Related papers: Blank Field X-Ray Sources

The origin of the X-ray background, in particular at hard (2-10 keV) energies, has been a debated issue for more than 30 years. The Chandra deep fields provide the deepest look at the X-ray sky and are the best dataset to study the X-ray…

We present a synthesis model of the X-ray background based on the cross-correlation between mid-infrared and X-ray surveys, where the distribution of type 2 sources is assumed to follow that of luminous infrared galaxies while type 1…

We describe in this paper the ROSAT Ultra Deep Survey (UDS), an extension of the ROSAT Deep Survey (RDS) in the Lockman Hole. The UDS reaches a flux level of 1.2 x 10E-15 erg/cm2/s in 0.5-2.0 keV energy band, a level ~4.6 times fainter than…

We report on a medium deep XMM-Newton survey of the Marano Field and optical follow-up observations. The mosaicked XMM-Newton pointings in this optical quasar survey field cover 0.6 square degree with a total of 120 ksec good observation…

We present the X-ray spectra of 86 optically-identified sources in the 13H XMM-Newton/Chandra deep field which have >70 X-ray counts. The sample consists of 50 broad line AGN, 25 narrow emission line galaxies, 6 absorption line galaxies,…

We have surveyed about 50 deg-2 of sky in the largely unexplored 5-10 keV band using the BeppoSAX MECS instrument, finding 180 sources. After correction for the non uniform sky coverage we find about 18 sources deg-2 with F(5-10keV) >=…

Compact star-forming galaxies were dominant galaxy types in the early Universe. Blueberry galaxies (BBs) represent their local analogues being very compact and having intensive star formation. Motivated by high X-ray emission recently found…

Some indications for tension have long been identified between cosmological constraints obtained from galaxy clusters and primary CMB measurements. Typically, assuming the matter density and fluctuations, as parameterized with Omega_m and…

ROSAT deep and shallow surveys have provided an almost complete inventory of the constituents of the soft X-ray background which led to a population synthesis model for the whole X-ray background with interesting cosmological consequences.…

Two nearby clusters of galaxies: A194 (z=0.018) and A1060 (z=0.0114) have been analyzed for their X-ray point source properties with XMM-Newton EPIC-PN data. A multi-band source detection technique was applied to both of the clusters,…

The origin of the extragalactic gamma-ray background (EGRB) is still an open question, even after nearly forty years of its discovery. The emission could originate from either truly diffuse processes or from unresolved point sources.…

BL Lac objects are an extreme type of active galactic nuclei (AGNs) that belong to the largest population of $\gamma$-ray sources: blazars. This class of AGNs shows a double-bumped spectral energy distribution that is commonly described in…

[abridged] We investigate the nature of the luminous X-ray source population detected in a (72 ks) Chandra ACIS-S observation of NGC 4038/39, the Antennae galaxies. We derive the average X-ray spectral properties of sources in different…

We have performed a detailed analysis of 3 optically normal galaxies extracted from the XMM Bright Serendipitous Source Sample. Thanks to the good statistics of the XMM-Newton data, we have unveiled the presence of an AGN in all of them. In…

X-ray bright optically normal galaxies (XBONGs) are galaxies with X-ray luminosities consistent with those of active galactic nuclei (AGNs) but no evidence of AGN optical emission lines. Crossmatching the Chandra Source Catalog version 2…

We identify sources with extremely hard X-ray spectra (i.e., with photon indices of Gamma<0.6 in the 13 sq. deg. NuSTAR serendipitous survey, to search for the most highly obscured AGNs detected at >10 keV. Eight extreme NuSTAR sources are…

We perform long-term ($\approx 15$ yr, observed-frame) X-ray variability analyses of the 68 brightest radio-quiet active galactic nuclei (AGNs) in the 6 Ms $Chandra$ Deep Field-South (CDF-S) survey; the majority are in the redshift range of…

Large-scale fluctuations of the X-ray background are investigated using the ROSAT All-Sky Survey. The autocorrelation function of the extragalactic background at 1 keV is determined at separations 0.1 - 40 deg. We detect a significant…

Using stellar luminosity functions derived from ROSAT data, the contributions of Galactic stars to the diffuse X-ray background are calculated for ROSAT PSPC energy bands. The model follows that of Guillout et al. (1996), but uses ROSAT…

We present an analysis of the X-ray emission of a large sample of z~3 Lyman break galaxies (LBGs), based on Chandra/ACIS observations of several LBG survey fields. 24 LBGs are directly detected in the X-ray. 13 of the LBGs have optical…