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Discovery of the narrow-line Seyfert 1 galaxy Markarian 335 in a historical low X-ray flux state
被引:60
作者:
Grupe, Dirk
Komossa, Stefanie
Gallo, Luigi C.
机构:
[1] Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA
[2] Max Planck Inst Extraterr Phys, D-85748 Garching, Germany
[3] Univ St Andrews, Sch Phys & Astron, SUPA, St Andrews KY16 9SS, Fife, Scotland
关键词:
galaxies : active;
galaxies : individual (Markarian 335);
galaxies : Seyfert;
ultraviolet : galaxies;
X-rays : galaxies;
D O I:
10.1086/523042
中图分类号:
P1 [天文学];
学科分类号:
0704 ;
摘要:
We report the discovery of the narrow- line Seyfert 1 galaxy Mrk 335 in an extremely low X- ray state. A comparison of Swift observations obtained in 2007 May and June/ July with all previous X- ray observations between 1971 and 2006 show the AGN to have diminished in flux by a factor of more than 30, the lowest X- ray flux Mrk 335 has ever been observed in. The Swift observations show an extremely hard X- ray spectrum at energies above 2 keV. Possible interpretations include partial- covering absorption or X- ray reflection from the disk. In this Letter we consider the partial- covering interpretation. The Swift observations can be well fit by a strong partial- covering absorber with varying absorption column density [N-H=(1-4)x10(23) cm(-2)] and a covering fraction. f(c)=0.9-1. When corrected for intrinsic absorption, the X-ray flux of Mrk 335 varies by only factors of 4 - 6. In the UV Mrk 335 shows variability on the order of 0.2 mag. We discuss the similarity of Mrk 335 to the highly variable NLS1 WPVS 007, and speculate about a possible link between NLS1 galaxies and broad- absorption- line quasars.
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页码:L111 / L114
页数:4
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