Temperature and entropy-area relation of quantum matter near spherically symmetric outer trapping horizons

Understand

We consider spherically symmetric spacetimes with an outer trapping horizon.

• Such spacetimes are generalizations of spherically symmetric black hole spacetimes where the central mass can vary with time, like in black hole collapse or black hole evaporation.
• These spacetimes possess in general no timelike Killing vector field, but admit a Kodama vector field which provides a replacement.
• Spherically symmetric spacelike cross-sections of the outer trapping horizon define in- and outgoing lightlike congruences.