Previous studies have revealed a population of galaxies in galaxy clusters with ram pressure stripped (RPS) tails of gas and embedded young stars. We observed 1.4 GHz continuum and HI emission with the Very Large Array in its B-configuration in two fields of the Coma cluster to study the radio properties of RPS galaxies. The best continuum sensitivities in the two fields are 6 and 8 $μ$Jy per 4'' beam respectively, which are 4 and 3 times deeper than those previously published. Radio continuum tails are found in 10 (8 are new) out of 20 RPS galaxies, unambiguously revealing the presence of relativistic electrons and magnetic fields in the stripped tails. Our results also hint that the tail has a steeper spectrum than the galaxy. The 1.4 GHz continuum in the tails is enhanced relative to their H$α$ emission by a factor of $\sim$7 compared to the main bodies of the RPS galaxies. The 1.4 GHz continuum of the RPS galaxies is also enhanced relative to their IR emission by a factor of $\sim$2 compared to star-forming galaxies. The enhancement is likely related to ram pressure and turbulence in the tail. We furthermore present HI detections in three RPS galaxies and upper limits for the other RPS galaxies. The cold gas in D100's stripped tail is dominated by molecular gas, which is likely a consequence of the high ambient pressure. No evidence of radio emission associated with ultra-diffuse galaxies is found in our data.
We have discovered large amounts of molecular gas, as traced by CO emission, in the ram pressure stripped gas tail of the Coma cluster galaxy D100 (GMP 2910), out to large distances of about 50 kpc. D100 has a 60 kpc long, strikingly narrow tail which is bright in X-rays and Hα. Our observations with the IRAM 30m telescope reveal in total ~ 10^9 M_sun of H_2 (assuming the standard CO-to-H_2 conversion) in several regions along the tail, thus indicating that molecular gas may dominate its mass. Along the tail we measure a smooth gradient in the radial velocity of the CO emission that is offset …
We investigate the effects of ram pressure on the molecular ISM in the disk of the Coma cluster galaxy NGC 4921, via high resolution CO observations. We present 6" resolution CARMA CO(1-0) observations of the full disk, and 0.4" resolution ALMA CO(2-1) observations of the leading quadrant, where ram pressure is strongest. We find evidence for compression of the dense interstellar medium (ISM) on the leading side, spatially correlated with intense star formation activity in this zone. We also detect molecular gas along kiloparsec-scale filaments of dust extending into the otherwise gas stripped…
We present new HST F275W, F475W, and F814W imaging of the region of the Coma cluster around D100, a spiral galaxy with a remarkably long and narrow ($60 \times 1.5$ kpc) ram pressure stripped gas tail. We find blue sources coincident with the H$α$ tail, which we identify as young stars formed in the tail. We also determine they are likely to be unbound stellar complexes with sizes of $\sim$ $50-100$ pc, likely to disperse as they age. From a comparison of the colors and magnitudes of the young stellar complexes with simple stellar population models, we find ages ranging from $\sim$ $1-50$ Myr,…
The Coma cluster is the nearest massive ($M \gtrsim 10^{15}\,\mathrm{M_\odot}$) galaxy cluster, making it an excellent laboratory to probe the influence of the cluster environment on galaxy star formation. Here, we present a sample of 41 galaxies with disturbed morphologies consistent with ram pressure stripping. These galaxies are identified visually using high-quality, multi-band imaging from the Canada-France-Hawaii telescope covering ~9 $\mathrm{deg^2}$ of the Coma cluster. These "stripping candidates" are clear outliers in common quantitative morphological measures, such as concentration-…
