General Relativistic effects and the NIR variability of Sgr A* II: A systematic approach to temporal asymmetry
Journal
Date Issued
2024
Author(s)
von Fellenberg Sebastiano D.
•
Witzel Gunther
•
Bauboeck Michi
•
Chung Hui-Hsuan
•
•
Martinez Greg
•
Sadun-Bordoni Matteo
•
ourdarot Guillaume B
•
Do Tuan
•
Drescher Antonia
•
Fazio Giovanni
•
Eisenhauer Frank
•
Genzel Reinhard
•
Gillessen Stefan
•
Hora Joseph L.
•
Mang Felix
•
Ott Thomas
•
Smith Howard A.
•
Ros Eduardo
•
Ribeiro Diogo C.
•
Widmann Felix
•
Willner S. P.
•
Zensus J. Anton
Abstract
A systematic study, based on the third-moment structure function, of Sgr A*'s
variability finds an exponential rise time
$\tau_{1,\rm{obs}}=14.8^{+0.4}_{-1.5}~\mathrm{minutes}$ and decay time
$\tau_{2,\rm{obs}}=13.1^{+1.3}_{-1.4}~\mathrm{minutes}$. This symmetry of the
flux-density variability is consistent with earlier work, and we interpret it
as caused by the dominance of Doppler boosting, as opposed to gravitational
lensing, in Sgr~A*'s light curve. A relativistic, semi-physical model of Sgr~A*
confirms an inclination angle $i<45$ degrees. The model also shows that the
emission of the intrinsic radiative process can have some asymmetry even though
the observed emission does not. The third-moment structure function, which is a
measure of the skewness of the light-curve increments, may be a useful summary
statistic in other contexts of astronomy because it senses only temporal
asymmetry, i.e., it averages to zero for any temporally symmetric signal.
Volume
688
Start page
L12
Issn Identifier
0004-6361
Ads BibCode
2024A&A...688L..12V
Rights
open.access
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