|
Description
The XMM-Large Scale Structure (XMM-LSS) survey, covering an area of 11.1 square degrees, contains more than 6,000 X-ray point-like sources detected with the XMM-Newton Observatory to a flux of 3 x 10<sup>-15</sup> erg/s/cm<sup>2</sup> in the 0.5-2.0 keV band. The vast majority of these sources have optical (CFHTLS: Canada France Hawaii Telescope Legacy Survey), infrared (SWIRE: Spitzer Wide-area InfraRed Extragalactic legacy survey) InfraRed Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS), near-infrared (UKIDSS: UKIRT Infrared Deep Sky Survey) and/or ultraviolet (GALEX: Galaxy Evolution Explorer) counterparts. The authors wished to investigate the environmental properties of the different types of the XMM-LSS X-ray sources by defining their environment using the i'-band CFHTLS W1 catalog of optical galaxies to a magnitude limit of 23.5 magnitudes. They have classified 4,435 X-ray selected sources on the basis of their spectra, spectral energy distributions (SEDs), and X-ray luminosities, and estimated their photometric redshifts, which have a 4-11 band photometry with an accuracy of sigma[Delta<sub>z</sub>/(1+z<sub>sp</sub>)] = 0.076, with 22.6% outliers for i' < 26 mag. The authors estimated the local overdensities of 777 X-ray sources that have spectro-z or photo-z calculated by using more than seven bands (accuracy of sigma[(Delta<sub>z</sub>/(1+z<sub>sp</sub>)] = 0.061, with 13.8% outliers) within the volume-limited region defined by 0.1 <= z <= 0.85 and -23.5 < M_i'_ < -20. Although X-ray sources may be found in variety of environments, a high fraction (~55-60%), as verified by comparing with the random expectations, reside in overdense regions. The galaxy overdensities within which X-ray sources reside show a positive recent redshift evolution (at least for the range studied; z <~ 0.85). The authors also find that X-ray selected galaxies, when compared to AGN, inhabit significantly higher galaxy overdensities, although their spatial extent appear to be smaller than that of AGN. Hard AGN (harness ratios HR >= -0.2) are located in more overdense regions than soft AGN (HR < -0.2), which is clearly seen in both redshift ranges, although it appears to be stronger in the higher redshift range (0.55 < z < 0.85). Furthermore, the galaxy overdensities (with delta > 1.5, where delta is defined in equation (3) of the reference paper) within which soft AGN are embedded appear to evolve more rapidly compared to the corresponding overdensities around hard AGN. This table contains the spectroscopic and/or photometric redshifts for 4,206 X-ray selected sources in the XMM-LSS field which have optical counterparts and have been classified by the authors. This table was created by the HEASARC in September 2013 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/557/A81">CDS Catalog J/A+A/557/A81</a> file table2.dat This is a service provided by NASA HEASARC .
|