We describe and constrain the origins of ISM structures likely created by ongoing ICM ram pressure stripping in two Virgo Cluster spirals, NGC 4522 and NGC 4402, using HST BVI images of dust extinction and stars, as well as supplementary HI, Halpha, and radio continuum images. This is the highest-resolution study to date of the physical processes that occur during an ICM-ISM ram pressure stripping interaction, ram pressure stripping's effects on the multi-phase, multi-density ISM, and the formation and evolution of ram-pressure-stripped tails. In dust extinction, we view the leading side of NG…
Ram Pressure Stripping can remove gas from satellite galaxies in clusters via a direct interaction between the intracluster medium (ICM) and the interstellar medium. This interaction is generally thought of as a contact force per area, however we point out that these gases must interact in a hydrodynamic fashion, and argue that this will lead to mixing of the galactic gas with the ICM wind. We develop an analytic framework for how mixing is related to the acceleration of stripped gas from a satellite galaxy. We then test this model using three "wind-tunnel" simulations of Milky Way-like galaxi…
High resolution (1'' $\times$ 2'') ALMA CO(2-1) observations of the ram pressure stripped galaxy NGC 4402 in the Virgo cluster show some of the clearest evidence yet for the impacts of ram pressure on the molecular ISM of a galaxy. The eastern side of the galaxy at $r \sim 4.5$ kpc, upon which ram pressure is incident, has a large (width $\sim$1 kpc, height $\sim$1 kpc above the disk midplane) extraplanar plume of molecular gas and dust. Molecular gas in the plume region shows distinct non-circular motions in the direction of the ram pressure; the kinematic offset of up to 60 km s$^{-1}$ is co…
We report the detection of H$α$ trails behind three new intermediate-mass irregular galaxies in the NW outskirts of the nearby cluster of galaxies Abell 1656 (Coma). Hints that these galaxies possess an extended component were found in earlier, deeper H$α$ observations carried out with the Subaru telescope. However the lack of a simultaneous $r$-band exposure, together with the presence of strong stellar ghosts in the Subaru images, prevented us from quantifying the detections. We therefore devoted one full night of H$α$ observation to each of the three galaxies using the San Pedro Martir 2.1m…
NGC 4522 is a Virgo spiral that is currently undergoing active ram pressure stripping. In previous single-dish observations, 12CO emission was detected outside of the stellar disk, some of which coincides with the extraplanar HI gas and H$α$ patches. The extraplanar gas identified in multi-wavelength data makes this galaxy an ideal case to study the impact of pressure due to the cluster medium on the interstellar gas of various phases. In this Letter, we present the high-resolution 12CO(1-0) and 13CO(1-0) data of NGC 4522 obtained using the Atacama Large Millimeter/submillimeter Array (ALMA). …
Early Results from the Coma Legacy IFU Survey (CLIFS): Ram Pressure Induced Shocks and Ionization in Jellyfish Tails
McMaster University（麦克马斯特大学）；University of Waterloo（滑铁卢大学）；Cardiff University（卡迪夫大学）；Astronomical Observatory of Padova（帕多瓦天文台）；University of Birmingham（伯明翰大学）；University of Cape Town（开普敦大学）
Ram-pressure stripping is a crucial evolutionary driver for cluster galaxies and jellyfish galaxies, characterized by very extended tails of stripped gas, are the most striking examples of it in action. Recently, those extended tails are found to show on-going star formation raising the question how the stripped, cold gas can survive long enough to form new stars outside the stellar disk. In this work, we summarize the most recent results achieved within the GASP collaboration to provide a holistic explanation for this phenomenon. We focus on two textbook examples of jellyfish galaxies, JO206 …
Ram-pressure stripping by the intracluster medium (ICM) is one of the most advocated mechanisms that affect the properties of cluster galaxies. A recent study based on a small sample has found that many galaxies showing strong signatures of ram-pressure stripping also possess an active galactic nucleus (AGN), suggesting a possible correlation between the two phenomena. This result has not been confirmed by a subsequent study. Building upon previous findings, here we combine MUSE observations conducted within the GASP program and a general survey of the literature to robustly measure the AGN fr…
