ is the corrected gas velocity dispersion and
$\sigma_{v,{\rm inst}}$ is the instrumental velocity dispersion.

####  3.2.3 Stellar Masses

We estimated the stellar masses ($M_{\ast}$) of our jellyfish galaxies using
the NIR images described in  Section 2.3. The GASP studies derived the stellar
masses from the spectral continuum fitting (Poggianti et al., 2017). However,
our GMOS/IFU data showed too low S/N of the continuum to apply the same method
as the GASP studies. Instead, we converted the NIR fluxes of the Spitzer/IRAC
$3.6~{}{\rm\mu m}$ and $4.5~{}{\rm\mu m}$ (W1 and W2 in the case of WISE data)
to stellar masses following the relation from Eskew et al. (2012).

$M_{\ast}=\xi\times 10^{5.65}\times S^{2.85}_{\rm 3.6\mu m}S^{-1.85}_{\rm
4.5\mu m}\times(d_{L}/0.05)^{2}~{}M_{\odot},$ (7)

where $\xi$ is the conversion factor from the Salpeter IMF (Salpeter, 1955) to
other IMFs, $S_{\rm 3.6\mu m}$ and $S_{\rm 4.5\mu m}$ are the NIR fluxes of
$3.6~{}{\rm\mu m}$ and $4.5~{}{\rm\mu m}$ in Jy, and $d_{L}$ is the luminosity
distance in Mpc. We applied $\xi=0.54$ for the Chabrier IMF (Chabrier, 2003)
with a mass range from 0.1 to 100 $M_{\odot}$. This method has been used for
estimating the stellar masses of star-forming galaxies in Abell 2744 (Rawle et
al., 2014).

We utilized photutils v1.0.2 (Bradley et al., 2021) to measure the NIR fluxes
of the jellyfish galaxies. We performed aperture photometry using rectangular
apertures with the size of the GMOS/IFU FOV ($5^{\prime\prime}\times
7^{\prime\prime}$) for all targets except for MACSJ0916-JFG1. Since
MACSJ0916-JFG1 was only observed by WISE with poor spatial resolution ($\rm
FWHM\sim 6\farcs 4$ in W1 and W2; Wright et al., 2010), we increased the
aperture size to twice the FWHM of the WISE images. The derived stellar masses
are listed in  Table 6, ranging from ${\rm log}~{}M_{\ast}/M_{\odot}=9.84$ to
10.90.

###  3.3 Definition of Disk and Tail

In this study, we spatially divided a jellyfish galaxy into two components –
“disk” and “tail”. The disk corresponds to the main body of the galaxy, and
the tail is the extraplanar region composed of ram-pressure stripped ISM
outside the disk. To compare our results with the GASP studies, we used the
definition of the galaxy boundary between the disk and tail as described in
Poggianti et al. (2019) and Gullieuszik et al. (2020). We made use of the
emission line maps of the ${\rm H\alpha}$+[N II] region from the GMOS/IFU
data. Although the GASP studies used continuum maps of the ${\rm H\alpha}$+[N
II] region, it was difficult for this study to use continuum maps due to low
S/N. The background level and standard deviation ($1\sigma$) were estimated
using the DAOPHOT MMM algorithm on the $3\sigma$-clipped data in the emission
line maps. We then manually masked the disturbed region of the galaxy,
removing tails and extraplanar clumps. With the masked map, we carried out
elliptical isophote fitting using PyRAF/Ellipse. The galaxy boundary between
the disk and tail was defined as an elliptical isophote with a surface
brightness of $1\sigma$ above the background level. The upper right panels of
Figures 7-11 display the defined boundaries in the five jellyfish galaxies
with red dashed ellipses.

Although we followed the definition from the GASP studies, the boundary
between the disk and tail used in this paper could not be fully consistent
with that in the GASP studies. This is because manual masking of disturbed
regions is a little arbitrary and the spatial resolution of the GMOS/IFU data
is quite different from that of MUSE data in the physical scale (e.g., the
mean seeing FWHM $0\farcs 7$ corresponds to $>3~{}{\rm kpc}$ for our targets
but $\sim 0.7~{}{\rm kpc}$ in the GASP targets). These limitations could
contribute to large fluctuations of the fraction of SFR in tails as shown in
Table 6.

Figure 5:  A BPT diagram of the integrated spectra of the five jellyfish
galaxies. Each galaxy is marked with the same order as in  Figure 2: (a)
MACSJ0916-JFG1, (b) MACSJ1752-JFG2, (c) A2744-F0083, (d) MACSJ1258-JFG1, and
(e) MACSJ1720-JFG1. We plot a solid line from Kauffmann et al. (2003), a
dotted line from Kewley et al. (2001), and a dashed line from Sharp & Bland-
Hawthorn (2010) to divide star-forming, composite, AGN, and LINER regions in
this diagram.  Figure 6:  Left panels: BPT diagrams of the Voronoi bins with
${\rm S/N}>3$ in MACSJ1752-JFG2 (upper: a non-AGN host galaxy) and
MACSJ1258-JFG1 (lower: an AGN host galaxy). The colors of the circle symbols
represent the BPT classifications: star-forming (blue), composite (orange),
and AGN$+$LINER regions (green). We color-code each symbol with the value of
log ([O III] $\lambda 5007/{\rm H}\beta)$. Right panels: Spatial maps of the
regions classified in the BPT diagrams. Here we exclude the Voronoi bins with
S/N lower than 3. Red dashed ellipse represents the boundary of the disk and
tail of this galaxy. The orientation and distance scale are marked in the
figure.

