A Suzaku Observation of NGC 4593: Illuminating the Truncated Disk

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The 3rd Suzaku international Conference "Energetic Cosmos : from Suzaku to ASTRO-H" (June 29-July 2, 2009. Grand Park Otaru Hotel), Otaru, Hokkaido Japan

We report results from a 2007 Suzaku observation of the Seyfert 1 AGN NGC 4593. The narrow Fe Kalpha emission line has a FWHM width approximately 4000 km s(exp -1), indicating emission from > approximately 5000 Rg. There is no evidence for a relativistically broadened Fe K line, consistent with the presence of a radiatively-efficient outer disk which is truncated or transitions to an interior radiatively-inefficient flow. The Suzaku observation caught the source in a low-flux state; comparison to a 2002 XMM-Newton observation indicates that the hard X-ray flux decreased by 3.6, while the Fe Kalpha line intensity and width sigma each roughly halved. One possibility is that the line profile in the XMM-Newton observation consists of a time-invariant narrow component, plus a broad component originating from the inner part of the truncated disk (approximately 300 Rg) which has responded to the drop in continuum flux. The Compton reflection component strength R is approximately 1.1, consistent with the measured Fe Kalpha line total equivalent width with an Fe abundance 1.7 times the solar value. The modest soft excess, modeled well by either thermal bremsstrahlung emission or by Comptonization of soft seed photons in an optical thin plasma, has fallen by a factor of approximately 20 from 2002 to 2007, ruling out emission from a region 5 light-years in size.

Meeting sponsors: The University of Tokyo, The Institute of Physical and Chemical Research, The Japan Society for the Promotion of Science

資料番号: AA0064574124

レポート番号: JAXA-SP-09-008E

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