2004 ASTRONOMY & ASTROPHYSICS - Indian Academy of Sciences

THEORETICAL ASTROPHYSICS
• The distribution of space velocities of neutron
stars arising out of the disruption of binary
systems was derived and the kick velocities
received by neutron stars at birth were
estimated.
• A relativistic theory of superdense matter with
short-range spin-2 meson exchange was
constructed and lower bounds on the masses of
rapidly rotating pulsars were obtained.
• The role of the central pulsar, and the
interstellar medium, on the morphology and
evolution of supernova remnants was
investigated in detail for the first time.
• Signatures of dynamical phenomena in stronggravity
regions close to neutron stars and black
holes were clarified.
• The effects of the centrifugal barrier in lowviscosity
accretion disks around black holes
were examined and the results were found to
be applicable to several observed systems.
• It was shown that the tangential component of
radiation forces on a thick accretion disk would
result in radiation driven jets.
• A physical mechanism was proposed for the
triggering of starbursts via shock compression of
molecular clouds in interacting galaxies.
• An unusual class of merging galaxies with spirallike
mass distribution and elliptical-like
kinematics were found from the analysis of
2MASS archival data.
• The lopsidedness of the disks in galaxies was
shown to be due to a self-consistent response
to the halo distortion.
• The H-theorem for collisionless stellar systems
was studied and a method was found for the
exact treatment of angular momentum, energy
transfer and disruption.
• The effect of two-body relaxation on a
flattened, rapidly rotating star cluster was
worked out.
• An elegant formulation of gravitational lensing
in terms of Fermat’s principle and wavefronts
was developed.
• Formation of Einstein Rings in gravitational lens
systems was predicted and confirmed
subsequently by observations.
Schematic of the Double Pulsar system. Courtesy: E.P.J. van den Heuvel /SCIENCE 2004
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