Article

Suzaku Observations of the Hard X-Ray Variability of MCG −6–30–15: the Effects of Strong Gravity around a Kerr Black Hole

G. Miniutti1Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge, UK [email protected]A. C. Fabian1Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge, UK [email protected]Naohisa Anabuki2Department of Earth and Space Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043Jamie Crummy1Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge, UK [email protected]Yasushi Fukazawa3Department of Physical Science, School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526Luigi Gallo4Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, Garching, GermanyYoshito Haba6Department of Astrophysics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602Kiyoshi Hayashida2Department of Earth and Space Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043Steve Holt7F. W. Olin College of Engineering, 1735 Great Plain Avenue, Needham, MA 02492, USAHideyo Kunieda8Department of Physics, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8602Josefin Larsson1Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge, UK [email protected]A. Markowitz9Astrophysics Science Division, Code 662, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USAC. Matsumoto8Department of Physics, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8602M. Ohno3Department of Physical Science, School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526J. N. Reeves10Department of Physics and Astronomy, John Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USATadayuki Takahashi5Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510Yasuo Tanaka4Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, Garching, GermanyYuichi Terashima11Department of Physics, Ehime University, 2-5 Bunkyocho, Matsuyama, Ehime 790-8577Ken’ichi Torii2Department of Earth and Space Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043Yoshihiro Ueda12Department of Astronomy, Kyoto University, Sakyo-ku, Kyoto 606-8502Masayoshi Ushio5Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510Shin Watanabe5Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Sagamihara, Kanagawa 229-8510M. Yamauchi13Department of Applied Physics, University of Miyazaki, 1-1 Gakuen-Kibanadi-Nishi, Miyazaki, Miyazaki 889-2192Tahir Yaqoob10Department of Physics and Astronomy, John Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA

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Abstract

Abstract Suzaku has, for the first time, enabled the hard X-ray variability of the Seyfert 1 galaxy MCG $-$6–30–15 to be measured. The variability in the 14–45 keV band, which is dominated by a strong reflection hump, is quenched relative to that at a few keV. This directly demonstrates that the whole reflection spectrum is much less variable than the power-law continuum. The broadband spectral variability can be decomposed into two components—a highly variable power-law and constant reflection—as previously inferred from other observations in the 2–10 keV band. The strong reflection and high iron abundance give rise to a strong broad iron line, which requires the inner disc radius to be at about 2 gravitational radii. Our results are consistent with the predictions of the light bending model which invokes the very strong gravitational effects expected very close to a rapidly spinning black hole.

Identifiers

DOI: 10.1093/pasj/59.sp1.s315

Citations and references

Cited by 40 references

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