In a new article in the diary Physical Review Lettersan international team of theoretical physicists described a scenario for the formation of primordial black holes from vacuum bubbles in the early Universe and discussed its intriguing realization that can naturally explain all dark matter.
“Baby universes” branching off from our Universe shortly after the Big Bang appear to us as black holes. Image credit: Kavli Institute for the Physics and Mathematics of the Universe.
Primordial black holes are hypothetical compact objects that formed in front of galaxies and stars in the early Universe.
They are a suitable candidate for dark matter, the missing matter that, according to astrophysicists, makes up 85% of the universe.
First imagined a few decades ago, these compact objects could play a central role in a variety of astrophysical phenomena, such as precursors of gravitational waves and seeds for the formation of supermassive black holes.
They can also play a role in the synthesis of heavy elements when they collide with and destroy neutron stars, releasing neutron-rich material.
In the new article, Dr. Alexander Kusenko of the Kavli Institute for the Physics and Mathematics of the Universe and the University of California, Los Angeles and his colleagues from Japan, the United States and Taiwan presented a ‘multiverse’ scenario of primordial black hole formation.
“The early Universe was so dense that any positive swing in density of more than 50% would create a black hole,” they explained.
“However, it is known that cosmological perturbations that seeded galaxies have are much smaller. Nevertheless, a number of processes in the early Universe could have created the right conditions for the formation of black holes. “
“An exciting possibility is that primal black holes may emerge from the ‘baby universes’ that formed during the inflation, a period of rapid expansion believed to be responsible for seeding the structures we observe today, such as galaxies and galaxy clusters. “
“Baby universes can branch off from our universe during the inflation process. A small baby (or “daughter”) universe would eventually collapse, but the large amount of energy released into the small volume creates a black hole. “
“An even stranger fate awaits a larger baby universe. If it is greater than some critical dimension, Einstein’s theory of gravity allows the baby universe to exist in a state that looks different from an observer inside and out. “
“An internal observer sees it as an expanding universe, while an external observer sees it as a black hole.”
“In both cases, the large and small baby universes are seen by us as primal black holes, hiding the underlying structure of multiple universes behind their event horizon.”
Dr. Kusenko and co-authors also showed that primordial black holes can be detected using the Hyper Suprime-Cam (HSC) of the 8.2 m Subaru telescope.
“We demonstrate with numerical studies that future observations of HSC, as well as other optical investigations such as the Vera C. Rubin Observatory, will be able to provide a definitive test for this generic primal black hole formation mechanism if it is the dominant one. source is. of dark matter, ”they said.
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Alexander Kusenko et al. 2020. Investigation of primary black holes from the multiverse with optical telescopes. Phys. Rev. Lett 125 (18): 181304; doi: 10.1103 / PhysRevLett.125.181304