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arXiv · 1109.1950

New Evidence for High Activity of the Super-Massive Black Hole in our Galaxy

Masayoshi Nobukawa·Syukyo G. Ryu·Takeshi Go Tsuru·Katsuji Koyama
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Abstract

Prominent K-shell emission lines of neutral iron (hereafter, FeI-K) and hard-continuum X-rays were found from molecular clouds (MCs) in the Sagittarius B (Sgr B) region with the two separate Suzaku observations in 2005 and 2009. The X-ray flux of FeI-K decreased in correlation to the hard-continuum flux by factor of 0.4-0.5 in 4 years, which is nearly equal to the light-travelling across the MCs. The rapid and correlated time-variability, the equivalent width of FeI-K, and the K-edge absorption depth of FeI are consistently explained by "X-ray echoes" due to the fluorescent and Thomson-scattering of an X-ray flare from an external source. The required flux of the X-ray flare depends on the distance to the MCs and the duration time. The flux, even in the minimum case, is larger than those of the brightest Galactic X-ray sources. Based on these facts, we conclude that the super-massive black hole, Sgr A*, exhibited a big-flare about a few hundred years ago and the luminosity of higher than 4x10^39 erg s^{-1}. The "X-ray echo" from Sgr B, located at a few hundred light-years from Sgr A*, now arrived at the Earth.

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Masayoshi Nobukawa, Syukyo G. Ryu, Takeshi Go Tsuru, Katsuji Koyama. 2011-09-09. New Evidence for High Activity of the Super-Massive Black Hole in our Galaxy. https://doi.org/10.1088/2041-8205%2F739%2F2%2Fl52

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