X-ray Echo from the Sagittarius C Complex and 500-year Activity History of Sagittarius A*

Abstract

This paper presents the Suzaku results obtained for the Sagittarius (Sgr) C region using the concept of X-ray reflection nebulae (XRNe) as the echo of past flares from the super massive black hole, Sgr A*. The Sgr C complex is composed of several molecular clouds proximately located in projected distance. The X-ray spectra of Sgr C were analyzed on the basis of a view that XRNe are located inside the Galactic center plasma X-ray emission with an oval distribution around Sgr A*. We found that the XRNe are largely separated in the line-of-sight position, and are associated with molecular clouds in different velocity ranges detected by radio observations. We also applied the same analysis to the Sgr B XRNe and completed a long-term light curve for Sgr A* occurring in the past. As a new finding, we determined that Sgr A* was experiencing periods of high luminosity already 500 years ago, which is longer than the previously reported value. Our results are consistent with a scenario that Sgr A* was continuously active with sporadic flux variabilities of Lx = 1-3 x 10^39 erg s^-1 in the past 50 to 500 years. The average past luminosity was approximately 4-6 orders of magnitude higher than that presently observed. In addition, two short-term flares of 5-10 years are found. Thus, the past X-ray flare should not be a single short-term flare, but can be interpreted as multiple flares superposed on a long-term high state.

9 pages, 6 figures, 3 tables, Accepted in PASJ (Publications of the Astronomical Society of Japan)

References in corpus (5)

• The Origin of Diffuse X-ray and $\gamma$-ray Emission from the Galactic Center Region: Cosmic Ray Particles
• The K-shell Line Distribution of Heavy Elements along the Galactic Plane Observed with Suzaku
• Discovery of Variable Iron Fluorescence from Reflection Nebulae in the Galactic Center
• The Sudden Death of the Nearest Quasar
• The X-ray lightcurve of Sgr A* over the past 150 years inferred from Fe-Ka line reverberation in Galactic Centre molecular clouds

Cited by in corpus (51)

• Black hole variability and the star formation-AGN connection: Do all star-forming galaxies host an AGN?
• The XMM-Newton view of the central degrees of the Milky Way
• Echoes of multiple outbursts of Sagittarius A* revealed by Chandra
• Herschel observations of EXtraordinary Sources: Analysis of the full Herschel/HIFI molecular line survey of Sagittarius B2(N)
• A Luminous Infrared Merger with Two Bipolar Molecular Outflows: ALMA and SMA Observations of NGC 3256
• Slow blue nuclear hypervariables in PanSTARRS-1
• Discovery of the recombining plasma in the south of the Galactic center; a relic of the past Galactic center activity?
• Possible Origin of the G2 Cloud from the Tidal Disruption of a Known Giant Star by Sgr A*
• Unbound Debris Streams and Remnants Resulting From the Tidal Disruptions of Stars by Supermassive Black Holes
• Diffuse X-Ray Sky in the Galactic Center
• Glimpses of the past activity of Sgr A* inferred from X-ray echoes in Sgr C
• An X-ray survey of the central molecular zone: variability of the Fe Ka emission line
• X-ray polarization evidence for a 200 years-old flare of Sgr A${}^{\ast }$
• The role of feedback in accretion on Low Luminosity AGN: Sgr A* case study
• Sagittarius A* as an Origin of the Galactic PeV Cosmic Rays?
• The Galactic LMXB Population and the Galactic Centre Region
• Hadronic origin of multi-TeV gamma rays and neutrinos from low-luminosity active galactic nuclei: implications of past activities of the Galactic center
• Spectrum of Relativistic and Subrelativistic Cosmic Rays in the 100 pc Central Region
• Spectral features of tidal-disruption candidates and alternative origins for such transient flares
• Particle Diffusion and Acceleration in Magnetorotational Instability Turbulence
• Prospects of 3D mapping of the Galactic Centre clouds with X-ray polarimetry
• Can Sgr A* flares reveal the molecular gas density PDF?
• Universal transition diagram from dormant to actively accreting supermassive black holes
• X-ray Observation of a Magnetized Hot Gas Outflow in the Galactic Center Region
• The origin of the 6.4 keV line emission and H${}_2$ ionization in the diffuse molecular gas of the Galactic center region
• NuSTAR and XMM-Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud
• Probing the clumping structure of Giant Molecular Clouds through the spectrum, polarisation and morphology of X-ray Reflection Nebulae
• Multiple accretion events as a trigger for Sgr A* activity
• Reflection nebulae in the Galactic Center: the case for soft X-ray imaging polarimetry
• Chemical modeling of the complex organic molecules in the extended region around Sagittarius B2
• On the Origin of the 6.4 keV Line in the Galactic Center Region
• Observing two dark accelerators around the Galactic Centre with Fermi Large Area Telescope
• Investigating the origin of the faint non-thermal emission of the Arches cluster using the 2015-2016 NuSTAR and XMM-Newton X-ray observations
• Millimeter-wave Spectral Line Surveys toward the Galactic Circumnuclear Disk and Sgr A*
• SRG/eROSITA view of X-ray reflection in the Central Molecular Zone: a snapshot in September-October 2019
• X-ray spectra of Sgr A East and diffuse X-ray background near the Galactic center
• Sgr B2 hard X-ray emission with INTEGRAL after 2009: still detectable?
• New Constraints on Cosmic Particle Populations at the Galactic Center using X-ray Observations of the Molecular Cloud Sagittarius B2
• Identifying Galactic Sources of High-Energy Neutrinos
• X-ray Scattering Echoes and Ghost Halos from the Intergalactic Medium: Relation to the nature of AGN variability
• Time-Variability of equivalent width of 6.4 keV line from the Arches Complex: reflected X-rays or charged particles?
• X-raying molecular clouds with a short flare: probing statistics of gas density and velocity fields
• Atomic Carbon in the Central Molecular Zone of the Milky Way : Possible Cosmic-ray Induced Chemistry or Time-Dependent Chemistry Associated with SNR Sagittarius A East
• Impact of intrinsic polarisation of Sgr A* historical flares on (polarisation) properties of their X-ray echoes
• The Advanced X-ray Imaging Satellite
• Prospects for IXPE and eXTP polarimetric archaeology of the reflection nebulae in the Galactic center
• Prospects for the polarimetric mapping of the Sgr A molecular cloud complex with IXPE
• Spectrum Composition of Galactic Center X-ray Emission with Point and Diffuse X-ray Sources
• 3D CMZ V: A new orbital model of our Galaxy's Center, informed by data across the electromagnetic spectrum
• High Energy Emission from the Galactic Center
• Diffuse gamma-ray emission from the Galactic center and implications of its past activities