9,161 research outputs found
Evidence of Class Transitions in GRS 1915+105 from IXAE Data
GRS 1915+105 shows at least twelve distinct classes of light curves. By
analysing the data obtained from Indian X-ray Astronomy Experiment (IXAE)
instrument aboard IRS-P3 satellite, we show that in at least two days,
transitions between one class to another were observed. In these days the
so-called class went to class and class went to
class. In the frequency-time plane such transitions exhibited change in
quasi-periodic oscillation (QPO) frequency. We could detect that low-frequency
QPOs can occur in anticipation of a class transition several hundred minutes
before the actual transitionComment: 14 pages, 3 figures, Astrophysical Journa
Determination of mass of IGR J17091-3624 from "Spectro-Temporal" variations during onset-phase of the 2011 outburst
The 2011 outburst of the black hole candidate IGR J17091-3624 followed the
canonical track of state transitions along with the evolution of Quasi-Periodic
Oscillation (QPO) frequencies before it began exhibiting various variability
classes similar to GRS 1915+105. We use this canonical evolution of spectral
and temporal properties to determine the mass of IGR J17091-3624, using three
different methods, viz : Photon Index () - QPO frequency ()
correlation, QPO frequency () - Time (day) evolution and broadband
spectral modelling based on Two Component Advective Flow. We provide a combined
mass estimate for the source using a Naive Bayes based joint likelihood
approach. This gives a probable mass range of 11.8 M - 13.7
M. Considering each individual estimate and taking the lowermost and
uppermost bounds among all three methods, we get a mass range of 8.7
M - 15.6 M with 90% confidence. We discuss the probable
implications of our findings in the context of two component accretion flow.Comment: 10 pages, 5 figures (4 in colour), 2 tables. Accepted for publication
in Ap
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