11/07/13 Josh Grindlay SO/NOAO Joint Colloquium Series
Prof. Josh Grindlay, Harvard
Black Hole Variability on Days-to-Century Timescales
Abstract
One of the original motivations for undertaking our Digital Access to a Sky-Century (DASCH) project was to measure or constrain the recurrence times of nova-like outbursts of stellar mass black holes accreting from low mass binary companions. The 1975 X-ray and optical outburst of A0620-00, later recognized as the prototype BH-LMXB, had been found by visual inspection of the Harvard plates to have had a similar event in 1917. With now >20 dynamically confirmed BH-LMXBs, and our “production scanning” of the Harvard plates and pipeline processing for a complete astrometric and photometric solution for each resolved object, DASCH can derive outburst recurrence times and thus new constraints on source populations. I will present results for the first 4 objects now covered by data releases DR1 and DR2. Likewise, for bright AGN (e.g. 3C273 and the PG sample of QSOs), century-long lightcurves and power spectra allow new measures of QSO variability and constraints on SMBH mass. I will describe the DASCH processing and analysis system which, thanks to NSF support, will enable the full-sky database (~ 1Pb) to be on line by 2017. I will show a few other early results to illustrate the potential of days-to-century Time Domain Astronomy for a range of objects, particularly those with rare outbursts.
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