NEW EVIDENCE FOR HIGH ACTIVITY OF THE SUPERMASSIVE BLACK HOLE IN OUR GALAXY
Journal Article
·
· Astrophysical Journal Letters
- Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan)
Prominent K-shell emission lines of neutral iron (hereafter Fe I-K lines) and hard-continuum X-rays from molecular clouds (MCs) in the Sagittarius B (Sgr B) region were found in two separate Suzaku observations in 2005 and 2009. The X-ray flux of the Fe I-K lines decreased in correlation with the hard-continuum flux by a factor of 0.4-0.5 in four years, which is almost equal to the light traveling across the MCs. The rapid and correlated time variability, the equivalent width of the Fe I-K lines, and the K edge absorption depth of Fe I 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 its time duration. Even for a case with a minimum distance, the flux is larger than those of the brightest Galactic X-ray sources. Based on these facts, we conclude that the supermassive black hole Sgr A* exhibited a large flare a few hundred years ago with a luminosity of more than 4 x 10{sup 39} erg s{sup -1}. The 'X-ray echo' from Sgr B, located a few hundred light-years from Sgr A*, has now reached the Earth.
- OSTI ID:
- 21565428
- Journal Information:
- Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 739; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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