Rotating Fermion-Boson Stars in R-squared Gravity
Abstract
Fermion-boson stars are compact equilibrium configurations composed of ordinary fermionic matter and a bosonic dark component interacting only through gravity. Such systems provide a natural framework for exploring deviations from standard neutron-star models, including the possible accumulation of dark matter inside neutron stars, and may be relevant for compact objects near the low-mass black-hole gap. We construct static and uniformly rotating fermion-boson stars within the framework of R-squared f(R) gravity, characterized by the functional form f(R)=R+aR2, where a is a positive parameter governing the effective mass scale from the scalar degree of freedom. The fermionic sector is modeled as a perfect fluid described by a tabulated equation of state at zero temperature, while the bosonic component is represented by a self-interacting complex bosonic field. Our results show that the scalar degree of freedom modifies the spatial distribution of both the bosonic field and the fermionic pressure, enlarges the domain of admissible equilibrium solutions, and increases the maximum supported masses relative to general relativity. Our models remain compatible with current astrophysical and gravitational-wave constraints, suggesting that fermion-boson stars in R-squared gravity offer a promising framework to investigate the combined effects of dark bosonic matter, rotation, and strong-field modifications of gravity in compact objects.
Versions
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BibTeX
@misc{fakhry2026rotating,
title = {{Rotating Fermion-Boson Stars in $R$-squared Gravity}},
author = {Saeed Fakhry and Jorge Castelo Mourelle and Nicolas Sanchis-Gual and Daniela Doneva and Stoytcho Yazadjiev and José A. Font},
howpublished = {arXiv},
year = {2026},
month = jul,
doi = {10.48550/arxiv.2607.04744},
eprint = {2607.04744},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.04744},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Rotating Fermion-Boson Stars in R-squared Gravity
AU - Saeed Fakhry
AU - Jorge Castelo Mourelle
AU - Nicolas Sanchis-Gual
AU - Daniela Doneva
AU - Stoytcho Yazadjiev
AU - José A. Font
PY - 2026
DA - 2026/07/06
PB - arXiv
DO - 10.48550/arxiv.2607.04744
UR - https://arxiv.org/abs/2607.04744
AB - Fermion-boson stars are compact equilibrium configurations composed of ordinary fermionic matter and a bosonic dark component interacting only through gravity. Such systems provide a natural framework for exploring deviations from standard neutron-star models, including the possible accumulation of dark matter inside neutron stars, and may be relevant for compact objects near the low-mass black-hole gap. We construct static and uniformly rotating fermion-boson stars within the framework of R-squared f(R) gravity, characterized by the functional form f(R)=R+aR^2, where a is a positive parameter governing the effective mass scale from the scalar degree of freedom. The fermionic sector is modeled as a perfect fluid described by a tabulated equation of state at zero temperature, while the bosonic component is represented by a self-interacting complex bosonic field. Our results show that the scalar degree of freedom modifies the spatial distribution of both the bosonic field and the fermionic pressure, enlarges the domain of admissible equilibrium solutions, and increases the maximum supported masses relative to general relativity. Our models remain compatible with current astrophysical and gravitational-wave constraints, suggesting that fermion-boson stars in R-squared gravity offer a promising framework to investigate the combined effects of dark bosonic matter, rotation, and strong-field modifications of gravity in compact objects.
ER -