##  4 Ionized Gas Properties of the Jellyfish Galaxies

###  4.1 BPT Diagnostics

In  Figure 5, we display the BPT diagram ([O III]$\lambda$5007/${\rm H\beta}$
vs. [N II]$\lambda$6584/${\rm H\alpha}$) of the five jellyfish galaxies using
the narrow components of the emission lines from their integrated spectra. All
data used except for A2744-F0083 were taken with the GMOS/IFU. For the BPT
diagram of A2744-F0083, we derived their flux ratios from the AAOmega spectra
(Owers et al., 2012) because the GMOS/IFU spectra of this galaxy did not cover
the ${\rm H\beta}$ and [O III] region. To determine the gas ionization
mechanisms of each galaxy, we classify galaxies into four regions (star-
forming, composite, AGN, and LINER) by adopting the well-known boundaries from
Kewley et al. (2001), Kauffmann et al. (2003), and Sharp & Bland-Hawthorn
(2010), as done in the GASP studies.

MACSJ0916-JFG1 (a) and MACSJ1752-JFG1 (b) are located in the star-forming
region, showing the lowest flux ratios of log([O III]$\lambda 5007/{\rm
H\beta})<-0.3$ and log([N II]$\lambda 6584/{\rm H\alpha})<-0.6$ among our
sample. A2744-F0083 (c) and MACSJ1258-JFG1 (d) are genuine AGN host galaxies
with log([O III]$\lambda 5007/{\rm H\beta})>0.5$. These galaxies also show
broad components of the Balmer emission lines (${\rm H\alpha}$ and ${\rm
H\beta}$) in their spectra, indicating that they are type I AGNs.
MACSJ1720-JFG1 (e) is located in the composite region, showing a higher ratio
of log([N II]$\lambda 6584/{\rm H\alpha})\sim-0.3$ than those from the two
star-forming galaxies (log([N II]$\lambda 6584/{\rm H\alpha})\sim-0.6$). This
indicates that the gas ionization in MACSJ1720-JFG1 cannot be solely explained
by star formation. However, it is difficult to say that this galaxy hosts a
type I AGN in its center, considering that its Balmer emission lines did not
show any broad components in our GMOS/IFU spectra and were fitted well with
single Gaussian components. It seems that other excitation mechanisms such as
shocks (Rich et al., 2011) or heat conduction (Boselli et al., 2016) could be
responsible for ionizing photons in this galaxy.

Figure 6 shows the BPT diagrams of Voronoi bins (left) and their spatial maps
(right) of the two jellyfish galaxies, which have relatively high S/N of the
BPT emission lines, as examples of a non-AGN host galaxy (MACSJ1752-JFG2) and
an AGN host galaxy (MACSJ1258-JFG1). We only plot the bins with S/N higher
than 3 for all the BPT emission lines. In the spatial map, we display all bins
with BPT classifications of star-forming (blue), composite (orange), and
AGN+LINER (green). For the remaining three galaxies, the Voronoi bins of the
GMOS/IFU data show very low S/N of ${\rm H\beta}$ and [O III] lines
(MACSJ0916-JFG1 and MACSJ1720-JFG1) or do not cover the wavelength range of
the ${\rm H\beta}$ and [O III] lines (A2744-F0083). We also plot the boundary
between the disk and tail of each galaxy (red dashed ellipse) as obtained from
the method described in  Section 3.3.

For MACSJ1752-JFG2, almost all bins belong to the star-forming region except
for one bin in the tail region. The central region shows log([N II]$\lambda
6584/{\rm H\alpha})\sim-0.6$ and log([O III]$\lambda 5007/{\rm
H\beta})\sim-0.3$, which are consistent with typical star-forming galaxies. It
is also remarkable that the eastern tail region exhibits a higher [O
III]/${\rm H\beta}$ ratio (log([O III]$\lambda 5007/{\rm H\beta})>0$) and a
lower [N II]/${\rm H\alpha}$ ratio (log([N II]$\lambda 6584/{\rm
H\alpha})<-0.75$) than the central region. The “composite” bin in the southern
tail has marginally low S/N, such that the gas ionization source is not clear.

MACSJ1258-JFG1 has high flux ratios of log([O III]$\lambda 5007/{\rm
H\beta})\sim 0.5$ and log([N II]$\lambda 6584/{\rm H\alpha})\sim-0.25$,
indicating that it hosts an AGN. In this figure, several Voronoi bins in the
central region and the head region in the east show low S/N of ${\rm H\beta}$
and [O III] lines. However, the Voronoi bins with ${\rm S/N}>3$ show that
there is a clear radial gradient of the BPT line ratios from the center to the
outer region. The outer disk and tail regions on the western side are
classified as composite regions, implying that both star formation and shock-
heating mechanisms contribute to gas ionization there.

###  4.2 SFRs, Gas Kinematics, and Dynamical States

We mainly analyze the ionized gas properties of each jellyfish galaxy using
${\rm H\alpha}$ emission lines. From  Figures 7 to  11, we map the
distributions of the ${\rm H\alpha}$ flux, the SFR surface density
($\Sigma_{\rm SFR}$), the radial velocity, and the gas velocity dispersion. We
select the Voronoi bins with ${\rm S/N~{}(H\alpha)}>3$ for the analysis.
Table 6 lists the stellar masses, dust extinction, SFRs, tail SFR fraction of
total SFR ($f_{\rm SFR}={\rm SFR(tail)/SFR(total)}$), and gas kinematics of
the jellyfish galaxies.

