ar X iv : a st ro - p h / 06 11 62 5 v 1 20 N ov 2 00 6 A possible dearth of hot gas in galaxy groups at intermediate redshift
نویسندگان
چکیده
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 ksec of observation, even though three of the 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. Subject headings: cosmology: observations – galaxies: clusters: general – X–rays: galaxies: clusters
منابع مشابه
ar X iv : a st ro - p h / 06 11 09 9 v 1 2 N ov 2 00 6 Nuclear Activity in UZC Compact Groups of Galaxies
متن کامل
ar X iv : a st ro - p h / 05 11 62 1 v 1 2 1 N ov 2 00 5 1 GALACTIC CORONA OR LOCAL GROUP INTERGALACTIC MEDIUM ?
Cosmological hydrodynamic simulations predict that the low redshift universe comprises a web of warm–hot intergalactic gas and galaxies, with groups of galaxies and clusters forming at dense knots in these filaments. Our own Galaxy being no exception is also expected to be surrounded by the warm–hot intergalactic medium, filling the Local Group. Some theoretical models also predict the existenc...
متن کاملar X iv : a st ro - p h / 03 11 08 9 v 1 4 N ov 2 00 3 Hot Gas in the Local Group and Low - Redshift Intergalactic Medium
There is increasing observational evidence that hot, highly ionized interstellar and intergalactic gas plays a significant role in the evolution of galaxies in the local universe. The primary spectral diagnostics of the warm-hot interstellar/intergalactic medium are ultraviolet and X-ray absorption lines of Ovi and Ovii. In this paper, I summarize some of the recent highlights of spectroscopic ...
متن کاملar X iv : a st ro - p h / 06 11 43 8 v 1 1 4 N ov 2 00 6 Lack of cooling flow clusters at z > 0 . 5
The goal of this work is to study the incidence rate of “cooling flows” in the high redshift clusters using Chandra observations of z > 0.5 objects from a new large, X-ray selected catalog [1]. We find that only a very small fraction of high-z objects have cuspy X-ray brightness profiles, which is a characteristic feature of the cooling flow clusters at z ∼ 0. The observed lack of cooling flows...
متن کاملar X iv : a st ro - p h / 05 11 19 6 v 1 7 N ov 2 00 5 The Volume Fraction of Ionized Intergalactic Gas at Redshift z = 6 . 5
The observed number density of Lyman-α sources implies a minimum volume of the inter-galactic medium that must be ionized, in order to allow the Lyman-α photons to escape attenuation. We estimate this volume by assigning to each Lyman-α emitter the minimum Stromgren sphere that would allow half its Lyman-α photons to escape. This implies a lower limit to ionized gas volume fraction of 20-50% at...
متن کامل