The star formation and nuclear accretion histories of normal galaxies in the ages survey

Casey R. Watson, Christopher S. Kochanek, William R. Forman, Ryan C. Hickox, Christine J. Jones, Michael J.I. Brown, Kate Brand, Arjun Dey, Buell T. Jannuzi, Almus T. Kenter, Steve S. Murray, Alexey Vikhlinin, Daniel J. Eisenstein, Giovani G. Fazio, Paul J. Green, Brian R. McNamara, Marcia Rieke, Joseph C. Shields

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


We combine IR, optical, and X-ray data from the overlapping, 9.3 deg 2 NOAO Deep Wide-Field Survey, AGN and Galaxy Evolution Survey (AGES), and XBoötes Survey to measure the X-ray evolution of 6146 normal galaxies as a function of absolute optical luminosity, redshift, and spectral type over the largely unexplored redshift range 0.1 ≲ z ≲ 0.5. Because only the closest or brightest of the galaxies are individually detected in X-rays, we use a stacking analysis to determine the mean properties of the sample. Our results suggest that X-ray emission from spectroscopically late-type galaxies is dominated by star formation, while that from early-type galaxies is dominated by a combination of hot gas and active galactic nucleus (AGN) emission. We find that the mean star formation and supermassive black hole accretion rate densities evolve like (1 + z)31, in agreement with the trends found for samples of bright, individually detectable starburst galaxies and AGN. Our work also corroborates the results of many previous stacking analyses of faint source populations, with improved statistics.

Original languageEnglish (US)
Pages (from-to)2206-2219
Number of pages14
JournalAstrophysical Journal
Issue number2
StatePublished - May 10 2009


  • Galaxy: evolution
  • cosmology: observations

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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