The Kavli Institute of Universe Physics and Mathematics (Kavli IPMU) is home to many interdisciplinary projects that benefit from the synergy of the Institute’s extensive expertise. One of the projects is to study black holes that may have formed in the early universe before the birth of stars and galaxies.
This type of primitive black hole (PBH) may account for all or part of the dark matter, and is responsible for some observed black holes Gravitational waves Signals, and supermassive black holes found in the center of the Milky Way and other galaxies. When they collide with neutron stars and destroy them, releasing neutron-rich material, they may also play a role in the synthesis of heavy elements.
A particularly exciting possibility is that the mysterious dark matter, which accounts for most of the matter in the universe, is composed of primitive black holes. A theorist Roger Penrose and two astronomers Reinhard Genzel and Andrea Ghez were awarded the 2020 Nobel Prize in Physics , Because their discovery confirmed the existence of black holes. Since black holes are known to exist in nature, they are very suitable for dark matter.
An international team of particle physicists, cosmologists, and astronomers, including Kavli IPMU members Alexander Kusenko, Misao Sasaki, Sunao Sugiyama, Masahiro Takada, and Volodymyr Takhistov, has made achievements in finding the basic theories of PBH, astrophysics and astronomical observations. latest progress.
In order to learn more about primordial black holes, the research team studied clues to the early universe.The early universe was so dense that any positive density fluctuations over 50% would produce Black hole. However, the cosmic disturbance of the known galaxy seeds is much smaller. However, many processes in the early universe may have created the right conditions for the formation of black holes.
An exciting possibility is that the original black hole may have formed from the “baby universe” formed during inflation, a period of rapid expansion, which is believed to be responsible for the structures we observe today (such as galaxies and galaxies Mission) The reason for sowing. During inflation, the baby universe can branch off from our universe. A small baby (or “daughter”) universe will eventually collapse, but the large amount of energy released in a small volume can lead to the formation of black holes.
The bigger baby world awaits a more peculiar fate. If it is greater than a certain critical size, Einstein’s theory of gravity allows the baby universe to exist in a state different from internal and external observers. Internal observers see it as an expanding universe, while external observers (such as us) see it as a black hole. In either case, we regard baby universes large and small as primitive black holes, which hide the basic structure of multiple universes behind their “event horizon”. The event horizon is a boundary under which all objects (even light) are captured and cannot escape the black hole.
The research team described the new situation of PBH formation in the paper and showed that the Super Suprime-Cam (HSC) of the 8.2m Subaru Telescope can be used to find the black hole in the huge “multiverse” scene. The management of Kavli IPMU played a vital role-near the mountain peak at 4,200 meters above sea level. Mauna Kea in Hawaii. Kavli IPMU principal researcher Masahiro Takada and his team are pursuing the goal of their exciting expansion of HSC search PBH. The HSC team recently reported Niakura, Takada, and others on the main limitations of PBHs. Natural Astronomy 3, 524–534 (2019)
Why is HSC essential in this research? HSC has the unique function of imaging the entire Andromeda galaxy every few minutes. If the black hole reaches one of the stars through the line of sight, the black hole’s gravity will bend the light and make the star appear brighter than before in a short time. The duration of the brightening of the star tells astronomers the mass of the black hole. Through HSC observations, one person can observe 100 million stars at the same time, thus casting a vast net for primitive black holes that may pass through a certain line of sight.
The earliest HSC observations have reported a very interesting candidate event, consistent with the PBH in the “multiverse”, the mass of the black hole is comparable to that of the moon. Encouraged by the first signs, and guided by the new theoretical understanding, the research team is conducting a new round of observations to expand the search range and provide deterministic tests to verify whether PBH in multi-universe scenarios can be used Solve all dark matter.
References: October 30, 2020, Alexander Kusenko, Sasaki Mio, Sugiyama Aoo, Takada Masahiro, Vladimir Tagistov and Eduardo Vitaliano, “Using an optical telescope Exploring primitive black holes from multiple universes”, October 30, 2020, Medical letter.
DOI: 10.1103 / PhysRevLett.125.181304