Fermion tunneling from dynamical horizons

¹  Department of Physics-University of Toronto - 60 St. George Street, Toronto, Ontario, M5S 1A7, Canada
²  Dipartimento di Fisica-Università di Trento and INFN, Gruppo Collegato di Trento - Via Sommarive 14, 38100 Povo (Trento) Italia, EU

Corresponding author: vanzo@science.unitn.it

Received: 7 March 2008
Accepted: 24 April 2008

Abstract

The instability against emission of fermionic particles by the trapping horizon of an evolving black hole is analyzed and confirmed using the Hamilton-Jacobi tunneling method. This method automatically selects one special expression for the surface gravity of a changing horizon. The results also apply to point masses embedded in an expanding universe. As a bonus of the tunneling method, we gain the insight that the surface gravity still defines a temperature parameter as long as the evolution is sufficiently slow that the black-hole pass through a sequence of quasi-equilibrium states, and that black holes should be semi-classically unstable even in a hypothetical world without bosonic fields.