Long-term X-ray variability of quasars in the Lockman Hole field observed with ROSAT

Yu Ichiro Ezoe, Naoko Iyomoto, Kazuo Makishima, Günter Hasinger

研究成果: ジャーナルへの寄稿学術誌査読

1 被引用数 (Scopus)

抄録

An improved method has been utilized to estimate the X-ray power spectral densities (PSD) and the variation time scales of three quasars in the Lockman Hole field. Five archival ROSAT PSPC data covering a two-year range were analyzed. To estimate PSD from sparse and unevenly-sampled lightcurves, a forward-method approach with extensive Monte Carlo simulations was adopted. A broken power-law type PSD with a constant Poisson noise component was assumed with a break frequency, fb. Then, assuming the PSD slope, α, to be -2 < α < -1, l/fb was constrained as ≳ 25 days for one object, while the constraints on the other two objects were very weak. The long-time scale of the one object is consistent with the view that luminous AGNs host massive black holes.

本文言語英語
ページ(範囲)981-986
ページ数6
ジャーナルPublications of the Astronomical Society of Japan
54
6
DOI
出版ステータス出版済み - 2002
外部発表はい

!!!All Science Journal Classification (ASJC) codes

  • 天文学と天体物理学
  • 宇宙惑星科学

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