The XMM large scale structure survey: properties and two-point angular correlations of point-like sources
English
Gandhi, P.[Institute of Astronomy, Madingley Road, University of Cambridge, CB3 0HA, UK ; European Southern Observatory, Casilla 19001, Santiago, Chile]
Garcet, Olivier[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS) >]
Disseau, L.[École Normale Supérieure, Paris, France ; European Southern Observatory, Casilla 19001, Santiago, Chile]
Pacaud, F.[CEA/DSM/DAPNIA, Service d'Astrophysique, Saclay, 91191 Gif-sur-Yvette, France]
Pierre, M.[CEA/DSM/DAPNIA, Service d'Astrophysique, Saclay, 91191 Gif-sur-Yvette, France]
Gueguen, A.[CEA/DSM/DAPNIA, Service d'Astrophysique, Saclay, 91191 Gif-sur-Yvette, France]
Alloin, D.[CEA/DSM/DAPNIA, Service d'Astrophysique, Saclay, 91191 Gif-sur-Yvette, France ; European Southern Observatory, Casilla 19001, Santiago, Chile]
Chiappetti, L.[INAF IASF Milano, via Bassini 15, 20133 Milano, Italy]
Gosset, Eric[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE) >]
Maccagni, D.[INAF IASF Milano, via Bassini 15, 20133 Milano, Italy]
Surdej, Jean[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astroph. extragalactique et observations spatiales (AEOS) >]
[en] 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 2× 10[SUP]-15[/SUP] and 8× 10[SUP]-15[/SUP] erg s[SUP]-1[/SUP] cm[SUP]-2[/SUP] respectively, as part of the XMM-Newton Large Scale Structure Survey. The log N-log S in both bands shows a steep slope at bright fluxes, but agrees well with other determinations below ~2 × 10[SUP]-14[/SUP] erg s[SUP]-1[/SUP] cm[SUP]-2[/SUP]. The detected sources resolve close to 30 per cent of the X-ray background in the 2-10 keV band. We study the two-point angular clustering of point sources using nearest neighbours and correlation function statistics and find a weak, positive signal for ~1130 sources in the 0.5-2 keV band, but no correlation for ~400 sources in the 2-10 keV band below scales of 100 arcsec. A sub-sample of ~200 faint sources with hard X-ray count ratios, that is likely to be dominated by obscured AGN, does show a positive signal with the data allowing for a large angular correlation length, but only at the ~2 (3)sigma level, based on re-sampling (Poisson) statistics. We discuss possible implications and emphasize the importance of wider, complete surveys in order to fully understand the large scale structure of the X-ray sky.
[Institute of Astronomy, Madingley Road, University of Cambridge, CB3 0HA, UK ; European Southern Observatory, Casilla 19001, Santiago, Chile]
