Galaxy kinematics in the XMMU J2235-2557 cluster field at z 1.4

Autor(en): José Manuel Pérez Martinez, Bodo Ziegler, Miguel Anibal Verdugo Olivares, Asmus Böhm, Masayuki Tanaka
Abstrakt: Aims: The relationship between baryonic and dark components in galaxies varies with the environment and cosmic time. Galaxy scaling relations describe strong trends between important physical properties. A very important quantitative tool in case of spiral galaxies is the Tully-Fisher relation (TFR), which combines the luminosity of the stellar population with the characteristic rotational velocity (Vmax) taken as proxy for the total mass. In order to constrain galaxy evolution in clusters, we need measurements of the kinematic status of cluster galaxies at the starting point of the hierarchical assembly of clusters and the epoch when cosmic star formation peaks.
Methods: We took spatially resolved slit FORS2 spectra of 19 cluster galaxies at z 1.4, and 8 additional field galaxies at 1 < z < 1.2 using the ESO Very Large Telescope. The targets were selected from previous spectroscopic and photometric campaigns as [OII] and H_α emitters. Our spectroscopy was complemented with HST/ACS imaging in the F775W and F850LP filters, which is mandatory to derive the galaxy structural parameters accurately. We analyzed the ionized gas kinematics by extracting rotation curves from the two-dimensional spectra. Taking into account all geometrical, observational, and instrumental effects, we used these rotation curves to derive the intrinsic maximum rotation velocity.
Results: V_max was robustly determined for six cluster galaxies and three field galaxies. Galaxies with sky contamination or insufficient spatial rotation curve extent were not included in our analysis. We compared our sample to the local B-band TFR and the local velocity-size relation (VSR), finding that cluster galaxies are on average 1.6 mag brighter and a factor 2-3 smaller. We tentatively divided our cluster galaxies by total mass (I.e., V_max) to investigate a possible mass dependency in the environmental evolution of galaxies. The averaged deviation from the local TFR is ⟨ ΔM_B ⟩ = -0.7 for the high-mass subsample (V_max > 200 km s^-1). This mild evolution may be driven by younger stellar populations (SP) of distant galaxies with respect to their local counterparts, and thus, an increasing luminosity is expected toward higher redshifts. However, the low-mass subsample (V_max < 200 km s^-1) is made of highly overluminous galaxies that show ⟨ ΔM_B ⟩ = -2.4 mag. When we repeated a similar analysis with the stellar mass TFR, we did not find significant offsets in our subsamples with respect to recent results at similar redshift. While the B-band TFR is sensitive to recent episodes of star formation, the stellar mass TFR tracks the overall evolution of the underlying stellar population. In order to understand the discrepancies between these two incarnations of the TFR, the reported B-band offsets can no longer be explained only by the gradual evolution of stellar populations with lookback time. We suspect that we instead see compact galaxies whose star formation was enhanced during their infall toward the dense regions of the cluster through interactions with the intracluster medium.
Based on observations with the European Southern Observatory Very Large Telescope (ESO-VLT), observing run ID 091.B-0778(B).
Organisation(en): Institut für Astrophysik
Externe Organisation(en): Leopold-Franzens-Universität Innsbruck, National Astronomical Observatory of Japan
Journal: Astronomy & Astrophysics
Band: 605
Anzahl der Seiten: 14
ISSN: 0004-6361
DOI: https://doi.org/10.1051/0004-6361/201630165
Publikationsdatum: 09-2017
Peer-reviewed: Ja
ÖFOS 2012: 103003 Astronomie, 103004 Astrophysik
Schlagwörter
ASJC Scopus Sachgebiete: Astronomy and Astrophysics, Space and Planetary Science
Link zum Portal: https://ucrisportal.univie.ac.at/de/publications/518aaf1b-fe5d-46c2-bcd4-34489be128d9

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