Antimatter stars may be hidden in the Milky Way

04/28/2021 at 08:00 CEST

Researchers at the Institut de Recherche en Astrophysique et Planétologie (IRAP), in France, have identified for the first time a set of antimatter stars present in the Milky Way.

They have discovered fourteen flashes in a gamma ray map of the sky that could reveal the existence of antistars in our galaxy.

The discovery is a double surprise: on the one hand, because, according to cosmological models, until now it has been believed that the Universe does not contain substantial amounts of antimatter.

On the other hand, because, even knowing that in some region of the Universe there may be enough antimatter to form antistars, we have never assumed that they can be close to us.

We have believed that neither on Earth, nor in our solar system, not even in the Milky Way, there are sufficient amounts of antimatter to represent a threat to life on our planet.

We have now discovered that enough antimatter exists in our own cosmic neighborhood to create stars with the hypothetical ability to destroy stars or celestial bodies of matter.

Close to home!

Close to home!The fourteen flashes detected emit a type of gamma ray that is only produced when antimatter meets normal matter and mutually annihilates each other.

This is what appears to be happening in our neighborhood, the researchers warn in an article published in the journal Physical Review D.

Antimatter is a form of matter made up of antiparticles, the fundamental characteristic of which is that they have an electrical charge opposite to that of the particles.

When matter and antimatter come into contact, they both transform into high-energy photons and produce gamma rays, like those detected in the fourteen flashes of the Milky Way.

At first, it is believed that the universe had the same amount of matter as antimatter, but for unknown reasons matter eventually dominated over antimatter.

We have never found large antimatter structures in the universe, which could shape stars, galaxies, planets, and even living things composed of antimatter.

Related topic: Antimatter is also quantum

First signs

First signsBut we are looking for them: since 2011, the Alpha Magnetic Spectrometer 2 (AMS-02) experiment, installed on board the International Space Station (ISS), has been tracking the universe to detect exotic matter by measuring cosmic rays.

In 2018, AMS-02 detected several anthelion nuclei, suggesting that some original antimatter survived in the universe to form antistars and even antigalaxies.

After ten years of observations of gamma rays detected by the Fermi space telescope, which at an altitude of 550 kilometers covers the entire sky several times a day, the IRAP researchers have recognized specific gamma rays that reveal the existence of possible antistars on the Via Milky.

Among the 5,787 gamma ray sources identified, 14 light points emitted gamma rays with energies of matter-antimatter annihilation.

For this reason, the authors of this research are convinced that these gamma radiations are not due to other astrophysical phenomena, such as a pulsar or a black hole.

Are hidden

Are hiddenThey even consider that, although only a nearby antistar could have produced the anthelion detected by AMS-02, there may be a more intense source of gamma rays that would be located beyond the galactic center, where they suppose more antimatter stars are hiding.

Researchers calculate, based on the data collected, that in our galaxy, which is home to between 100 and 400 billion stars, there would only be one antistar for every 400,000 stars of matter. Beyond the galactic center, the ratio reaches one antistar for every 10 matter stars.

In any case, the authors of the research emphasize that these are preliminary results and that it is still not possible to be completely sure that there are antimatter stars in the Milky Way.

They also consider that its hypothetical existence does not explain the great unsolved mystery: why matter dominates over antimatter throughout the known universe.

Reference

ReferenceConstraints on the antistar fraction in the Solar System neighborhood from the 10-year Fermi Large Area Telescope gamma-ray source catalog. Simon Dupourqué, Luigi Tibaldo, and Peter von Ballmoos. Phys. Rev. D 103, 083016, 20 April 2021. DOI: https: //doi.org/10.1103/PhysRevD.103.083016

Top image: 14 celestial gamma-ray sources (colored dots on this map of the entire Milky Way sky; yellow indicates bright sources and blue shows faint sources) may come from stars made of antimatter. SIMON DUPOURQUÉ / IRAP