Spectral and Temporal Properties of MAXI J1836-194 during 2011 Outburst

TL;DR

This study analyzes the 2011 outburst of black hole candidate MAXI J1836-194 using spectral modeling to understand accretion flow properties and state transitions, revealing unique spectral state behavior.

Contribution

It applies the TCAF model to RXTE data to extract accretion parameters and classifies the spectral states based on accretion rate ratios and QPOs, highlighting differences from typical BHC outbursts.

Findings

Spectral states identified as hard and hard-intermediate only.

No soft or soft-intermediate states observed during the outburst.

Quasi-periodic oscillations appeared sporadically.

Abstract

We study black hole candidate (BHC) MAXI~J1836-194 during its 2011 outburst with Two Component Advective Flow (TCAF) model using RXTE/PCU2 data in $2.5-25$~keV band. From spectral fit, accretion flow parameters such as Keplerian disk rate ($\dot{m_d}$), sub-Keplerian halo rate ($\dot{m_h}$), shock location ($X_{s}$) and compression ratio (R) are extracted directly. During the entire phase of the outburst, quasi-periodic oscillations (QPOs) are observed sporadically. From the nature of the variation of accretion rate ratio (ARR=$\dot{m_h}$ / $\dot{m_d}$) and QPOs, entire period of the outburst is classified in two spectral states, such as, hard (HS), hard-intermediate (HIMS). Unlike other transient BHCs, no signature of soft (SS) and soft-intermediate (SIMS) spectral states are observed during entire phase of the outburst