A R Prasanna
Articles written in Pramana – Journal of Physics
Volume 5 Issue 5 November 1975 pp 289-293 General Relativity
In this paper we have extended our earlier studies of solutions of Einstein-Cartan equations to the case where a magnetic field co-exists with the matter distribution. We have obtained an exact solution of Einstein-Cartan-Maxwell equations representing a static cylinder of perfect fluid with an axial magnetic field
Volume 8 Issue 3 March 1977 pp 229-244 Astrophysics
In this paper we have studied the motion of charged particles in a dipole magnetic field on the Schwarzscbild background geometry. A detailed analysis has been made in the equatorial plane through the study of the effective potential curves. In the case of positive canonical angular momentum the effective potential has two maxima and two minima giving rise to a well-defined potential well rear the event horizon. This feature of the effective potential categorises the particle orbits into four classes, depending on their energies. (i) Particles, coming from infinity with energy less than the absolute maximum of
In the case when particles are not confined to the equatorial plane we have found that the particles execute oscillatory motion between two mirror points if the magnetic field is sufficiently high, but would continuously fall towards the event horizon otherwise.
Volume 8 Issue 4 April 1977 pp 395-395 Erratum
Volume 11 Issue 4 October 1978 pp 359-377 General Relativity
In this paper we study the trajectories of charged particles in an electromagnetic field superimposed on the Kerr background. The electromagnetic fields considered are of two types: (i) a dipole magnetic field with an associated quadrupole electric field, (ii) a uniform magnetic field. The contribution of the background geometry to the electromagnetic field is taken through the solutions of Petterson and Wald respectively. The effective potential is studied in detail for the
Volume 14 Issue 2 February 1980 pp 113-118 General Relativity
The charged particle orbits in electromagnetic fields on Kerr background as viewed from a locally non-rotating frame do not exhibit non-gyrating bound orbits, which was an essential feature in the earlier study of Prasanna and Vishveshwara, thus showing the non gyration to be due to the effect of dragging of inertial frames produced by the rotating black hole.
Volume 19 Issue 2 August 1982 pp 141-150 General Relativity
Charged particle orbits off the equatorial plane of a Kerr black hole in an external electromagnetic field is studied, both for dipole as well as uniform magnetic field. Particles are found to get trapped by the magnetic field if the initial value of the parallel velocity is small. Bending of the field lines in the vicinity of the hole and the consequent trapping of the particles in an otherwise uniform magnetic field indicates the significance of general relativistic effects in such cases.
Volume 33 Issue 4 October 1989 pp 449-454 Relativity
We investigate the ratio of spin precession frequency to orbital frequency for a spinning charged particle confined to circular orbit in the equatorial plane of a compact object, with a uniform magnetic field, as described by the Wald and the Ernst potentials. In order to see the difference in behaviours for particles with different
Volume 36 Issue 5 May 1991 pp 445-488 Review
In this we briefly review the discussions on accretion dynamics, the standard scenario and the ones including the effects of electromagnetic fields. The emphasis throughout is to show the relevance of general relativistic formalism in discussing the dynamics of magnetofluid around compact objects.
Volume 37 Issue 5 November 1991 pp 405-412
Following the approach of optical reference geometry we derive the expression for the total force in the radial direction acting on a charged particle in magnetic fields superimposed on the static Schwarzschild background and show the possible existence of bound orbits for particles in the field of ultra compact objects at distances
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