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C. R. Watson, C. S. Kochanek (Ohio State), D. J. Eisenstein (Steward Observatory), K. Brand (NOAO), M. J. I. Brown (Princeton University Observatory), A. Dey, B. T. Jannuzi, J. Najita (NOAO), A. Vikhlinin, A. T. Kenter, G. G. Fazio, W. R. Forman, P. J. Green, C. J. Jones (Harvard CfA), B. R. McNamara (Ohio University), S. S. Murray (Harvard CfA), M. Rieke (Steward Observatory), J. C. Shields (Ohio University)
We combine optical data from the NOAO Deep Wide Field Survey (NDWFS), X-ray data from the XBoötes X-ray survey, and spectral information from the AGN and Galaxy Evolution Survey (AGES) to measure the X-ray evolution of normal galaxies as a function of absolute optical luminosity, redshift, and spectral type over the largely unexplored range 0 < z < 0.5. Because only the closest or brightest of the galaxies are individually detected in X-rays, we perform a stacking analysis to determine the mean properties of the sample. We use radial emission profiles of low redshift galaxies and the hardness ratios and X-ray to optical luminosity ratios of all galaxies to estimate the relative contributions of stellar and nuclear sources. These tests suggest that the X-ray emission from spectroscopically late-type galaxies is dominated by HMXBs, while that from early-type galaxies is dominated by AGN. We find that the mean star formation rate and the AGN accretion luminosity evolve as ~ (1+z)3, in good agreement with the results of previous studies.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.