To compute and correct the SFRs, we derive dust extinction magnitudes from the
flux-weighted mean Balmer decrement (${\rm H\alpha/H\beta}$). While the Balmer
decrement and the extinction magnitude can slightly decrease from the center
to the outskirts (a median decrease of $\sim 0.25~{}{\rm mag}$ reported in
Poggianti et al. (2017)), we choose to assume a constant value throughout the
galaxy due to the poor S/N of the ${\rm H\beta}$ emission lines in the outer
regions. As a result, the five jellyfish galaxies in this study shows a median
total SFR of 22.0 $M_{\odot}~{}{\rm yr^{-1}}$ and a median tail SFR of 6.8
$M_{\odot}~{}{\rm yr^{-1}}$. These SFRs are much higher than those of the GASP
sample, with a median total SFR of 1.1 $M_{\odot}~{}{\rm yr^{-1}}$ and a
median tail SFR of 0.03 $M_{\odot}~{}{\rm yr^{-1}}$. In addition, the median
SFR fraction in the tail is also much higher in this study ($f_{\rm
SFR}=22\%$) than in the GASP studies ($f_{\rm SFR}=3\%$). Lee et al. (2022)
presented a detailed comparison of the star formation activity of the five
jellyfish galaxies in this study with that of other known jellyfish galaxies
including the GASP sample, considering galaxy stellar mass, redshift, and
jellyfish morphology. As a result, they suggested a positive correlation
between the star formation activity of jellyfish galaxies and the host cluster
properties.

For ionized gas kinematics, we derive radial velocities using the peak
wavelength measured from fitting. We show line-of-sight radial velocity maps
measured with respect to the central Voronoi bins. Following the definition
used in Wisnioski et al. (2015), We calculate the maximum rotational velocity
at a circularized radius of the disk ($R_{\rm disk,c}=\sqrt{ab}$, where $a$
and $b$ are the galactocentric radii of the semi-major and semi-minor axis) as
an indicator of the rotational speed of ionized gas within the disk.

In addition, we derive gas velocity dispersions as described in  Section 3.2.2
to investigate the dynamical states of the ionized gas in each jellyfish
galaxy. The median ${\rm H\alpha}$ velocity dispersion obtained by the GASP
studies is $27~{}{\rm km~{}s^{-1}}$, suggesting that the ${\rm
H\alpha}$-emitting clumps are dynamically cold (Bellhouse et al., 2019;
Poggianti et al., 2019). With this information, we compare the distribution of
the gas velocity dispersions in our sample with that of the GASP jellyfish
galaxies.

Table 6: Properties of the Jellyfish Galaxies

Galaxy Name | $\log M_{\ast}$ | ${\rm H\alpha/H\beta}$ | $A_{V}$ | Total SFR | Tail SFR | $f_{\rm SFR}$ | $|\Delta v|_{\rm disk}$ | $\sigma_{v,{\rm gas}}$
---|---|---|---|---|---|---|---|---
| ($M_{\odot}$) |  | (mag) | ($M_{\odot}~{}{\rm yr^{-1}}$) | ($M_{\odot}~{}{\rm yr^{-1}}$) | (%) | (${\rm km~{}s^{-1}}$) | (${\rm km~{}s^{-1}}$)
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9)
MACSJ0916-JFG1 | 10.18 | $3.16\pm 0.29$ | 0.31 | $7.12\pm 0.36$ | $0.56\pm 0.26$ | 7.9 | 54.4 | $30.0\pm 13.0$
MACSJ1752-JFG2 | 9.84 | $4.78\pm 0.10$ | 1.61 | $30.43\pm 0.17$ | $6.76\pm 0.13$ | 22.2 | 73.2 | $43.1\pm 12.6$
A2744-F0083∗ | 10.59 | $4.14\pm 0.06$ | 1.16 | $22.00\pm 0.10$ | $7.53\pm 0.08$ | 34.2 | 89.5 | $45.3\pm 5.3$
MACSJ1258-JFG1∗ | 10.90 | $4.64\pm 0.19$ | 1.52 | $35.71\pm 0.25$ | $16.80\pm 0.20$ | 47.0 | 134.5 | $100.5\pm 15.0$
MACSJ1720-JFG1 | 10.64 | $4.05\pm 1.40$ | 1.09 | $17.37\pm 1.12$ | $3.28\pm 0.81$ | 18.9 | 103.5 | $104.5\pm 15.8$

††footnotetext: Notes.

††footnotetext: Columns are: (1) Name of jellyfish galaxy; (2) NIR-derived
stellar mass within the GMOS/IFU FOV; (3) Mean flux ratio of ${\rm H\alpha}$
to ${\rm H\beta}$ derived from the integrated spectra; (4) The $V$-band
magnitude of dust extinction derived from (3); (5) Total SFR value estimated
when (4) is uniformly applied; (6) SFR in the tail region; (7) The tail SFR
fraction of total SFR ($f_{\rm SFR}={\rm SFR(tail)/SFR(total)}$); (8) The
maximum rotational velocity at a radius of disk; (9) Flux-weighted mean value
of gas velocity dispersion.

††footnotetext: Asterisks (∗) mark AGN host galaxies.

Figure 7:  Upper left: HST color image of MACSJ0916-JFG1 overlaid with the
${\rm H\alpha}$ flux contour (magenta solid lines) derived from the GMOS/IFU
data. We mark the orientation, distance scale, and redshift of this galaxy.
Upper right: The SFR density (${\rm\Sigma_{SFR}}$) map estimated from the
${\rm H\alpha}$ luminosity. Red dashed circle represents the boundary of the
disk and tail of this galaxy. Gray contours denote the spatial distribution of
${\rm H\alpha}$ flux. Right color bar shows the scale and range of the values.
Lower left: The radial velocity map derived from the peak wavelength of ${\rm
H\alpha}$ emission line. We display the relative velocity of each bin with
respect to the central Voronoi bin with the highest ${\rm H\alpha}$ flux.
Lower right: The gas velocity dispersion map derived from the width of ${\rm
H\alpha}$ emission line.

