TY - JOUR
T1 - Galaxy cluster assembly at z = 0.37
AU - Gonzalez, Anthony H.
AU - Tran, Kim Vy H.
AU - Conbere, Michelle N.
AU - Zaritsky, Dennis
N1 - Funding Information:
We are indebted to A. Vikhlinin and M. Markevitch for their assistance and for providing us with codes employed in the Chandra analysis. Support for this work was provided by NASA through Chandra award GO2-3183X3 issued by the Chandra X-Ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS 8-03060. A. H. G. is funded by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST 04-07085, K.-V. H. T. acknowledges support from the Swiss National Science Foundation, and D. Z. acknowledges fellowships from the David and Lucile Packard Foundation and the Alfred P. Sloan Foundation.
PY - 2005/5/10
Y1 - 2005/5/10
N2 - We present X-ray and spectroscopic confirmation of a cluster assembling from multiple, distinct galaxy groups at z = 0.371. Initially detected in the Las Campanas Distant Cluster Survey, the structure contains at least four X-ray-detected groups that lie within a maximum projected separation of 4 Mpc and within Δv = 550 km s-1 of one another. Using Chandra imaging and wide-field optical spectroscopy, we show that the individual groups lie on the local σ-T relation and derive a total mass of M ≥ 5 × 1014 M⊙ for the entire structure. We demonstrate that the groups are gravitationally bound to one another and will merge into a single cluster with about one-third or more the mass of Coma. We also find that although the cluster is in the process of forming, the individual groups already have a higher fraction of passive members than the field. This result indicates that galaxy evolution on group scales is key to developing the early-type galaxies that dominate the cluster population by z ∼ 0.
AB - We present X-ray and spectroscopic confirmation of a cluster assembling from multiple, distinct galaxy groups at z = 0.371. Initially detected in the Las Campanas Distant Cluster Survey, the structure contains at least four X-ray-detected groups that lie within a maximum projected separation of 4 Mpc and within Δv = 550 km s-1 of one another. Using Chandra imaging and wide-field optical spectroscopy, we show that the individual groups lie on the local σ-T relation and derive a total mass of M ≥ 5 × 1014 M⊙ for the entire structure. We demonstrate that the groups are gravitationally bound to one another and will merge into a single cluster with about one-third or more the mass of Coma. We also find that although the cluster is in the process of forming, the individual groups already have a higher fraction of passive members than the field. This result indicates that galaxy evolution on group scales is key to developing the early-type galaxies that dominate the cluster population by z ∼ 0.
KW - Galaxies: clusters: general
KW - Galaxies: evolution
KW - X-rays: galaxies: clusters
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U2 - 10.1086/430518
DO - 10.1086/430518
M3 - Article
AN - SCOPUS:19844381617
SN - 0004-637X
VL - 624
SP - L73-L76
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2 II
ER -