2008/06/02 by Tesla E. Jeltema, T. E. Jeltema, J. S. Mulchaey +3 · 4 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Cluster (spacecraft) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Intracluster medium #Merge (version control) #Scaling #astro-ph
paper · pdf · doi:10.1086/590550
published in The Astrophysical Journal 685(1), 138-146 (IOP Publishing) · 23 pages, 6 figures, accepted for publication in ApJ
arxiv created 2008/06/02 · openalex publication_date 2008/09/18 · arxiv updated 2010/11/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
Using deep Chandra and optical spectroscopic observations, we investigate an intriguing young massive group, RX J1648.7+6109, at z = 0.376, and we combine these observations with previous measurements to fit the scaling relations of intermediate-redshift groups and poor clusters. RX J1648 appears to be in an early stage of formation; while it follows X-ray scaling relations, its X-ray emission is highly elongated, and it lacks a central, dominant BCG. Instead, RX J1648 contains a central string of seven bright galaxies, which have a smaller velocity dispersion, are on average brighter, and have less star formation [lower EW([O II]) and EW(Hδ)] than other group galaxies. The four to five brightest galaxies in this string should sink to the center and merge through dynamical friction by z = 0, forming a BCG consistent with a system of RX J1648's mass even if 5%-50% of the light is lost to an intracluster light component. The L X − T X relation for intermediate-redshift groups/poor clusters is very similar to the low-redshift cluster relation and consistent with the low-redshift group relation. In contrast, the L X − σ v and σ v − T X relations reveal that intermediate-redshift groups/poor clusters have significantly lower velocity dispersions for their X-ray properties compared to low-redshift systems; however, the intermediate-redshift relations are currently limited to a small range in luminosity.