https://doi.org/10.1140/epjc/s10052-025-15005-z
Regular Article - Theoretical Physics
Black hole in Dehnen 
dark matter halo: exact solution, lensing, light ring, and thermodynamics
Department of Physics, Faculty of Science, Mahidol University, 10400, Bangkok, Thailand
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Received:
14
September
2025
Accepted:
26
October
2025
Published online:
5
November
2025
In this work, we present the exact solution of a static, spherically symmetric black hole embedded in a Dehnen dark matter halo. We explore both its optical and thermodynamic properties. Using the principle of least action, we derive the null geodesics to analyze and illustrate the corresponding gravitational lensing and light ring phenomena in the presence of the dark matter halo. We then turn to the thermodynamics of the black hole–dark matter system, examining the mass function, entropy, temperature, heat capacity, and Gibbs free energy to assess both local and global stability. Our results show that the surrounding dark matter halo plays a crucial role: it not only enhances the thermodynamic stability of the black hole but also enables the occurrence of phase transitions.
An erratum to this article is available online at https://doi.org/10.1140/epjc/s10052-025-15242-2.
© The Author(s) 2025
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Funded by SCOAP3.