####  4.2.1 MACSJ0916-JFG1

In  Figure 7, it is clear that the ${\rm H\alpha}$ flux distribution of
MACSJ0916-JFG1 is well-matched with its optical light distribution. The
asymmetric feature of the ${\rm H\alpha}$ flux perfectly reproduces the
eastern tail in the optical image. The ${\rm H\alpha}$ flux contours confirm
that recent star formation has occurred in the blue knots in the disk and
tail.

In the SFR surface density map, we distinguish the disk and tail regions as
described in  Section 3.3. The disk region within the $1\sigma$ boundary (red
dashed ellipse) includes most of the Voronoi bins except for those in the
eastern tail. The SFR surface density is highly concentrated in the central
region. The flux-weighted mean of the Balmer decrement is 3.16, corresponding
to a $V$-band extinction magnitude of 0.31 mag, which is the lowest value
among our sample. The total SFR is estimated to be 7.12 $M_{\odot}~{}{\rm
yr^{-1}}$, with 6.55 $M_{\odot}~{}{\rm yr^{-1}}$ for the disk and 0.56
$M_{\odot}~{}{\rm yr^{-1}}$ for the tail. The tail SFR fraction of total SFR
is $f_{\rm SFR}=7.9\%$, which is the lowest value out of the five jellyfish
galaxies.

This galaxy shows a weak rotation of ionized gas in its disk. The line-of-
sight velocity relative to the galactic center is $-63.7~{}{\rm km~{}s^{-1}}$
(towards the observer) in the northern star-forming knots and $45.1~{}{\rm
km~{}s^{-1}}$ (away from the observer) in the eastern tail. In the disk
region, the maximum rotational velocity is estimated to be $54.4~{}{\rm
km~{}s^{-1}}$ at a disk radius of $R_{\rm disk,c}\sim 1\farcs 4$. The star-
forming knots follow the disk rotation well, which is consistently shown in
our sample.

The flux-weighted mean of the gas velocity dispersion is
$\langle\sigma_{v,\rm{gas}}\rangle=30.0~{}{\rm km~{}s^{-1}}$, with
$\langle\sigma_{v,\rm{gas}}\rangle=31~{}{\rm km~{}s^{-1}}$ for the disk and
$\langle\sigma_{v,\rm{gas}}\rangle=15~{}{\rm km~{}s^{-1}}$ for the tail
region. In particular, the eastern tail region shows a very low gas velocity
dispersion. The low gas velocity dispersion of this galaxy implies that the
star-forming regions are dynamically cold, which is consistent with the GASP
studies.

Figure 8:  Same as  Figure 7 but for MACSJ1752-JFG2.  Figure 9:  Same figure
as  Figure 7 but for A2744-F0083.  Figure 10:  Same as  Figure 7 but for
MACSJ1258-JFG1.  Figure 11:  Same as  Figure 7 but for MACSJ1720-JFG1.

####  4.2.2 MACSJ1752-JFG2

In  Figure 8, MACSJ1752-JFG2 shows a long tail extending $\sim 25~{}{\rm kpc}$
($\sim 5\arcsec$ in the angular scale) from the galactic center towards the
southern direction. In the ${\rm H\alpha}$ flux distribution, our GMOS/IFU
data successfully covers the southern tail except for a few faint blue knots
in the outer region. This galaxy also shows two disturbed regions at a
galactocentric distance of $\sim 5~{}{\rm kpc}$ towards the south and east
directions, exhibiting luminous blue knots. The ${\rm H\alpha}$ flux
distribution reproduces these peculiar substructures very well, which is
indicative of ongoing star formation in the substructures.

In the SFR surface density map, the “tail” region outside the $1\sigma$
boundary (red dashed ellipse) includes the southern tail and some star-forming
knots in the east. This galaxy shows the highest ${\rm H\alpha}$ to ${\rm
H\beta}$ ratio among our sample (${\rm H\alpha/H\beta=4.78}$), corresponding
to a dust extinction magnitude of $1.61~{}{\rm mag}$. Correcting for dust
extinction, we obtain a total SFR of 30.43 $M_{\odot}~{}{\rm yr^{-1}}$ (23.67
$M_{\odot}~{}{\rm yr^{-1}}$ in the disk and 6.76 $M_{\odot}~{}{\rm yr^{-1}}$
in the tail) with a tail SFR fraction of $f_{\rm SFR}=22.2\%$. This indicates
that the star formation activity is very strong in both the disk and the tail
of this object.

MACSJ1752-JFG2 shows a disk rotation with a maximum rotational velocity of
73.2 ${\rm km~{}s^{-1}}$. It seems that the substructures follow the disk
rotation well, but the southern tail shows a high relative velocity of $\sim
100$ ${\rm km~{}s^{-1}}$. This can be a sign of ongoing RPS, indicating that
the tail is stripped away from the center of the galaxy.

We obtain the flux-weighted mean of gas velocity dispersion of
$\langle\sigma_{v,\rm{gas}}\rangle=43.1~{}{\rm km~{}s^{-1}}$, indicating that
this galaxy is dynamically cold as well. The mean velocity dispersions of the
disk ($\langle\sigma_{v,\rm{gas}}\rangle=42~{}{\rm km~{}s^{-1}}$) and tail
($\langle\sigma_{v,\rm{gas}}\rangle=47~{}{\rm km~{}s^{-1}}$) do not show a
significant difference. However, there is some difference in the velocity
dispersion between the two bright knots in the south and east $\sim 5~{}{\rm
kpc}$ from the center. The southern large knot shows lower velocity dispersion
($\langle\sigma_{v,\rm{gas}}\rangle\sim 25~{}{\rm km~{}s^{-1}}$) than the
eastern one ($\langle\sigma_{v,\rm{gas}}\rangle\sim 50~{}{\rm km~{}s^{-1}}$).
This implies that these two knots have different dynamical states, suggesting
that ionized gas in the eastern knot is more turbulent than that in the
southern one.

