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AGN/galaxy separation in the ROSAT Bright Survey

I. Lehmann, Günther Hasinger, Axel D. Schwope, Thomas Böller

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Abstract

The X-ray luminosity function (XLF) of galaxies is dominated by AGN (classified by their optical spectra) above Lx=10**42 erg/s, below this value by normal galaxies. The X-ray flux of AGN at low X-ray luminosity therefore contains contributions from stellar processes (winds, supernova explosions etc.). Until now it is not clear which fraction of the observed X-ray flux has to be associated to the underlying stellar emission. We started to investigate a complete luminosity-limited sample of AGN and galaxies with log Lx < 42.5 to discriminate between the nuclear and galaxy flux. Using the ROSAT HRI data we calculated the radial wobble-corrected profiles of the sources which were compared to a new HRI point spread function (PSF) template derived from 21 X-ray bright stars. The majority of the low-luminosiy AGN shows evidence for a significant fraction of extended X-ray emission.

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The X-ray luminosity function (XLF) of galaxies is dominated by AGN (classified by their optical spectra) above Lx=10**42 erg/s, below this value by normal galaxies. The X-ray flux of AGN at low X-ray luminosity therefore contains contributions from stellar processes (winds, supernova explosions etc.). Until now it is not clear which fraction of the observed X-ray flux has to be associated to the underlying stellar emission. We started to investigate a complete luminosity-limited sample of AGN and galaxies with log Lx < 42.5 to discriminate between the nuclear and galaxy flux. Using the ROSAT HRI data we calculated the radial wobble-corrected profiles of the sources which were compared to a new HRI point spread function (PSF) template derived from 21 X-ray bright stars. The majority of the low-luminosiy AGN shows evidence for a significant fraction of extended X-ray emission.

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Available abstract

The X-ray luminosity function (XLF) of galaxies is dominated by AGN (classified by their optical spectra) above Lx=10**42 erg/s, below this value by normal galaxies. The X-ray flux of AGN at low X-ray luminosity therefore contains contributions from stellar processes (winds, supernova explosions etc.). Until now it is not clear which fraction of the observed X-ray flux has to be associated to the underlying stellar emission. We started to investigate a complete luminosity-limited sample of AGN and galaxies with log Lx < 42.5 to discriminate between the nuclear and galaxy flux. Using the ROSAT HRI data we calculated the radial wobble-corrected profiles of the sources which were compared to a new HRI point spread function (PSF) template derived from 21 X-ray bright stars. The majority of the low-luminosiy AGN shows evidence for a significant fraction of extended X-ray emission.

Key concepts: ROSAT, Astrophysics, Galaxy, Separation (statistics), Astronomy, Physics, Mathematics, Statistics

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