NICER and Swift Detect the Black Hole Candidate IGR J17091-3624 in Outburst
ATel #15282; J. M. Miller, P. Draghis (Univ. Michigan), K. Gendreau, Z. Arzoumanian (NASA/GSFC)
on 16 Mar 2022; 14:07 UT
Credential Certification: Jon Miller (jonmm@umich.edu)
Subjects: X-ray, Request for Observations, Binary, Black Hole, Transient
The stellar-mass black hole candidate IGR J17091-3624 is notable for its striking similarities to GRS 1915+105, and its numerous, distinctive, multi-wavelength variability states (e.g., Court et al. 2017).
Monitoring with the Neil Gehrels Swift/BAT suggests that IGR J17091-3264 is now in outburst:
https://swift.gsfc.nasa.gov/results/transients/weak/IGRJ17091-3624/
A follow-up observation with NICER started on 14 March 2022 at 16:32:20 (UT). The first exposure was 1.3 ks in duration. The spectrum can be described using an absorbed power-law model: N_H = 1.25(1) E+22 cm^-2, Gamma = 1.46(1), Norm = 0.146(2). The 0.3-10.0 keV absorbed flux was measured to be F = 9.0(1) E-10 erg/cm2/s.
Additional NICER exposures suggest complex emission and absorption in the Fe K band that may be consistent with prior reports of a disk wind (e.g., King et al. 2012), and evidence of transient QPO-like variability. NICER will continue to monitor the source as visibility windows permit.
Observations at all wavelengths, but especially in radio, are encouraged.
Court, J. M. C., et al., 2017, MNRAS, 468, 4748
King, A., et al., 2012, ApJ, 746, L20
