Hubble Space Telescope near-infrared and optical imaging of faint radio sources in the distant cluster C1 0939+4713

被引:111
作者
Smail, I
Morrison, G
Gray, ME
Owen, FN
Ivison, RJ
Kneib, JP
Ellis, RS
机构
[1] Univ Durham, Dept Phys, Durham DH1 3LE, England
[2] Natl Radio Astron Observ, Socorro, NM 87801 USA
[3] Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England
[4] UCL, Dept Phys & Astron, London WC1E 6BT, England
[5] Observ Midi Pyrenees, CNRS UMR5572, F-31400 Toulouse, France
关键词
galaxies : clusters : individual (C1 0939+4713); galaxies : evolution; galaxies : starburst; infrared : galaxies; radio continuum : galaxies;
D O I
10.1086/307934
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present deep Hubble Space Telescope Near-Infrared Camera and Multiobject Spectrograph (NICMOS) and Wide Field and Planetary Camera 2 (WFPC2) optical imaging of a small region in the core of the distant rich cluster Cl 0939 + 4713 (z = 0.41). We compare the optical and near-infrared morphologies of cluster members and find apparent small-scale optical structures within the galaxies that are absent in the near-infrared. We conclude that strong dust obscuration is a common feature in the late-type galaxies in distant clusters. We then concentrate on a sample of 10 faint radio galaxies lying within our NICMOS field and selected from a very deep 1.4 GHz VLA map of the cluster with a 1 sigma flux limit of 9 mu Jy. Using published data we focus on the spectral properties of the eight radio-selected cluster members and show that these comprise a large fraction of the poststarburst population in the cluster. The simplest interpretation of the radio emission from these galaxies is that they are currently forming massive stars, contradicting their classification as poststarburst systems based on the optical spectra. We suggest that this star formation is hidden from view in the optical by the same obscuring dust that is apparent in our comparison on the optical and near-infrared morphologies of these galaxies. We caution that even in the rest-frame optical the effects of dust cannot be ignored when comparing samples of distant galaxies to low-redshift systems, particularly if dust is as prevalent in distant galaxies as appears to be the case in our study.
引用
收藏
页码:609 / 620
页数:12
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