## Abstract

An analytic solution is presented for the thermal radiation spectrum from a star undergoing catastrophic collapse to a black hole. The matter distribution and gravitational field are modeled by the Oppenheimer-Snyder solution for spherical, homogeneous, dust-ball collapse. The radiation flux emitted during the implosion is calculated assuming the star is initially subjected to a dynamically small, isothermal temperature perturbation. The flux is derived in the diffusion approximation for a constant opacity source and is determined for distant, as well as comoving observers. Both a Newtonian and general-relativistic analysis are performed. As seen by a distant observer, the intensity at late times appears as a constant blackbody originating from a shrinking annular region about the black hole. The corresponding effective temperature is a simple function of the initial stellar parameters. The total luminosity is constant to a comoving observer at late times, but decays exponentially according to a distant observer. Though highly idealized, our exact solution may serve as a useful benchmark for testing fully relativistic, radiation-transport codes now under construction to handle more complicated collapse scenarios.

Original language | English (US) |
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Pages (from-to) | 1858-1867 |

Number of pages | 10 |

Journal | Physical Review D |

Volume | 40 |

Issue number | 6 |

DOIs | |

State | Published - 1989 |

Externally published | Yes |

## ASJC Scopus subject areas

- Physics and Astronomy (miscellaneous)