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Title: SUZAKU MONITORING OF THE IRON K EMISSION LINE IN THE TYPE 1 ACTIVE GALACTIC NUCLEUS NGC 5548

Abstract

We present seven sequential weekly observations of NGC 5548 conducted in 2007 with the Suzaku X-ray Imaging Spectrometer (XIS) in the 0.2-12 keV band and Hard X-ray Detector (HXD) in the 10-600 keV band. The iron Kalpha line is well detected in all seven observations and Kbeta line is also detected in four observations. In this paper, we investigate the origin of the Fe K lines using both the width of the line and the reverberation mapping method. With the co-added XIS and HXD spectra, we identify Fe Kalpha and Kbeta line at 6.396{sup +0.009}{sub -0.007} keV and 7.08{sup +0.05}{sub -0.05} keV, respectively. The width of line obtained from the co-added spectra is 38{sup +16}{sub -18} eV (FWHM = 4200{sup +1800}{sub -2000} km s{sup -1}) which corresponds to a radius of 20{sup +50}{sub -10} light days, for the virial production of 1.220 x 10{sup 7} M{sub sun} in NGC 5548. To quantitatively investigate the origin of the narrow Fe line by the reverberation mapping method, we compare the observed light curves of Fe Kalpha line with the predicted ones, which are obtained by convolving the continuum light curve with the transfer functions in a thin shell and an inclined disk.more » The best-fit result is given by the disk case with i = 30 deg. which is better than a fit to a constant flux of the Fe K line at the 92.7% level (F-test). However, the results with other geometries are also acceptable (P>50%). We find that the emitting radius obtained from the light curve is 25-37 light days, which is consistent with the radius derived from the Fe K line width. Combining the results of the line width and variation, the most likely site for the origin of the narrow iron lines is 20-40 light days away from the central engine, though other possibilities are not completely ruled out. This radius is larger than the Hbeta emitting parts of the broad-line region at 6-10 light days (obtained by the simultaneous optical observation), and smaller than the inner radius of the hot dust in NGC 5548 (at about 50 light days).« less

Authors:
; ; ; ;  [1];  [2];  [3];  [4];  [5];  [6]; ;  [7]
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)
  3. Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16 802 (United States)
  4. Astrophysics Group, School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom)
  5. Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-264, 04510 Mexico DF (Mexico)
  6. Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43 210 (United States)
  7. Institute of Astronomy, School of Science, University of Tokyo, Mitaka, Tokyo 181-0015 (Japan)
Publication Date:
OSTI Identifier:
21394444
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 710; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/710/2/1228; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DUSTS; EMISSION; GEOMETRY; HARD X RADIATION; IRON; KEV RANGE; LINE WIDTHS; MAPPING; QUASARS; SPECTRA; SPECTROMETERS; TRANSFER FUNCTIONS; X-RAY GALAXIES; COSMIC RADIO SOURCES; COSMIC RAY SOURCES; COSMIC X-RAY SOURCES; ELECTROMAGNETIC RADIATION; ELEMENTS; ENERGY RANGE; FUNCTIONS; GALAXIES; IONIZING RADIATIONS; MATHEMATICS; MEASURING INSTRUMENTS; METALS; RADIATIONS; TRANSITION ELEMENTS; X RADIATION

