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Precision fe k-alpha and fe k-beta line spectroscopy of the seyfert 1.9 galaxy ngc 2992 with suzaku
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Haba, Yoshito Selemitos, Peter J. Takahashi, Tadayuki Griffiths, Richard E. Reeves Sr., James Murphy, Kendrah D. Kokubun, Motohide Inoue, Hajime Yaqoob, Tahir Mushotzky, Richard Ptak, Andrew Okajima, Takashi Markowitz, Alex Itoh, Takeshi Kelley, Richard Terashima, Yuichi |
| Copyright Year | 2006 |
| Description | We present detailed time-averaged X-ray spectroscopy in the 0.5-10 keV band of the Seyfert 1.9 galaxy NGC 2992 with the Suzaku X-ray Imaging Spectrometers (XIS). The source had a factor approximately 3 higher 2-10 keV flux (approximately 1.2 x l0(exp -11) erg per square cm per s) than the historical minimum and a factor approximately 7 less than the historical maximum. The XIS spectrum of NGC 2992 can be described by several components. There is a primary continuum, modeled as a power-law with a photon index of Gamma = 1.57(sup +0.06) (sup -0.03) that is obscured by a Compton-thin absorber with a column density of 8.01(sup +0.6) (sup -0.5)x l0 (exp 21) per square cm. . There is another, weaker, unabsorbed power-law component (modeled with the same slope as the primary), that is likely to be due to the primary continuum being electron-scattered into our line-of-sight by a region extended on a scale of hundreds of parsecs. We measure the Thomson depth of the scattering zone to be Tau = 0.072 +/- 0.021. An optically-thin thermal continuum emission component, which probably originates in the same extended region, is included in the model and yields a temperature and luminosity of KT = 0.656(sup +0.088) (sup -0.0.61) keV and approximately 1.2 +/- 0.4 x l0 (exp 40) erg per s respectively. We detect an Fe K emission complex which we model with broad and narrow lines and we show that the intensities of the two components are decoupled at a confidence level > 3 sigma. The broad Fe K alpha line has an equivalent width of 118(sup +32) (sup -61) eV and could originate in an accretion disk (with inclination angle greater than approximately 30 deg) around the putative central black hole. The narrow Fe K alpha line has an equivalent width of 1632(sup +47) (sup -26) eV and is unresolved (FWHM < 4630 km per s) and likely originates in distant matter. The absolute flux in the narrow line implies that the column density out of the line-of-sight could be much higher than measured in the line-of-sight, and that the mean (historically-averaged) continuum luminosity responsible for forming the line could be a factor of several higher than that measured from the data. We also detect the Fe K Beta line (corresponding to the narrow Fe K alpha line) with a high signal-to-noise ratio and describe a new robust method to constrain the ionization state of Fe responsible for the Fe K alpha and Fe K Beta lines that does not require any knowledge of possible gravitational and Doppler energy shifts affecting the line energies. For the distant line-emitting matter (e. g. the putative obscuring torus) we deduce that the predominant ionization state is lower than Fe VIII (at 99% confidence), conservatively taking into account residual calibration uncertainties in the XIS energy scale and theoretical and experimental uncertainties in the Fe K fluorescent line energies. From the limits on a possible Compton-reflection continuum it is likely that the narrow Fe K alpha and Fe K Beta lines originate in a Compton-thin structure. |
| File Size | 2069845 |
| Page Count | 37 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20070020263 |
| Archival Resource Key | ark:/13960/t22c4095q |
| Language | English |
| Publisher Date | 2006-01-01 |
| Access Restriction | Open |
| Subject Keyword | Astrophysics Imaging Spectrometers Seyfert Galaxies Active Galactic Nuclei Ionization Luminosity Spaceborne Telescopes K Lines Nuclear Radiation Spectroscopy X Ray Astronomy Accretion Disks Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
