Related papers: Finding Fossil Groups: Optical Identification and …
Galaxy pairs may represent a way station in the evolutionary path from poor groups to giant isolated ellipticals (or fossil groups). To test this evolutionary scenario, we investigated the environment of 4 galaxy pairs composed of a giant…
We characterize the optical counterparts to the compact X-ray source population within the nearby spiral galaxy M81 using multi-band Hubble Space Telescope (HST) imaging data. By comparing the optical luminosities and colors measured for…
We have undertaken a multiwavelength project to study the relatively unknown properties of groups and poor clusters of galaxies at intermediate redshifts. In this paper, we describe the XMM-Newton observations of six X-ray selected groups…
We have used the ROSAT All-Sky Survey to detect a known supercluster at z=0.087 in the North Ecliptic Pole region. The X-ray data greatly improve our understanding of this supercluster's characteristics, approximately doubling our knowledge…
"Fossil" galaxy groups, each dominated by a relatively isolated giant elliptical galaxy, have many properties intermediate between groups and clusters of galaxies. We used the {\sl Suzaku} X-ray observatory to observe the X-ray brightest…
Isolated compact groups of galaxies (CGs) present a range of dynamical states, group velocity dispersions, and galaxy morphologies with which to study galaxy evolution, particularly the properties of gas both within the galaxies and in the…
We consider the possibility that masses and gravitational potentials of galaxy cluster, estimated at X-ray wavelengths, could be explained without assuming huge amounts of dark matter, but in the context of $f(R)$-gravity. Specifically, we…
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…
Galaxy groups form the environment of the majority of galaxies in the local Universe, and many host an extended hot intra-group medium whose radiative cooling appears to fuel, and be stabilised by, feedback from AGN in group-central…
We use the Sloan Digital Sky Survey to construct a sample of 625 brightest group and cluster galaxies (BCGs) together with control samples of non-BCGs matched in stellar mass, redshift, and color. We investigate how the systematic…
Building upon three late-type galaxies in the Virgo cluster with both a predicted black hole mass of less than $\sim$10$^5$ M$_{\odot}$ and a centrally-located X-ray point-source, we reveal 11 more such galaxies, more than tripling the…
The majority of Galactic globular clusters (GCs) contain multiple stellar populations displaying specific chemical abundance variations. In particular, GCs generally contain a `primordial' population with abundances similar to field stars,…
Galaxy cluster cosmology relies on complete and pure samples spanning a large range of masses and redshifts. In Xu et al. (2018) and Xu et al. (2022), we discovered an apparently new population of galaxy groups and clusters with, on…
It is well established that brightest cluster galaxies (BCGs), residing in the center of galaxy clusters, are typically massive and quenched galaxies with cD or elliptical morphology. An optical survey suggested that an exotic galaxy…
We study six groups and clusters of galaxies suggested in the literature to be `fossil' systems (i.e. to have luminous diffuse X-ray emission and a magnitude gap of at least 2 mag-R between the first and the second ranked member within half…
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…
We present a catalogue of bulgeless galaxies, which includes 19225 objects selected in four of the deepest, largest multi-wavelength datasets available -- COSMOS, AEGIS, GEMS and GOODS -- at intermediate redshift ($0.4 \leq z \leq 1.0$).…
Many globular clusters (GCs) in the Milky Way (MW) have been studied in recent years, especially in hidden regions such as those of the Galactic bulge. Our main goal is to understand what we can learn if we include these new objects into…
We investigate the origin and evolution of fossil groups in a concordance LCDM cosmological simulation. We consider haloes with masses between $(1-5)\times10^{13} \hMsun$ and study the physical mechanisms that lead to the formation of the…
We examined 134 Chandra observations of the population of X-ray sources associated with globular clusters (GCs) in the central region of M31. These are expected to be X-ray binary systems (XBs), consisting of a neutron star or black hole…