Remarkable dust extinction features in the deep HST V and I images of the face-on Coma cluster spiral galaxy NGC 4921 show in unprecedented ways how ram pressure strips the ISM from the disk of a spiral galaxy. New VLA HI maps show a truncated and highly asymmetric HI disk with a compressed HI distribution in the NW, providing evidence for ram pressure acting from the NW. Where the HI distribution is truncated in the NW region, HST images show a well-defined, continuous front of dust that extends over 90 degrees and 20 kpc. This dust front separates the dusty from dust-free regions of the gala…
Exploiting the data from the GAs Stripping Phenomena in galaxies with MUSE (GASP) program, we compare the integrated Star Formation Rate- Mass relation (SFR-M_ast) relation of 42 cluster galaxies undergoing ram pressure stripping ("stripping galaxies") to that of 32 field and cluster undisturbed galaxies. Theoretical predictions have so far led to contradictory conclusions about whether ram pressure can enhance the star formation in the gas disks and tails or not and until now a statistically significant observed sample of stripping galaxies was lacking. We find that stripping galaxies occupy …
Revisiting ram pressure stripping in Wolf-Lundmark-Melotte: No evidence for stripped HI with LGLBS
University of Wisconsin–Madison（威斯康星大学麦迪逊分校）；National Radio Astronomy Observatory（国家射电天文台）；New Mexico Institute of Mining and Technology（新墨西哥矿业理工学院）；Indiana University（印第安纳大学）；Flatiron Institute（平顶山研究所）；University of Washington（华盛顿大学）；The Ohio State University（俄亥俄州立大学）
We show that there is a new class of gas tails - slingshot tails - which form as a subhalo (i.e. a subcluster or early-type cluster galaxy) moves away from the cluster center towards the apocenter of its orbit. These tails can point perpendicular or even opposite to the subhalo direction of motion, not tracing the recent orbital path. Thus, the observed tail direction can be misleading, and we caution against naive conclusions regarding the subhalo's direction of motion based on the tail direction. A head-tail morphology of a galaxy's or subcluster's gaseous atmosphere is usually attributed to…
We present a study of the orbits, environments and morphologies of 13 ram-pressure stripped galaxies in the massive, intermediate redshift (z$\sim0.3-0.4$) galaxy clusters A2744 and A370, using MUSE integral-field spectroscopy and HST imaging from the Frontier Fields Program. We compare different measures of the locations and morphologies of the stripped sample with a sample of 6 poststarburst galaxies identified within the same clusters, as well as the general cluster population. We calculate the phase space locations of all cluster galaxies and carry out a substructure analysis, finding that…
It is often stated that the removal of gas by ram pressure stripping of a galaxy disk is not a common process in galaxy groups. In this study, with the aid of an observational classification of galaxies and a simple physical model, we show that this may not be true. We examined and identified 45 ram-pressure stripped galaxy candidates from a sample of 1311 galaxy group members within 125 spectroscopically-selected galaxy groups. 13 of these galaxies are the most secure candidates with multiple distinct features. These candidate ram pressure stripped galaxies have similar properties to those fo…
Studies of cluster galaxies are increasingly finding galaxies with spectacular one-sided tails of gas and young stars, suggestive of intense ram-pressure stripping. These so-called "jellyfish" galaxies typically have late-type morphology. In this paper, we present MUSE observations of an elliptical galaxy in Abell 2670 with long tails of material visible in the optical spectra, as well as blobs with tadpole-like morphology. The spectra in the central part of the galaxy reveals a stellar component as well as ionized gas. The stellar component does not have significant rotation, while the ionize…
