Abstract
Making use of both MUSE observations of 85 galaxies from the survey GASP (GAs Stripping Phenomena in galaxies with MUSE) and a large sample from MaNGA (Mapping Nearby Galaxies at Apache ...Point Observatory survey), we investigate the distribution of gas metallicity gradients as a function of stellar mass for local cluster and field galaxies. Overall, metallicity profiles steepen with increasing stellar mass up to 10
10.3
M
⊙
and flatten out at higher masses. Combining the results from the metallicity profiles and the stellar mass surface density gradients, we propose that the observed steepening is a consequence of local metal enrichment due to in situ star formation during the inside-out formation of disk galaxies. The metallicity gradient−stellar mass relation is characterized by a rather large scatter, especially for 10
9.8
<
M
⋆
/
M
⊙
< 10
10.5
, and we demonstrate that metallicity gradients anti-correlate with the galaxy gas fraction. Focusing on the galaxy environment, at any given stellar mass, cluster galaxies have systematically flatter metallicity profiles than their field counterparts. Many subpopulations coexist in clusters: galaxies with shallower metallicity profiles appear to have fallen into their present host halo sooner and have experienced the environmental effects for a longer time than cluster galaxies with steeper metallicity profiles. Recent galaxy infallers, like galaxies currently undergoing ram pressure stripping, show metallicity gradients more similar to those of field galaxies, suggesting they have not felt the effect of the cluster yet.
ABSTRACT
Gas discs of late-type galaxies are flared, with scale heights increasing with the distance from the galaxy centres and often reaching kpc scales. We study the effects of gas disc flaring on ...the recovered dark matter halo parameters from rotation curve decomposition. For this, we carefully select a sample of 32 dwarf and spiral galaxies with high-quality neutral gas, molecular gas, and stellar mass profiles, robust H i rotation curves obtained via 3D kinematic modelling, and reliable bulge-disc decomposition. By assuming vertical hydrostatic equilibrium, we derive the scale heights of the atomic and molecular gas discs and fit dark matter haloes to the rotation curves self-consistently. We find that the effect of the gas flaring in the rotation curve decomposition can play an important role only for the smallest, gas-dominated dwarfs, while for most of the galaxies, the effect is minor and can be ignored. We revisit the stellar- and baryon-to-halo mass relations (M*–M200 and Mbar–M200). Both relations increase smoothly up to $M_{200} \approx 10^{12}~\rm { M_\odot }$, with galaxies at this end having high M*/M200 and Mbar/M200 ratios approaching the cosmological baryon fraction. At higher M200, the relations show a larger scatter. Most haloes of our galaxy sample closely follow the concentration–mass (c200–M200) relation resulting from N-body cosmological simulations. Interestingly, the galaxies deviating above and below the relation have the highest and lowest stellar and baryon factions, respectively, which suggests that the departures from the c200–M200 law are regulated by adiabatic contraction and an increasing importance of feedback.
Abstract
Ram pressure stripping has been proven to be effective in shaping galaxy properties in dense environments at low redshift. The availability of Multi Unit Spectroscopic Explorer (MUSE) ...observations of a sample of distant (
z
∼ 0.3–0.5) clusters has allowed one to search for galaxies subject to this phenomenon at significant lookback times. In this paper we describe how we discovered and characterized 13 ram-pressure-stripped galaxies in the central regions of two intermediate redshift (
z
∼ 0.3–0.4) clusters, A2744 and A370, using the MUSE spectrograph. Emission-line properties as well as stellar features have been analyzed to infer the presence of this gas-only stripping mechanism, that produces spectacular ionized gas tails (H
α
and even more astonishing O
ii
(3727, 3729)) departing from the main galaxy body. The inner regions of these two clusters reveal the predominance of such galaxies among blue star-forming cluster members, suggesting that ram pressure stripping was even more effective at intermediate redshift than in today’s universe. Interestingly, the resolved O
ii
/H
α
line ratio in the stripped tails is exceptionally high compared to that in the disks of these galaxies, (which is comparable to that in normal low-
z
galaxies), suggesting lower gas densities and/or an interaction with the hot surrounding intracluster medium.
