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- ItemScaling relations of z ∼ 0.25–1.5 galaxies in various environments from the morpho-kinematics analysis of the MAGIC sample(Les Ulis : EDP Sciences, 2022) Mercier, W.; Epinat, B.; Contini, T.; Abril-Melgarejo, V.; Boogaard, L.; Brinchmann, J.; Finley, H.; Krajnović, D.; Michel-Dansac, L.; Ventou, E.; Bouché, N.; Dumoulin, J.; Pineda, J.C.B.Context. The evolution of galaxies is influenced by many physical processes, which may vary depending on their environment. Aims. We combine Hubble Space Telescope (HST) and Multi-Unit Spectroscopic Explorer (MUSE) data of galaxies at 0.25-1.5 to probe the impact of environment on the size-mass relation, the main sequence (MS) relation, and the Tully-Fisher relation (TFR). Methods. We perform a morpho-kinematics modelling of 593 [O-II] emitters in various environments in the COSMOS area from the MUSE-gAlaxy Groups In Cosmos survey. The HST F814W images are modelled with a bulge-disk decomposition to estimate their bulge-disk ratio, effective radius, and disk inclination. We use the [O-II]λλ3727, 3729 doublet to extract the galaxies ionised gas kinematics maps from the MUSE cubes, and we model those maps for a sample of 146 [O-II] emitters, including bulge and disk components constrained from morphology and a dark matter halo. Results. We find an offset of 0.03 dex (1 significant) on the size-mass relation zero point between the field and the large structure sub-samples, with a richness threshold of N=10 to separate between small and large structures, and of 0.06 dex (2) with N=20. Similarly, we find a 0.1 dex (2A) difference on the MS relation with N=10 and 0.15 dex (3) with N=20. These results suggest that galaxies in massive structures are smaller by 14% and have star formation rates reduced by a factor of 1.31.5 with respect to field galaxies at z 0.7. Finally, we do not find any impact of the environment on the TFR, except when using N=20 with an offset of 0.04 dex (1). We discard the effect of quenching for the largest structures, which would lead to an offset in the opposite direction. We find that, at z0.7, if quenching impacts the mass budget of galaxies in structures, these galaxies would have been affected quite recently and for roughly 0.7-+1.5 Gyr. This result holds when including the gas mass but vanishes once we include the asymmetric drift correction.
- ItemNew criteria for the selection of galaxy close pairs from cosmological simulations: Evolution of the major and minor merger fraction in MUSE deep fields(Les Ulis : EDP Sciences, 2019) Ventou, E.; Contini, T.; Bouché, N.; Epinat, B.; Brinchmann, J.; Inami, H.; Richard, J.; Schroetter, I.; Soucail, G.; Steinmetz, M.; Weilbacher, P.M.It remains a challenge to assess the merger fraction of galaxies at different cosmic epochs in order to probe the evolution of their mass assembly. Using the Illustris cosmological simulation project, we investigate the relation between the separation of galaxies in a pair, both in velocity and projected spatial separation space, and the probability that these interacting galaxies will merge in the future. From this analysis, we propose a new set of criteria to select close pairs of galaxies along with a new corrective term to be applied to the computation of the galaxy merger fraction. We then probe the evolution of the major and minor merger fraction using the latest Multi-Unit Spectroscopic Explorer (MUSE) deep observations over the Hubble Ultra Deep Field, Hubble Deep Field South, COSMOS-Gr30, and Abell 2744 regions. From a parent sample of 2483 galaxies with spectroscopic redshifts, we identify 366 close pairs spread over a large range of redshifts (0:2 < z < 6) and stellar masses (107-1011 M ). Using the stellar mass ratio between the secondary and primary galaxy as a proxy to split the sample into major, minor, and very minor mergers, we found a total of 183 major, 142 minor, and 47 very minor close pairs corresponding to a mass ratio range of 1:1-1:6, 1:6-1:100, and lower than 1:100, respectively. Due to completeness issues, we do not consider the very minor pairs in the analysis. Overall, the major merger fraction increases up to z ≈2-3 reaching 25% for pairs where the most massive galaxy has a stellar mass M· = 109:5 M . Beyond this redshift, the fraction decreases down to ∼5% at z≈6. The major merger fraction for lower-mass primary galaxies with M· = 109:5 M seems to follow a more constant evolutionary trend with redshift. Thanks to the addition of new MUSE fields and new selection criteria, the increased statistics of the pair samples allow us to significantly shorten the error bars compared to our previous analysis. The evolution of the minor merger fraction is roughly constant with cosmic time, with a fraction of 20% at z < 3 and a slow decrease to 8-13% in the redshift range 3 ≤ z ≤ 6.
- ItemEvidence for ram-pressure stripping in a cluster of galaxies at z = 0.7(Les Ulis : EDP Sciences, 2019) Boselli, A.; Epinat, B.; Contini, T.; Abril-Melgarejo, V.; Boogaard, L. A.; Pointecouteau, E.; Ventou, E.; Brinchmann, J.; Carton, D.; Finley, H.; Michel-Dansac, L.; Soucail, G.; Weilbacher, P.M.Multi-Unit Spectroscopic Explorer (MUSE) observations of the cluster of galaxies CGr32 (M200≅ 2×1014 M⊙) at = 0.73 reveal the presence of two massive star-forming galaxies with extended tails of diffuse gas detected in the [O II]λλ3727-3729 Å emission-line doublet. The tails, which have a cometary shape with a typical surface brightness of a few 10-18 erg s-1 cm-2 arcsec-2, extend up to ≅ 100 kpc (projected distance) from the galaxy discs, and are not associated with any stellar component. All this observational evidence suggests that the gas was removed during a ram-pressure stripping event. This observation is thus the first evidence that dynamical interactions with the intracluster medium were active when the Universe was only half its present age. The density of the gas derived using the observed [O II]λ3729/[O II]λ3726 line ratio implies a very short recombination time, suggesting that a source of ionisation is necessary to keep the gas ionised within the tail.