arXiv subjects

Soumodeep Mitra

Publications and source records attributed to Soumodeep Mitra.

5 recordsLinked to original sources

arXiv2026

Dynamical Tidal response of compact stars -- An EFT approach

We apply the point particle EFT approach to a compact star to systematically compute dynamical tidal love numbers for various non-rotating compact objects, extending the treatment of {arXiv:2307.10391[hep-th], arXiv:2407.08327 [gr-qc]}. We calculate the scattering amplitude in Black Hole Perturbation Theory(BPHT) for \textit{arbitrary} non-rotating compact stars using the Mano-Suzuki-Takasugi(MST) method with non zero surface reflectivity and match it with that obtained from point particle EFT order by order in the low frequency expansion. This sets up a systematic framework for extracting the static and dynamical tidal love numbers(TLNs) to any order in the multipole expansion. In this paper, we employ the technique to compute the Next-to-Next-to Leading Order TLN upto a universal constant and its Renormalization Group equation for non-viscous Neutron stars and Neutron stars admixed with Bosonic or Fermionic dark matter.

gr-qc↗

arXiv2025

Extreme mass ratio inspirals in rotating dark matter spikes

Gravitational wave (GW) signals from extreme mass ratio inspirals (EMRIs) are a key observational target for the Laser Interferometer Space Antenna (LISA). The waveforms may be affected by the astrophysical environment surrounding the central black hole (BH), and in particular by the surrounding dark matter (DM) distribution. In this work, we consider the effect of a rotating DM "spike" around a central Kerr BH, and assess its detectability with LISA. Using a fully relativistic model for the rotating spike, we investigate its effect on the inspiral and hence on the emitted GW signals. We compute dephasings and mismatches to quantify how the spin of the primary BH affects the binary dynamics and the gravitational waveform. We show that the modifications due to the spin of the primary BH improve the detection prospects of DM spikes with LISA, and must be taken into account for future parameter estimation studies. We also estimate within post-Newtonian theory how the environment affects the background metric, and show that this effect is mostly negligible for the systems we consider.

gr-qc↗

arXiv2023

Probing the quantum nature of black holes with ultra-light boson environments

Quantum black holes (BHs), thought of as an excited multilevel system, can be effectively modelled by replacing an event horizon with a partially reflective membrane. This emergent feature affects their interaction with hosting environments, with the most pronounced effects happening for particles with mass~$m_{\rm p}\lesssim (10 M_{\odot}/M)\,10^{-11}\mathrm{\,eV}$, where~$M$ is the BH mass. We show that ultra-light bosons -- a viable dark matter candidate -- can be used to probe the quantum nature of BHs. We derive analytical expressions for the accretion rate and dynamical friction acting on exotic compact objects moving through an ultra-light scalar field, finding that while the accretion rate is sensitive to the quantum BH's reflectivity, the dynamical friction is the same as for classical BHs. We then use these expressions to estimate the orbital dephasing in the inspiralling of different binaries in the Laser Interferometer Space Antenna (LISA) band. Our results indicate that LISA may be able to discriminate quantum from classical BHs through their different accretion rates.

gr-qc↗

arXiv2021

Quantum Gravity Corrections to the Mean Field Theory of Nucleons

In this paper, we analyze the correction to the mean field theory potential for a system of nucleons. It will be argued that these corrections can be obtained by deforming the Schrödinger's equation describing a system of nucleons by a minimal length in the background geometry of space-time. This is because such a minimal length occurs due to quantum gravitational effects, and modifies the low energy quantum mechanical systems. In fact, as the mean field potential for the nucleons is represented by the Woods-Saxon potential, we will explicitly analyze such corrections to this potential. We will obtain the corrections to the energy eigenvalues of the deformed Schrödinger's equation for the Woods-Saxon potential. We will also construct the wave function for the deformed Schrödinger's equation.

physics.gen-ph↗

arXiv2020

Strong cosmic censorship conjecture with NUT charge and conformal coupling

Strong cosmic censorship conjecture is central to the deterministic nature of general relativity, since it asserts that given any generic initial data on a spacelike hypersurface, the future can be uniquely predicted. However, recently it has been found that for charged black holes in asymptotically de Sitter spacetimes, the metric and massless scalar fields can be extended beyond the Cauchy horizon. This spells doom on the strong cosmic censorship conjecture, which prohibits precisely this scenario. In this work we try to understand the genericness of the above situation by studying the effect of NUT charge and conformally coupled scalar field on the violation of strong cosmic censorship conjecture for charged asymptotically de Sitter black holes. We have shown that even in the presence of the NUT charge and a conformally coupled scalar field strong cosmic censorship conjecture in indeed violated for such black holes with Cauchy horizon. Moreover, the presence of conformal coupling makes the situation even worse, in the sense that the scalar field is extendible across the Cauchy horizon as a $C^{1}$ function. On the other hand, the strong cosmic censorship conjecture is respected for conformally coupled scalar field in rotating black hole spacetimes with NUT charge. This reinforces the belief that possibly for astrophysical black holes, strong cosmic censorship conjecture is respected, irrespective of the nature of the scalar field.

gr-qc↗