Related papers: Supersoft X-Ray Sources in M31
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…
All 63 discrete X-ray sources brighter than L_{\rm X} = 5x10^{36} erg/s in any of four XMM-Newton observations of the core of M31 were surveyed for time variability over time-scales of seconds to thousands of seconds, and for intensity…
The nearby barred spiral galaxy NGC 1313 has been observed with the PSPC instr- ument on board the ROSAT X-ray satellite. Ten individual sources are found. Three sources (X-1, X-2 and X-3 [SN~1978K]) are very bright (~10^40 erg/s) and are…
Two new bright X-ray sources in globular clusters, and many less luminous ones in globular clusters and in old open clusters, have been discovered with ROSAT. Accurate positions obtained with ROSAT help identification with optical objects,…
I analyze 101 observations from the ROSAT archive to search for X-ray sources in or near 55 globular clusters. New sources are found in the cores of NGC362 (a double source), NGC6121 (marginally significant), NGC6139, and NGC6266; and…
Chandra observations of nearby galaxies have revealed a number of X-ray sources characterized by high luminosities ($L_X > \sim10^{36}$ erg s$^{-1}$) and $k T$ in the range $100 - 350$ eV. These ``quasisoft X-ray sources'' (QSSs) are harder…
Studies were made of ASCA spectra of seven ultra-luminous compact X-ray sources (ULXs) in nearby spiral galaxies; M33 X-8 (Takano et al. 1994), M81 X-6 (Fabbiano 1988b; Kohmura et al. 1994; Uno 1997), IC 342 Source 1 (Okada et al. 1998),…
In this paper we investigate the X-ray spectra and X-ray spectral variability of compact X-ray sources for 3 Chandra observations of the Local Group galaxy M33. The observations are centered on the nucleus and the star forming region NGC…
We study three transient X-ray sources, that were bright in the central region of M31 galaxy in the year 2000. Observations with Chandra and XMM-Newton allowed us for the first time in the history of X-ray astronomy, to build light curves…
We present the results of Chandra observations of off-nuclear X-ray sources in the spiral galaxy M51 (NGC 5194). 113 X-ray sources have been detected in the field of view and 84 among them project within the disk of NGC 5194. Six and twenty…
The X-ray source populations within galaxies are typically difficult to identify and classify from X-ray data alone. We are able to break through this barrier by combining deep new Chandra ACIS-I observations with extensive Hubble Space…
We present optical identification and characterization of counterparts of four objects previously catalogued as ultra-luminous X-ray sources. The objects were selected from the Colbert & Ptak (2002) catalogue. The optical counterparts are…
We report on optical searches in the error circles of 93 ROSAT survey sources located at low galactic latitudes (|b| < 20 deg). These sources were extracted from the ROSAT Galactic Plane Survey using various selection criteria on hardness…
We searched for X-ray counterparts of optical novae detected in M 31 and M 33. We combined an optical nova catalogue from the WeCAPP survey with optical novae reported in the literature and correlated them with the most recent X-ray…
We have found compact X-ray sources in the center of 21 (54%) of 39 nearby face-on spiral and elliptical galaxies with available ROSAT HRI data. ROSAT X-ray luminosities (0.2 - 2.4 keV) of these compact X-ray sources are ~ 1e37 - 1e40 erg/s…
We cross-identified the ROSAT Bright Source Catalog (RBSC) and the NRAO VLA Sky Survey (NVSS) to construct the RBSC-NVSS sample of the brightest X-ray sources (>= 0.1 counts/s or ~1E-12 ergs/cm/cm/s in the 0.1-2.4 keV band) that are also…
We have created 0.3--10 keV, 13 year, unabsorbed luminosity lightcurves for 528 X-ray sources in the central 20' of M31. We have 174 Chandra observations spaced at ~1 month intervals thanks to our transient monitoring program, deeper…
We present a comprehensive study of the soft X-ray properties of the BeppoSAX High-Energy Large Area Survey (HELLAS) sources. A large fraction (about 2/3) of the hard X-ray selected sources is detected by ROSAT. The soft X-ray colors for…
The ASCA satellite made 107 pointing observations on a 5 x 5 deg^2 region around the center of our Milky Way Galaxy (the Galactic Center) from 1993 to 1999. In the X-ray images of the 0.7--3 keV or 3--10 keV bands, we found 52 point sources…
We present the X-ray data and the optical identifications for a deep ROSAT PSPC observation in the "Marano field". In the inner region of the ROSAT field (15' radius) we detected 50 X-ray sources with Sx >= 3.7x10^(-15) erg/cm^2/s. When…