AC1 - Spectral and Temporal properties of Black Holes and neutron stars and the theoretical models |
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Speaker |
Lubinski, Piotr |
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| Talk Title |
New Insights Into The Plasma Region Near Black Holes From Hard X-ray Observations |
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Abstract |
The properties of the plasma residing in the centre of the black hole accreting system remain an open question despite several decades of observational and theoretical efforts. Since the plasma is emitting mainly in the hard X-ray/soft gamma-ray band, the INTEGRAL satellite operating in that band is currently one of the best tools for a direct diagnosis of the plasma properties. In this talk a review of the results of two examples of such studies will be presented. The first study is based on data collected during 16 years of monitoring of the Cyg X-1 emission. This huge data set allowed us to get more insights into the geometry of the plasma region in different spectral states of the object. In particular, we identify some substates of the hard state and make a deeper diagnosis of the state transitions. In addition, we provide new information on the plasma behaviour during the jet emission, using contemporary radio observations. The second study is based on data taken by the INTEGRAL satellite during the outburst of transient black hole system, V404 Cygni, in 2015. This was the brightest event observed by INTEGRAL and brought a lot of new information on the system evolution during the outburst. The results of detailed spectral analysis will be presented. We will show that a single Componization component, purely thermal or hybrid, is not sufficient to explain the hard X-ray emission during a strong radio emission period. We will also present new results on the presence of the positron annihilation feature in the V404 Cygni spectra. |
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