Related papers: Luminosity Functions and Point Source Properties f…

X-ray point sources in galaxies are dominated by X-ray binaries (XRBs) that are variables or transients and whether their variability would alter the X-ray luminosity functions (XLF) is still in debate. Here we report on NGC 7331 as an…

We have identified 127 discrete sources in a Chandra observation of M83, with a detection limit of ~ 3 x 10^{36} erg/s in the 0.3-8.0 keV band. We discuss the individual properties of about 20 bright sources with L_x >~ 10^{38} erg/s, and…

We have analysed the soft X-ray emission from the nuclear source of the nearby spiral galaxy M81, using the available data collected with ROSAT, ASCA, BeppoSAX and Chandra. The source flux is highly variable, showing (sometimes dramatic: a…

We have obtained snapshot images of an X-ray nova in M31 from Chandra ACIS-I and the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). The Chandra position of the X-ray nova was R.A.=00:44:06.68 +/- 1.74", Dec.=+41:12:20.0 +/-…

Luminous supersoft X-ray sources found in the Milky Way and Magellanic Clouds are likely white dwarfs that steadily or cyclically burn accreted matter on their surface, which are promising type Ia supernova progenitors. Observations of…

We present an analysis of the X-ray properties of a sample of solar- and late-type field stars identified in the Chandra Cosmic Evolution Survey (COSMOS), a deep (160ks) and wide (0.9 deg2) extragalactic survey. The sample of 60 sources was…

In an XMM-Newton raster observation of the bright local group spiral galaxy M33 we study the population of X-ray sources (X-ray binaries, supernova remnants, super-shells) down to a 0.5-10 keV luminosity of 10^35 erg s^-1 -- more than a…

We append an additional fifteen years (2009-2024) to the Chandra X-ray light curve of M31*, the supermassive black hole at the center of M31, the Andromeda galaxy. Extending and expanding on the work in Li et al. 2011, we show that M31* has…

We have searched for unresolved X-ray sources in the vicinity of two rich clusters of galaxies: Abell 1995 (A1995) and MS 0451.6-0305 (MS0451), using the Chandra X-ray observatory. We detected significantly more unresolved sources around…

We have carried out a Chandra observation of the globular cluster M54. We detected 7 sources located within the half-mass radius of M54, at a flux limit of 1.5x10^-15 erg/s/cm in the 0.3-8 keV energy band. The spatial distribution and the…

We present the results of X-ray observations of four bright transients sources detected in the July 2004 XMM-Newton observations of the central bulge of M31. Two X-ray sources, XMMU J004315.5+412440 and XMMU J004144.7+411110, were…

The face-on spiral galaxy M74 (NGC 628) was observed by XMM on 2002 February 2. In total, 21 sources are found in the inner 5' from the nucleus (after rejection of a few sources associated to foreground stars). Hardness ratios suggest that…

We report the detailed analysis of the X-ray properties of the discrete sources detected in a long (72 ks) \chandra ACIS-S observation of the Antennae galaxies. We detect 49 sources, down to a detection limit of ~ 10^{38} erg\s; 18 sources…

Chandra has resolved the starburst nuclear region of the face-on grand-design spiral M83. Eighty-one point sources are detected above 3.5 sigma in the ACIS S3 image, and 15 of them are within the inner 16-arcsec region of the galaxy. A…

We report the results of a programme of dual-epoch Chandra ACIS-S observations of five ultraluminous X-ray sources (ULXs) in nearby spiral galaxies. All five ULXs are detected as unresolved, point-like X-ray sources by Chandra, though two…

A very sensitive X-ray investigation of the giant HII region N11 in the LMC was performed using the Chandra X-ray Observatory. The 300ks observation reveals X-ray sources with luminosities down to 10^32 erg/s, increasing by more than a…

X-ray sources in spiral galaxies can be approximately classified into bulge and disk populations. The bulge (or hard) sources have X-ray colors which are consistent with Low Mass X-ray Binaries (LMXB) but the the disk sources have softer…

The Chandra data archive after eight years' accumulation is a treasure for various studies, and in this paper we exploit this valuable resource to study the X-ray point source populations in nearby galaxies. By December 14, 2007, 383…

We have obtained snapshot images of a transient X-ray source in M31 from Chandra ACIS-I and the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). The Chandra position of the X-ray nova was R.A.=00:42:56.038 +/-0.08'',…

The first systematic study of the serendipitous X-ray source density around 10 high z (0.24<z<1.2) clusters performed with Chandra is presented. A factor \~2 overdensity has been found in 4 cluster fields. The result is statistically highly…