Open AccessThe angular correlation function of the ROSAT All‐Sky Survey Bright Source Catalogue
Author(s) -
Akylas A.,
Georgantopoulos I.,
Plionis M.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03682.x
Subject(s) - rosat , physics , astrophysics , sky , redshift , correlation function (quantum field theory) , declination , stars , point source , cluster analysis , quasar , universe , astronomy , active galactic nucleus , galaxy , optics , statistics , mathematics , optoelectronics , dielectric
We have derived the angular correlation function of a sample of 2096 sources detected in the ROSAT All‐Sky Survey (RASS) Bright Source Catalogue, in order to investigate the clustering properties of active galactic nuclei (AGN) in the local Universe. Our sample is constructed by rejecting all known stars, as well as extended X‐ray sources. Areas with | b |<30° and declination δ <−30° are also rejected owing to the high or uncertain neutral hydrogen absorption. Cross‐correlation of our sample with the Hamburg/RASS optical identification catalogue suggests that the vast majority of our sources are indeed AGN. A 4.1 σ correlation signal between 0° and 8° was detected with w ( θ <8°)=2.5±0.6×10 −2 . Assuming a two‐point correlation function of the form w ( θ )=( θ θ 0 ) −0.8 , we find θ 0 =0062. Deprojection on three dimensions, using Limber's equation, yields a spatial correlation length of r 0 ≈6.0±1.6 h −1 Mpc. This is consistent with the AGN clustering results derived at higher redshifts in optical surveys and suggests a comoving model for the clustering evolution.