Particle Motion in Regular Black Hole Spacetimes Supported by a Galactic Halo

TL;DR

This paper studies how dark matter halos influence particle motion and observable properties of regular black holes, revealing that halo parameters significantly affect strong-field phenomena and black hole signatures.

Contribution

It introduces two analytic models of black holes with dark matter halos, analyzing their impact on geodesics, shadows, and stability, highlighting the role of halo density profiles.

Findings

Halo scale parameter significantly alters strong-field observables.

Increasing halo parameter reduces characteristic radii and enhances orbital instability.

Steeper density falloff causes minimal deviations from Schwarzschild black holes.

Abstract

We investigate particle motion in regular and asymptotically flat black hole spacetimes supported by Dehnen-type dark-matter halos. Two analytic models are analyzed, allowing a systematic study of circular geodesics, photon-sphere properties, shadow radius, Lyapunov exponent, ISCO frequency, binding energy, and Hawking temperature. The corrected numerical results show that the halo scale parameter can significantly modify strong-field observables. In both models, for moderate density slopes, increasing the halo parameter reduces characteristic radii while enhancing orbital instability and accretion efficiency. For steeper density falloff, however, deviations from the Schwarzschild case remain small. These results demonstrate that halo-induced modifications of optical and dynamical black hole signatures are strongly controlled by the density profile parameters.