An atlas of exotic variability in IGR J17091−3624: a comparison with GRS 1915+105

Abstract

We performed an analysis of all RXTE observations of the Low Mass X-ray Binary and Black Hole Candidate IGR J17091-3624 during the 2011-2013 outburst of the source. By creating lightcurves, hardness-intensity diagrams and power density spectra of each observation, we have created a set of 9 variability 'classes' that phenomenologically describe the range of types of variability seen in this object. We compare our set of variability classes to those established by Belloni et al. (2000) to describe the similar behaviour of the LMXB GRS 1915+105, finding that some types of variability seen in IGR J17091-3624 are not represented in data of GRS 1915+105. We also use all available X-ray data of the 2011-2013 outburst of IGR J17091-3624 to analyse its longterm evolution, presenting the first detection of IGR J17091-3624 above 150 keV as well as noting the presence of 're-flares' during the latter stages of the outburst. Using our results we place new constraints on the mass and distance of the object, and find that it accretes at 33% of its Eddington limit. As such, we conclude that Eddingtonlimited accretion can no longer be considered a sufficient or necessary criterion for GRS 1915+105-like variability to occur in Low Mass X-Ray Binaries.

Correlating the non-linear time series and spectral properties of IGR J17091–3624: is it similar to GRS 1915+105?

“…In our probe of the properties of IGR J17091-3624 during its 2011-2013 outburst, we follow closely the classification described in Court et al (2017)…”

“…The data we use in our analysis were obtained during the 2011 − 2013 outburst of IGR J17091-3624 from RXTE, XMM-Newton and Chandra. To allow for easy and efficient cross verification, we use the same data reported by Court et al (2017). In all cases, we use single orbit data for each observation ID (ObsID).…”

“…We consider the energy range 0.5 − 8.0 keV for spectral analysis. ObsID 0677980201 has been categorised Class IV variability properties by Court et al (2017). The second observation (ObsID: 070038130) was carried out after decommissioning RXTE and, hence, cannot be compared with RXTE data.…”

“…We consider the energy range 0.5 − 8.0 keV for spectral analysis. According to Court et al (2017), ObsID 12405 resembles a Class VII lightcurve. ObsID 12406 on the other hand is considered to show properties similar to those seen in Class IX.…”

“…The colour values provide a straight-forward and non-subjective way to track spectral evolution. Court et al 2017 probed loop directions in the HID of IGR J17091-3624. The CD in the left panel of Fig.…”