X-ray Flare from the Galactic Center Detected by Swift/XRT
ATel #16785; Mark Reynolds (Ohio State University/University of Michigan), Jon Miller (University of Michigan), Nathalie Degenaar (University of Amsterdam), Rudy Wijnands (University of Amsterdam), Jamie Kennea (Penn State University) on behalf of a larger collaboration.
on 22 Aug 2024; 14:00 UT
Credential Certification: Mark Reynolds ([email protected])
Subjects: Radio, Infra-Red, X-ray, AGN, Black Hole, Transient
We report the detection of an X-ray flare during regular monitoring observations of the
Galactic center with the Neil Gehrels Swift observatory (Degenaar+ 2015). In a 0.89 ks XRT
observation on 2024-08-21 (09:13UT), a flare is detected originating from the direction of Sgr A*.
The source is observed with a net count rate of 0.053+/-0.008 ct/s resulting in a total of 52 counts
detected during the observation. Assuming a fixed column density of 9.1e22 cm^-2 (Degenaar+ 2013) and fitting with a power-law in the 2 - 10 keV bandpass, we measure Gamma = 1.10 +/- 0.47
(68% confidence) resulting in an absorbed flux of fx = (1.55 -1.03 +0.06)e-11 erg/s/cm^2 (2-10 keV, 68% conf.), or a luminosity of ~ 1.2e35 erg/s for an assumed distance of 8 kpc. A subsequent observation ~ 80 ks later shows the flux from this region to have returned to background levels.
The position of the source of this flare is nominally consistent with the position of Sgr A*. Swift
monitoring of the GC region continues and additional significant activity will be reported in
subsequent telegrams.
Our daily Swift X-ray monitoring campaign of the Galactic center will continue throughout
2024. Updates on new observations are immediately posted at the Swift Sgr A* Monitoring Campaign
Website (http://swift-sgra.com/)
References:
Degenaar et al. 2013, ApJ 769, 155
Degenaar et al. 2015, JHEA 7, 137
Swift Sgr A* Monitoring Campaign Website
