ROSAT Deep Surveys
Abstract
A series of 20 deep pointed observations with the Rosat Position Sensitive Proportional Counter (PSPC) is discussed. 530 x-ray sources with 0.5 to 2 keV fluxes down to 3 times 10 to the -15th power erg/sq cm.s were discovered in 5.9 sq deg. The N (greater than S) relation of the sources selected in the 0.5 to 2 keV band shows a density in excess of 200 sq deg at the faintest fluxes and a flattening below 2 times 10 to the -14th power erg/sq cm.s. The average spectrum of these sources is a power law with energy index 1.2 +/- 0.1. The absorption column densities are consistent with the galactic HI columns. More than 50 percent of the 1 to 2 keV background was resolved into discrete sources in the deepest field. The total background spectrum shows an emission line feature around 0.65 keV, most probably due to OVII to OVIII from a 2,000,000K plasma. Above about 1 keV, the background is dominated by a power law spectrum with a normalization of 13.4 +/- 0.2 keV/sq cm s sr keV and a slope 1.2 +/- 0.1, that is, considerably steeper then the extrapolation from higher energies. An angular correlation function in the 0.9 to 2 keV band was constructed, averaged over 14 fields. The 1 sigma upper limits for structure in the background on scales of 2 to 10 arcmin are 10 to 5 percent.
- Publication:
-
X-ray Emission from Active Galactic Nuclei and the Cosmic X-ray Background
- Pub Date:
- March 1992
- Bibcode:
- 1992xrea.conf..321H
- Keywords:
-
- Background Radiation;
- Cosmic X Rays;
- Deep Space;
- Proportional Counters;
- Rosat Mission;
- X Ray Sources;
- X Ray Spectra;
- Absorption Spectra;
- Correlation;
- Emission Spectra;
- Energy Spectra;
- Line Spectra;
- Power Spectra;
- Radiant Flux Density;
- X Ray Astronomy;
- Astronomy