Primordial Black Holes from Bubbles.
Deng, Heling.
2019
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We use theoretical analysis and numerical simulations to study a primordial black hole model, in which black holes are formed from bubbles that nucleate during inflation. Such bubbles can be formed via quantum tunneling of a scalar field in a double well potential. If the two wells have different energy scales, the resulting bubbles have an interior close to the true vacuum. They start with a small ... read moresize, and then expand into the false vacuum at the speed of light. After inflation ends, the bubbles are quickly slowed down, transferring their momentum to a shock wave that propagates outwards into the radiation background. If the two wells of the scalar field potential are degenerate, the bubbles are spherical domain walls. They nucleate with the Hubble size, and then get stretched by the inflationary expansion. After inflation, the repulsive nature of the bubble walls pushes the ambient radiation fluid away, and a shell of rarefaction wave propagates outwards. In both vacuum bubble and spherical domain wall scenarios, the fate of the bubbles depends on their sizes at the end of inflation. Small bubbles eventually collapse into a singularity; large bubbles grow without bound into a baby universe, which is connected to our universe by a wormhole that eventually turns into two black holes at the two mouths of the wormhole throat. In both scenarios the resulting black hole population has a wide distribution of masses and can have significant astrophysical effects. They may provide a significant part or even the whole of the dark matter, account for LIGO observations and may also provide seeds for supermassive black holes observed at galactic centers. Perturbations of the radiation fluid by the bubbles may also lead to spectral distortion in the cosmic microwave background.
Thesis (Ph.D.)--Tufts University, 2019.
Submitted to the Dept. of Physics.
Advisor: Alexander Vilenkin.
Committee: Jose Blanco- Pillado, Larry Ford, Ken Olum, and Krzysztof Sliwa.
Keyword: Physics.read less - ID:
- bk128q21c
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