Cluster spiral galaxies suffer catastrophic losses of the cool, neutral gas component of their interstellar medium due to ram pressure stripping, contributing to the observed quenching of star formation in the disk compared to galaxies in lower density environments. However, the short term effects of ram pressure on the star formation rate and AGN activity of galaxies undergoing stripping remain unclear. Numerical studies have recently demonstrated cosmic rays can dramatically influence galaxy evolution for isolated galaxies, yet their influence on ram pressure stripping remains poorly constra…
We present the first high-resolution map of the cold molecular gas distribution, as traced by CO(2-1) emission with ALMA, in a prominent ram pressure stripped tail. The Norma cluster galaxy ESO 137-001 is undergoing a strong interaction with the surrounding intra-cluster medium and is one of the nearest jellyfish galaxies with a long multi-phase tail. We have mapped the full extent of the tail at 1" (350 pc) angular resolution and found a rich distribution of mostly compact CO regions extending to nearly 60 kpc in length and 25 kpc in width. In total about 10^9 M_sun of molecular gas was detec…
We present the first study of the effect of ram-pressure "unwinding" the spiral arms of cluster galaxies. We study 11 ram-pressure stripped galaxies from GASP (GAs Stripping Phenomena in galaxies) in which, in addition to more commonly observed "jellyfish" features, dislodged material also appears to retain the original structure of the spiral arms. Gravitational influence from neighbours is ruled out and we compare the sample with a control group of undisturbed spiral galaxies and simulated stripped galaxies. We first confirm the unwinding nature, finding the spiral arm pitch angle increases …
We present the highest-resolution study to date of the ISM in galaxies undergoing ram pressure stripping, using HST BVI imaging of NGC 4522 and NGC 4402, Virgo Cluster spirals that are well-known to be experiencing ICM ram pressure. We find that throughout most of both galaxies, the main dust lane has a fairly well-defined edge, with a population of GMC-sized (tens- to hundreds-of-pc scale), isolated, highly extincting dust clouds located up to ~1.5 kpc radially beyond it. Outside of these dense clouds, the area has little or no diffuse dust extinction, indicating that the clouds have decouple…
Spatially resolved PAH$_{3.3}$ emission and stellar ages in ram pressure stripped clumps at $z\sim0.3$
INAF, Osservatorio Astronomico di Padova（国家天体物理研究所，帕多瓦天文台）；Dipartimento di Fisica e Astronomia ‘G. Galilei’, Università di Padova（帕多瓦大学，伽利略物理与天文系）；Instituto de Radioastronomia y Astrofisica, UNAM, Campus Morelia（墨西哥国立自治大学，莫雷利亚校区射电天文学与天体物理学研究所）；IPAC, California Institute of Technology（加州理工学院，红外处理与分析中心）；University of California, Los Angeles（加利福尼亚大学洛杉矶分校）
Jellyfish are cluster galaxies that experience strong ram-pressure effects that strip their gas. Their H$α$ images reveal ionized gas tails up to 100 kpc, which could be hosting ongoing star formation. Here we report the ultraviolet (UV) imaging observation of the jellyfish galaxy JO201 obtained at a spatial resolution $\sim$ 1.3 kpc. The intense burst of star formation happening in the tentacles is the focus of the present study. JO201 is the "UV-brightest cluster galaxy" in Abell 85 ($z \sim$ 0.056) with knots and streams of star formation in the ultraviolet. We identify star forming knots b…
The diffuse ionized gas (DIG) is an important component of the interstellar medium and it can be affected by many physical processes in galaxies. Measuring its distribution and contribution in emission allows us to properly study both its ionization and star formation in galaxies. Here, we measure for the first time the DIG emission in 38 gas-stripped galaxies in local clusters drawn from the GAs Stripping Phenomena in galaxies with MUSE survey (GASP). These galaxies are at different stages of stripping. We also compare the DIG properties to those of 33 normal galaxies from the same survey. To…
