[OSU Physics logo]

HEP/Astro Seminar -- Wednesday, 26 April 2000

The Last Eight Minutes of a Primordial Black Hole

Joseph Kapusta, (Minnesota)


About eight minutes before a black hole expires it has a decreasing mass of 1010 g, an increasing temperature of 1 TeV, and an increasing luminosity of 7×1027 erg/s. I show that such a black hole is surrounded by a quasi-stationary shell of matter undergoing radial hydrodynamic expansion. The inner radius of this shell is bounded by ten times the Schwarzschild radius of 1.6×10-5 fm and has a temperature about one-tenth that of the black hole. The outer radius, as defined by the photosphere, is about 1000 fm, has a local temperature of 100 keV, and is moving with a Lorentz gamma factor of 107. Most of the emitted radiation is in photons with small amounts in gravitons and neutrinos. I calculate the instantaneous photon spectrum and then integrate it over the last eight minutes to obtain the energy distribution dNγ/dE = 4 π mP2/15 E3 for E > several TeV. The flux of photons arriving at Earth is calculated assuming the primodial black holes are distributed in the galactic halo, and limits on the rate density of these explosions are determined.

3:30pm, Smith Lab 4079

George T. Fleming (gfleming@mps.ohio-state.edu), last updated 29 March 2000.