A Time-Variable X-Ray Echo: Indications of a Past Flare of the Galactic-Center Black Hole

Abstract

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*.

5 pages, 3 figures, accepted for publication in PASJ Vol 60, second Suzaku special issue

References in corpus (4)

• Iron and Nickel Line Diagnostics for the Galactic Center Diffuse Emission
• The Origin of Diffuse X-ray and $\gamma$-ray Emission from the Galactic Center Region: Cosmic Ray Particles
• Discovery of Variable Iron Fluorescence from Reflection Nebulae in the Galactic Center
• Discoveries of Diffuse Iron Line Sources from the Sgr B Region

Cited by in corpus (30)

• Discovery of a superluminal Fe K echo at the Galactic Center: The glorious past of Sgr A* preserved by molecular clouds
• The XMM-Newton view of the central degrees of the Milky Way
• Galactic center at very high-energies
• XIPE: the X-ray Imaging Polarimetry Explorer
• The K-shell Line Distribution of Heavy Elements along the Galactic Plane Observed with Suzaku
• Traces of past activity in the Galactic Centre
• Galactic Center Research: Manifestations of the Central Black Hole
• X-ray Echo from the Sagittarius C Complex and 500-year Activity History of Sagittarius A*
• X-ray Diagnostics of Giant Molecular Clouds in the Galactic Center Region and Past Activity of Sgr A*
• The X-ray lightcurve of Sgr A* over the past 150 years inferred from Fe-Ka line reverberation in Galactic Centre molecular clouds
• New Evidence for High Activity of the Super-Massive Black Hole in our Galaxy
• Not that long time ago in the nearest galaxy: 3D slice of molecular gas revealed by a 110 years old flare of Sgr A*
• An X-Ray Face-on View of the Sgr B Molecular Clouds Observed with Suzaku
• Diffuse X-Ray Sky in the Galactic Center
• K-shell Emission of Neutral Iron Line from Sgr B2 Excited by Subrelativistic Protons
• Glimpses of the past activity of Sgr A* inferred from X-ray echoes in Sgr C
• Sensitivity of the Fe K-alpha Compton shoulder to the geometry and variability of the X-ray illumination of cosmic objects
• The long-term millimeter activity of active galactic nuclei
• POLARIX: a pathfinder mission of X-ray polarimetry
• Neutrinos and γ-rays from the Galactic Center Region After H.E.S.S. Multi-TeV Measurements
• 74 MHz Nonthermal Emission from Molecular Clouds: Evidence for a Cosmic Ray Dominated Region at the Galactic Center
• X-Ray Reflection Nebulae with Large Equivalent Widths of Neutral Iron Ka Line in the Sgr C Region
• Spectrum of Relativistic and Subrelativistic Cosmic Rays in the 100 pc Central Region
• Prospects of 3D mapping of the Galactic Centre clouds with X-ray polarimetry
• Leptonic origin of the 100 MeV gamma-ray emission from the Galactic Centre
• Physical Contact between the +20 km/s Cloud and the Galactic Circumnuclear Disk
• Suzaku Observation Adjacent to the South End of the Radio Arc
• Suzaku observation of the Phoenix Galaxy
• Spatial and Temporal Variations of the Diffuse Iron 6.4 keV Line in the Galactic Center Region
• The Suzaku Hard X-ray Survey on the Galactic Center Region