### Abstract

We investigate the consequences of the collapse-induced radiation anticipated before formation of the event horizon. After reviewing the principles underlying semi-classical analysis of black holes we illustrate them by modelling collapse of evaporating massive thin dust shells using two families of metrics for the exterior geometry: the outgoing Vaidya metric and the retarded Schwarzschild metric. We describe how hypothetical pre-Hawking radiation modifies the equation of motion for the shell. Provided that a non-zero radiation flux is perceived by a distant observer, the shell never gets closer than a certain sub-Planckian distance from the Schwarzschild radius. This distance depends only on the shell's mass and evaporation rate. The stress-energy tensor is everywhere finite, but a comoving observer encounters firewall-like energy density and flux. We emphasize the logical connections between different assumptions within the semi-classical approach and discuss consequences of the apparent contradictions between them.

Language | English |
---|---|

Article number | 185005 |

Pages | 1-25 |

Number of pages | 25 |

Journal | Classical and Quantum Gravity |

Volume | 35 |

Issue number | 18 |

DOIs | |

Publication status | Published - 17 Aug 2018 |

### Keywords

- thin shells
- pre-Hawking radiation
- collapse

### Cite this

*Classical and Quantum Gravity*,

*35*(18), 1-25. [185005]. https://doi.org/10.1088/1361-6382/aad70e

}

*Classical and Quantum Gravity*, vol. 35, no. 18, 185005, pp. 1-25. https://doi.org/10.1088/1361-6382/aad70e

**Role of evaporation in gravitational collapse.** / Baccetti, Valentina; Mann, Robert B.; Terno, Daniel R.

Research output: Contribution to journal › Article › Research › peer-review

TY - JOUR

T1 - Role of evaporation in gravitational collapse

AU - Baccetti, Valentina

AU - Mann, Robert B.

AU - Terno, Daniel R.

PY - 2018/8/17

Y1 - 2018/8/17

N2 - We investigate the consequences of the collapse-induced radiation anticipated before formation of the event horizon. After reviewing the principles underlying semi-classical analysis of black holes we illustrate them by modelling collapse of evaporating massive thin dust shells using two families of metrics for the exterior geometry: the outgoing Vaidya metric and the retarded Schwarzschild metric. We describe how hypothetical pre-Hawking radiation modifies the equation of motion for the shell. Provided that a non-zero radiation flux is perceived by a distant observer, the shell never gets closer than a certain sub-Planckian distance from the Schwarzschild radius. This distance depends only on the shell's mass and evaporation rate. The stress-energy tensor is everywhere finite, but a comoving observer encounters firewall-like energy density and flux. We emphasize the logical connections between different assumptions within the semi-classical approach and discuss consequences of the apparent contradictions between them.

AB - We investigate the consequences of the collapse-induced radiation anticipated before formation of the event horizon. After reviewing the principles underlying semi-classical analysis of black holes we illustrate them by modelling collapse of evaporating massive thin dust shells using two families of metrics for the exterior geometry: the outgoing Vaidya metric and the retarded Schwarzschild metric. We describe how hypothetical pre-Hawking radiation modifies the equation of motion for the shell. Provided that a non-zero radiation flux is perceived by a distant observer, the shell never gets closer than a certain sub-Planckian distance from the Schwarzschild radius. This distance depends only on the shell's mass and evaporation rate. The stress-energy tensor is everywhere finite, but a comoving observer encounters firewall-like energy density and flux. We emphasize the logical connections between different assumptions within the semi-classical approach and discuss consequences of the apparent contradictions between them.

KW - thin shells

KW - pre-Hawking radiation

KW - collapse

UR - http://www.scopus.com/inward/record.url?scp=85053142130&partnerID=8YFLogxK

U2 - 10.1088/1361-6382/aad70e

DO - 10.1088/1361-6382/aad70e

M3 - Article

VL - 35

SP - 1

EP - 25

JO - Classical and Quantum Gravity

T2 - Classical and Quantum Gravity

JF - Classical and Quantum Gravity

SN - 0264-9381

IS - 18

M1 - 185005

ER -