MR. DIPANJAN MUKHERJEE

Accreting neutron stars are broadly classified into two classes, high mass X-ray binaries (HMXB) with surface fields ~ 10^{12}G and low mass X-ray binaries (LMXB) with field strengths ~ 10^{8}G. In this talk I will discuss the following points: 1) In accreting systems matter is channelled by the magnetic fields to the poles of neutron stars forming an accretion mound. We model such accretion mounds by numerically solving the Grad-Shafranov equation. We investigate the distortion in the local field due to the accreted matter. We also perform 3D MHD simulation to study the stability of such mounds. 2) For HMXB systems, cyclotron lines in X-ray spectra are a direct probe of the local magnetic field. Using the density and field configurations of the accretion mounds evaluated previously, we model the expected emission features that may be observed from such systems. We apply our results to understand the emission from accretion columns of some known sources like Vela X-1. 3) We have also made preliminary estimates of magnetic fields of known pulsating LMXB sources by spectral and temporal analysis of RXTE archival data. For this work we have followed the Psaltis-Chakrabarty method of constraining the fields. I will discuss the results and compare with previous field estimates from other methods.