Cross-correlation of the 2-10 keV XRB with radio sources: constraining the large-scale structure of the x-ray background

Abstract

We present cross-correlation analyses of the HEAO 2-10 keV diffuse X-ray map with both the combined GB6/Parkes-MIT-NRAO (GB6-PMN) 5 GHz and the FIRST 1.4 GHz radio surveys. The cross-correlation functions (CCFs) of both radio surveys with the unresolved X-ray background were detected at the 5 sigma level. While the large angular resolution (3 degrees) of the X-ray map makes it difficult to separate the contributions of clustering from those of Poisson fluctuations, the amplitude of the CCF provides important constraints on the X-ray emissivity of the radio sources as well as on the clustering properties of radio and X-ray sources. These constraints are subject to a number of modeling parameters, e.g. the X-ray luminosity evolution, clustering evolution, the radio luminosity function, cosmological model, etc. For reasonable choices of paramters the X-ray/FIRST CCF is consistent with a correlation scale length of 6/h Mpc. This is somewhat smaller than the scale length inferred from the autocorrelation function of the FIRST survey and implies that X-ray sources are less strongly clustered than strong radio sources, a result which is consistent with previous constraints on X-ray clustering. The X-ray/GB6-PMN CCF is several times larger and is likely to be dominated by Poisson fluctuations. This implies that 2 percent of the diffuse X-ray background arises from the GB6-PMN sources.

25 pages, with 8 figures included. Submitted to ApJ. [email protected]

References in corpus (8)

• The correlation function of radio sources
• ASCA observations of deep ROSAT fields I. the nature of the X-ray source populations
• The X-Ray Background as a Probe of Density Fluctuations at High Redshift
• A deep ROSAT Survey - XIV. X-ray emission from faint galaxies
• Measuring the power spectrum of density fluctuations at intermediate redshift with X-ray background observations
• Detailed Analysis of the Cross-Correlation Function between the X-Ray Background and Foreground Galaxies
• AGN predictions for the Hubble Deep Field and the X-ray background
• Probing Density Fluctuations using the FIRST Radio Survey

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