MG12 - Talk detail
 

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 Participant 

Institution

Session

Talk

Abstract

Two temperature accretion flows around rotating black holes and determining the Kerr parameter of sources

We model two temperature viscous accretion flows in the sub-Keplerian regime around rotating black holes. The model successfully explains observed luminosities from ultra- to under-luminous sources and predicts the spin frequency of black holes.

Lorentz symmetry violation in neutrinos in curved spacetime and its consequences

The neutrino propagating in curved spacetimes, e.g. around black holes, in early curved universe, violates Lorentz and then CPT symmetry, at least in the local coordinate. In this talk, first I will recall, based on my works in last seven years, how do the Lorentz and CPT violation arise through Dirac equation in curved spacetime: it is due to coupling of spin of the neutrino to background spin connection. Then I will address the modified dispersion relation and how does the neutrino asymmetry arise and then neutrino oscillation probability get affected as a consequence of this.

Kilo Hertz QPOs in LMXBs and determing spin of Sco X-1

We show that multiple properties of kHz QPOs observed from LMXBs are possible to explain by a unified model, considering the accretion flow to be a forced oscillator. The model successfully explains properties of QPOs observed from six neutron stars and four black holes; hence unified. From the best observational fit, we argue that Sco X-1 may be a slow rotator of spin frequency ~300Hz.

Chaos in black hole and neutron star systems: based on satellite data from LMXBs

The accretion disk around a compact object is a nonlinear general relativistic system involving magnetohydrodynamics. Naturally the question arises whether such a system is chaotic (deterministic) or stochastic (random) which might be related to the associated transport properties whose origin is still not confirmed yet. By computing correlation dimension based on observed data, we show that the black hole system GRS 1915+105 behaves as a low dimensional chaos in certain temporal classes. We also show that neutron stars, which are unique for their kHz QPOs arised presumably from nonlinear mechanisms around them, such that Sco X-1, Cyg X-2 are low dimensional chaotic systems. Based on our analysis, we argue that Cyg X-3 may be a neutron star.

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