Jellyfish galaxies in clusters are key tools to understand environmental processes at work in dense environments. The advent of Integral Field Spectroscopy has recently allowed to study a significant sample of stripped galaxies in the cluster environment at z$\sim 0.05$, through the GAs Stripping Phenomena in galaxies with MUSE (GASP) survey. However, optical spectroscopy can only trace the ionized gas component through the H$_α$ emission that can be spatially resolved on kpc scale at this redshift. The complex interplay between the various gas phases (ionized, neutral, molecular) is however y…
Using MUSE observations from the GASP survey, we study 54 galaxies undergoing ram-pressure stripping (RPS) spanning a wide range in galaxy mass and host cluster mass. We use this rich sample to study how the star formation rate (SFR) in the tails of stripped gas depends on the properties of the galaxy and its host cluster. We show that the interplay between all the parameters involved is complex and that there is not a single, dominant one in shaping the observed amount of SFR. Hence, we develop a simple analytical approach to describe the mass fraction of stripped gas and the SFR in the tail,…
For the first time, we reveal large amounts of cold molecular gas in a ram pressure stripped tail, out to a large, intracluster distance from the galaxy. With the APEX telescope we have detected 12CO(2-1) emission corresponding to more than 10^9 Msun of H_2 in three Ha bright regions along the tail of the Norma cluster galaxy ESO 137-001, out to a projected distance of 40 kpc from the disk. ESO 137-001 has an 80 kpc long and bright X-ray tail associated with a shorter (40 kpc) and broader tail of numerous star-forming H II regions. The amount of about 1.5x10^8 Msun of H_2 found in the most dis…
Ram-pressure-induced star formation in low-mass galaxies infalling on-to the Coma cluster: insights from DESI
Universite Paris Cite（巴黎西岱大学）；CNRS（法国国家科学研究中心）；Astroparticule et Cosmologie（亚原子粒子与宇宙学）；Sternberg Astronomical Institute（斯滕伯格天文研究所）；M.V. Lomonosov Moscow State University（莫斯科罗蒙诺索夫国立大学）；Center for Astrophysics | Harvard & Smithsonian（哈佛史密森尼天体物理中心）；Institut d’Astrophysique de Paris (UMR 7095: CNRS & Sorbonne Université)（巴黎天体物理学研究所）；Sorbonne Université（索邦大学）；INAF Osservatorio Astronomico di Trieste（的里雅斯特天文台）；IFPU: Institute for Fundamental Physics of the Universe（宇宙基础物理研究所）；Faculty of Space Research, M.V. Lomonosov Moscow State University（莫斯科罗蒙诺索夫国立大学空间研究学院）
Cluster galaxies moving through the intracluster medium (ICM) are expected to lose some of their interstellar medium (ISM) through ISM-ICM interactions. We perform high resolution (40 pc) three-dimensional hydrodynamical simulations of a galaxy undergoing ram pressure stripping including radiative cooling in order to investigate stripping of a multiphase medium. The clumpy, multiphase ISM is self-consistently produced by the inclusion of radiative cooling, and spans six orders of magnitude in gas density. We find no large variations in the amount of gas lost whether or not cooling is involved,…
The molecular gas of four ram pressure stripped galaxies in the core of the Hydra I cluster
Instituto de Astrofísica de Andalucía (CSIC)（安达卢西亚天体物理研究所）；European Southern Observatory（欧洲南方天文台）；Chalmers University of Technology（查尔姆斯理工大学）；ASTRON, the Netherlands Institute for Radio Astronomy（荷兰射电天文研究所）；University of Cape Town（开普敦大学）；South African Astronomical Observatory（南非天文台）；Universidad Técnica Federico Santa María（弗雷德里科·圣玛丽亚技术大学）；Millennium Nucleus for Galaxies (MINGAL)（银河系千年核）；Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester（曼彻斯特大学物理与天文学院乔德雷克银行天体物理学中心）；United Kingdom SKAO Regional Centre (UKSRC)（英国SKAO区域中心）；Finnish Centre for Astronomy with ESO, (FINCA)（芬兰ESO天文中心）
