Possible evidence from the flaring activity of Sgr A* for a star at a distance of ~3.3 Schwarzscild radii from the blackhole

Abstract

The frequent flaring events in the X-ray and the NIR radiation of Sgr A* seem not to be periodic in time. However, statistical regularities, here termed "modulations by a pacemaker", are found in the recorded arrival times of both types of events. The characteristic time of the X-ray pacemaker is 149 min and that of the NIR pacemaker is 40 min. Their reality as derived from observed data can be accepted at larger than 4.6σ and 3.8σ levels of statistical confidence, respectively. These results can be interpreted as evidence for a star that revolves around the BH of Sgr A* in a slightly elliptical precessing orbit, at a distance of 3-3.5 Schwarzschild radii of the BH. The period of the X-ray pacemaker, which is not a periodicity of the flare occurrences themselves, is the epicyclic period of the star orbital motion. This is the time interval between 2 successive passages of the star through the peri-center of its orbit. The NIR pacemaker period is the sidereal binary period of the star revolution. The origin of the X-ray flares is in episodes of intense mass loss from the star that occur preferably near the pericenter phase of the binary revolution. The NIR flares originate or are triggered by processes that are internal to the star. The radiation emitted in the direction of Earth is slightly modulated by the changing aspect ratio of the two components of the BH\star binary to the line of sight from Earth at the sidereal binary frequency.

Minor corrections, matching published version

References in corpus (22)

• An Update on Monitoring Stellar Orbits in the Galactic Center
• An Improved Distance and Mass Estimate for Sgr A* from a Multistar Orbit Analysis
• Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243
• Revisited Mass-Radius relations for exoplanets below 120 Earth masses
• X-ray hiccups from SgrA* observed by XMM-Newton. The second brightest flare and three moderate flares caught in half a day
• GSN 069 -- A Tidal Disruption Near-Miss
• Time Dependent Models of Flares from Sagittarius A*
• Investigating the Relativistic Motion of the Stars Near the Supermassive Black Hole in the Galactic Center
• Polarized NIR and X-ray Flares from SgrA*
• NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A* flares
• Simultaneous NIR/sub-mm observation of flare emission from SgrA*
• Polarized light from Sgr A* in the near-infrared $K_s$-band
• A power-law break in the near-infrared power spectrum of the Galactic center black hole
• Spectroscopic Detection of a Cusp of Late-type Stars around the Central Black Hole in the Milky Way
• Spitzer/IRAC Observations of the Variability of Sgr A* and the Object G2 at 4.5 microns
• Coordinated NIR/mm observations of flare emission from Sagittarius A*
• Sagittarius A* High Energy X-ray Flare Properties During NuSTAR Monitoring of the Galactic Center from 2012 to 2015
• ALMA Detection of Bipolar Outflows: Evidence for Low Mass Star Formation within 1pc of Sgr A*
• Flares and variability from Sagittarius A*: five nights of simultaneous multi-wavelength observations
• Photometric Flaring Fraction of M dwarf Stars from the SkyMapper Southern Survey
• A 149 minute periodicity underlies the X-ray flaring of Sgr A*
• A Pacemaker with P=2.48 hour Modulated the Generator of Flares in the X-ray Light Curve of Sgr A* in the year 2012

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