Dilip K. Chakraborty

Orbits of a Charged Particle in a Skew Uniform Magnetic Field on Kerr Back Ground Geometry

In this paper we discuss the particle trajectories in a uniform magnetic field superimposed on Kerr geometry. The rotation axis of the Kerr black hole makes an angle with the asymptotic magnetic field. We find that the particle is trapped for suitable initial conditions.

Some general relativistic effects on the dynamics of fluid disks rotating around a Schwarzschild black hole

In this paper we present various classes of solutions for perfect fluid disks rotating around Schwarzschild black holes. We study the profiles of pressure, density and specific angular momentum and the formation of cusp-like structures at the inner edge of the disks. Using the trial function method, we calculate the frequency of the global axi-symmetric oscillations. We compare the results with those of the corresponding Newtonian calculations to find the general relativistic effects.

Oscillations of fluid disks rotating around compact objects

Frequency of global axisymmetric oscillations of a perfect fluid disk rotating around a compact object is investigated by trial function method. A formula for the frequency of local radial oscillation is presented.

Distribution of the Intrinsic Shapes of Elliptical Galaxies

We determine the distribution of the intrinsic shapes of the light distribution of elliptical galaxies by combining the profiles of photometric data from the literature with triaxial models. The models exhibit ellipticity variations and position angle twist. We use ensembles of models so that the shape estimates are largely model independent. We follow the methodology as described in Statler(1994) which is modified to suit our requirements. We find that short to long axial ratios at very small and at very large radii, and the absolute value of the triaxiality difference are the best constrained shape parameters. Using a flat prior, the shapes of elliptical galaxies are reported by Chakraborty et al.(2008). We now use a modified prior and therefore the shapes reported here are more reliable.Using modified prior, we have found the distribution of shape by analyzing twenty elliptical galaxies. We classify the ellipticals as flat or round depending upon the values of the short to long axial ratio. The plot sh...

General relativistic study of perfect fluid disk in linearised kerr geometry

In this chapter we present a detailed general relativistic formulation for the study of structure of perfect fluid disk rotating around Kerr black hole.

A study of stability of rotating fluid disks using a variational principle

Stability of non-self gravitating, non-accreting fluid disk rotating around a Schwarzschild black hole is studied by using a variational principle. We find a set of solutions which depending on the value of a parameter, either a stable or an unstable specific angular momentum distribution (Rayleighs criterion). Using these solutions we find that the calculations based on the variational principle yield results which agree with the Rayleigh criteria when a suitable choice of the trial function is made.

Intrinsic Shape of Elliptical Galaxy NGC 661

We investigated the intrinsic shape of the luminosity density of the triaxial galaxy NGC 661 by comparing its observed profiles of photometric parameters with the projected surface brightness of model galaxies. We examined NGC 661 which shows a small scale variation in the ellipticity profile at ∼ 0.3 r e . We suggest complex form of density distributions which might explain it.