Neutron stars in gravity

Clésio E. Mota; Juan M. Z. Pretel; César O. V. Flores

doi:10.1140/epjc/s10052-024-13042-8

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2024) 84: 673
https://doi.org/10.1140/epjc/s10052-024-13042-8

Regular Article - Theoretical Physics

Neutron stars in $f (R, L_{m}, T)$ gravity

Clésio E. Mota¹, Juan M. Z. Pretel² and César O. V. Flores³^,4^c

¹ Departamento de Física, CFM-Universidade Federal de Santa Catarina, C.P. 476, CEP 88.040-900, Florianópolis, SC, Brazil
² Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150 URCA, CEP 22290-180, Rio de Janeiro, RJ, Brazil
³ Centro de Ciências Exatas, Naturais e Tecnológicas, CCENT-Universidade Estadual da Região Tocantina do Maranhão, C.P. 1300, CEP 65901-480, Imperatriz, MA, Brazil
⁴ Departamento de Física, CCET-Universidade Federal do Maranhão, Campus Universitário do Bacanga, CEP 65080-805, São Luís, MA, Brazil

^c cesarovfsky@gmail.com

Received: 2 May 2024
Accepted: 24 June 2024
Published online: 6 July 2024

Abstract

This study explores the behavior of compact stars within the framework of $f (R, L_{m}, T)$ $$f(R,L_m,T)$$ gravity, focusing on the functional form $f (R, L_{m}, T) = R + α T L_{m}$ $f(R,L_m,T) = R + \alpha TL_m$ . The modified Tolman–Oppenheimer–Volkoff (TOV) equations are derived and numerically solved for several values of the free parameter $α$ $\alpha$ by considering both quark and hadronic matter—described by realistic equations of state (EoSs). Furthermore, the stellar structure equations are adapted for two different choices of the matter Lagrangian density (namely, $L_{m} = p$ $$L_m= p$$ and $L_{m} = - ρ$ $L_m= -\rho$ ), laying the groundwork for our numerical analysis. As expected, we recover the traditional TOV equations in General Relativity (GR) when $α \to 0$ $\alpha \rightarrow 0$ . Remarkably, we found that the two choices for $L_{m}$ $$L_m$$ have appreciably different effects on the mass-radius diagrams. Results showcase the impact of $α$ $\alpha$ on compact star properties, while final remarks summarize key findings and discuss implications, including compatibility with observational data from NGC 6397’s neutron star. Overall, this research enhances comprehension of $f (R, L_{m}, T)$ $$f(R,L_m,T)$$ gravity’s effects on compact star internal structures, offering insights for future investigations.

© The Author(s) 2024

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