Star formation activity in a young galaxy cluster at z=0.866

Abstract

The galaxy cluster RXJ1257$+$4738 at $z=0.866$ is one of the highest redshift clusters with a richness of multi-wavelength data, and thus a good target to study the star formation-density relation at early epochs. Using a sample of spectroscopically-confirmed cluster members, we derive the star formation rates of our galaxies using two methods, (I) the relation between SFR and total infrared luminosity extrapolated from the observed \textit{Spitzer} MIPS 24$\mu$m imaging data, and (II) spectral energy distribution (SED) fitting using the MAGPHYS code, including eight different bands. We show that, for this cluster, the SFR-density relation is very weak and seems to be dominated by the two central galaxies and the SFR presents a mild dependence on stellar mass, with more massive galaxies having higher SFR. However, the specific SFR (SSFR) decreases with stellar mass, meaning that more massive galaxies are forming less stars per unit of mass, and thus suggesting that the increase in star-forming members is driven by cluster assembly and infall. If the environment is somehow driving the SF, one would expect a relation between the SSFR and the cluster centric distance, but that is not the case. A possible scenario to explain this lack of correlation is the contamination by infalling galaxies in the inner part of the cluster which may be on their initial pass through the cluster center. As these galaxies have higher SFRs for their stellar mass, they enhance the mean SSFR in the center of the cluster.

Accepted for publication in ApJ. 12 pages, 6 figures

References in corpus (11)

• Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
• A simple model to interpret the ultraviolet, optical and infrared emission from galaxies
• The DEEP2 Galaxy Redshift Survey: The Role of Galaxy Environment in the Cosmic Star-Formation History
• The DEEP2 Galaxy Redshift Survey: The Relationship Between Galaxy Properties and Environment at z ~ 1
• Optical spectroscopy and X-ray detections of a sample of quasars and AGN selected in the mid-infrared from two Spitzer wide-area surveys
• The VIMOS VLT Deep Survey: The build-up of the colour-density relation
• Spitzer/MIPS 24um Observations of Galaxy Clusters: An Increasing Fraction of Obscured Star-forming Members from z=0.02 to z=0.83
• IR observations of MS 1054-03: Star Formation and its Evolution in Rich Galaxy Clusters
• The XMM Cluster Survey: The Dynamical State of XMMXCS J2215.9-1738 at z=1.457
• The Evolution of Dusty Star formation in Galaxy Clusters to z = 1: Spitzer IR Observations of the First Red-Sequence Cluster Survey
• Multi-wavelength landscape of the young galaxy cluster RXJ1257.2+4738 at z=0.866: I. The infrared view

Cited by in corpus (2)

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