Probable Dust Scattering Rings from Flaring in the Black Hole GRS 1915+105
ATel #15976; J. M. Miller, P. A. Draghis, M. C. Brumback, D. Bogensberger, M. Reynolds, X. Xiang (Univ. Michigan); A. Beardmore (Univ. of Leicester)
on 3 Apr 2023; 21:17 UT
Credential Certification: Jon Miller (jonmm@umich.edu)
Subjects: X-ray, Transient
Recently, the Neil Gehrels Swift Observatory BAT detected strong flaring in the stellar-mass black hole GRS 1915+105 (atel #15964, atel #15968). This black hole is known to lie behind a relatively large foreground column density of N_H = 4.0 E+22 cm^-2 [1]. The combination of these flares and column density created the possibility that dust scattering rings could be observed, similar to the case of V404 Cyg [2]. We therefore requested a series of short imaging observations with the Swift/XRT.
In OBSID 0012178135, which started on 2023 April 1 at 23:32:37, there is evidence of dust scattering rings in the full band image, at an angular radius of 75+/-15 arc seconds, corresponding to a radius of 3.13 +/- 0.91 pc [3]. Several flares have recently been observed from GRS 1915+105, so it is possible that this structure actually represents a series of dust rings. Alternatively, or additionally, the flares are not as sharp as a typical gamma-ray burst, and this could serve to create less distinctive features.
A full analysis is underway, but a flare light curve and initial dust ring image can be seen here:
https://sites.lsa.umich.edu/jonmm/2023/04/03/386/
https://sites.lsa.umich.edu/jonmm/2023/04/02/383/
We thank the Swift team for quickly executing these observations.
[1] Miller, J. M., et al., 2016, ApJ, 821, L9
[2] Heinz, S., et al., 2016, ApJ, 825,15
[3] Reid, M. J., et al., 2014, ApJ, 796, 2R
