Poster Abstracts - Kepler - NASA

POSTER ABSTRACTSP1024. POSTER SESSION IIUNDERSTANDING QUASAR VARIABILITY THROUGH KEPLER. A. E. Wehrle 1 , S. C. Unwin 2 , P. J. Wiita3 , and D. Silano 3 ,1 Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301,awehrle@spacescience.org,2 JPL, Mail Code 301-170S, 4800 Oak Grove Drive, Pasadena, CA 91101,Stephen.c.unwin@jpl.nasa.gov, 3 The College of New Jersey, Department of Physics, P.O. Box 7718, Ewing, NJ08628, wiitap@tcnj.edu, silano2@tcnj.edu.We are monitoring four flat spectrum radio quasars(blazars) and one powerful radio galaxy, Cygnus A, tosearch for variability on timescales comparable to thelight crossing time of the accretion disk around thecentral supermassive black hole and the base of therelativistic jet. We want to see if some optical variabilityin quasars is due to a bright feature in the accretiondisk as it approaches the last stable orbit, or if it is dueto inhomogeneities in the jet, possibly in a helicalstructure. When the quasars are in quiescent, faintstates, a quasi-periodic light curve indicates an accretiondisk origin, and provides a dynamical means ofmeasuring a lower limit to the mass of the supermassiveblack hole which may be compared to those derivedby other methods, such as the shape of X-ray ironK$\alpha$ lines and stellar velocity dispersions. Whenthe quasars are in bright states, then long-lived quasiperiodicoscillations (QPOs) are very probably fromhelical features in the jets, but if several differentshort-lived QPOs are seen in one quasar, then theemission is probably coming from turbulence behind ashock. If during a faint state, instead of QPOs, we detectaperiodic variations, including high and lowbreaks in the power spectrum density (PSD), then wemay obtain the physical scales of the inner and outeredges of accretion disks and hence the BH mass. Aperiodicvariations during a high state, with breaks in thePSD, could yield the smallest and largest physicalscales corresponding to light travel times, modulo theDoppler factor, in the relativistic jet.Kepler is ideally suited to the necessary measurementsby delivering highly stable photometry continuouslyon timescales from minutes to days. The principalchallenge of our Kepler data analysis is that the automaticpipeline removal of day-to-week-scale drifts alsoremoves real astrophysical brightness variations. Wewill present preliminary results on short timescalevariations.2011 Kepler Science Conference - NASA Ames Research Center 227