Repeated X-ray Flaring Activity in Sagittarius A*

Abstract

Investigating the spectral and temporal characteristics of the X-rays coming from Sagittarius A* (Sgr A*) is essential to our development of a more complete understanding of the emission mechanisms in this supermassive black hole located at the center of our Galaxy. Several X-ray flares with varying durations and spectral features have already been observed from this object. Here we present the results of two long XMM-Newton observations of the Galactic nucleus carried out in 2004, for a total exposure time of nearly 500 ks. During these observations we detected two flares from Sgr A* with peak 2-10 keV luminosities about 40 times (L ~ 9x10^34 erg s−1) above the quiescent luminosity: one on 2004 March 31 and another on 2004 August 31. The first flare lasted about 2.5 ks and the second about 5 ks. The combined fit on the Epic spectra yield photon indeces of about 1.5 and 1.9 for the first and second flare respectively. This hard photon index strongly suggests the presence of an important population of non-thermal electrons during the event and supports the view that the majority of flaring events tend to be hard and not very luminous.

8 pages, 7 figures, Accepted for publication in the Astrophysical Journal

References in corpus (21)

• Chandra X-ray Spectroscopic Imaging of Sgr A* and the Central Parsec of the Galaxy
• The First Measurement of Spectral Lines in a Short-Period Star Bound to the Galaxy's Central Black Hole: A Paradox of Youth
• Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A*
• Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre
• Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre
• The Supermassive Black Hole at the Galactic Center
• Stellar dynamics in the central arcsecond of our galaxy
• The Nature of the 10 Kilosecond X-ray Flare in Sgr A*
• XMM-Newton observation of the brightest X-ray flare detected so far from SgrA*
• A Deep Chandra Catalog of X-ray Point Sources toward the Galactic Center
• On The Nature of the Variable Infrared Emission from Sgr A*
• First Simultaneous NIR/X-ray Detection of a Flare from SgrA*
• An Overabundance of Transient X-ray Binaries within 1 pc of the Galactic Center
• X-ray flares reveal mass and angular momentum of the Galactic Center black hole
• A New X-Ray Flare from the Galactic Nucleus Detected with the XMM-Newton Photon Imaging Cameras
• An Accretion-Induced X-ray Flare in Sgr A*
• Electron Acceleration around the Supermassive Black Hole at the Galactic Center
• A Remarkable Low-Mass X-ray Binary within 0.1 pc of the Galactic Center
• New Constraints on the Nature of Radio Emission in Sagittarius A*
• A Radio Transient 0.1 pc from Sagittarius A*
• The Position of Sgr A${}^{\ast }$ at the Galactic Center

Cited by in corpus (50)

• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• WATCHDOG: A Comprehensive All-Sky Database of Galactic Black Hole X-ray Binaries
• Radiative Models of Sgr A* from GRMHD Simulations
• An X-ray, IR, and Submillimeter Flare of Sagittarius A*
• Polarimetry of near-infrared flares from Sagittarius A*
• A Chandra/HETGS Census of X-ray Variability From Sgr A* During 2012
• Chandra-HETGS Observations of the Brightest Flare Seen from Sgr A*
• A Multi-Wavelength Study of Sgr A*: The Role of Near-IR Flares in Production of X-ray, Soft $\gamma$-ray and Sub-millimeter Emission
• A near-IR variability study of the Galactic black hole: a red noise source with no detected periodicity
• A Constant Spectral Index for Sagittarius A* During Infrared/X-ray Intensity Variations
• X-ray hiccups from SgrA* observed by XMM-Newton. The second brightest flare and three moderate flares caught in half a day
• A powerful flare from Sgr A* confirms the synchrotron nature of the X-ray emission
• The Flare Activity of SgrA*; New Coordinated mm to X-Ray Observations
• A polarised infrared flare from Sagittarius A* and the signatures of orbiting plasma hotspots
• The XMM-Newton view of the central degrees of the Milky Way
• Simultaneous Chandra, CSO and VLA Observations of Sgr A*: The Nature of Flaring Activity
• Simultaneous Multi-Wavelength Observations of Sgr A* during 2007 April 1-11
• How to hide large scale outflows: size constraints on the jets of Sgr A*
• Fifteen years of XMM-Newton and Chandra monitoring of Sgr A*: Evidence for a recent increase in the bright flaring rate
• NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A* flares
• A Persistent High-Energy Flux from the Heart of the Milky Way : Integral's view of the Galactic Center
• Stochastic Electron Acceleration During the NIR and X-ray Flares in Sagittarius A*
• A 600 minute near-infrared lightcurve of Sagittarius A*
• Concurrent X-ray, near-infrared, sub-millimeter, and GeV gamma-ray observations of Sgr A*
• Stochastic Acceleration in the Galactic Center HESS Source
• The X-ray Flux Distribution of Sagittarius A* as Seen by Chandra
• The X-ray flaring properties of Sgr A* during six years of monitoring with Swift
• Chandra Spectral and Timing Analysis of Sgr A*'s Brightest X-ray Flares
• The pattern of accretion flow onto Sgr A*
• Periodic Modulations in an X-ray Flare from Sagittarius A*
• A power-law break in the near-infrared power spectrum of the Galactic center black hole
• Self-consistent spectra from radiative GRMHD simulations of accretion onto Sgr A*
• A Testable the Stochastic Acceleration Model for Flares in Sagittarius A*
• Statistics of X-ray flares of Sagittarius A*: evidence for solar-like self-organized criticality phenomenon
• Exploring plasma evolution during Sagittarius A* flares
• Multiwavelength Light Curves of Two Remarkable Sagittarius A* Flares
• A Systematic Chandra study of Sgr A${}^{\star }$: I. X-ray flare detection
• A magnetohydrodynamic model for multi-wavelength flares from Sagittarius~A${}^{\star }$ (I): model and the near-infrared and X-ray flares
• Sixteen years of X-ray monitoring of Sagittarius A*: Evidence for a decay of the faint flaring rate from 2013 August, 13 months before a rise in the bright flaring rate
• Accretion of Low Angular Momentum Material onto Black Holes: Radiation Properties of Axisymmetric MHD Flows
• No sign of G2's encounter affecting Sgr A*'s X-ray flaring rate from $Chandra$ observations
• A Systematic Chandra study of Sgr A${}^{\star }$: II. X-ray flare statistics
• MC Simulations of the Broadband Spectra of Sagittarius A* through the use of GRMHD
• Soft gamma-ray constraints on a bright flare from the Galactic Center supermassive black hole
• Astrophysics in 2006
• Modulated X-ray Emissivity near the Stress Edge in Sgr A*
• High Energy Activity of the Super-Massive Black Hole at the Galactic Center
• Flares from spiral waves by lensing and time-delay amplification?
• Polarimetric Imaging of Sgr A* in its Flaring State
• High Energy Emission from the Galactic Center