Related papers: Time variability of X-ray sources in the M 31 cent…

Using a combination of ground-based and HST imaging, we have constructed a catalog of 179 supernova remnants (SNRs) and SNR candidates in the nearby spiral galaxy M51. Follow-up spectroscopy of 66 of the candidates confirms 61 of these as…

We present the XMM-Newton Medium sensitivity Survey (XMS), including a total of 318 X-ray sources found among the serendipitous content of 25 XMM-Newton target fields. The XMS comprises four largely overlapping source samples selected at…

We present the first survey results of hard X-ray point sources in the Galactic Center (GC) region by NuSTAR. We have discovered 70 hard (3-79 keV) X-ray point sources in a 0.6 deg^2 region around Sgr A* with a total exposure of 1.7 Ms, and…

Using hard (E>10 keV) X-ray observations with NuSTAR, we are able to differentiate between accretion states, and thus compact object types, of neutron stars and black holes in X-ray binaries (XRBs) in M31, our nearest Milky Way-type…

We have observed two low concentration Galactic globular clusters with the X-ray observatory XMM-Newton. We detect 47 faint X-ray sources in the direction of M 55 and 62 in the field of view of NGC 3201. Using the statistical Log N-Log S…

We present 21 new long-term variable radio sources found commensally in two years of weekly MeerKAT monitoring of the low-mass X-ray binary GX 339-4. The new sources vary on time scales of weeks to months and have a variety of light curve…

We report on the results of a four-year long X-ray monitoring campaign of the central 1.2 square degrees of our Galaxy, performed with Chandra and XMM-Newton between 2005 and 2008. Our study focuses on the properties of transient X-ray…

We have discovered a persistent, but highly variable X-ray source in the nearby starburst galaxy NGC 253. The source varies at the level of a factor of about 5 in count rate on timescales of a few hours. Two long observations of the source…

We have carried out an in-depth study of low-mass X-ray binaries (LMXBs) detected in the nearby lenticular galaxy NGC 3115, using the Megasecond Chandra X-Ray Visionary Project observation (total exposure time 1.1 Ms). In total we found 136…

We report the results of XMM-Newton observations of the Galactic mixed-morphology supernova remnant G350.0$-$2.0. Diffuse thermal X-ray emission fills the north-western part of the remnant surrounded by radio shell-like structures. We did…

We have detected 18 sources over 6 sigma threshold within two regions 8.3X16.9 arcmin^2 and 8.3X33.6 arcmin^2 in the vicinity of the point with alpha=03h31m02.45s (J2000) and delta=+43degree47arcmin58.5arcsec (J2000) using a CHANDRA ACIS…

The optical identification of large number of X-ray sources such as those from the ROSAT All-Sky Survey is challenging with conventional spectroscopic follow-up observations. We investigate two ROSAT All-Sky Survey fields of size 10 * 10…

The purpose of this study is to explore the population of X-ray point sources in the bulge of M31, with the primary goal to contrast properties of various subpopulations, such as persistent and transient sources, primordial LMXBs and…

We analyse all the available Chandra observations of the Cartwheel Galaxy and its compact group, taken between 2001 and 2008, with the main aim of addressing the variability in the X-ray band for this spectacular collisional ring galaxy. We…

We report the results of an optical campaign carried out by the XMM-Newton Survey Science Centre with the specific goal of identifying the brightest X-ray sources in the XMM-Newton Galactic Plane Survey of Hands et al. (2004). In addition…

We searched optical/UV/IR counterparts of seven supersoft X-ray sources (SSS) in M31 in the Hubble Space Telescope (HST) "Panchromatic Hubble Andromeda Treasury" (PHAT) archival images and photometric catalog. Three of the SSS were…

We present a multi-object optical spectroscopy follow-up study of X-ray sources in a field along the Galactic Plane (l=327.42 deg, b=2.26 deg) which is part of the Chandra Multi-wavelength Plane survey (ChaMPlane). We obtained spectra for…

Ultra-luminous X-ray sources (ULXs) are a class of extra-galactic, point-like, off-nuclear X-ray sources with X-ray luminosity from $\sim 10^{39}$~erg s$^{-1}$ to $10^{41}$~erg s$^{-1}$. We investigated the temporal and broadband X-ray…

We present a spectroscopic study of 41 hard X-ray sources detected serendipitously with high significance (> 5 sigma in the 2-10 keV band) in seven EPIC performance/verification phase observations. The large collecting area of EPIC allows…

Identifying X-ray binary (XRB) candidates in nearby galaxies requires distinguishing them from possible contaminants including foreground stars and background active galactic nuclei. This work investigates the use of supervised machine…