####  4.2.3 A2744-F0083

A2744-F0083 is the most spectacular galaxy, exhibiting numerous star-forming
knots outside the main disk and non-ordered tails. There are very bright star-
forming knots at both the eastern and western sides of the disk. These knots
have comparable sizes and luminosities to compact dwarf galaxies (Owers et
al., 2012). The ${\rm H\alpha}$ flux distribution is highly asymmetric,
peaking in the eastern region. There are also long tails and extraplanar knots
to $\sim 25~{}{\rm kpc}$ ($\sim 5\farcs 5$) towards the southwestern direction
from the center, but the ${\rm H\alpha}$ S/N of our GMOS/IFU data is very low
in these regions. This is because the observation program of A2744-F0083 used
the R400 grating with higher spectral resolution and lower S/N for this
galaxy. Thus, we mainly analyze the ionized gas properties of the region
within $\sim 10~{}{\rm kpc}$ ($\sim 2\farcs 2$) from the center for this
galaxy.

The SFR surface density map shows very strong star formation activity in the
disk and in the eastern tail region. Since we remove the AGN contribution to
the SFR by subtracting the Voronoi bins with log([N II]$\lambda 6584/{\rm
H\alpha})>-0.4$, several bins in the central region are excluded in the map.
For dust correction, we obtain a ${\rm H\alpha}$/${\rm H\beta}$ ratio of 4.14
from the AAOmega fiber spectra. The total SFR is 22.00 $M_{\odot}~{}{\rm
yr^{-1}}$ with a disk SFR of 14.47 $M_{\odot}~{}{\rm yr^{-1}}$ and a tail SFR
of 7.53 $M_{\odot}~{}{\rm yr^{-1}}$ ($f_{\rm SFR}=34.2\%$). The high SFR ratio
in the tail indicates that the blue knots in the east undergo vigorous star
formation. For comparison, Rawle et al. (2014) estimated the SFR of this
galaxy to be 34.2 $M_{\odot}~{}{\rm yr^{-1}}$ based on the sum of the UV and
IR luminosities. Different SFR indicators could result in this difference of
SFRs because the ${\rm H\alpha}$ luminosity used in this study traces more
recent star formation than the UV and IR luminosities (Kennicutt & Evans,
2012).

The radial velocity map shows a clear disk rotation. The maximum rotational
velocity is 89.5 ${\rm km~{}s^{-1}}$ in the disk ($R_{\rm disk,c}\sim 1\farcs
4$). Outside the disk, the star-forming knots in the eastern region show a
radial velocity of $-88~{}{\rm km~{}s^{-1}}$. The symmetric feature of the
radial velocity distribution indicates that the star-forming regions follow
the disk rotation well.

In the gas velocity dispersion map, we observe a clear radial gradient from
the central disk ($\langle\sigma_{v,\rm{gas}}\rangle=54~{}{\rm km~{}s^{-1}}$)
to the tail region ($\langle\sigma_{v,\rm{gas}}\rangle=18~{}{\rm
km~{}s^{-1}}$). This is because the ${\rm H\alpha}$ emission lines from the
central disk are contaminated by the AGN activity, which broadens the line
profiles. This feature has been also shown in the GASP jellyfish galaxies
hosting AGNs (Poggianti et al., 2019). Star-forming knots in the tail region
are dynamically cold, which is similar to those in MACSJ0916-JFG1 and
MACSJ1752-JFG2.

####  4.2.4 MACSJ1258-JFG1

MACSJ1258-JFG1 is the most massive galaxy ($\log M_{\ast}/M_{\odot}=10.90$)
among our sample and hosts a type I AGN. In addition, it has a luminous tail
as long as $\sim 10~{}{\rm kpc}$ ($\sim 2\farcs 1$) in the northern region and
plenty of blue knots are distributed around the disk. There is also an
asymmetric tail feature in the southwestern region of the galaxy. Overall,
these substructures seem to be consistent with the ${\rm H\alpha}$ flux
distribution of this galaxy.

Like A2744-F0083, the SFR surface density map excludes the central region with
the BPT classification of AGN or LINER. We obtain a mean Balmer decrement of
4.64, which corresponds to a $V$-band extinction magnitude of 1.52 mag. We
measure a total SFR of 35.71 $M_{\odot}~{}{\rm yr^{-1}}$, with a disk SFR of
18.91 $M_{\odot}~{}{\rm yr^{-1}}$and a tail SFR of 16.80 $M_{\odot}~{}{\rm
yr^{-1}}$ ($f_{\rm SFR}=47\%$). The $f_{\rm SFR}$ value is the highest among
our targets. This high fraction of the tail SFR might result from strong star
formation activity in the substructures in the northern and the southwestern
regions ($\sim 10~{}{\rm kpc}$ from the center of the galaxy).

The radial velocity map shows a strong rotation with a maximum rotation
velocity of 134.5 ${\rm km~{}s^{-1}}$ in the disk. The northern tail shows a
radial velocity of $\sim-100$ ${\rm km~{}s^{-1}}$ and the southern region
shows a radial velocity of $\sim 150$ ${\rm km~{}s^{-1}}$. These substructures
follow the disk rotation well.

