Related papers: The BeppoSAX High Energy Large Area Survey (HELLAS…

In this paper we report the first results on a medium survey program conducted in the 2-10 keV energy band using data from the GIS2 instrument onboard the ASCA satellite. We have selected from the ASCA public archive (as of February 14,…

We report on the first census of INTEGRAL/IBIS detections ($\gtrsim 4\sigma$ significance) above 100 keV based on the Core Program and public Open time observations up to April 2005. There are 49 sources detected in the 100-150 keV band of…

The number of extragalactic sources detected at very hight energy (VHE, E$>$100GeV) has dramatically increased during the past years to reach more than fifty. The High Energy Stereoscopic System (H.E.S.S.) had observed the sky for more than…

We analyze X-ray sources detected over 4.2 pseudo-contiguous sq. deg. in the 0.5-2 keV and 2-10 keV bands down to fluxes of 2x10^{-15} and 8x10^{-15} erg/s/cm^2 respectively, as part of the XMM Large Scale Structure Survey. The logN-logS in…

We present a uniform and systematic analysis of the 0.6-10 keV X-ray spectra of radio-loud active galactic nuclei (AGN) observed by ASCA. The sample 10 BLRGs, 5 QSRs, 9 NLRGs, and 10 RGs. At soft X-rays, about half of the NLRGs and all of…

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…

The estimate of the number and space density of obscured AGN over cosmic time still represents an open issue. While the obscured AGN population is a key ingredient of the X-ray background synthesis models and is needed to reproduce its…

The sky around the North Ecliptic Pole (NEP), at $\alpha$(2000) = 18$^h00^m00^s$, $\delta$(2000) = +66\degr33\arcmin39\arcsec, has the deepest exposure of the entire {\it ROSAT} All - Sky Survey (RASS). The NEP is an undistinguished region…

Recently, Papadopoulos et al., 2010 using sub-mm CO molecular line observations of nearby ultra-luminous IRAS galaxies, (U)LIRGs, have found that exceptionally large gas column densities (N_H > 10^25 cm-2) can be present across some of the…

Sub/millimeter galaxies are a key population for the study of galaxy evolution because the majority of star formation at high redshifts occurred in galaxies deeply embedded in dust. To search for this population, we have performed an…

We present the results of our identification of 11 X-ray sources detected on the half of the sky $0^\circ<l<180^\circ$ in the 4-12 keV energy band on the combined map of the first five all-sky surveys with the Mikhail Pavlinsky ART-XC…

We present a small sample of Chandra X-ray sources selected from the fields of ACIS observations which probe fluxes around the break in the hard band source counts. The targets of these fields include 9 nearby galaxy clusters, 1 distant…

We present results of deep surveys of three extragalactic fields, M81 (exposure of 9.7 Ms), LMC (6.8 Ms) and 3C 273/Coma (9.3 Ms), in the hard X-ray (17-60 keV) energy band with the IBIS telescope onboard the INTEGRAL observatory, based on…

We present the spectral energy distributions (SEDs) of a hard X-ray selected sample. The sample contains 136 sources with F(2-10 keV)>10^-14 erg/cm^2/s and 132 are AGNs. The sources are detected in a 1 square degree area of the…

We present optical spectroscopy for an X-ray and optical flux-limited sample of 677 XMM-Newton selected targets covering the 2 deg^2 COSMOS field, with a yield of 485 high-confidence redshifts. The majority of the spectra were obtained over…

We report on the first ten identifications of sources serendipitously detected by the NuSTAR to provide the first sensitive census of the cosmic X-ray background (CXB) source population at >10 keV. We find that these NuSTAR-detected 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…

We present a catalog of 2-10 keV ASCA Gas Imaging Spectrometer images of fields containing bright sources of GeV emission. The images cover $\sim 85%$ of the 95% confidence position contour for 28 of the 30 sources with $> 1$ GeV fluxes…

We present the X-ray source number counts in two energy bands (0.5-2 and 2-10 keV) from a very large source sample: we combine data of six different surveys, both shallow wide field and deep pencil beam, performed with three different…

We present preliminary results from the first 3 months of the Swift BAT high galactic latitude survey in the 14--195 keV band. The survey reaches a flux of \~10^{-11} erg/cm^2/s and has ~2.7' (90% confidence) positional uncertainties for…