科研之友
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摘要
We present results of a 100 ks XMM-Newton observation of the Seyfert 1.5 AGN NGC 3227. Our best-fit broadband model to the European Photon Imaging Camera (EPIC)-pn spectrum consists of a moderately flat (photon index of 1.57) hard X-ray power law absorbed by cold gas with a column density of 3 x 10(21) cm(2), plus a strong soft excess, modeled as a steep power law with a photon index of 3.35, absorbed by cold gas with a column density of 9 x 10(20) cm(-2). The soft excess increases in normalization by similar to 20% in similar to 20 ks, independently of the hard X-ray emission component, and the UV continuum, tracked via the Optical Monitor, also shows a strong increasing trend over the observation, consistent with reprocessing of soft X-ray emission. Warm absorber signatures are evident in both the EPIC and the Reflection Grating Spectrometer spectra; we model two absorbing layers, with ionization parameters log xi = 1.2 and 2.9 erg cm s(-1), and with similar column densities (similar to 10(21) to 2 x 10(21) cm(-2)). The outflow velocities relative to systemic of the high- and low-ionization absorbers are estimated to be -(2060(-170)(+240) ) km s(-1) and -(420(-190)(+430) ) km s(-1), respectively. The Fe K alpha line FWHM width is 7000 +/- 1500 km s(-1); its inferred distance from the black hole is consistent with the broad-line region and with the inner radius of the dust reverberation mapped by Suganuma et al. An emission feature near 6.0 keV is modeled equally well as a narrow redshifted Fe K line, possibly associated with a disk "hot spot," or as the red wing to a relativistically broadened Fe line profile. Swift Burst Alert Telescope and archival Rossi X-Ray Timing Explorer (RXTE) data suggest at most a weak Compton reflection hump (R less than or similar to 0.5), and a high- energy cutoff near 100 keV. From RXTE monitoring, we find tentative evidence for a significant fraction of the Fe line flux to track variations in the continuum on timescales < 700 days.
- 出版日期2009-2-1
