Accretion flow dynamics of MAXI J1836-194 during its 2011 outburst from TCAF solution

Arghajit Jana, Dipak Debnath, Sandip K. Chakrabarti, Santanu Mondal, Aslam Ali Molla

Published 2016-01-09Version 1

The Galactic transient X-ray binary MAXI J1836-194 was discovered on 29th Aug. 2011. Here we make a detailed study of the spectral and timing properties of its 2011 outburst using archival data of RXTE Proportional Counter Array instrument. The evolution of accretion flow dynamics of the source during the outburst through spectral analysis with Chakrabarti-Titarchuk's two-component advective flow (TCAF) solution as a local table model in XSPEC. We also fitted spectra with combined disk blackbody and power-law models and compare it with that of the TCAF model fitted results. The source is found to be in hard and hard-intermediate spectral states only during entire phase of this outburst. No soft and soft-intermediate spectral states are observed. This could be due to the fact that this object belongs to a special class of sources (with, e.g., MAXI J1659-152, Swift J1753.5-0127, etc.) having very short orbital periods and the companion is profusely mass losing or the disk is immersed inside an excretion disk. In these cases, flows in the accretion disk is primarily dominated by low viscous sub-Keplerian flow and the Keplerian rate is not high enough to initiate softer states. Low frequency quasi-periodic oscillations (QPOs) are observed sporadically, although as in normal outbursts of transient black holes, monotonic evolutions of QPO frequency during both rising and declining phases are observed.