Dramatic decrease in X-ray flux for Zw229-15

ATel #3458; Richard Mushotzky ( U of Maryland), Rick Edelson
on 29 Jun 2011; 19:16 UT
Credential Certification: Richard Mushotzky (richard@astro.umd.edu)

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The narrow-line Seyfert 1 galaxy Zw 229-15 (19h05m25.9s +42d27m40s) exhibited a dramatic decrease in X-ray flux during Swift monitoring in June 2011. During the ~18 days from 2011 May 29 22:26 through June 17 7:48, the source reached a peak count rate of 0.17 cts/sec and a mean Swift 0.3-10 keV count rate of 0.096 c/s (All times in UT). The source flux then dropped to a mean count rate of 0.023 c/s over the next ~11 days ending June 28 2:23, reaching a low of 0.005 c/s at June 27 00:23.The most recent Swift light curve and spectra of this source can be accessed at http://www.swift.ac.uk/user_objects/tprods/USERPROD_67.132.100.28_1309347553962which shows that the source is still in a very low state. Daily monitoring with Swift will continue for at least another 10 days, or until the source returns to the pre-decline count rate of ~0.1 c/s. At a distance of 118 Mpc and a conversion factor based on the average Swift XRT spectrum (column density of 7x10^20 and photon index slope of 1.9) the source has a minimum luminosity of log L(x)<41.5 ergs/cm2/sec in the 0.3-8 kev band. Optical and IR photometric and spectroscopic monitoring are encouraged to determine the response of the line emitting regions and the IR continuum to this radical change in source luminosity.

Swift XRT Light Curve