Citation Formats

Yuan, Liu, Elvis, Martin, Wilkes, Belinda J, Brickhouse, Nancy, Nicastro, Fabrizio, McHardy, Ian M, Grupe, Dirk, Reeves, James, Krongold, Yair, Mathur, Smita, Minezaki, Takeo, Yoshii, Yuzuru, and Zhang Shuangnan, E-mail: yliu@cfa.harvard.ed, E-mail: elvis@cfa.harvard.ed, E-mail: yuan-liu@mails.tsinghua.edu.c. SUZAKU MONITORING OF THE IRON K EMISSION LINE IN THE TYPE 1 ACTIVE GALACTIC NUCLEUS NGC 5548. United States: N. p., 2010. Web. doi:10.1088/0004-637X/710/2/1228.
Yuan, Liu, Elvis, Martin, Wilkes, Belinda J, Brickhouse, Nancy, Nicastro, Fabrizio, McHardy, Ian M, Grupe, Dirk, Reeves, James, Krongold, Yair, Mathur, Smita, Minezaki, Takeo, Yoshii, Yuzuru, & Zhang Shuangnan, E-mail: yliu@cfa.harvard.ed, E-mail: elvis@cfa.harvard.ed, E-mail: yuan-liu@mails.tsinghua.edu.c. SUZAKU MONITORING OF THE IRON K EMISSION LINE IN THE TYPE 1 ACTIVE GALACTIC NUCLEUS NGC 5548. United States. https://doi.org/10.1088/0004-637X/710/2/1228
Yuan, Liu, Elvis, Martin, Wilkes, Belinda J, Brickhouse, Nancy, Nicastro, Fabrizio, McHardy, Ian M, Grupe, Dirk, Reeves, James, Krongold, Yair, Mathur, Smita, Minezaki, Takeo, Yoshii, Yuzuru, and Zhang Shuangnan, E-mail: yliu@cfa.harvard.ed, E-mail: elvis@cfa.harvard.ed, E-mail: yuan-liu@mails.tsinghua.edu.c. 2010. "SUZAKU MONITORING OF THE IRON K EMISSION LINE IN THE TYPE 1 ACTIVE GALACTIC NUCLEUS NGC 5548". United States. https://doi.org/10.1088/0004-637X/710/2/1228.
@article{osti_21394444,
title = {SUZAKU MONITORING OF THE IRON K EMISSION LINE IN THE TYPE 1 ACTIVE GALACTIC NUCLEUS NGC 5548},
author = {Yuan, Liu and Elvis, Martin and Wilkes, Belinda J and Brickhouse, Nancy and Nicastro, Fabrizio and McHardy, Ian M and Grupe, Dirk and Reeves, James and Krongold, Yair and Mathur, Smita and Minezaki, Takeo and Yoshii, Yuzuru and Zhang Shuangnan, E-mail: yliu@cfa.harvard.ed, E-mail: elvis@cfa.harvard.ed, E-mail: yuan-liu@mails.tsinghua.edu.c},
abstractNote = {We present seven sequential weekly observations of NGC 5548 conducted in 2007 with the Suzaku X-ray Imaging Spectrometer (XIS) in the 0.2-12 keV band and Hard X-ray Detector (HXD) in the 10-600 keV band. The iron Kalpha line is well detected in all seven observations and Kbeta line is also detected in four observations. In this paper, we investigate the origin of the Fe K lines using both the width of the line and the reverberation mapping method. With the co-added XIS and HXD spectra, we identify Fe Kalpha and Kbeta line at 6.396{sup +0.009}{sub -0.007} keV and 7.08{sup +0.05}{sub -0.05} keV, respectively. The width of line obtained from the co-added spectra is 38{sup +16}{sub -18} eV (FWHM = 4200{sup +1800}{sub -2000} km s{sup -1}) which corresponds to a radius of 20{sup +50}{sub -10} light days, for the virial production of 1.220 x 10{sup 7} M{sub sun} in NGC 5548. To quantitatively investigate the origin of the narrow Fe line by the reverberation mapping method, we compare the observed light curves of Fe Kalpha line with the predicted ones, which are obtained by convolving the continuum light curve with the transfer functions in a thin shell and an inclined disk. The best-fit result is given by the disk case with i = 30 deg. which is better than a fit to a constant flux of the Fe K line at the 92.7% level (F-test). However, the results with other geometries are also acceptable (P>50%). We find that the emitting radius obtained from the light curve is 25-37 light days, which is consistent with the radius derived from the Fe K line width. Combining the results of the line width and variation, the most likely site for the origin of the narrow iron lines is 20-40 light days away from the central engine, though other possibilities are not completely ruled out. This radius is larger than the Hbeta emitting parts of the broad-line region at 6-10 light days (obtained by the simultaneous optical observation), and smaller than the inner radius of the hot dust in NGC 5548 (at about 50 light days).},
doi = {10.1088/0004-637X/710/2/1228},
url = {https://www.osti.gov/biblio/21394444}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 710,
place = {United States},
year = {Sat Feb 20 00:00:00 EST 2010},
month = {Sat Feb 20 00:00:00 EST 2010}
}