Ram-pressure stripping (RPS) is the mechanism most often invoked to explain the observed differences between cluster and field galaxies. In the local Universe, its effect on the star-forming ...properties of the galaxies has been largely elucidated and the general consensus is that this process first compresses the gas available in galaxy disks, boosting the star formation for a limited amount of time, and then removes the remaining gas, leading to quenching. Much less is known about the effect and preponderance of RPS at higher redshifts, due to the lack of statistical samples. Exploiting VLT/MUSE observations of galaxies at 0.2 < z < 0.55 and a published catalog of ram-pressure-stripped galaxies, we compare the global star formation rate–mass (SFR– M * ) relation of 29 cluster galaxies undergoing RPS to that of 26 undisturbed field and cluster galaxies that constitute our control sample. Stripping galaxies occupy the upper envelope of the SFR– M * relation of the control sample, showing a systematic enhancement of SFR at any given mass. The boost is > 3 σ when considering the SFR occurring in both the tail and the disk of the galaxies. The enhancement is also seen on local scales: Considering spatially resolved data, ram-pressure stripped galaxies have large Σ SFR values overall, especially for Σ * > 10 7.5 M ⊙ kpc −2 . RPS seems to leave the same imprint on the SFR– M * and Σ SFR –Σ * relations both in the local Universe and at z ∼ 0.35.
Abstract
We present results from MUSE spatially resolved spectroscopy of 21 post-starburst galaxies in the centers of eight clusters from
z
∼ 0.3 to
z
∼ 0.4. We measure spatially resolved star ...formation histories (SFHs), the time since quenching (
t
Q
), and the fraction of stellar mass assembled in the past 1.5 Gyr (
μ
1.5
). The SFHs display a clear enhancement of star formation prior to quenching for 16 out of 21 objects, with at least 10% (and up to >50%) of the stellar mass being assembled in the past 1.5 Gyr and
t
Q
ranging from less than 100 to ∼800 Myr. By mapping
t
Q
and
μ
1.5
, we analyze the quenching patterns of the galaxies. Most galaxies in our sample have quenched their star formation from the outside in or show a side-to-side/irregular pattern, both consistent with quenching by ram pressure stripping. Only three objects show an inside-out quenching pattern, all of which are at the high-mass end of our sample. At least two of them currently host an active galactic nucleus. In two post-starbursts, we identify tails of ionized gas indicating that these objects had their gas stripped by ram pressure very recently. Post-starburst features are also found in the stripped regions of galaxies undergoing ram pressure stripping in the same clusters, confirming the link between these classes of objects. Our results point to ram pressure stripping as the main driver of fast quenching in these environments, with active galactic nuclei playing a role at high stellar masses.
Abstract
We present a study of the orbits, environments, and morphologies of 13 ram-pressure stripped galaxies in the massive, intermediate redshift (
z
∼ 0.3−0.4) galaxy clusters A2744 and A370, ...using MUSE integral-field spectroscopy and Hubble Space Telescope imaging from the Frontier Fields Program. We compare different measures of the locations and morphologies of the stripped sample with a sample of six post-starburst 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 the ram-pressure stripped galaxies in A370 are not associated with any substructures, but are likely isolated infalling galaxies. In contrast, the ram-pressure stripped galaxies in A2744 are strictly located within a high-velocity substructure, moving through a region of dense X-ray emitting gas. We conclude that their ram-pressure interactions are likely to be the direct result of the merger between two components of the cluster. Finally, we study the morphologies of the stripped and post-starburst galaxies, using numerical measures to quantify the level of visual disturbances. We explore any morphological deviations of these galaxies from the cluster population, particularly the weaker cases that have been confirmed via the presence of ionized gas tails to be undergoing ram-pressure stripping, but are not strongly visually disturbed in the broadband data. We find that the stripped sample galaxies are generally divergent from the general cluster sample, with post-starburst galaxies being intermediary in morphology between stripped galaxies and red passive cluster members.
