Dark matter could make the universe glow brighter

(ORDO NEWS) — The barely noticeable radiation from interstellar space turned out to be stronger than calculations predict. Perhaps part of this excess is created by axions – elusive particles of dark matter.

Interstellar space is dark, but not black. Where there are no visible sources of light, microwaves of the oldest cosmic microwave background can be found. The dust barely glows, creating the infrared background of the universe.

The cosmic background is also registered in the optical range. It is assumed that it is created by sources that are inaccessible to direct observation: for example, stars and galaxies located very far away.

A few years ago, the New Horizons space probe crossed Pluto’s orbit and was able to see the optical background in detail that no other instruments can.

The onboard telescope LORRI found that its emission is almost twice as bright as can be predicted using existing theories and models.

Now astrophysicists at Johns Hopkins University have hypothesized that the excess radiation could be due to dark matter.

Dark matter does not emit, absorb or scatter radiation, remaining invisible in any telescope. It can be traced only by the gravitational influence that large clusters have on the motions of stars and galaxies.

Such observations show that there is many times more dark matter in the Universe than ordinary matter and that it is this matter that determines its evolution on a large scale.

There are many hypotheses that predict the properties of dark matter particles, although none of them has yet received any firm confirmation. Candidates include axions, which can be extremely light and numerous.

Theoretically, their mass should be many orders of magnitude smaller than that of large bosons, and during decay they should emit a pair of photons.

The search for axions, or at least the radiation they create, has been going on for a long time, but so far has not yielded any results.

The authors of the new article suggest that they can be detected in the interstellar optical background.

According to the calculations of scientists, excess radiation can occur due to the decay of axions in an extremely powerful magnetic field, with a particle mass in the range of 8-20 electron volts.

This is much more than some theories predict – hundredths and thousandths of an electron volt. For comparison, the mass of an electron is about 0.5 MeV.

New observations can confirm or refute these calculations. On the same New Horizons distant probe, there is an instrument for working in the ultraviolet range.

And in the future, similar telescopes may appear that will cover the highest energy waves, up to x-rays and gamma rays.

All this will make it possible to refine the new hypothesis and, finally, to capture particles of dark matter. Past work gives some hope for this.

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