The small-scale autocorrelation function of the X-ray background
Abstract
We have studied the angular correlation function of the 1-3 keV X-ray background using data from five deep Einstein IPC fields. Only counts in the central part of the detector (0.25^deg2^), where the response is nearly flat, have been considered. After removing possible ( > 3 σ sources, we have fitted a Gaussian to the autocorrelation function from 1 to 15 arcmin. This shows a signal below 5 arcmin, although it is not clear whether it is due to the cosmic X-ray background. On the assumption that detector effects, other than baseline (i.e. non-cosmic) counts, do not lower anisotropies, an upper limit for the autocorrelation function at 5 arcmin is ~9 per cent (at 95 per cent confidence level) after estimating the contribution from non-cosmic background. The implications of this upper limit for the large-scale structure of the X-ray Universe are discussed.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 1989
- DOI:
- 10.1093/mnras/237.1.119
- Bibcode:
- 1989MNRAS.237..119B
- Keywords:
-
- Background Radiation;
- Galactic Evolution;
- Intergalactic Media;
- Red Shift;
- X Ray Sources;
- Autocorrelation;
- Heao 2;
- Universe;
- Space Radiation