Rana Nandi

Nonequilibrium phase transition in compact stars through a violent shock

In this letter we study the dynamics of a first order phase tran sitio from nucleonic to quark matter in neutron stars. Usin g standard equations of state for these two phases we find the de nsity range where such a transition is possible. Then we stud y the transformation of the star assuming that the quark core is fo rmed via a spherical shock wave. The thermodynamical condit i s in the quark core are found from the conservation laws across th e transition region. Their dependence on the density and vel ocity of the incoming nuclear matter are studied. It is found that the shock is especially violent in the beginning of the conversi on process when the velocity of the infalling matter is especially high . As the shock propagates further from the center the front ve locity first increases and reaches a maximum value when the incoming velo city is around 0.2. Finally, the front velocity quickly goes to zero when incoming matter velocity approaches zero. We have show n that the density and pressure jumps are especially large in the begining of the transition process.

Neutron Star Crust in Strong Magnetic Fields

We discuss the effects of strong magnetic fields through Landau quantization of electrons on the structure and stability of nuclei in neutron star crust. In strong magnetic fields, this leads to the enhancement of the electron number density with respect to the zero field case. We obtain the sequence of equilibrium nuclei of the outer crust in the presence of strong magnetic fields adopting most recent versions of the experimental and theoretical nuclear mass tables. For B ~ 1016G, it is found that some new nuclei appear in the sequence and some nuclei disappear from the sequence compared with the zero field case. Further we investigate the stability of nuclei in the inner crust in the presence of strong magnetic fields using the Thomas-Fermi model. The coexistence of two phases of nuclear matter - liquid and gas, is considered in this case. The proton number density is significantly enhanced in strong magnetic fields B ~ 1017G through the charge neutrality. We find nuclei with larger mass number in the presence of strong magnetic fields than those of the zero field. These results might have important implications for the transport properties of the crust in magnetars.

INNER CRUSTS OF NEUTRON STARS IN STRONGLY QUANTIZING MAGNETIC FIELDS

We study the ground-state properties of inner crusts of neutron stars in the presence of strong magnetic fields of {approx}10{sup 17} G. Nuclei coexist with a neutron gas and reside in a uniform gas of electrons in the inner crust. This problem is investigated within the Thomas-Fermi model. We extract the properties of nuclei based on the subtraction procedure of Bonche, Levit, and Vautherin. The phase space modification of electrons due to Landau quantization in the presence of strong magnetic fields leads to the enhancement of electron as well as proton fractions at lower densities of {approx}0.001 fm{sup -3}. We find the equilibrium nucleus at each average baryon density by minimizing the free energy and show that, in the presence of strong magnetic fields, it is lower than that in the field-free case. The size of the spherical cell that encloses a nucleus along with the neutron and electron gases becomes smaller in strong magnetic fields compared to the zero-field case. Nuclei with larger mass and atomic numbers are obtained in the presence of strong magnetic fields compared with cases of zero field.

Effect of the Coulomb interaction on the liquid-gas phase transition of nuclear matter

We investigate the role of the Coulomb interaction on the liquid-gas phase transition of nuclear matter with three different values of proton fraction (

Magnetised Neutron Star Crusts and Torsional Shear Modes of Magnetars

Y_p

Shear viscosity in antikaon condensed matter

=0.5,0.3 and 0.1), relevant for heavy-ion physics as well as various astrophysical scenarios, within the framework of quantum molecular dynamics. We perform simulations for a wide range of density and temperature with and without the Coulomb interaction and calculate the two-point correlation functions of nucleon density fluctuations for all the configurations to determine the phase transition region. We also determine the critical end point of the liquid-gas phase transition for all three values of proton fraction considered. We observe that the Coulomb interaction reduces the transition temperature by about 2 MeV for nuclear matter with

Nuclei in Strongly Magnetised Neutron Star Crusts

Y_p

Nucleation of antikaon condensed matter in protoneutron stars

=0.5 and 0.3 and by about 1 MeV for nuclear matter with

Melting of antikaon condensate in protoneutron stars

Y_p

Shear viscosity and the nucleation of antikaon condensed matter in protoneutron stars

=0.1. However, the critical density is found to be more or less insensitive to the Coulomb interaction.