Black hole and naked singularity geometries supported by threeform fields
Abstract
We investigate static and spherically symmetric solutions in a gravity theory that extends the standard HilbertEinstein action with a Lagrangian constructed from a threeform field A_{α β γ}, which is related to the field strength and a potential term. The field equations are obtained explicitly for a static and spherically symmetric geometry in vacuum. For a vanishing threeform field potential the gravitational field equations can be solved exactly. For arbitrary potentials numerical approaches are adopted in studying the behavior of the metric functions and of the threeform field. To this effect, the field equations are reformulated in a dimensionless form and are solved numerically by introducing a suitable independent radial coordinate. We detect the formation of a black hole from the presence of a Killing horizon for the timelike Killing vector in the metric tensor components. Several models, corresponding to different functional forms of the threefield potential, namely, the Higgs and exponential type, are considered. In particular, naked singularity solutions are also obtained for the exponential potential case. Finally, the thermodynamic properties of these black hole solutions, such as the horizon temperature, specific heat, entropy and evaporation time due to the Hawking luminosity, are studied in detail.
 Publication:

European Physical Journal C
 Pub Date:
 July 2020
 DOI:
 10.1140/epjc/s1005202081781
 arXiv:
 arXiv:2004.06605
 Bibcode:
 2020EPJC...80..617B
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  High Energy Astrophysical Phenomena;
 High Energy Physics  Theory
 EPrint:
 19 pages, 22 figures