Related papers: X-ray Spectra of the RIXOS source sample

Fluctuations of the surface brightness of cosmic X-ray background (CXB) carry unique information about faint and low luminosity source populations, which is inaccessible for conventional large-scale structure (LSS) studies based on resolved…

Large area catalogs of galaxy clusters constructed from ROSAT All Sky Survey provide the base for our knowledge on the population of clusters thanks to the long-term multiwavelength efforts on their follow-up. Advent of large area…

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 present the results of deep near-infrared observations of 11 hard X-ray selected sources in the Hellas2XMM survey, with faint optical magnitude (R>24) and high X-ray-to-optical flux ratio. All but one of the sources have been detected in…

We analyse the ROSAT PSPC hardness ratio and the 0.5-2 keV to 2-10 keV flux ratio of 65 Active Galactic Nuclei (AGN) for which there are both ROSAT archival observations available and 2-10 keV fluxes, mostly from the HEAO-1 MC-LASS survey.…

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 searched for high-z quasars within the X-ray source population detected in the contiguous $\sim 140^2$ eFEDS field observed by eROSITA during the performance verification phase. We collected the available spectroscopic information in the…

This work studies the optical emission line properties of a sample of 155 low-redshift bright X-ray selected ROSAT Seyfert~1 type AGN for which adequate signal-to-noise ratio spectroscopic observations are available. We measured emission…

We report preliminary results from an arcsecond-resolution X-ray survey of nearby galaxies using ACIS on board Chandra. The total sample consists of 41 low-luminosity AGNs, including Seyferts, LINERs, and LINER/H II transition objects. In…

The spectrum of the 0.1-7.0 keV cosmic X-ray background (CXB) at galactic latitudes >|25| degrees has been measured using the BeppoSAX Low-Energy Spectrometer Concentrator (LECS). Above 1 keV the spectrum is consistent with a power-law of…

Luminosity functions are one of the most important observational clues when studying galaxy evolution over cosmic time. In this paper we present the X-ray luminosity functions of X-ray detected AGN in the SXDS and GWS fields. The limiting…

We present mid-infrared spectroscopy of a sample of 16 optically faint infrared luminous galaxies obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. These sources were jointly selected from Spitzer and Chandra…

We present new results on the cosmological evolution of unabsorbed (type-1) active galactic nuclei (AGN) selected in the soft (0.5-2 keV) X-ray band. From a variety of ROSAT, XMM-Newton and Chandra surveys we selected a total of ~1000 AGN…

We present observations in the 0.1-100 keV spectral band of 8 Seyfert 2 galaxies, obtained by means of BeppoSAX. These sources were selected according to their [OIII] optical emission line flux, to avoid biases against obscuration on the pc…

We present optical spectroscopic identifications of hard X-ray (5-10 keV) selected sources belonging to the HELLAS sample obtained with BeppoSAX down to a 5-10 keV flux limit of f_{5-10 keV}~3x10^-14 erg cm^-2 s^-1. The sample consists of…

We present optical identifications and a multi-band catalogue of a sample of 478 X-ray sources in the XMM and Chandra surveys of the central 0.6 deg^2 of the ELAIS-S1 field. The optical/infrared counterpart of each X-ray source was…

An analysis of the spatial fluctuations in 15 deep ASCA SIS0 images has been conducted in order to probe the 2-10 keV X-ray source counts down to a flux limit 2E-14 erg/cm2/s. Special care has been taken in modelling the fluctuations in…

We present the results of the X-ray spectral analysis of the first deep X-ray survey with the XMM-Newton observatory during Performance Verification. We restrict the analysis to the sample of 98 sources with more than 70 net counts (flux…

X-ray surveys facilitate investigations of the environment of AGNs. Deep Chandra observations revealed that the AGNs source surface density rises near clusters of galaxies. The natural extension of these works is the measurement of spatial…

We present a study of X-ray AGN overdensities in 16 Abell clusters, within the redshift range 0.073<z<0.279, in order to investigate the effect of the hot inter-cluster environment on the triggering of the AGN phenomenon. The X-ray AGN…