Joule–Thomson expansion of black holes in STU supergravity

Abstract

In this research paper, we study the Joule–Thomson (JT) expansion of the STU black hole with a higher number of electric charges arranged within the parameter space [Formula: see text]. The study involves revealing the charge effect on the JT expansion in the case of four/three equal/unequal charge configurations. The process of JT expansion consists of analyzing the inversion and isenthalpic curves to describe the heating and cooling zones. In relation to the associated inversion curves, the findings show that as the electric charge increases, the inversion temperature and the inversion pressure in all sets of charge configurations increase monotonically. As far as the isenthalpic curve is concerned, which entails two regions separated by the inversion curve, these regions are nothing more than the upper region, i.e. the heating process, and the lower region, i.e. the cooling process. Moreover, the isenthalpic curve shows that for each case of charge configuration, mass increases cause an increase in inversion temperature. Therefore, the effect of the number and the parameter space on the isenthalpic and inversion curves is demonstrated. We then investigate the ratio between the minimum inversion temperature and the critical temperature. Overall, this paper provides a detailed study of the JT expansion of the STU black hole multiple charges.