Stripe 82X: X-ray Survey in SDSS Stripe 82

We have begun a wide area X-ray survey to fill in the missing piece of the L-z plane in X-ray surveys: rare high luminosity quasars at high redshift. Since such objects are rare, a wide volume of the Universe has to be explored to locate them. Though spectroscopic and multi-wavelength follow-up of detected X-ray sources is a major challenge in X-ray surveys, we have avoided this obstacle by targeting a region of the sky with pre-existing "follow-up," the Sloan Digital Sky Survey region Stripe 82 which contains a veritable treasure trove of multi-wavelength coverage. The combination of Chandra and XMM-Newton coverage in Stripe 82 is currently ∼16.5 deg2, including ∼4.6 deg2 of proprietary XMM-Newton observations awarded to our team in AO 10. Our survey area will increase by another ∼16 deg2 in the upcoming XMM-Newton AO 13 cycle. Highlights of Stripe 82X so far include:

• Detecting more/comparable number of high luminosity (L0.5-10keV ≥ 1045 erg s-1) quasars than predicted by model predictions prior to our dedicated spectroscopic follow-up program. This under-explored regime of SMBH growth is more important than previously accounted for.
• A third of the X-ray sources not detected in SDSS are found in the infrared, making them candidates for obscured high luminosity AGN at high redshift.
• We discovered the first "changing-look" quasar in Stripe 82X, which transitioned from a Type 1 quasar to a Type 1.9 AGN in under 10 years. Sky & Telescope magazine wrote a nice piece about this result and we issued a press release through Yale University.

For details of the archival Chandra coverage in Stripe 82, see LaMassa et al. 2013a and for the XMM-Newton coverage, see LaMassa et al. 2013b. X-ray sources matched to multi-wavelength catalogs (via a maximum likelihood estimator, as discussed in LaMassa et al. 2013b) can be downloaded for the Chandra sources and XMM-Newton sources. If you use these data for your work, please reference LaMassa et al. 2013a and LaMassa et al. 2013b. Details of column headings can be found in Appendix B of LaMassa et al. 2013b.

And stay tuned for results of our expanded survey!