Nonlinear Scalarization of Schwarzschild Black Hole in Scalar-Torsion Teleparallel Gravity

TL;DR

This paper introduces new scalarized black hole solutions in scalar-torsion teleparallel gravity, demonstrating their thermodynamic stability and preference over Schwarzschild black holes, with multiple solution branches distinguished by scalar field nodes.

Contribution

It presents novel scalarized black hole solutions in scalar-torsion teleparallel gravity, analyzing their stability, thermodynamics, and solution branches, which was not previously explored.

Findings

Scalarized black holes are thermodynamically preferred over Schwarzschild.

Multiple solution branches exist, distinguished by scalar field nodes.

Scalarized solutions are meta-stable without phase transitions.

Abstract

We consider a scalar field coupled to the torsion in Teleparallel Gravity with a coupling function that does not allow for a tachyonic instability to occur, and it leads to the formation of new black holes with scalar hair. The scalarized black hole solutions are asymptotically flat, and they are studied under their thermodynamics, and we show that they are meta-stable solutions without phase transitions of first and second order. Also, we demonstrate the existence of distinct branches of solutions classified by the number of nodes of the scalar field. For the branches analysed, the scalarized solutions have lower free energy than the Schwarzschild black hole; therefore, they are always thermodinamically preferred. Also, we show that the scalarized black holes are entropically favoured compared to the Schwarzschild solution.