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Speaker |
Debnath, Dipak |
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Coauthors |
S. K. Chakrabarti, S. Mondal, A. A. Molla, A. Jana, D. Chatterjee |
| Talk Title |
Possible ASTROSAT observation of transient black hole candidates to study spectral and timing properties of these objects with TCAF Solution |
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Abstract |
ASTROSAT is India's first multi-wavelength astronomy satellite, will be launched in the last quarter of 2015. It can be used to study astronomical objects in a wide range of electromagnetic energy band from UV to hard X-rays. With a very high spectral, timing as well as spacial resolutions from different scientific instruments of the satellite, one can make a detailed spectral and timing study of transient black hole candidates (BHCs) during their outbursts. Recently, we have included Chakrabarti-Titarchuk (1995) Two-Component Advective Flow (TCAF) model in HEASARC's spectral analysis package XSPEC as a local additive table model to fit black hole with the model, and we found that it is quite capable to explain both the spectral and temporal properties of BHCs very successfully. From our spectral fits with TCAF, one can directly extract physical flow parameters, such as two types of accretion (Keplerian disk and sub-Keplerian halo) rates and shock parameters (location and strength of the shock). From shock parameters, one can also predict frequency of primary dominating quasi-periodic oscillations (QPOs). Based on a comparison of halo to disk accretion rate ratio (ARR) along with the nature of QPOs (if present), we are able to provide a physical understanding of the classification of the entire outburst phase of the BHCs into different spectral states (such as, hard, hard-intermediate, soft-intermediate, and soft, etc). Multi-wavelength data of ASTROSAT will provide us a platform to understand spectral as well as temporal variability of transient BHCs in a better sense with spectral fits using TCAF. |
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