Renewed Activity in the Galactic Black Hole IGR J17091-3624
ATel #8742; J. M. Miller, M. Reynolds (Michigan), J. Kennea (Swift/PSU), A. L. King (Stanford), J. Tomsick (UC Berkeley)
on 26 Feb 2016; 18:55 UT
Credential Certification: Jon Miller (jonmm@umich.edu)
Subjects: X-ray, Binary, Black Hole, Transient
IGR J17091-3624 is a remarkable black hole transient. It displays the
rich set of peculiar "states" and X-ray QPOs observed in GRS 1915+105
(Altamirano et al. 2011, Altamirano & Belloni 2012). High-resolution
X-ray spectroscopy has revealed an ultra-fast disk wind (0.03-0.05c,
King et al. 2012).
Following a steady rise in the Swift/BAT, we requested a 1 ks snapshot
with the XRT. The observation started on 2016 Feb. 26 at 00:44:39 UT.
The source is strongly detected, with nearly 1300 photons accumulated
in 0.98 ks. The "photon counting" mode spectrum is piled-up (and weak
mirror arcs from a nearby source affect the image in a minor way).
A power-law as hard as Gamma = 1.3-1.4 is a reasonable fit to the XRT
spectrum and suggests a flux of approximately 2 E-10 erg/cm^2/s
(0.3-10.0 keV).
Observations in all bands are encouraged.
We thank the Swift PI and team for quickly observing IGR J17091-3624.
Altamirano, D., et al., 2011, ApJ, 742, L17
Altamirano, D., Belloni, T., 2012, ApJ, 747, L4
King, A. L., et al., 2012, 746, L20
