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Alex Markowitz (Univ. of California, San Diego; Karl Remeis Sternwarte & ECAP)

First X-ray-Based Statistical Tests for Clumpy-Torus Models: Eclipse Events from X-ray Monitoring of Seyfert AGN
Wann Am 08.04.2014 von 11:00 bis 12:00
  • Kolloquium
  • Special Seminar
Wo SH, Hörsaal
Termin übernehmen vCal / iCal

We present an analysis of multi-timescale variability in line-of-sight X-ray absorbing gas as a function of optical classification in a large sample of Seyfert AGN to derive the first X-ray statistical constraints for clumpy-torus models. We systematically search for discrete absorption events in the vast archive of Rossi X-ray Timing Explorer monitoring of 55 nearby type Is and Compton-thin type IIs.

We detect 12 eclipse events in 8 objects, roughly tripling the number previously published from this archive. Event durations span hours to years. The column density profile for an eclipsing cloud in NGC 3783 is doubly spiked, possibly indicating a cloud that is being tidally sheared.

We infer the clouds' distances from the black hole to span \sim 0.3 - 140 \times 10^4 R_g. In seven objects, the clouds' distances are commensurate with the outermost portions of the BLR, or the inner regions of infrared-emitting dusty tori. We discuss implications for cloud distributions in the context of clumpy-torus models.