Aspects of the dyonic Kerr-Sen-AdS4 black hole and its ultraspinning version

We explore some (especially, thermodynamical) properties of the dyonic Kerr-Sen-AdS(4) black hole and its ultraspinning counterpart, and check whether or not both black holes satisfy the first law and Bekenstein-Smarr mass formulas. To this end, new Christodoulou-Ruffini-like squared-mass formulas for the usual dyonic Kerr-Sen-AdS(4) solution and its ultraspinning cousin are deduced. Similar to the ultraspinning Kerr-Sen-AdS(4) black hole case, we demonstrate that the ultraspinning dyonic Kerr-Sen-AdS(4) black hole does not always violate the reverse isoperimetric inequality (RII) since the value of the isoperimetric ratio can either be larger/smaller than, or equal to unity, depending upon the range of the solution parameters, as is the case only with an electric charge. This property is apparently distinct from that of the superentropic dyonic Kerr-Newman-AdS(4) black hole, which always strictly violates the RII, although both of them have some similar properties in other aspects, such as the horizon geometry and conformal boundary.

Automated summary

This study investigates the thermodynamical properties of the dyonic Kerr-Sen-AdS(4) black hole and its ultraspinning counterpart, deducing new squared-mass formulas and examining the violation of the reverse isoperimetric inequality. The ultraspinning dyonic Kerr-Sen-AdS(4) black hole is found not always to violate the RII, in contrast to the superentropic dyonic Kerr-Newman-AdS(4) black hole. Despite some similarities, such as horizon geometry and conformal boundary, these two types of black holes exhibit distinct properties regarding the RII.