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Ritam Mallick

Publications and source records attributed to Ritam Mallick.

61 records · Page 4Linked to original sources
arXiv2010

Solving the relativistic rankine-hugoniot condition in presence of magnetic field in astrophysical scenario

Rankine-Hugoniot condition has been solved to study phase transition in astrophysical scenario mainly in the case of phase transition from neutron star (NS) to quark star (QS). The phase transition is brought about by a combustion front, which travels from the center to the surface. The equations of state and temperature plays a huge role in determining the nature of the front propagation, which brings about the phase transition in neutron stars (NSs). Magnetic field has been introduced and the modified conservation condition for the perpendicular and oblique shocks is obtained. Numerical solution of the perpendicular shock has been shown in the figures, which finds that the magnetic field helps in shock generation. It indirectly hints at the instability of the matter and thereby the NS for very high magnetic field, implying that NSs can only support finite magnetic field strength.

astro-ph.HE↗
arXiv2009

Magnetic field inhibits the conversion of neutron stars to quark stars

Neutron stars provide a natural laboratory to test some unique implications of Quantum Chromodynamics (QCD)- the underlying theory of strong interactions- at extreme conditions of very high baryon density. It has been suggested that the true ground state of QCD is strange quark matter, and, consequently, neutron stars should convert to strange quark stars under suitable conditions. Substantial efforts have been, and are being, spent in studying the details of such conversion. In this letter, we show that the presence of high magnetic field, an essential feature of neutron stars, strongly inhibits the conversion of neutron stars to bare quark stars.

astro-ph.HE↗
arXiv2008

A General Relativistic study of the neutrino path and calculation of minimum photosphere for different stars

A detailed general relativistic (GR) calculation of the neutrino path for a general metric describing a rotating star is studied. We have calculated the neutrino path along a plane, with the consideration that the neutrino does not at any time leave the plane. The expression for the minimum photosphere radius (MPR) is obtained and matched with the Schwarzschild limit. The MPR is calculated for the stars with two different equations of state (EOS) each rotating with two different velocities. The results shows that the MPR for the hadronic star is much greater than the quark star and the MPR increases as the rotational velocity of the star decreases. The MPR along the polar plane is larger than that along the equatorial plane.

astro-ph↗
arXiv2008

Conversion of nuclear to 2-flavour quark matter in rotating compact stars: A general relativistic perspective

The conversion of neutron star to strange star is argued to be a two step process. The first process involves the deconfinement of nuclear to two-flavour quark matter. The GR results shows that the propagating front breaks up into fragments which propagate with different velocities along different directions. The time taken for this conversion to happen is of the order of few $ms$. This calculation indicates the inadequacy of non-relativistic (NR) or even Special Relativistic (SR) treatments for these cases.

astro-ph↗
arXiv2007

Effect of General Relativity and rotation on the energy deposition rate for $ν+ \barν \to e^+ + e^- $ inside a compact star

We have studied the $ν+ \barν \to e^+ + e^- $ energy deposition rate in a rotating compact star. This reaction is important for the study of gamma ray bursts. The General Relativistic (GR) effects on the energy deposition rate have been incorporated. We find that the efficiency of the process is larger for a rotating star. The total energy deposition rate increases by more than an order of magnitude due to rotation. The dependence of this energy deposition rate on the deformation parameter of the star has also been discussed.

astro-ph↗
arXiv2006

The conversion of Neutron star to Strange star : A two step process

The conversion of neutron matter to strange matter in a neutron star have been studied as a two step process. In the first step, the nuclear matter gets converted to two flavour quark matter. The conversion of two flavour to three flavour strange matter takes place in the second step. The first process is analysed with the help of equations of state and hydrodynamical equations, whereas, in the second process, non-leptonic weak interaction plays the main role. Velocities and the time of travel through the star of these two conversion fronts have been analysed and compared.

astro-ph↗