Related papers: X-ray Observations of Optically Selected Giant Ell…

The group of galaxies RXJ1340.6+4018 has approximately the same bolometric X-ray luminosity as other bright galaxy groups and poor clusters such as the Virgo cluster. However, 70% of the optical luminosity of the group comes from a dominant…

This paper given at the meeting on "Mapping, Measuring and Modelling the Universe" presents three topics: 1) the study of the clusters and groups of galaxies found serendipitously in the North Ecliptic Pole (NEP) region of the ROSAT all-sky…

The scenario of galaxy formation is believed to follow a structure that builds up from the bottom, with large galaxies being formed by several merging episodes of smaller ones. In this scenario a number of galaxies can be expected to be…

It has been known for over 30 years that Galactic globular clusters (GCs) are overabundant by orders of magnitude in bright X-ray sources per unit mass relative to the disk population. Recently a quantitative understanding of this…

We present MMT spectroscopic observations of two massive galaxy cluster candidates at redshift $z\sim0.07$ that show extended and diffuse X-ray emission in the ROSAT All Sky Survey (RASS) images. The targets were selected from a previous…

Context: We use the first XMM serendipitous source catalogue (1XMM) to compile a sample of normal X-ray galaxies Aims: We seek to expand the database of X-ray selected normal galaxies at intermediate redshifts and examine the relation…

We suggest the radii and luminosities of the X-ray emitting halos of elliptical galaxies define a fundamental plane with the star velocity dispersions, as for the corresponding optical observables. Since the X-ray emitting material usually…

We present the X-ray and optical properties of the galaxy groups selected in the Chandra X-Bo\"otes survey. Our final sample comprises 32 systems at \textbf{$z<1.75$}, with 14 below $z = 0.35$. For these 14 systems we estimate velocity…

We analyze six X-ray bright elliptical galaxies, observed with Chandra and XMM-Newton, and approximate their gravitational potentials by isothermal spheres phi(r)=v_c^2 ln(r) over a range of radii from ~0.5 to ~25 kpc. We then compare the…

Currently, the number of galaxy clusters identified using galaxy data has far exceeded the number derived from intracluster medium data. In this study, we used positional information from large optical cluster catalogues to search for…

Properties of groups of galaxies depend sensitively on the algorithm for group selection, and even the most recent catalogs of groups built from redshift-space selection should suffer from projections and infalling galaxies. The…

Clusters of galaxies at high redshift (z>1) are vitally important to understand the evolution of the large scale structure of the Universe, the processes shaping galaxy populations and the cycle of the cosmic baryons, and to constrain…

(Abridged) Distant galaxy clusters provide important tests of the growth of large scale structure in addition to highlighting the process of galaxy evolution in a consistently defined environment at large look back time. We present a sample…

Elliptical galaxies are generally luminous sources of X-ray radiation, and contain large amounts of hot, interstellar gas. In the brighter X-ray galaxies, the inferred masses of hot gas are consistent with those expected given the present…

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…

Feedback from supernovae and AGN shapes galaxy formation and evolution, yet its impact remains unclear. Galaxy groups offer a crucial probe, as their binding energy is comparable to that available from their central AGN. The XMM-Newton…

We describe some of the first X-ray detections of groups of galaxies at high redshifts (z~0.4), based on the UK deep X-ray survey of McHardy et al (1998). Combined with other deep ROSAT X-ray surveys with nearly complete optical…

Multiwavelength observations of the hard X-ray selected sources by Chandra and XMM-Newton surveys have significantly improved our knowledge of the objects responsible of the hard X-ray background. A surprising finding is the discovery of a…

The X-ray emission from normal elliptical galaxies has two major components: soft emission from diffuse gas and harder emission from populations of accreting (low-mass) stellar X-ray binaries (LMXB). If LMXB populations are tied to the…

We have discovered a strong lensing fossil group (J0454) at z=0.26, projected near the well-studied cluster MS0451-0305. Using multicolour Subaru/Suprime-Cam and CFHT/Megaprime imaging together with Keck spectroscopy we identify member…