2019ApJ...871..161B -
Astrophys. J., 871, 161-161 (2019/February-1)
Simultaneous X-ray and infrared observations of Sagittarius A*'s variability.
BOYCE H., HAGGARD D., WITZEL G., WILLNER S.P., NEILSEN J., HORA J.L., MARKOFF S., PONTI G., BAGANOFF F., BECKLIN E.E., FAZIO G.G., LOWRANCE P., MORRIS M.R. and SMITH H.A.
Abstract (from CDS):
Emission from Saggitarius A* is highly variable at both X-ray and infrared (IR) wavelengths. Observations over the last ∼20 yr have revealed X-ray flares that rise above a quiescent thermal background about once per day, while faint X-ray flares from Sgr A* are undetectable below the constant thermal emission. In contrast, the IR emission of Sgr A* is observed to be continuously variable. Recently, simultaneous observations have indicated a rise in IR flux density around the same time as every distinct X-ray flare, while the opposite is not always true (peaks in the IR emission may not be coincident with an X-ray flare). Characterizing the behavior of these simultaneous X-ray/IR events and measuring any time lag between them can constrain models of Sgr A*'s accretion flow and the flare emission mechanism. Using 100+ hours of data from a coordinated campaign between the Spitzer Space Telescope and the Chandra X-ray Observatory, we present results of the longest simultaneous IR and X-ray observations of Sgr A* taken to date. The cross-correlation between the IR and X-ray light curves in this unprecedented data set, which includes four modest X-ray/IR flares, indicates that flaring in the X-ray may lead the IR by approximately 10-20 min with 68% confidence. However, the 99.7% confidence interval on the time-lag also includes zero, i.e., the flaring remains statistically consistent with simultaneity. Long-duration and simultaneous multi-wavelength observations of additional bright flares will improve our ability to constrain the flare timing characteristics and emission mechanisms, and must be a priority for Galactic Center observing campaigns.
Abstract Copyright:
© 2019. The American Astronomical Society. All rights reserved.
Journal keyword(s):
accretion, accretion disks - black hole physics - Galaxy: center - radiation mechanisms: non-thermal
Errata:
erratum vol. 912, art. 168 (2021)
Simbad objects:
3
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