Friday, October 22, 2021

Stars made of antimatter could lurk in the Milky Way

 

Fourteen pinpricks of sunshine on a gamma-ray map of the sky may match the invoice for antistars, stars made from antimatter, brand new research suggests.

These antistar candidates appear to present in the form of gamma rays which might be produced when antimatter — matter’s oppositely charged counterpart — meets regular matter and annihilates. This may occur on the surfaces of antistars as their gravity attracts in regular matter from the interstellar house, researchers report online April 20 in Physical Review D.

“If, by any chance, one can prove the existence of the antistars … that would be a major blow for the standard cosmological model,” says Pierre Salati, a theoretical astrophysicist on the Annecy-le-Vieux Laboratory of Theoretical Physics in France not concerned within the work. It “would really imply a significant change in our understanding of what happened in the early universe.”

It’s usually thought that though the universe was born with equal quantities of matter and antimatter, the trendy universe contains almost no antimatter (SN: 3/24/20). Physicists usually assume that because the universe developed, some processes led to matter particles vastly outnumbering their antimatter alter egos (SN: 11/25/19). But an instrument on the International Space Station not too long ago solid doubt on this assumption by detecting hints of some antihelium nuclei. If these observations are confirmed, such stray antimatter may have been shed by antistars.

Intrigued by the chance that a few of the universe’s antimatter could have survived within the type of stars, a group of researchers examined 10 years of observations from the Fermi Gamma-ray Space Telescope. Among practically 5,800 gamma-ray sources within the catalog, 14 factors of sunshine gave off gamma rays with energies anticipated of matter-antimatter annihilation, however didn’t appear like some other identified kind of gamma-ray supply, reminiscent of a pulsar or black gap.

Based on the variety of noticed candidates and the sensitivity of the Fermi telescope, the group calculated what number of antistars may exist within the photovoltaic neighborhood. If antistars existed throughout the aircraft of the Milky Way, the place they may accrete a lot of fuel and mud made from strange matter, they may emit a lot of gamma rays and be straightforward to identify. As a result, the handful of detected candidates would suggest that just one antistar exists for every 400,000 regular stars.

If then again, antistars tended to exist outdoors the aircraft of the galaxy, they might have a lot much less alternative to accrete regular matter and be a lot tougher to search out. In that situation, there might be as much as one antistar lurking amongst every 10 regular stars.

But proving that any celestial object is an antistar could be extraordinarily tough, as a result of apart from the gamma rays that would come up from matter-antimatter annihilation, the sunshine given off by antistars is anticipated to look similar to the sunshine from regular stars. “It would be practically impossible to say that [the candidates] are actually antistars,” says research co-author Simon Dupourqué, an astrophysicist on the Institute of Research in Astrophysics and Planetology in Toulouse, France. “It would be much easier to disprove.”

Astronomers may watch how gamma rays or radio alerts from the candidates change over time to double-check that these objects aren’t actually pulsars. Researchers may additionally search for optical or infrared alerts that may point out the candidates are literally black holes.

“Obviously this is still preliminary … but it’s interesting,” says Julian Heeck, a physicist at the University of Virginia in Charlottesville not concerned with the work.

The existence of antistars would suggest that substantial quantities of antimatter someway managed to outlive in remoted pockets of house. But Heeck doubts that antistars if they exist, could be plentiful sufficient to account for all of the universe’s lacking antimatter. “You would still need an explanation for why matter overall dominates over antimatter.”

 

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