Bose-Einstein condensate stars in combined Rastall-Rainbow gravity

TL;DR

This study explores Bose-Einstein condensate stars within the combined Rastall-Rainbow gravity framework, revealing how the theory's parameters influence stellar properties and aligning theoretical models with observational data.

Contribution

It introduces a novel analysis of BEC stars in Rastall-Rainbow gravity, showing the significant impact of Rainbow function on star mass and radius, and demonstrating observational consistency with less bosonic self-interaction.

Findings

Rainbow parameter significantly affects maximum star mass and radius.

Temperature has negligible effect on maximum mass.

RR theory allows BEC stars consistent with pulsar data with smaller self-interaction.

Abstract

We study zero and finite temperature static Bose-Einstein condensate (BEC) stars in the combined Rastall-Rainbow (RR) theory of gravity by considering different BEC equation of states (EoSs). We obtain the global properties of BEC stars by solving the modified Tolman-Oppenheimer-Volkoff equations with values of Rastall parameter $\kappa$ and Rainbow function $\Sigma$ chosen accordingly to get the results in theories of Rastall, Rainbow and RR. We observe that the parameter $\kappa$ has negligible effect on the maximum mass of the stars considered, whereas $\Sigma$ alters it significantly, and increasing the value of $\kappa$ beyond a certain limit results in unstable solutions for any value of $\Sigma$. We report that the inclusion of temperature in our analysis expands the parameter space by including more values of $\kappa$. However, temperature has negligible effect on the maximum mass of the stellar profiles in all the three theories. We find that the maximum masses and radii of the stars within RR theory can have good agreement with the observational data on pulsars for all the EoSs considered and in particular, the Colpi-Wasserman-Shapiro EoS, which was ruled out in General Relativity (GR). We also find that, in contrast to the results of GR, BEC stars consistent with observations can be realised in the RR theory with smaller bosonic self-interaction strength.