Abstract Details

Name: Mohammad Hasan
Affiliation: Space Science Programme Office, ISRO Head Quarters
Conference ID: ASI2020_254
Title : Time evolution of interior magnetic field of neutron star through ambipolar diffusion- numerical study in one dimension
Authors and Co-Authors : Mohammad Hasan, Akhila K
Abstract Type : Poster
Abstract Category : Stars, ISM and Galaxy
Abstract : We study the one dimensional evolution of the core magnetic field of neutron star under the influence of ambipolar diffusion through the non-superfluid mantle of the star. The time scale over which the core magnetic field traverses through the mantle to reach to the surface of the neutron star has important implications in understanding the burst mechanism from magnetars and observed magnetar like burst from low magnetic field neutron stars. The sharp discontinuities are found in magnetic field where the conducting plasma (combined Fermi fluid of electron and proton) meet oppositely due to ambipolar drift velocity. Also plasma develops a sharp velocity gradient as it advances in the mantle. Extensive numerical study is carried out to understand the dependency of the field diffusion time with plasma density, mantle temperature and the strength of the core field. We found that for a magnetized core of 10^{16} Gauss , the magnetic field takes a relaxed dipole configuration in around 250 million years for a mantle temperature T=1 ×10^8 K . This time is around few million years for T= 2 ×10^8 K. The time scales are in approximate same order as of the estimated age of magnetars (believed to be relatively younger). It is well know that the Ohmic time scale of field diffusion is more than the presently accepted age of the Universe and. Therefore such study are important to understand the origin of high surface magnetic field ( ̴10^16 Gauss) of magnetars.