Related papers: Interacting X-ray Binaries in Globular Clusters: 4…
The millisecond pulsars discovered in globular clusters are diagnostic tools for studying the dynamics of the clusters, the intracluster ionized gas and the evolution of the binaries embedded in the cluster. In the first two years of a…
We used a set of archived HST/WFPC2 images to probe the stellar population in the core of the nearby Galactic Globular Cluster (GGC) 47 Tuc. From the ultraviolet (UV) Color Magnitude Diagrams (CMDs) obtained for ~4,000 stars detected within…
As ancient, gravitationally bound stellar populations, globular clusters are abundant, vibrant laboratories characterized by high frequencies of dynamical interactions coupled to complex stellar evolution. Using surface brightness and…
We have systematically studied the X-ray emission properties of globular cluster millisecond pulsars in order to evaluate their spectral properties and luminosities in a uniform way. Cross-correlating the radio timing positions of the…
We have observed the old open clusters M 67 and NGC 188 with the ROSAT PSPC. In M 67 we detect a variety of X-ray sources. The X-ray emission by a cataclysmic variable, a single hot white dwarf, two contact binaries, and some RS CVn systems…
We searched for infrared counterparts to the cluster of X-ray point sources discovered by Chandra in the Galactic Center Region (GCR). While the sources could be white dwarfs, neutron stars, or black holes accreting from stellar companions,…
Chandra observations of distant elliptical galaxies have revealed large numbers of Low Mass X-ray Binaries (LMXBs) accreting at rates in excess of 10^{-8} solar masses per year. The majority of these LMXBs reside in globular clusters (GCs)…
We report results from Hubble Space Telescope WFPC2 imaging of the field of the luminous, bursting X-ray source in the globular cluster NGC 6441. Although the X-ray position is known to a precision of a few arcseconds, this source is only…
We have investigated the effect of the number of primordial binaries on the relationship between the total number of detected binaries within globular cluster and its collision rate. We have used simulated populations of binary stars in…
We report the results of pulsar searches in ten globular clusters using the Robert C. Byrd Green Bank Telescope. One new binary millisecond pulsar has been discovered in NGC 5986 with P=2.6 ms, P_orb=1.3 d, and a minimum companion mass of…
We investigate the dynamical formation and evolution of binaries containing neutron stars in dense globular clusters. Our numerical simulations combine a simple Monte Carlo prescription for stellar dynamics, a sophisticated binary…
Population synthesis is used to model the number of neutron stars in globular clusters that are observed as LMXBs and millisecond PSRs. The dynamical interaction between binary and single stars in a GC are assumed to take place with a…
We report on the Chandra X-ray Observatory ACIS-S3 imaging observation of the Galactic globular cluster M4 (NGC 6121). We detect 12 X-ray sources inside the core and 19 more within the cluster half-mass radius. The limiting luminosity of…
X-ray bursts from bright sources in globular clusters of our galaxy show that at least 11 (of a total 13) of these sources are neutron stars. One of the low-luminosity X-ray sources in omega Cen is a neutron star accreting at a low rate.…
We identify through their X-ray spectra one certain (W37) and two probable (W17 and X4) quiescent low-mass X-ray binaries (qLMXBs) containing neutron stars in a long Chandra X-ray exposure of the globular cluster 47 Tucanae, in addition to…
In studying encounters between binaries and single stars, one is interested in three classes of events: exchanges of stars, hardening of the original binary by a third star, and the production of merged objects. We present a means for…
We summarize results of a search for X-ray-emitting binary stars in the massive globular cluster Omega Centauri (NGC 5139) using Chandra and HST. ACIS-I imaging reveals 180 X-ray sources, of which we estimate that 45-70 are associated with…
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…
Based on archival {\it Chandra} data, we have carried out an X-ray survey of 69, or nearly half the known population of, Milky Way globular clusters (GCs), focusing on weak X-ray sources, mainly cataclysmic variables (CVs) and coronally…
We report on the Chandra X-ray Observatory and Hubble Space Telescope observation of two low core density globular clusters, NGC6144 and E3. By comparing the number of X-ray sources inside the half-mass radius to those outside, we found 6…