Related papers: What X-ray source counts can tell about large-scal…

We study the spatial distribution of a 95% complete sample of 508 X-ray point sources (XPS) detected in the 0.5-2.0 keV band in Chandra ACIS-I observations of 51 massive galaxy clusters found in the MACS survey. Covering the redshift range…

We present results from a Chandra X-ray Observatory study of the field X-ray source populations in 4 different observations: two high-redshift (z~0.5) clusters of galaxies 3C295 and RXJ003033.2+261819; and two non-cluster fields with…

Many X-ray observations of GigaHertz Peaked Spectrum and Compact Steep Spectrum sources have been made with Chandra X-ray Observatory and XMM-Newton Observatory over the last few years. The X-ray spectra contribute the important information…

We present Ginga measurements of the spatial fluctuations in the diffuse X-ray background. When combined with earlier results, the new data constrain the extragalactic log N - log S relation in the 2-10 keV energy band to a form close to…

We report the discovery of eight X-ray sources with periodic variability in 487 ks of observations of the Galactic center with Chandra. The sources are identified from a sample of 285 objects detected with 100-4200 net counts. Their periods…

What do we see when we look at a nearby, well-resolved galaxy? Thousands of individual sources are detected in multiband imaging observations of even a fraction of a nearby galaxy, and characterizing those sources is a complex process. This…

Cross-correlations of the WMAP full sky K, Ka, Q, V, and W band maps with the 1.4 GHz NVSS source count map and the HEAO I A2 2-10 keV full sky X-ray flux map are used to constrain rms fluctuations due to unresolved microwave sources in the…

We describe detailed simulations of X-ray-emitting populations to evaluate the levels of contamination by both Galactic and extragalactic X-ray sources unrelated to a star-forming region under study. For Galactic contaminations, we consider…

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…

The flux density from undetected sources in the observing beam of a telescope produces source confusion noise in the resulting maps of the sky, and thus limits sensitivity. In a recent paper we discussed this effect in the…

The large-scale (~ 20') diffuse x-ray background surrounding a sample of quasars observed during ROSAT PSPC pointed observations is studied using a new source-detection algorithm, the scaling-index method. This algorithm, which can identify…

(abridged) We present a catalog of 2357 point sources detected during 590 ks of Chandra observations of the 17-by-17 arcminute field around Sgr A*. This field encompasses a physical area of 40 by 40 pc at a distance of 8 kpc. The…

Summary of abstract: The existence of a new population of yet unrecognized x-ray sources has been often suggested to resolve some pecularities in the properties of the x-ray background (XRB), and has recently been indicated by an analysis…

We have found compact, near-nuclear X-ray sources in 21 (54\%) of a complete sample 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…

The Swift AGN and Cluster Survey (SACS) uses 125 deg^2 of Swift XRT serendipitous fields with variable depths surrounding gamma-ray bursts to provide a medium depth (4e-15 erg/s/cm^2) and area survey filling the gap between deep, narrow…

We investigate the serendipitous X-ray source population revealed in XMM-Newton observations targeted in the Galactic Plane within the region 315<l<45 and |b|<2.5 deg. Our study focuses on a sample of 2204 X-ray sources at intermediate to…

Recent Chandra and XMM-Newton surveys have confirmed that the cosmic X-ray background is mostly due to accretion onto super-massive black holes, integrated over cosmic time. Here we review the results obtained from the photometric and…

[ABRIGED] We present the optical identification of a sample of 695 X-ray sources detected in the first 1.3 deg^2 of the XMM-COSMOS survey, down to a 0.5-2 keV (2-10 keV) limiting flux of ~10^-15 erg cm-2 s-1 (~5x10^-15 erg cm^-2 s-1). We…

Cosmic rays (CRs) are an integral component of the interstellar medium, producing broadband emission while interacting with other Galactic matter components like the interstellar gas or magnetic fields. In addition to observations,…

We investigate the X-ray number counts in the 1-2 Ms Chandra Deep Fields (CDFs) to determine the contributions of faint X-ray source populations to the extragalactic X-ray background (XRB). X-ray sources were separated into Active Galactic…