Speaker
Description
The 2017 Nobel Prize in Physics was awarded to three members of the
American LIGO (LIGO) team for the world's first detection of
gravitational waves. The gravitational waves were created by the
collision of binary black holes, each weighing
about 30 times more than the sun, about 1.3 billion light years
away. At the same time, this was the first observation to detect the
existence of a black hole without using electromagnetic
waves. However, the origin of such heavy black holes is still largely
unknown. Theoretically, density fluctuations (or curvature
perturbation) are predicted to have been created by inflation in the
early Universe. The theoretical model is that quantum fluctuations in
the inflaton field become density fluctuations. On
large scales, galaxies and galaxy clusters were formed by the collapse
of dark matter and matter seeded by those density fluctuations.
On the other hand, theory predicts that primordial black holes (PBHs)
and secondary gravitational waves were created from large density
fluctuations on untested small scales. The masses of PBHs vary, with
the lighter ones emitting Hawking radiation and evaporating away,
while the heavier ones remain to the present day and are candidates
for dark matter. Some of them may also form the black hole binary
stars mentioned above. For these reasons, the study of the formation
of PBHs and gravitational waves on small scales has been pointed out
as a possible key to solving the mystery of the birth of the Universe.
In my talk, the theoretical models will be explained from the
standpoints of both particle theory and cosmology. Finally, I discuss
how future observations will distinguish primordial black holes from
astrophysical black holes.
| Secondary category for the parallel session (optional) | Cosmology |
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