Tuesday, June 18, 2013

1306.3745 (Dipak Debnath et al.)

Characterization of GX 339-4 outburst of 2010-11: Analysis by XSPEC using Two Component Advective Flow model    [PDF]

Dipak Debnath, Santanu Mondal, Sandip K. Chakrabarti
We study the spectral properties of the Galactic transient black hole candidate (BHC) GX 339-4 during its 2010-11 outburst with Two Component (Keplerian and sub-Keplerian) Advective Flow (TCAF) model after its inclusion in XSPEC as a local model. We also compare our TCAF model fitted results with combined disk black body (DBB) and power-law (PL) model fitted spectral results and find similar types of smooth variation in thermal (Keplerian or disk black body) as well as non-thermal (power-law or sub-Keplerian) fluxes. For spectral fit, we use 2.5-25 keV spectral data of PCA instrument onboard RXTE satellite. From the TCAF model fit, accretion flow parameters, such as the Keplerian (disk) rate, sub-Keplerian (halo) rate, location of the shock and strength of the shock are extracted. Our study provides a comprehensive understanding of the mass accretion processes and properties of the accretion disk around the BHC during the outburst phases. Based on the comparison of the halo to disk accretion rate ratio (ARR) with the presence or absence of the quasi-periodic oscillations (QPOs), we have classified the entire outburst into four different spectral states, such as, hard, hard-intermediate, soft-intermediate, and soft. We also found that these spectral states form a hysteresis loop in the sequence: hard -> hard-intermediate -> soft-intermediate -> soft -> soft-intermediate -> hard-intermediate -> hard. We discover onset of monotonically increasing/decreasing nature of QPO frequency during the rising/declining phases of the outburst always accompanies by sudden rise in ARR, i.e., in halo rates as compared to the disk rate. Interestingly, on the days of transition from the hard state to hard-intermediate spectral state (during the rising phase) or vise-versa (during declining phase), ARR is observed to be maximum.
View original: http://arxiv.org/abs/1306.3745

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