Comptonizing Efficiencies of IGR 17091-3624 and its similarity to GRS 1915+105

TL;DR

This study compares the Comptonizing Efficiency of IGR 17091-3624 with GRS 1915+105, revealing similar variability class characteristics that are independent of black hole mass, based on the scaling of source sizes.

Contribution

The paper demonstrates that Comptonizing Efficiency is a mass-independent parameter for classifying variability in black hole candidates, supported by comparative analysis of two sources.

Findings

CE similarity between IGR 17091-3624 and GRS 1915+105

CE scaling with black hole mass

Variability classification based on CE is mass-independent

Abstract

Variability classes in the enigmatic black hole candidate GRS 1915+105 are known to be correlated with the variation of the Comptonizing Efficiency (CE) which is defined to be the ratio between the number of power-law (hard) photons and seed (soft) photons injected into the Compton cloud. Similarities of light curves of several variability classes of GRS 1915+105 and IGR 17091-3624, some of which are already reported in the literature, motivated us to compute CE for IGR 17091-3624 as well. We find that they are similar to what were reported earlier for GRS 1915+105, even though masses of these objects could be different. The reason is that the both the sizes of the sources of the seed photons and of the Comptonizing corona scale in the same way as the mass of the black hole. This indicates that characterization of variability classes based on CE is likely to be black hole mass independent, in general.