A new paper lead by Susovan Maity at Harish-Chandra Research Institute on Carter-Penrose diagrams for emergent spacetime around accreting Kerr black holes is now accepted in the Phys. Rev. D for publication.

Abstract

In this work, we construct and study the Carter-Penrose diagram for sonic black hole and white hole analogues as manifested in the analogue spacetime embedded inside the flow of hydrodynamic inviscid matter onto astrophysical rotating black holes. For general relativistic black hole accretion in the Kerr metric, we show that linear perturbation of the axially symmetric matter flow having certain geometrical configurations leads to the emergence of black hole like acoustic spacetime. Such an analogue spacetime is shown to be endowed with one white hole like sonic horizon flanked by two black hole like acoustic horizons. We construct the compactified causal structures, i.e., the Carter Penrose diagrams for such emergent spacetime to study the corresponding horizon effects. For the first time in literature, the Carter Penrose formalism is carried out for analogue spacetime embedded within a natural large scale fluid flow under the influence of strong gravity.

Carter-Penrose diagrams for emergent spacetime in axisymmetrically accreting black hole systems
Maity, S., Shaikh, M. A., Tarafdar, P. & Das, T. K.
Phys. Rev. D, 106, 044062, (2022).