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Angular correlation functions of X-ray point-like sources in the full exposure XMM-LSS field ⋆
Manolis Plionis
Acceso Abierto
X-rays: galaxies
Galaxies: active
Aims. Our aim is to study the large-scale structure of different types of AGN using the medium-deep XMM-LSS survey. Methods. We measure the two-point angular correlation function of ∼ 5700 and 2500 X-ray point-like sources over the ∼ 11 sq. deg. XMM-LSS field in the soft (0.5-2 keV) and hard (2-10 keV) bands. For the conversion from the angular to the spatial correlation function we used the Limber integral equation and the luminosity-dependent density evolution model of the AGN X-ray luminosity function. Results. We have found significant angular correlations with the power-law parameters γ = 1.81 ± 0.02, θ₀ = 1.3′′ ± 0.2′′ for the soft, and γ = 2.00 ± 0.04, θ₀ = 7.3′′ ± 1.0′′ for the hard bands. The amplitude of the correlation function w(θ) is higher in the hard tan in the soft band for fₓ≲10⁻¹⁴ erg s⁻¹ cm⁻² and lower above this flux limit. We confirm that the clustering strength θ₀ grows with the flux limit of the sample, a trend which is also present in the amplitude of the spatial correlation function, but only for the soft band. In the hard band, it remains almost constant with r₀ ≃ 10 h⁻¹ Mpc, irrespective of the flux limit. Our analysis of AGN subsamples with different hardness ratios shows that the sources with a hard-spectrum are more clustered than soft-spectrum ones. This result may be a hint that the two main types of AGN populate different environments. Finally, we find that our clustering results correspond to an X-ray selected AGN bias factor of ∼ 2.5 for the soft band sources (at a median ¯z ≃ 1.1) and ∼ 3.3 for the hard band sources (at a median ¯z ≃ 1), which translates into a host dark matter halo mass of ∼ 10¹³ h⁻¹Mꙩ and ∼ 1013.7 h⁻¹Mꙩ for the soft and hard bands, respectively.
Astronomy & Astrophysics
Público en general
Elyiv, A., et al., 2012, Angular correlation functions of X-ray point-like sources in the full exposure XMM-LSS field ⋆, Astronomy & Astrophysics, Vol. 537(A131):1-14
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Appears in Collections:Artículos de Astrofísica

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