2006/11/30 by David S. Spiegel, Frits Paerels, F. Paerels +2
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/511253
published as Astrophys.J.658:288-298,2007 · 16 pages, 5 figures, reference added in section 1, typos corrected, published in ApJ
openalex publication_date 2007/03/14 · arxiv created 2007/04/30 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We examine the X-ray luminosity of galaxy groups in the CNOC2 survey at redshifts 0.1 < z < 0.6. Previous work examining the gravitational lensing signal of the CNOC2 groups has shown that they are likely to be genuine, gravitationally bound objects. Of the 21 groups in the field of view of the EPIC pn camera on XMM-Newton , not one was visible in over 100 ks of observation, even though three of them have velocity dispersions high enough that they would easily be visible if their luminosities scaled with their velocity dispersions in the same way as nearby groups' luminosities scale. We consider the possibility that this is due to the reported velocity dispersions being erroneously high and conclude that this is unlikely. We therefore find tentative evidence that groups at intermediate redshift are underluminous relative to their local cousins.