Three-dimensional black holes with scalar hair coupled to a Maxwell-like electrodynamics

TL;DR

This paper presents new classes of charged black hole solutions with scalar hair in a non-linear Einstein-dilaton system, analyzing their thermodynamics and stability, and addressing indeterminacy issues with specific ansatz functions.

Contribution

It introduces two novel classes of charged black holes with scalar hair in a non-linear Einstein-dilaton system, overcoming indeterminacy with specific ansatz functions and analyzing their thermodynamic properties.

Findings

Found black holes with one, two, or no horizons.

Validated the first law of thermodynamics for these black holes.

Analyzed and compared thermal stability using multiple methods.

Abstract

By consideration of a Einstein-dilaton non-linear charged gravitating system, it has been shown that this theory is confronted with the problem of indeterminacy. It means that the number of independent differential equations is one less than the number of unknowns. To overcome this problem, the power-law and exponential ansatz functions have been used, separately. Through solving the field equations, in the presence of a Coulomb-like electric field, it has been found that this theory includes two novel classes of charged black holes (BHs) with unusual asymptotic behavior, for each ansatz. It has been found that, under some circumstances, both of the ansatz functions lead to the same results. The novel exact solutions show BHs with one horizon, two horizons and without horizon. Using a Smarr-type mass formula validity of the first law of BH thermodynamics (FLT) has been proved, after calculating the thermodynamic and conserved quantities. Making use of thermodynamical and geometrical approaches, thermal stability of the BHs has been analyzed. Results of the aforementioned methods have been compared by use of the plots.