Constraints on Large-Scale Clustering from the Autocorrelation Properties of the X-Ray Background
Abstract
We discuss expectations for the angular correlation function of intensity fluctuations of the extragalactic 2-10 keV X-ray background (XRB) in relation to the two-point spatial correlation functions, ξ(r), of X-ray sources. A simple analytic formula for the amplitude of intensity correlations, {GAMMA}(θ), holding in the low-redshift, small- separation approximation, is derived. The HEAO 1 A-2 upper limits on {GAMMA}(θ) have been exploited to derive constraints on the local ξ(r) functions of rich clusters of galaxies, of active galactic nuclei (AGNs), and on the AGN-cluster cross-correlation, as well as on evolution of the correlation functions with cosmic time. X-ray data are found to be compatible with the Bahcall and Soneira estimates of ξ_cluster-cluster_ as well as with the results of recent studies of quasars clustering. Constraints on evolution models are discussed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1990
- DOI:
- 10.1086/168440
- Bibcode:
- 1990ApJ...351...22D
- Keywords:
-
- Active Galactic Nuclei;
- Galactic Clusters;
- Quasars;
- X Ray Sources;
- Autocorrelation;
- Computational Astrophysics;
- Galactic Evolution;
- Heao 1;
- Red Shift;
- Seyfert Galaxies;
- Astrophysics;
- COSMOLOGY;
- GALAXIES: CLUSTERING;
- QUASARS;
- X-RAYS: SOURCES