Finding rare AGN: XMM-newton and chandra observations of SDSS stripe 82

Stephanie M. LaMassa, C. Megan Urry, Nico Cappelluti, Francesca Civano, Piero Ranalli, Eilat Glikman, Ezequiel Treister, Gordon Richards, David Ballantyne, Daniel Stern, Andrea Comastri, Carie Cardamone, Kevin Schawinski, Hans Böhringer, Gayoung Chon, Stephen S. Murray, Paul Green, Kirpal Nandra

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


We have analysed the XMM-Newton and Chandra data overlapping ~16.5 deg2 of Sloan Digital Sky Survey Stripe 82, including ~4.6 deg2 of proprietary XMM-Newton data that we present here. In total, 3362 unique X-ray sources are detected at high significance. We derive the XMM-Newton number counts and compare them with our previously reported Chandra logN-logS relations and other X-ray surveys. The Stripe 82 X-ray source lists have been matched to multiwavelength catalogues using a maximum likelihood estimator algorithm.We discovered the highest redshift (z = 5.86) quasar yet identified in an X-ray survey. We find 2.5 times more high-luminosity (Lx = 1045 erg s-1) AGN than the smaller area Chandra and XMM-Newton survey of COSMOS and 1.3 times as many identified by XBoötes. Comparing the high-luminosity active galactic nuclei (AGN) we have identified with those predicted by population synthesis models, our results suggest that this AGN population is a more important component of cosmic black hole growth than previously appreciated. Approximately a third of the X-ray sources not detected in the optical are identified in the infrared, making them candidates for the elusive population of obscured high-luminosity AGN in the early universe

Original languageEnglish (US)
Article numberstt1837
Pages (from-to)3581-3601
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Dec 2013
Externally publishedYes


  • Catalogues
  • X-rays:Galaxies
  • galaxies:Active
  • quasars:General
  • quasars:Supermassive black holes
  • surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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