MR. DIPANJAN MUKHERJEE

We model magnetically confined accretion mounds on accreting neutron star poles by numerically solving the Grad-Shafranov equation for axisymmetric static MHD equilibria. From our solutions we model the cyclotron spectra that will be emitted from the region by integrating the emission from all parts of the mound to get the resultant spectra. We perform a phase dependent analysis of the spectra to study the effect of the viewing geometry on the resultant emission from the local mound with distorted magnetic field. We have also explored the stability of the accretion mounds using the MHD simulation code PLUTO. We find that pressure and gravity driven modes disrupt the equilibria of the confined accretion mound for heights larger than a threshold. This will result in formation of dynamical structures as matter spreads over the neutron star surface. Such effects will influence the shape and nature of the cyclotron spectra from such High Mass X-ray Binaries, which are expected to be observed in great detail by upcoming missions such as ASTROSAT.