%0 Journal Article
%T CLASH-VLT: Enhancement of (O/H) in z £¿=£¿ 0.35 RX J2248£¿4431 cluster galaxies
%A B. I. Ciocan
%A B. L. Ziegler
%A C. Maier
%A M. Verdugo
%J -
%D 2020
%R 10.1051/0004-6361/201936712
%X <i>Aims.<i/> Gas-phase metallicities offer insight into the chemical evolution of galaxies as they reflect the recycling of gas through star formation and galactic inflows and outflows. Environmental effects such as star-formation quenching mechanisms play an important role in shaping the evolution of galaxies. Clusters of galaxies at <i>z<i/>£¿< £¿0.5 are expected to be the sites where environmental effects can be clearly observed with present-day telescopes.<i>Methods.<i/> We explored the Frontier Fields cluster RX J2248£¿443 at <i>z<i/>£¿=£¿0.348 with VIMOS/VLT spectroscopy from CLASH-VLT, which covers a central region corresponding to almost 2 virial radii. The fluxes of [OII] <i>¦Ë<i/>3727, H<i>¦Â<i/>, [OIII] <i>¦Ë<i/>5007, H<i>¦Á<i/> and [NII] <i>¦Ë<i/>6584 emission lines were measured allowing the derivation of (O/H) gas metallicities, star formation rates based on extinction-corrected H<i>¦Á<i/> fluxes, and contamination from active galactic nuclei. We compared our sample of cluster galaxies to a population of field galaxies at similar redshifts.<i>Results.<i/> We use the location of galaxies in projected phase-space to distinguish between cluster and field galaxies. Both populations follow the star-forming sequence in the diagnostic diagrams, which allow the ionising sources in a galaxy to be disentangled, with only a low number of galaxies classified as Seyfert II. Both field and cluster galaxies follow the ¡°main sequence¡± of star-forming galaxies, with no substantial difference observed between the two populations. In the mass¨Cmetallicity (MZ) plane, both high-mass field and cluster galaxies show comparable (O/H)s to the local SDSS MZ relation, with an offset of low-mass galaxies (log(<i>M<i/>/<i>M<i/><sub>¡Ñ<sub/>) < 9.2) towards higher metallicities. While both the metallicities of ¡°accreted¡± (<i>R<i/>£¿< £¿<i>R<i/><sub>500<sub/>) and ¡°infalling¡± (<i>R<i/>£¿> £¿<i>R<i/><sub>500<sub/>) cluster members are comparable at all masses, the cluster galaxies from the ¡°mass complete¡± bin (which is the intermediate mass bin in this study: 9.2£¿< £¿log(<i>M<i/>/<i>M<i/><sub>¡Ñ<sub/>) < 10.2), show more enhanced metallicities than their field counterparts by a factor of 0.065 dex with a ¡«1.8<i>¦Ò<i/> significance. The intermediate-mass field galaxies are in accordance with the expected (O/H)s from the fundamental metallicity relation, while the cluster members deviate strongly from the model predictions, namely by a factor of ¡«0.12 dex. The results of this work are in accordance with studies of other clusters at <i>z<i/>£¿< £¿0.5 and favour the scenario in which the hot
%U https://www.aanda.org/articles/aa/full_html/2020/01/aa36712-19/aa36712-19.html