1. Radiative Transfer theory: Polarized line formation in solar and stellar atmospheres:

Advanced scattering theories to correctly interpret the observed spectro-polarimetric data: Rayleigh scattering on atomic bound states, frequency and angular correlations of light scattering on atoms, quantum interference phenomena between atomic states (like J-state and F-state interferences), isotope shift, lower level atomic polarization, etc.

Formulating the quantum and classical theory of light scattering on atomic or molecular model, developing numerical programs to compute the resulting scattering matrix, developing efficient iterative techniques to solve the concerned polarized radiative transfer equation including the scattering matrix.

Physical effects in the presence of arbitrary strength magnetic fields (covering Hanle to Zeeman to Paschen-Back effect regimes) and calculating scattering matrices in polarized radiative transfer theory to finally derive the
detailed structure of the vector magnetic field.

The techniques developed above have so far been applied for realistic modeling of polarized spectrum of the Sun.

2. Radiative Transfer Theory:  Go to Top

Reflection effect in close binaries, models of dust shells, line formation in solar atmospheres.

3. Pulsars:  Go to Top

Pulsar radio emission mechanism: (i) single particle emission and (ii) coherent plasma emission; aberration-retardation and polar cap current effects on the pulsar polarization profiles; estimation of radio emission altitudes in pulsar magnetosphere; generation of Micropulses and subpulses in pulsars; orthogonal Polarization modes in radio pulsars; drifting mechanism in pulsars.

4. Exoplanets:  Go to Top

Detection methods for Exoplanets around ultra-cool dwarfs, exo-moons around self-luminous exoplanets, characterisation and habitability of exoplanets, polarization of Brown Dwarfs and Exoplanets.

5. Astrophysical turbulence and magnetic fields:  Go to Top

Understanding non-linear dynamo saturation of magnetic fields in galaxies and clusters by simulations; when, where and how galaxy outflows are launched and, estimation of observable parameters of turbulence and cosmic magnetic fields in the light of upcoming radio telescopes. Developing state of the art numerical algorithms for simulating highly compressible three-dimensional MHD turbulence and low beta plasmas. Problems in passive scalar mixing in magnetized plasmas and the evolution of magnetic fields during primordial star formation.

6. MHD Theory:  Go to Top

Dynamo theory, solutions to the Grad Shafranov equation, Force- free magnetic fields, Topological properties such as magnetic helicity, winding numbers, braiding and reconnection theory.

7. Solar plasmas:  Go to Top

Generation and evolution of magnetic structures on the solar photosphere; Hall effect; ambipolar diffusion and Ohmic dissipation

8. Cosmology: Dark matter, Dark energy and nuetrinos:  Go to Top

Dark matter candidates beyond WIMP (like warm dark matter, axion dark matter) which have imprints in cosmological structure formation and are of interest both in particle physics and cosmology; they can change the re-ionization observables and can be constrained from CMB spectral distortion.

Another major component of our Universe is dark energy whose nature is a complete mystery. One possible candidate for it is cosmological constant but there is no good theoretical explanation for its very tiny observed magnitude as compared to its predicted theoretical value. Though CMB and other experiments prefer cosmological constant over other dynamical dark energy models, it is a possibility that dynamical dark energy could be present in nature and its signature can be found in high redshift dark energy surveys.

The neutrino is the only known particle whose mass is comparable to the present dark matter density. There has been lot of work connecting neutrino and dark matter and dark energy. There is a neutrino called sterile neutrino which might be present in nature and play the role of dark matter. The aim is to get its signature in N-body simulation of structure formation and also in X-ray data from galaxy and galaxy clusters.

9. Cosmology: Early Universe, recombination and reionization, Statistics of Cosmological fields  Go to Top

Early Universe: Generation of cosmological perturbations, inflation model building and confronting with observational data, observational constraints on quantum gravity models; Physics of the epochs of recombination and reionization; Statistics of cosmological fields - CMB temperature and polarization, differential brightness temperature of 21 cm emissions, dark matter and galaxy density fields: developing statistical tools to analyze cosmological fields.

10. Black hole Astrophysics:  Go to Top

Study of stellar dynamics around black holes, kinematics and oscillation in particle orbits around spinning black holes, properties of electrodynamical jets, gas dynamics of accretion; applications to stellar and supermassive black holes. Relativistic flows of plasmas around and from Black hole systems. Cosmological formation of black holes.

11. Structure and Dynamics of Galaxies:  Go to Top

Violent relaxation, structure of ellipticals, M-Sigma relation.

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Last updated on: September 30, 2021