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arXiv · 0806.2157

Spitzer/MIPS 24um Observations of Galaxy Clusters: An Increasing Fraction of Obscured Star-forming Members from z=0.02 to z=0.83

Amélie Saintonge·Kim-Vy H. Tran·Brad P. Holden
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Abstract

We study the mid-infrared properties of 1315 spectroscopically confirmed members in eight massive (M>5x10^14 Msun) galaxy clusters covering the redshift range from 0.02 to 0.83. The selected clusters all have deep Spitzer MIPS 24um observations, Hubble and ground-based photometry, and extensive redshift catalogs. We observe for the first time an increase in the fraction of cluster galaxies with mid-infrared star formation rates higher than 4 solar masses per year from 3% at z=0.02 to 13% at z=0.83. This increase is reproduced even when considering only the most massive members (Mstars >4x10^10 Msun). The 24 micron observations reveal stronger evolution in the fraction of blue/star-forming cluster galaxies than color-selected samples: the number of red but strongly star-forming cluster galaxies increases with redshift, and combining these with the optically-defined Butcher-Oemler members increases the total fraction of blue/star-forming cluster galaxies to ~30% at z=0.83. These results, the first of our Spitzer/MIPS Infra-Red Cluster Survey (SMIRCS), support earlier studies indicating the increase in star-forming members is driven by cluster assembly and galaxy infall, as is expected in the framework of hierarchical formation.

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Amélie Saintonge, Kim-Vy H. Tran, Brad P. Holden. 2008-09-30. Spitzer/MIPS 24um Observations of Galaxy Clusters: An Increasing Fraction of Obscured Star-forming Members from z=0.02 to z=0.83. https://doi.org/10.1086/592730

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