Abstract
Ram pressure stripping is a crucial evolutionary driver for cluster galaxies. It is thought to be able to accelerate the evolution of their star formation, trigger the activity of their ...central active galactic nucleus (AGN) and the interplay between galactic and environmental gas, and eventually dissipate their gas reservoirs. We explored the outcomes of ram pressure stripping by studying the nonthermal radio emission of the jellyfish galaxy JW100 in the cluster A2626 (
z
= 0.055), by combining LOw Frequency Array, MeerKAT, and Very Large Array observations from 0.144 to 5.5 GHz. We studied the integrated spectra of the stellar disk, the stripped tail, and the AGN; mapped the spectral index over the galaxy; and constrained the magnetic field intensity to between 11 and 18
μ
G in the disk and <10
μ
G in the tail. The stellar disk radio emission is dominated by a radiatively old plasma, likely related to an older phase of a high star formation rate. This suggests that the star formation was quickly quenched by a factor of 4 in a few 10
7
yr. The radio emission in the tail is consistent with the stripping scenario, where the radio plasma that originally accelerated in the disk is subsequently displaced in the tail. The morphology of the radio and X-ray emissions supports the scenario of the accretion of magnetized environmental plasma onto the galaxy. The AGN nonthermal spectrum indicates that relativistic electron acceleration may have occurred simultaneously with a central ionized gas outflow, thus suggesting a physical connection between the two processes.
Abstract
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 observed metallicity profiles indicate that more than 40% of the most metal-poor stripped clouds are constituted by cooled ICM, in qualitative agreement with simulations that predict mixing between the metal-rich ISM and the metal-poor ICM.
GASP XXXIX: MeerKAT hunts Jellyfish in A2626 Deb, Tirna; Verheijen, Marc A W; Poggianti, Bianca M ...
Monthly Notices of the Royal Astronomical Society,
09/2022, Letnik:
516, Številka:
2
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
We present MeerKAT H i observations of six jellyfish candidate galaxies (JFCGs) in the galaxy cluster, A2626. Two of the six galaxies JW100 and JW103, which were identified as JFCGs from ...B-band images, are confirmed as jellyfish galaxies (JFGs). Both of the JFGs have low H i content, reside in the cluster core, and move at very high velocities (∼ 3σcl). The other JFCGs, identified as non-jellyfish galaxies, are H i rich, with H i morphologies revealing warps, asymmetries, and possible tidal interactions. Both the A2626 JFGs and three other confirmed JFGs from the GASP sample show that these galaxies are H i stripped but not yet quenched. We detect H i, H α, and CO(2-1) tails of similar extent (∼50 kpc) in JW100. Comparing the multiphase velocity channels, we do not detect any H i or CO(2-1) emission in the northern section of the tail where H α emission is present, possibly due to prolonged interaction between the stripped gas and the intracluster medium. We also observe an anticorrelation between H i and CO(2-1), which hints at an efficient conversion of H i to H2 in the southern part of the tail. We find that both ram-pressure stripping and H i-to-H2 conversion are significant depletion channels for atomic gas. H i-to-H2 conversion is more efficient in the disc than in the tail.
We study the gas kinematics of a sample of six isolated gas-rich low surface brightness galaxies, of the class called ultra-diffuse galaxies (UDGs). These galaxies have recently been shown to be ...outliers from the baryonic Tully–Fisher relation (BTFR), as they rotate much slower than expected given their baryonic mass, and to have a baryon fraction similar to the cosmological mean. By means of a 3D kinematic modelling fitting technique, we show that the H i in our UDGs is distributed in ‘thin’ regularly rotating discs and we determine their rotation velocity and gas velocity dispersion. We revisit the BTFR adding galaxies from other studies. We find a previously unknown trend between the deviation from the BTFR and the exponential disc scale length valid for dwarf galaxies with circular speeds ≲ 45 km s^−1, with our UDGs being at the extreme end. Based on our findings, we suggest that the high baryon fractions of our UDGs may originate due to the fact that they have experienced weak stellar feedback, likely due to their low star formation rate surface densities, and as a result they did not eject significant amounts of gas out of their discs. At the same time, we find indications that our UDGs may have higher-than-average stellar specific angular momentum, which can explain their large optical scale lengths.
PDF
