2004/04/21 by S. Basilakos, A. Georgakakis, M. Plionis +1 · 4 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/421973
published as Astrophys.J. 607 (2004) L79-L82 · 12 pages, 3 figures, ApJL accepted
arxiv created 2004/04/21 · openalex publication_date 2004/04/28 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/07/31
This Letter presents the clustering properties of hard (2-8 keV) X-ray-selected sources detected in a wide-field (≈2 deg 2 ), shallow [ f X (2-8 keV) ≈ 10 -14 ergs cm -2 s -1 ], and contiguous XMM-Newton survey. We perform an angular correlation function analysis using a total of 171 sources to the above flux limit. We detect an ~4 σ correlation signal out to 300'' with w (θ < 300'') ≃ 0.13 ± 0.03. Modeling the two-point correlation function as a power law of the form w (θ) = (θ 0 /θ) γ-1 , we find θ 0 = 48.9 arcsec and γ = 2.2 ± 0.30. Fixing the correlation function slope to γ = 1.8, we obtain θ 0 = 22.2 arcsec. Using Limber's integral equation and a variety of possible luminosity functions of the hard X-ray population, we find a relatively large correlation length, ranging from r 0 ~ 9 to 19 h -1 Mpc (for γ = 1.8 and the concordance cosmological model), with this range reflecting also different evolutionary models for the source luminosities and clustering characteristics. The relatively large correlation length is comparable to that of extremely red objects and luminous radio sources.