The mean gas velocity dispersion of this galaxy is estimated to be
$\langle\sigma_{v,\rm{gas}}\rangle=100.5~{}{\rm km~{}s^{-1}}$, which is higher
than those of MACSJ0916-JFG1 and MACSJ1752-JFG2. The mean gas velocity
dispersion within the disk is $\langle\sigma_{v,\rm{gas}}\rangle=93.5~{}{\rm
km~{}s^{-1}}$, which might be affected by AGN activity like A2744-F0083. The
northern tail shows a lower mean velocity dispersion with
$\langle\sigma_{v,{\rm gas}}\rangle\sim 50~{}{\rm km~{}s^{-1}}$, whereas the
southern region shows a mean gas velocity dispersion of $\langle\sigma_{v,{\rm
gas}}\rangle\sim 90~{}{\rm km~{}s^{-1}}$. This indicates that ionized gas in
the northern tail is dynamically cold and that in the southern region is more
turbulent than the northern region.

####  4.2.5 MACSJ1720-JFG1

MACSJ1720-JFG1 exhibits interesting substructures such as a bright arc-shaped
region at the head of the disk and several blue extraplanar knots in the tail
region. The blue knots are located at both the north and south sides of the
disk. The ${\rm H\alpha}$ flux map from the GMOS/IFU data reproduces these
optical features well.

The SFR surface density map shows that the distribution of star formation
activity is strongly concentrated at the the center of the galaxy. We
estimated a mean Balmer decrement, obtaining ${\rm H\alpha}$/${\rm
H\beta}$$=4.05\pm 1.40$ ($A_{V}=1.09~{}{\rm mag}$). We derive a total SFR of
17.37 $M_{\odot}~{}{\rm yr^{-1}}$, with a disk SFR of 14.09 $M_{\odot}~{}{\rm
yr^{-1}}$and a tail SFR of 3.28 $M_{\odot}~{}{\rm yr^{-1}}$ ($f_{\rm
SFR}=19\%$).

The radial velocity map shows a clear disk rotation on the axis of the east-
west direction. The maximum rotation velocity within the disk is 122.0 ${\rm
km~{}s^{-1}}$. The northern tail shows a radial velocity of $\sim 120$ ${\rm
km~{}s^{-1}}$ and the blue blob in the southern region shows a radial velocity
of $\sim-100$ ${\rm km~{}s^{-1}}$. These disturbed features also rotate
following the disk of this galaxy, which is similar to other jellyfish
galaxies.

This galaxy shows a mean gas velocity dispersion of
$\langle\sigma_{v,\rm{gas}}\rangle=104.5~{}{\rm km~{}s^{-1}}$, which is much
higher than those of MACSJ0916-JFG1 and MACSJ1752-JFG2, but similar to that of
MACSJ1258-JFG1. This indicates that ionized gas in the star-forming knots of
this galaxy seems to be more turbulent than that in the star-forming regions
in other jellyfish galaxies. Other shock-heating mechanisms are likely to
contribute to the gas ionization in this galaxy, as also suggested by its
location in the composite region in the BPT diagram (see  Figure 5).

Figure 12:  Projected phase-space diagrams of our sample (star symbols) and
the GASP jellyfish galaxies (circles). We normalize clustercentric distance
($R_{\rm cl}$) and absolute relative velocity ($|v_{\rm los}|$) with cluster
virial radius ($R_{200}$) and velocity dispersion ($\sigma_{v,{\rm cl}}$),
respectively. All the data are color-coded by total SFR (left) and tail SFR
(right). The color bars on the top denote the logarithmic scale of each SFR.
Gray dashed lines represent the boundaries of the five regions that were
roughly defined by infall stages of cluster galaxies (Rhee et al., 2017; Mun
et al., 2021): Region A (first infall), B (recent infall), C (intemediate
infall), D (ancient infall), and E (field). We divide the whole sample into
three categories by stellar mass: low-mass ($M_{\ast}<5\times
10^{9}~{}M_{\odot}$; upper), intermediate-mass ($5\times
10^{9}~{}M_{\odot}<M_{\ast}<5\times 10^{10}~{}M_{\odot}$; middle), and high-
mass ($M_{\ast}>5\times 10^{10}~{}M_{\odot}$; lower) galaxies.  Figure 13:
Same as  Figure 12, but we divide the sample into three categories by cluster
velocity dispersion: low-mass ($\sigma_{v,{\rm cl}}<600~{}{\rm km~{}s^{-1}}$;
upper), intermediate-mass ($600~{}{\rm km~{}s^{-1}}<\sigma_{v,{\rm
cl}}<900~{}{\rm km~{}s^{-1}}$; middle), and high-mass ($\sigma_{v,{\rm
cl}}>900~{}{\rm km~{}s^{-1}}$; lower) clusters.

##  5 Phase-space Diagrams of the Jellyfish Galaxies

Phase-space diagrams are useful to understand the impact of environmental
effects on cluster galaxies concerning their orbital histories (Rhee et al.,
2017; Jaffé et al., 2018; Mun et al., 2021). We display the projected phase-
space diagrams of our targets and the GASP jellyfish galaxies (Gullieuszik et
al., 2020) by categorizing the sample based on stellar mass ( Figure 12) and
host cluster velocity dispersion ( Figure 13). Lee et al. (2022) showed the
phase-space diagrams of the jellyfish galaxies with different categories of
jellyfish morphology. We plot the 2D clustercentric distance normalized by the
virial radius of the host cluster ($R_{\rm cl}/R_{200}$) on the x-axis, and we
plot the velocity relative to the cluster normalized by the cluster velocity
dispersion ($|\Delta v_{\rm los}|/\sigma_{v,{\rm cl}}$) on the y-axis. We
measure the line-of-sight velocity of each galaxy with $\Delta v_{\rm
los}=c\times(z_{\rm gal}-z_{\rm clu})/(1+z_{\rm clu})$ where $c$ is the speed
of light, $z_{\rm gal}$ is the galaxy redshift, and $z_{\rm clu}$ is the
cluster redshift.