Using the VESTIGE survey, a deep narrow-band H$α$ imaging survey of the Virgo cluster carried on at the CFHT with MegaCam, we discovered a long diffuse tail of ionised gas in the edge-on late-type galaxy NGC 4330. This peculiar feature witnesses an ongoing ram pressure stripping (RPS) event able to remove the gas in the outer disc region. Tuned hydrodynamic simulations suggest that the RPS event is occurring almost face-on, making NGC 4330 the ideal candidate to study the effects of the perturbation in the direction perpendicular to the disc plane. We present here two new independent sets of F…
Hydrodynamical simulations show that the ram-pressure stripping in galaxy clusters fosters a strong interaction between stripped interstellar medium (ISM) and the surrounding medium, with the possibility of intracluster medium (ICM) cooling into cold gas clouds. Exploiting the MUSE observation of three jellyfish galaxies from the GAs Stripping Phenomena in galaxies with MUSE (GASP) survey, we explore the gas metallicity of star-forming clumps in their gas tails. We find that the oxygen abundance of the stripped gas decreases as a function of the distance from the parent galaxy disk; the observ…
We report the discovery of bent double jets in the elliptical galaxy NGC 1272, a member of the Perseus cluster. The jets have a radius of curvature of ~2 kpc, much smaller than the galaxy half-light radius of ~11 kpc. This bending is likely a result of ram pressure, and indicates that the intracluster gas enters deep within the galaxy and that the interstellar medium of NGC 1272 has been significantly removed. X-ray observations of the surrounding intracluster medium allow us to constrain the pressure within the jet. We find that the standard assumptions of equipartition often used in interpre…
In the Local Group, quenched gas-poor dwarfs galaxies are most often found close to the Milky Way and Andromeda, while star forming gas-rich ones are located at greater distances. This so-called morphology-density relation is often interpreted as the consequence of the ram pressure stripping of the satellites during their interaction with the Milky Way hot halo gas. While this process has been often investigated, self-consistent high resolution simulations were still missing. In this study, we have analysed the impact of both the ram pressure and tidal forces induced by a host galaxy on dwarf …
NGC 4654 is a Virgo galaxy seen almost face-on, which undergoes nearly edge-on gas ram pressure stripping and a fly-by gravitational interaction with another massive galaxy, NGC 4639. NGC 4654 shows a strongly compressed gas region near the outer edge of the optical disk, with HI surface densities (HSDR), exceeding the canonical value of 10-15 Msun/pc2. New IRAM 30m HERA CO(2-1) data of NGC 4654 are used to study the physical conditions of the ISM. The CO-to-H$_2$ conversion factor was estimated and found to be one to two times the Galactic value with significant decrease in the ratio between …
ALMA-JELLY II. Constraining the radial profiles of the quenching timescales in ram-pressure-stripped galaxies
Università di Milano-Bicocca（米兰比可卡大学）；INAF - Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）；Aix Marseille Univ, CNRS, CNES, LAM（艾克斯-马赛大学、法国国家科学研究中心、法国国家空间研究中心、天体物理与行星学实验室）；INAF - Osservatorio Astronomico di Cagliari（意大利国家天体物理研究所卡利亚里天文台）；INAF - Osservatorio Astronomico di Trieste（意大利国家天体物理研究所的里雅斯特天文台）；Yale University（耶鲁大学）；Astronomical Institute of the Czech Academy of Sciences（捷克科学院天文研究所）；The University of Alabama in Huntsville（阿拉巴马大学亨茨维尔分校）；University of Hertfordshire Centre for Astrophysics Research（赫特福德大学天体物理学研究中心）；Observatoire de Paris, LUX, Collège de France, CNRS, PSL University, Sorbonne Uni（巴黎天文台、卢克瑟姆实验室、法兰西学院、法国国家科学研究中心、巴黎文理研究大学、索邦大学）
Within the GASP survey, aimed at studying the effect of the ram-pressure stripping on the star formation quenching in cluster galaxies, we analyze here ALMA observations of the jellyfish galaxy JW100. We find an unexpected large amount of molecular gas ($\sim 2.5 \times 10^{10} M_{\odot}$), 30\% of which is located in the stripped gas tail out to $\sim$35 kpc from the galaxy center. The overall kinematics of molecular gas is similar to the one shown by the ionized gas, but for clear signatures of double components along the stripping direction detected only out to 2 kpc from the disk. The line…
