English

Anisotropic Dark Matter Bosonic Stars in regularized 4D Einstein$-$Gauss$-$Bonnet gravity

General Relativity and Quantum Cosmology 2025-10-21 v1 High Energy Astrophysical Phenomena High Energy Physics - Theory

Abstract

In this work, we have constructed anisotropic bosonic dark-matter star (DMS) solutions in the context of a regularized four-dimensional Einstein-Gauss-Bonnet (4D EGB) gravity theory. Using dimensional regularization, we solve modified Tolman-Oppenheimer-Volkoff equations for a self-interacting complex scalar field in the dilute polytropic regime, pr=Kρ2p_r = K \rho^2, with anisotropy parameterized as σ=βpr(1e2λ)\sigma = \beta\, p_r \left( 1 - e^{-2\lambda} \right). We perform a comprehensive numerical analysis across the (α,β)(\alpha,\beta) parameter domain, where α[0,8] km2\alpha \in [0,8]~\mathrm{km}^2 and β[2,0]\beta \in [-2,0], to examine mass-radius relations and evaluate multiple stability indicators including static equilibrium dM/dpcdM/dp_c, sound-speed causality, the radial adiabatic index Γr\Gamma_r, and energy conditions. Positive Gauss-Bonnet coupling enhances both the maximum mass and compactness (e.g., Mmax1.62MM_{\rm max} \approx 1.62\, M_\odot at α=0\alpha=0 rising to 2.09M\approx 2.09\, M_\odot at α=8 km2\alpha = 8~\mathrm{km}^2), while negative anisotropy reduces them (e.g., from 2.21M\approx 2.21\, M_\odot at β=0\beta=0 to 1.73M\approx 1.73\, M_\odot at β=2\beta = -2). The resulting configurations remain statically stable up to the mass peak and satisfy physical criteria. This work extends previous isotropic boson-star analyses by systematically incorporating anisotropy within a regularized 4D EGB framework. These findings provide observationally relevant predictions for compact dark-matter objects under modified gravity.

Keywords

Cite

@article{arxiv.2510.15549,
  title  = {Anisotropic Dark Matter Bosonic Stars in regularized 4D Einstein$-$Gauss$-$Bonnet gravity},
  author = {Mohamamd Mazhari},
  journal= {arXiv preprint arXiv:2510.15549},
  year   = {2025}
}

Comments

10 pages, 9 figures, 2 Table