In  Figures 12 and  13, we display total SFRs (left panels) and tail SFRs
(right panels) at the top of each panel by categorizing the star formation
activity: “weak” (red), “moderate” (green), and “strong” (blue) star
formation. Gray dashed lines denote the regions (from A to E) classified in
Rhee et al. (2017) and Mun et al. (2021), showing the approximate stages of
galaxy infall to the clusters: Region A (first infall), B (recent infall), C
(intermediate infall), D (ancient infall), and E (field). In this study, we
classify the location of jellyfish galaxies as “inner region” ($R_{\rm
cl}/R_{200}\leq 0.5$) and “outer region” ($R_{\rm cl}/R_{200}>0.5$) in their
host clusters.

In  Figure 12, we plot phase-space diagrams for different bins of galaxy
stellar mass: low-mass ($M_{\ast}<5\times 10^{9}~{}M_{\odot}$), intermediate-
mass ($5\times 10^{9}~{}M_{\odot}<M_{\ast}<5\times 10^{10}~{}M_{\odot}$), and
high-mass ($M_{\ast}>5\times 10^{10}~{}M_{\odot}$). In the low-mass regime,
almost all GASP jellyfish galaxies show weak star formation activity (17/18 in
total SFR and 16/18 in tail SFR). They are primarily located in the outer
region ($R_{\rm cl}/R_{200}>0.5$), with only four of them in the inner region
($R_{\rm cl}/R_{200}\leq 0.5$). Note that no galaxies are located in the
ancient infall region, implying that the low-mass jellyfish galaxies might be
in the early stages of cluster infall.

In the intermediate-mass regime, the GASP jellyfish galaxies show a wide range
of clustercentric distances and velocities in their host clusters. These
galaxies are also primarily located in the outer region. Most of them show
weak star formation activity in terms of tail SFRs. In contrast, four
jellyfish galaxies in this study are located in the inner region of the
clusters, and they show moderate or strong star activity. With the combined
sample of the GASP survey and this study, this panel shows that the fraction
of galaxies with weak star formation activity is higher in the outer region
(9/18 in total SFR and 15/18 in tail SFR) than in the inner region (1/12 in
total SFR and 4/12 in tail SFR).

In the high-mass regime, there are 10 GASP jellyfish galaxies and
MACSJ1258-JFG1 in this study. All massive jellyfish galaxies are located in
the inner region of the host clusters. Most of the jellyfish galaxies show
moderate or strong star formation activity. The panels in this figure
indicates that jellyfish galaxies with higher stellar mass and lower
clustercentric distances are likely to exhibit stronger star formation
activity on both global (total SFR) and local (tail SFR) scales. This trend
has also been observed in Gullieuszik et al. (2020) (see their Figure 4).

In  Figure 13, we plot the phase-space diagrams in different bins of cluster
velocity dispersion: low-mass hosts ($\sigma_{v,{\rm cl}}<600~{}{\rm
km~{}s^{-1}}$), intermediate-mass hosts ($600~{}{\rm
km~{}s^{-1}}<\sigma_{v,{\rm cl}}<900~{}{\rm km~{}s^{-1}}$), and high-mass
hosts ($\sigma_{v,{\rm cl}}>900~{}{\rm km~{}s^{-1}}$). For the low-mass host
clusters, half of the 14 GASP galaxies are located outside the virial radius.
A majority of the jellyfish galaxies show weak star formation activity, but
galaxies in the inner region mostly show stronger star formation activity than
those in the outer region. This trend can be also seen in intermediate-mass
host clusters. Most galaxies in the outer region show weak star formation
activity (9/11 in total and tail SFR), whereas those in the inner region have
a lower fraction of weak star formation activity (4/16 in total SFR and 9/16
in tail SFR). For the high-mass host clusters, there are 14 GASP jellyfish
galaxies and 4 galaxies in this study. In terms of total SFRs, the fraction of
galaxies with moderate and strong star formation activity (12/18) is higher in
high-mass clusters than in low-mass (6/14) and intermediate-mass (13/27)
clusters. This trend is also seen with tail SFRs: 3/14 in low-mass, 9/27 in
intermediate-mass, and 8/18 in high-mass clusters. This indicates that the
star formation activity of jellyfish galaxies in high-mass clusters is likely
to be more enhanced compared to those in low-mass and intermediate-mass
clusters. In addition, there are no GASP galaxies located in the first infall
region (“A”) in these massive clusters in contrast to low- and intermediate-
mass clusters. This implies that the jellyfish galaxies in massive clusters
are at a later phase of cluster infall than in low-mass clusters.

Combining the GASP sample and our sample, these phase-space diagrams reveal
the following. First, our jellyfish galaxy sample is located in the inner
region with a wide range of relative velocities. Second, it is clearly shown
that jellyfish galaxies in the inner region tend to have higher SFRs than
those in the outer region. Third, the star formation activity of jellyfish
galaxies tends to increase as galaxy stellar mass increases, as shown in
Figure 12. This reflects the SFR-mass relation of jellyfish galaxies as also
shown in Figure 2 and 4 in Lee et al. (2022).

Finally, the star formation activity of jellyfish galaxies tend to increase as
the host cluster velocity dispersion increases, as shown in  Figure 13. In
this context, Lee et al. (2022) revealed that jellyfish galaxies with strong
RPS signatures show more enhanced star formation activity in more massive
clusters with a higher degree of RPS.

