Witzel, G., Martinez, G., Willner, S. P., Becklin, E. E., Boyce, H., Do, T., Eckart, A., Fazio, G. G., Ghez, A., Gurwell, M. A., Haggard, D., Herrero-Illana, R., Hora, J. L., Li, Z., Liu, J., Marchili, N., Morris, Mark R., Smith, Howard A., Subroweit, M. and Zensus, J. A. (2021). Rapid Variability of Sgr A* across the Electromagnetic Spectrum. Astrophys. J., 917 (2). BRISTOL: IOP PUBLISHING LTD. ISSN 1538-4357

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Abstract

Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We have analyzed a comprehensive submillimeter (including new observations simultaneous with NIR monitoring), NIR, and 2-8 keV data set. Submillimeter variations tend to lag those in the NIR by similar to 30 minutes. An approximate Bayesian computation fit to the X-ray first-order structure function shows significantly less power at short timescales in the X-rays than in the NIR. Less X-ray variability at short timescales, combined with the observed NIR-X-ray correlations, means the variability can be described as the result of two strictly correlated stochastic processes, the X-ray process being the low-pass-filtered version of the NIR process. The NIR-X-ray linkage suggests a simple radiative model: a compact, self-absorbed synchrotron sphere with high-frequency cutoff close to NIR frequencies plus a synchrotron self-Compton scattering component at higher frequencies. This model, with parameters fit to the submillimeter, NIR, and X-ray structure functions, reproduces the observed flux densities at all wavelengths, the statistical properties of all light curves, and the time lags between bands. The fit also gives reasonable values for physical parameters such as magnetic flux density B approximate to 13 G, source size L approximate to 2.2R ( S ), and high-energy electron density n ( e ) approximate to 4 x 10(7) cm(-3). An animation illustrates typical light curves, and we make public the parameter chain of our Bayesian analysis, the model implementation, and the visualization code.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Witzel, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Martinez, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Willner, S. P.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Becklin, E. E.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Boyce, H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Do, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Eckart, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Fazio, G. G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ghez, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gurwell, M. A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Haggard, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Herrero-Illana, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hora, J. L.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Li, Z.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Liu, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Marchili, N.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Morris, Mark R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Smith, Howard A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Subroweit, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Zensus, J. A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-599243
DOI: 10.3847/1538-4357/ac0891
Journal or Publication Title: Astrophys. J.
Volume: 917
Number: 2
Date: 2021
Publisher: IOP PUBLISHING LTD
Place of Publication: BRISTOL
ISSN: 1538-4357
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
SUPERMASSIVE BLACK-HOLE; SIMULTANEOUS MULTIWAVELENGTH OBSERVATIONS; SIMULTANEOUS X-RAY; GALACTIC-CENTER; FLARING ACTIVITY; INFRARED FLARES; LIGHT CURVES; SAGITTARIUS; EMISSION; SUBMILLIMETERMultiple languages
Astronomy & AstrophysicsMultiple languages
URI: http://kups.ub.uni-koeln.de/id/eprint/59924

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