arXiv subjects

Jitesh R Bhatt

Publications and source records attributed to Jitesh R Bhatt.

4 recordsLinked to original sources

arXiv2020

Viscosity in cosmic fluids

The effective theory of large-scale structure formation based on $Λ$CDM paradigm predicts finite dissipative effects in the resulting fluid equations. In this work, we study how viscous effect that could arise if one includes self-interaction among the dark-matter particles combines with the effective theory. It is shown that these two possible sources of dissipation can operate together in a cosmic fluid and the interplay between them can play an important role in determining dynamics of the cosmic fluid. In particular, we demonstrate that the viscosity coefficient due to self-interaction is added inversely with the viscosity calculated using effective theory of $Λ$CDM model. Thus the larger viscosity has less significant contribution in the effective viscosity. Using the known bounds on $\,σ/m$ for self-interacting dark-matter, where $\,σ\,$ and $m$ are the cross-section and mass of the dark-matter particles respectively, we discuss role of the effective viscosity in various cosmological scenarios.

astro-ph.CO↗

arXiv2020

Magnetic fields in a hot dense neutrino plasma and the Gravitational Waves

In the present work, we have studied the spectrum of the primordial gravitational waves due to magnetic instability in the presence of neutrino asymmetry. The magnetic instability generates a helical magnetic field on a large scale. The anisotropic stress generated by the magnetic field shown to be a source of primordial gravitational waves (GWs) at the time of matter-neutrino decoupling. We expect that the theoretically predicted GWs by this mechanism may be detected by Square Kilometer Array (SKA) or pulsar time array (PTA) observations. We also compare our findings with the results obtained by the earlier work where the effect of magnetic instability was not considered.

astro-ph.CO↗

arXiv2019

Probing vorticity in heavy ion collision with dilepton production

We study the effect of vorticity present in heavy ion collisions (HICs) on the temperature evolution of hot quark-gluon plasma in the presence of spin-vorticity coupling. The initial global rotation entails a nontrivial dependence of the longitudinal flow velocity on the transverse coordinates and also develops a transverse velocity component that depends upon the longitudinal coordinate. Both of these velocities lead to a 2+1 dimensional expansion of the fireball. It is observed that with finite vorticity and spin-polarization the fireball cools faster as compared to the case without vorticity. Furthermore, we discuss the consequence of this on the production of thermal dileptons.

hep-ph↗

arXiv2016

The Planckonions

We consider a spherically symmetric stellar configuration with a density profile $ρ(r)=\frac{c^2}{8πG r^2} $. This configuration satisfies the Schwarzchild black hole condition $\frac {2GM}{c^2 R}=~1$ for every $ r =R $. We refer it as "Planckonion". The interesting thing about the Plankonion is that it has an onion like structure. The central sphere with radius of the Plank-lenght $ L_p=\sqrt{(\frac {2\hbar G}{c^3})}$ has one unit of the Planck-mass $M_p=\sqrt {(\frac {c\hbar}{2G})}$. Subsequent spherical shells of radial width $L_p$ contain exactly one unit of $M_p$. We study this stellar configuration using Tolman-Oppenheimer-Volkoff equation and show that the equation is satisfied if pressure $P(r)=-ρ(r)$. On the geometrical side, the space component of the metric blows up at every point. The time component of the metric is zero inside the star but only in the sense of a distribution (generalized function). The Planckonions mimic some features of black holes but avoid appearance of central singularity because of the violation of null energy conditions.

physics.gen-ph↗