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D. Altamirano et al. 2011 ApJ 742 L17 doi:10.1088/2041-8205/742/2/L17
D. Altamirano1, T. Belloni2, M. Linares3, M. van der Klis1, R. Wijnands1, P. A. Curran4, M. Kalamkar1, H. Stiele2, S. Motta2, T. Muñoz-Darias2,5, P. Casella6, and H. Krimm7,8
Show affiliationsWe report on the first 180 days of Rossi X-Ray Timing Explorer observations of the outburst of the black hole candidate IGR J17091-3624. This source exhibits a broad variety of complex light curve patterns including periods of strong flares alternating with quiet intervals. Similar patterns in the X-ray light curves have been seen in the (up to now) unique black hole system GRS 1915+105. In the context of the variability classes defined by Belloni et al. for GRS 1915+105, we find that IGR J17091-3624 shows the ν, ρ, α, λ, β, and μ classes as well as quiet periods which resemble the χ class, all occurring at 2-60 keV count rate levels which can be 10-50 times lower than observed in GRS 1915+105. The so-called ρ class "heartbeats" occur as fast as every few seconds and as slow as ~100 s, tracing a loop in the hardness-intensity diagram which resembles that previously seen in GRS 1915+105. However, while GRS 1915+105 traverses this loop clockwise, IGR J17091-3624 does so in the opposite sense. We briefly discuss our findings in the context of the models proposed for GRS 1915+105 and find that either all models requiring near Eddington luminosities for GRS 1915+105-like variability fail, or IGR J17091-3624 lies at a distance well in excess of 20 kpc, or it harbors one of the least massive black holes known (<3 M ☉).
binaries: close; black hole physics; stars: individual (IGR J17091-3624, GRS 1915+105); X-rays: binaries
Issue 2 (2011 December 1)
Received 2011 September 12, accepted for publication 2011 October 12
Published 2011 November 4
Total article downloads: 630
D. Altamirano et al. 2011 ApJ 742 L17
