Primordial Black Holes & Search For Dark Matter From Multiverse

Related Articles

Related Articles

The Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) is home to many interdisciplinary projects which benefit from the synergy of a wide range of expertise available at the institute.

One such project is the study of black holes that could have formed in the early universe, before stars and galaxies were born.

Such primordial black holes (PBHs) could account for all or part of dark matter, be responsible for some of the observed gravitational waves signals, and seed supermassive black holes found in the center of our Galaxy and other galaxies. They could also play a role in the synthesis of heavy elements when they collide with neutron stars and destroy them, releasing neutron-rich material. In particular, there is an exciting possibility that the mysterious dark matter, which accounts for most of the matter in the universe, is composed of primordial black holes. The 2020 Nobel Prize in physics was awarded to a theorist, Roger Penrose, and two astronomers, Reinhard Genzel and Andrea Ghez, for their discoveries that confirmed the existence of black holes. Since black holes are known to exist in nature, they make a very appealing candidate for dark matter.

 

The recent progress in fundamental theory, astrophysics, and astronomical observations in search of PBHs has been made by an international team of particle physicists, cosmologists and astronomers, including Kavli IPMU members Alexander Kusenko, Misao Sasaki, Sunao Sugiyama, Masahiro Takada and Volodymyr Takhistov.

To learn more about primordial black holes, the research team looked at the early universe for clues. The early universe was so dense that any positive density fluctuation of more than 50 percent would create a black hole. However, cosmological perturbations that seeded galaxies are known to be much smaller. Nevertheless, a number of processes in the early universe could have created the right conditions for the black holes to form.

One exciting possibility is that primordial black holes could form from the “baby universes” created during inflation, a period of rapid expansion that is believed to be responsible for seeding the structures we observe today, such as galaxies and clusters of galaxies. During inflation, baby universes can branch off of our universe. A small baby (or “daughter”) universe would eventually collapse, but the large amount of energy released in the small volume causes a black hole to form.

An even more peculiar fate awaits a bigger baby universe. If it is bigger than some critical size, Einstein’s theory of gravity allows the baby universe to exist in a state that appears different to an observer on the inside and the outside. An internal observer sees it as an expanding universe, while an outside observer (such as us) sees it as a black hole. In either case, the big and the small baby universes are seen by us as primordial black holes, which conceal the underlying structure of multiple universes behind their “event horizons.” The event horizon is a boundary below which everything, even light, is trapped and cannot escape the black hole.

In their paper, the team described a novel scenario for PBH formation and showed that the black holes from the “multiverse” scenario can be found using the Hyper Suprime-Cam (HSC) of the 8.2m Subaru Telescope, a gigantic digital camera—the management of which Kavli IPMU has played a crucial role—near the 4,200 meter summit of Mt. Mauna Kea in Hawaii. Their work is an exciting extension of the HSC search of PBH that Masahiro Takada, a Principal Investigator at the Kavli IPMU, and his team are pursuing. The HSC team has recently reported leading constraints on the existence of PBHs in Niikura, Takada et. al. (Nature Astronomy 3, 524–534 (2019)).

Why was the HSC indispensable in this research? The HSC has a unique capability to image the entire Andromeda galaxy every few minutes. If a black hole passes through the line of sight to one of the stars, the black hole’s gravity bends the light rays and makes the star appear brighter than before for a short period of time. The duration of the star’s brightening tells the astronomers the mass of the black hole. With HSC observations, one can simultaneously observe one hundred million stars, casting a wide net for primordial black holes that may be crossing one of the lines of sight.

The first HSC observations have already reported a very intriguing candidate event consistent with a PBH from the “multiverse,” with a black hole mass comparable to the mass of the Moon. Encouraged by this first sign, and guided by the new theoretical understanding, the team is conducting a new round of observations to extend the search and to provide a definitive test of whether PBHs from the multiverse scenario can account for all dark matter.

University of Tokyo

Header Image – Baby universes branching off of our universe shortly after the Big Bang appear to us as black holes. Image Credit: Kavli IPMU

Download the HeritageDaily mobile application on iOS and Android

More on this topic

LATEST NEWS

Study Sheds New Light on the Behaviour of the Giant Carnivorous Dinosaur Spinosaurus

New research from Queen Mary University of London and the University of Maryland, has reignited the debate around the behaviour of the giant dinosaur Spinosaurus.

New Skull of Tube-Crested Dinosaur Reveals Evolution of Bizarre Crest

The first new skull of a rare species of the dinosaur Parasaurolophus (recognized by the large hollow tube that grows on its head) discovered in 97 years.

Women Influenced Coevolution of Dogs and Humans

In a cross-cultural analysis, Washington State University researchers found several factors may have played a role in building the mutually beneficial relationship between humans and dogs, including temperature, hunting and surprisingly - gender.

Dinosaur Embryo Helps Crack Baby Tyrannosaur Mystery

They are among the largest predators ever to walk the Earth, but experts have discovered that some baby tyrannosaurs were only the size of a Border Collie dog when they took their first steps.

First People to Enter the Americas Likely Did so With Their Dogs

The first people to settle in the Americas likely brought their own canine companions with them, according to new research which sheds more light on the origin of dogs.

Climate Change in Antiquity: Mass Emigration Due to Water Scarcity

The absence of monsoon rains at the source of the Nile was the cause of migrations and the demise of entire settlements in the late Roman province of Egypt.

Archaeologists Discover Bas-Relief of Golden Eagle at Aztec Templo Mayor

A team of archaeologists from the Instituto Nacional de Antropologia e Historia (INAH) have announced the discovery of a bas-relief depicting an American golden eagle (aquila chrysaetos canadensis).

Lost Alaskan Fort of the Tlingit Discovered

Researchers from Cornell University and the National Park Service have discovered the remnants of a wooden fort in Alaska – the Tlingit people’s last physical bulwark against Russian colonisation forces in 1804.

Popular stories

Exploring the Stonehenge Landscape

The Stonehenge Landscape contains over 400 ancient sites, that includes burial mounds known as barrows, Woodhenge, the Durrington Walls, the Stonehenge Cursus, the Avenue, and surrounds the monument of Stonehenge which is managed by English Heritage.

The Iron Age Tribes of Britain

The British Iron Age is a conventional name to describe the independent Iron Age cultures that inhabited the mainland and smaller islands of present-day Britain.

The Roman Conquest of Wales

The conquest of Wales began in either AD 47 or 48, following the landing of Roman forces in Britannia sent by Emperor Claudius in AD 43.

Vallum Antonini – The Antonine Wall

The Antonine Wall (Vallum Antonini) was a defensive wall built by the Romans in present-day Scotland, that ran for 39 miles between the Firth of Forth, and the Firth of Clyde (west of Edinburgh along the central belt).