Evolution of spectral and temporal properties of MAXI~J1836-194 during 2011 outburst. (arXiv:1812.01918v1 [astro-ph.HE])

Evolution of spectral and temporal properties of MAXI~J1836-194 during 2011 outburst. (arXiv:1812.01918v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Jana_A/0/1/0/all/0/1">Arghajit Jana</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Debnath_D/0/1/0/all/0/1">Dipak Debnath</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chakrabarti_S/0/1/0/all/0/1">Sandip K. Chakrabarti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mondal_S/0/1/0/all/0/1">Santanu Mondal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Molla_A/0/1/0/all/0/1">Aslam Ali Molla</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chatterjee_D/0/1/0/all/0/1">Debjit Chatterjee</a>

We study transient Galatic black hole candidate MAXI~J1836-194 during its
2011 outburst using RXTE/PCA archival data. 2.5-25~keV spectra are fitted with
Two Component Advective Flow (TCAF) model fits file as an additive table local
model in XSPEC. From TCAF model spectral fits, physical parameters such as
Keplerian disk rate, sub-Keplerian halo rate, shock location and compression
ratio are extracted directly for better understanding of accretion processes
around the BHC during this outburst. Low frequency quasi-periodic oscillation
(QPO) are observed sporadically during the entire epoch of the outburst, with a
general trend of increasing frequency during rising and decreasing frequency
during declining phases of the outburst, as in other transient BHCs. The nature
of the variation of the accretion rate ratio (ratio of halo and disk rates) and
QPOs (if observed), allows us to properly classify entire epoch of the outburst
into following two spectral state, such as hard (HS), hard-intermediate (HIMS).
These states are observed in the sequence of HS (Ris.) $rightarrow$ HIMS
(Ris.) $rightarrow$ HIMS (Dec.) $rightarrow$ HS (Dec.). This outburst of
MAXI~J1836-194 could be termed as `failed’ outburst, since no observation of
soft (SS) and soft-intermediate (SIMS) spectral state are found during the
entire outburst.

We study transient Galatic black hole candidate MAXI~J1836-194 during its
2011 outburst using RXTE/PCA archival data. 2.5-25~keV spectra are fitted with
Two Component Advective Flow (TCAF) model fits file as an additive table local
model in XSPEC. From TCAF model spectral fits, physical parameters such as
Keplerian disk rate, sub-Keplerian halo rate, shock location and compression
ratio are extracted directly for better understanding of accretion processes
around the BHC during this outburst. Low frequency quasi-periodic oscillation
(QPO) are observed sporadically during the entire epoch of the outburst, with a
general trend of increasing frequency during rising and decreasing frequency
during declining phases of the outburst, as in other transient BHCs. The nature
of the variation of the accretion rate ratio (ratio of halo and disk rates) and
QPOs (if observed), allows us to properly classify entire epoch of the outburst
into following two spectral state, such as hard (HS), hard-intermediate (HIMS).
These states are observed in the sequence of HS (Ris.) $rightarrow$ HIMS
(Ris.) $rightarrow$ HIMS (Dec.) $rightarrow$ HS (Dec.). This outburst of
MAXI~J1836-194 could be termed as `failed’ outburst, since no observation of
soft (SS) and soft-intermediate (SIMS) spectral state are found during the
entire outburst.

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