Curvature Effect on the Speed of Sound

Fuente: arXiv
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Main Authors: Verma, Anshuman, Saha, Asim Kumar, Mallick, Ritam
Format: Preprint
Published: 2026
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author Verma, Anshuman
Saha, Asim Kumar
Mallick, Ritam
author_facet Verma, Anshuman
Saha, Asim Kumar
Mallick, Ritam
contents The speed of sound refers to the rate at which information travels from one point to another. It is a positive quantity and bounded by causality. It is defined as the rate of change of pressure with respect to the system's density. In this article, we derive a covariant equation for the sound wave and demonstrate how the wave equation is modified in the general relativistic formalism. One can then define an effective speed of sound by attenuating the usual definition of sound speed with the gravitational metric potential. The general relativistic curvature effect is observed to reduce the speed of sound when computed inside a neutron star. This effectively makes the star relatively softer (according to the equation of state). The change in the effective sound speed can be easily visualised if one redefines the non-radial modes in terms of it. The modes do not change, but the space-time curvature reduces the amplitude of the oscillation modes. The formalism is suited for studying astrophysical compact objects.
format Preprint
id arxiv_https___arxiv_org_abs_2601_11005
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Curvature Effect on the Speed of Sound
Verma, Anshuman
Saha, Asim Kumar
Mallick, Ritam
High Energy Astrophysical Phenomena
The speed of sound refers to the rate at which information travels from one point to another. It is a positive quantity and bounded by causality. It is defined as the rate of change of pressure with respect to the system's density. In this article, we derive a covariant equation for the sound wave and demonstrate how the wave equation is modified in the general relativistic formalism. One can then define an effective speed of sound by attenuating the usual definition of sound speed with the gravitational metric potential. The general relativistic curvature effect is observed to reduce the speed of sound when computed inside a neutron star. This effectively makes the star relatively softer (according to the equation of state). The change in the effective sound speed can be easily visualised if one redefines the non-radial modes in terms of it. The modes do not change, but the space-time curvature reduces the amplitude of the oscillation modes. The formalism is suited for studying astrophysical compact objects.
title Curvature Effect on the Speed of Sound
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2601.11005