##  6 Summary

In this study, we presented an observational study of the five jellyfish
galaxies in the MACS clusters and Abell 2744 at $z>0.3$ based on Gemini
GMOS/IFU observations. Using these data, we investigated the ionized gas
properties of these jellyfish galaxies such as ionization mechanisms,
kinematics, and SFRs. Lee et al. (2022) also used the ${\rm H\alpha}$-derived
SFRs in this study and suggested positive correlations between the star
formation activity of jellyfish galaxies and their host cluster properties.
Our main results can be summarized as follows.

  1. 1.

The BPT diagrams of [O III]$\lambda$5007/${\rm H\beta}$ and [N
II]$\lambda$6584/${\rm H\alpha}$ show that the five jellyfish galaxies have
different ionization mechanisms. MACSJ0916-JFG1 and MACSJ1752-JFG2 are located
in the star-forming region, indicating that the gas contents in these galaxies
are ionized purely by star formation. On the other hand, A2744-F0083 and
MACSJ1258-JFG1 are located in the AGN region with high line ratios of [O
III]$\lambda$5007/${\rm H\beta}$ and [N II]$\lambda$6584/${\rm H\alpha}$.
MACSJ1720-JFG1 is located in the composite region, implying a mixed
contribution of star formation and other shock-heating mechanisms.

  2. 2.

The spatial distributions of the ${\rm H\alpha}$ flux are well-matched with
the optical features in all five jellyfish galaxies. This indicates that the
ionized gas distribution is consistent with that of the stellar light
distribution in the jellyfish galaxies.

  3. 3.

The radial velocity distributions of the jellyfish galaxies indicate that
ionized gas in the disk and tail regions rotates around the center of each
galaxy. Some tail regions (e.g. eastern side of MACSJ1752-JFG2) show high
relative velocities with respect to the center of the galaxy, which indicates
signs of RPS.

  4. 4.

MACSJ0916-JFG1, MACSJ1752-JFG2 and the tail regions in A2744-F0083 and
MACSJ1258-JFG1 show a mean velocity dispersion lower than $50~{}{\rm
km~{}s^{-1}}$, which is consistent with the mean value of star-forming clumps
in the GASP jellyfish galaxies. This implies that the ionized gas in those
regions is dynamically cold. In contrast, MACSJ1720-JFG1 and the central
regions in A2744-F0083 and MACSJ1258-JFG1 show mean velocity dispersions
higher than $50~{}{\rm km~{}s^{-1}}$, indicating that the ionized gas is more
turbulent than typical star-forming regions. This could be associated with the
AGN activity or other shock-heating mechanisms.

  5. 5.

The total and tail SFRs of the five jellyfish galaxies are much higher than
those of the GASP sample. The median SFRs of our targets are 22.0
$M_{\odot}~{}{\rm yr^{-1}}$ in total and 6.8 $M_{\odot}~{}{\rm yr^{-1}}$ in
the tails, whereas those of the GASP sample are 1.1 $M_{\odot}~{}{\rm
yr^{-1}}$ in total and 0.03 $M_{\odot}~{}{\rm yr^{-1}}$ in the tails. In
addition, the median SFR fraction in the tail ($f_{\rm SFR}$) is also much
higher in this study ($f_{\rm SFR}=22\%$) than in the GASP studies ($f_{\rm
SFR}=3\%$).

  6. 6.

In the projected phase-space diagrams, the jellyfish galaxies in this study
are located in the inner region with a wide range of orbital velocities
relative to the cluster center. Combining the GASP sample and our sample, we
find that jellyfish galaxies with higher stellar masses and higher host
cluster velocity dispersions are more likely to be located in the inner region
of the clusters with more enhanced star formation activity.

We thank the anonymous referee for his/her important comments and suggestions
to improve the submitted manuscript. This study was supported by the National
Research Foundation grant funded by the Korean Government
(NRF-2019R1A2C2084019). This work was supported by K-GMT Science Program (PID:
GS-2019A-Q-214, GN-2019A-Q-215, GS-2019B-Q-219, and GN-2021A-Q-205) of Korea
Astronomy and Space Science Institute (KASI). Based on observations obtained
at the international Gemini Observatory, a program of NSF’s NOIRLab, acquired
through the Gemini Observatory Archive at NSF’s NOIRLab and processed using
the Gemini IRAF package, which is managed by the Association of Universities
for Research in Astronomy (AURA) under a cooperative agreement with the
National Science Foundation on behalf of the Gemini Observatory partnership:
the National Science Foundation (United States), National Research Council
(Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio
de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência,
Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space
Science Institute (Republic of Korea). This research has made use of the
NASA/IPAC Extragalactic Database (NED), which is operated by the Jet
Propulsion Laboratory, California Institute of Technology, under contract with
the National Aeronautics and Space Administration. This research is based on
observations made with the NASA/ESA Hubble Space Telescope and the Galaxy
Evolution Explorer obtained from the Mikulski Archive for Space Telescopes
(MAST) data archive at the Space Telescope Science Institute (STScI). STScI is
operated by the Association of Universities for Research in Astronomy, Inc.,
under NASA contract NAS 5-26555. This publication makes use of data products
from the Wide-field Infrared Survey Explorer, which is a joint project of the
University of California, Los Angeles, and the Jet Propulsion
Laboratory/California Institute of Technology, funded by the National
Aeronautics and Space Administration. This work is based in part on
observations made with the Spitzer Space Telescope, which was operated by the
Jet Propulsion Laboratory, California Institute of Technology under a contract
with NASA.

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