NEW EVIDENCE FOR HIGH ACTIVITY OF THE SUPERMASSIVE BLACK HOLE IN OUR GALAXY

Journal Article · Sat Oct 01 00:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/739/2/L52· OSTI ID:21565428

Nobukawa, M; Ryu, S G; Tsuru, T G; Koyama, K ^[1]

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1. 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, Vol. 739, Issue 2; Other Information: DOI: 10.1088/2041-8205/739/2/L52; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BLACK HOLES
FLUORESCENCE
GALAXIES
IRON
K SHELL
THOMSON SCATTERING
X RADIATION
ELECTROMAGNETIC RADIATION
ELECTRONIC STRUCTURE
ELEMENTS
EMISSION
INELASTIC SCATTERING
IONIZING RADIATIONS
LUMINESCENCE
METALS
PHOTON EMISSION
RADIATIONS
SCATTERING
TRANSITION ELEMENTS