Related papers: X-rays from Open Clusters
The activity levels of stars are influenced by several stellar properties, such as stellar rotation, spectral type and the presence of stellar companions. In analogy to binaries, planetary companions are also thought to be able to cause…
The cosmological constraining power of modern galaxy cluster catalogs can be improved by obtaining low-scatter mass proxy measurements for even a small fraction of sources. In the context of large upcoming surveys that will reveal the…
We present the X-ray source detection procedure that we have developed for the purpose of assembling and characterizing controlled samples of cluster of galaxies for the XMM Large Scale Structure Survey. We describe how we model the…
We have designed a medium deep large area X-ray survey with XMM - the XMM Large Scale Structure survey, XMM-LSS - with the scope of extending the cosmological tests attempted using ROSAT cluster samples to two redshift bins between 0<z<1…
We review recent work that investigates the formation of stellar clusters, ranging in scale from globular clusters through open clusters to the small scale aggregates of stars observed in T associations. In all cases, recent advances in…
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…
The current paradigm of cosmic formation and evolution of galaxy clusters foresees growth mostly through merging. Galaxies in the infall region or in the core of a cluster undergo transformations owing to different environmental stresses.…
I review recent observational progress in the search for and study of distant galaxy clusters in the X-ray band, with particular emphasis on the evolution of the abundance of X-ray clusters out to z~1. Several on-going deep X-ray surveys…
We present the results of a combination of new stellar rotation periods and extensive information about membership in the young open clusters M35 and M34. The observations show that late-type members of both clusters divide into two…
X-ray spectroscopy of cooling-flow clusters reveal an unexpected deficit of soft X-ray emission lines from gas at ~1/3 of the ambient plasma temperature, across a wide range of X-ray luminosities and virial temperatures. We propose excess…
We present first strong observational evidence that the X-ray cool-core bias or the apparent bias in the abundance of relaxed clusters is absent in our REFLEX volume-limited sample (ReVols). We show that these previously observed biases are…
Nearby associations of stars which are coeval are important benchmark laboratories because they provide robust measurements of stellar ages. The study of such coeval groups makes it possible to better understand star formation by studying…
We used archival ROSAT observations to investigate the X-ray surface brightness profiles of a sample of 26 clusters in the redshift range (0.04-0.06). For 15 of these clusters accurate temperature (kT>3.5 keV) were available from the…
The HST data archive contains images of several nearby spirals, suitable for detailed studies of the properties of individual star clusters and their surroundings. By combining structural information derived from HST images with…
Recent observations of high energy (> 20 keV) X-ray emission in a few clusters extend and broaden our knowledge of physical phenomena in the intracluster space. This emission is likely to be nonthermal, probably resulting from Compton…
We have performed a uniform analysis of 79 clusters of galaxies with the ROSAT HRI and ASCA to study the X-ray structure and evolution of clusters in the redshift range 0.1 < z < 1. We determined the average X-ray temperatures and the…
A new method for a simultaneous search for clusters of galaxies in X-ray photon maps and optical galaxy maps is described. The merging of X-ray and optical data improves the source identification so that a large amount of telescope time for…
We suggest that the seven radio-quiet isolated neutron stars observed with ROSAT are young cooling objects associated to recent near-by supernova explosions which formed runaway stars and the Local Bubble, affecting the topology of the…
Observations of gravitational lensing indicate that the mass distribution in clusters of galaxies (where most of the mass is dark matter) is highly peaked towards the center, while X-ray observations imply that the gas is more extended. The…
A sample consisting of 27 X-ray selected galaxy clusters from the XMM-LSS survey is used to study the evolution in the X-ray surface brightness profiles of the hot intracluster plasma. These systems are mostly groups and poor clusters, with…