Oscillatory properties of strange quark stars described by the vector MIT bag model

Luiz L. Lopes; José C. Jiménez; Luis B. Castro; César V. Flores

doi:10.1140/epjc/s10052-025-14224-8

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2025) 85: 515
https://doi.org/10.1140/epjc/s10052-025-14224-8

Regular Article - Theoretical Physics

Oscillatory properties of strange quark stars described by the vector MIT bag model

Luiz L. Lopes¹^a, José C. Jiménez²^,3, Luis B. Castro⁴ and César V. Flores⁴^,5

¹ Centro Federal de Educação Tecnológica de Minas Gerais Campus VIII, CEP 37.022-560, Varginha, MG, Brazil
² Department of Astrophysics, Brazilian Center for Research in Physics (CBPF), Rua Dr. Xavier Sigaud, 150, URCA, CEP 22210-180, Rio de Janeiro, RJ, Brazil
³ Universidad Tecnológica del Perú, Arequipa, Peru
⁴ Departamento de Física-CCET, Universidade Federal do Maranhão, UFMA, Campus Universitário do Bacanga, CEP 65080-805, São Luís, Maranhão, Brazil
⁵ Centro de Ciências Exatas, Naturais e Tecnológicas, Universidade Estadual da Região Tocantina do Maranhão, UEMASUL, CEP 65901-480, Imperatriz, Maranhão, Brazil

^a llopes@cefetmg.br

Received: 13 December 2024
Accepted: 17 April 2025
Published online: 10 May 2025

Abstract

We investigated the radial and non-radial fundamental (f) mode oscillations of self-bound (quark) stars obtained after employing the Vector MIT (vMIT) bag model. Within this model, we computed the equation of state for strange quark matter satisfying thermodynamic consistency. This allowed us to obtain the corresponding behavior of the speed of sound, mass-radius relation, and gravitational redshift. In particular, our choice of $G_{V} = 0.30 {fm}^{2}$ $G_V = 0.30~\hbox {fm}^2$ produces masses and radii in agreement with recent astronomical data (e.g. from NICER and HESS J1731). In fact, we tested that variations of the remaining vMIT parameters slightly modify this conclusion. Then, we proceeded to compute the radial oscillation frequencies of the f-mode, which is tightly connected to the dynamical stability of these compact stars. We found that increments of the $G_{V}$ $$G_V$$ parameter have a stabilizing property around the maximal-mass stars for a given stellar family. We also calculated the gravitational-wave frequencies of the non-radial f-mode. Our results show that they are restricted to be in the range (1.6–1.8) kHz for high-mass stars and to (1.5–1.6) kHz for low-mass stars. Finally, we propose a universal relation between these frequencies and the square root of the average density. All these last results are important in distinguishing strange stars from ordinary neutron stars in future gravitational-wave detections coming from compact sources with activated non-radial modes.

© The Author(s) 2025

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