时变X射线回波：银河系中心黑洞过去耀斑的指示
A Time-Variable X-Ray Echo: Indications of a Past Flare of the Galactic-Center Black Hole
摘要：
本文利用朱雀星和钱德拉星的观测资料，对Sgr B2区6.40keV中性铁谱线通量的时变进行了研究。6.68 keV的高电离铁谱线是由银河系中心漫射X射线（GCDX）产生的，因此是时间不变的。通过比较6.68keV和6.40keV的谱线通量，我们发现来自Sgr B2复合体区的6.40keV谱线通量是随时间变化的，特别是被称为“Sgr B2云”的巨大分子云M0.66-0.02是高度可变的。6.40 keV谱线强度和空间分布的变化强烈支持SgrB 2区的分子云是银河系中心（GC）黑洞Sgr A* 辐射的X射线反射星云的假设。
英文摘要：
A time-variability study of the neutral iron line flux at 6.40keV in the Sgr B2 region from data of Suzaku and Chandra is presented. The highly ionized iron line at 6.68keV is due to Galactic Center Diffuse X-rays (GCDX), and is thus time invariable. By comparing the 6.68keV and 6.40keV line fluxes, we found that the 6.40keV flux from the SgrB2 complex region is time variable; particularly the giant molecular cloud M0.66-0.02, known as ``Sgr B2 cloud'' is highly variable. The variability of the 6.40keV line in intensity and spatial distribution strongly supports the scenario that the molecular clouds in the SgrB2 region are X-ray Reflection Nebulae irradiated by the Galactic Center (GC) black hole Sgr A*.
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