Journal of High Energy Physics

, Volume 2011, Issue 2, pp 1-30

First online:

Hawking-like radiation from evolving black holes and compact horizonless objects

  • Carlos BarcelóAffiliated withInstituto de Astrofísica de Andalucía, IAA-CSIC
  • , Stefano LiberatiAffiliated withSISSA/International School for Advanced Studies, and INFN, Sezione di Trieste
  • , Sebastiano SonegoAffiliated withDipartimento di Fisica, Università di Udine
  • , Matt VisserAffiliated withSchool of Mathematics, Statistics and Operations Research, Victoria University of Wellington Email author 

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Usually, Hawking radiation is derived assuming (i) that a future eternal event horizon forms, and (ii) that the subsequent exterior geometry is static. However, one may be interested in either considering quasi-black holes (objects in an ever-lasting state of approach to horizon formation, but never quite forming one), where (i) fails, or, following the evolution of a black hole during evaporation, where (ii) fails. We shall verify that as long as one has an approximately exponential relation between the affine parameters on the null generators of past and future null infinity, then subject to a suitable adiabatic condition being satisfied, a Planck-distributed flux of Hawking-like radiation will occur. This happens both for the case of an evaporating black hole, as well as for the more dramatic case of a collapsing object for which no horizon has yet formed (or even will ever form). In this article we shall cast the previous statement in a more precise and quantitative form, and subsequently provide several explicit calculations to show how the time-dependent Bogoliubov coefficients can be calculated.


Black Holes Models of Quantum Gravity 2D Gravity Spacetime Singularities