Exceptionally hot cosmic structures could indicate the presence of “dark photons” and thus explain the mysterious dark matter in the universe. This has been suggested by simulations conducted by a research group led by James S. Bolton from the University of Nottingham in the UK. Dark photons belong to a whole “zoo” of hypothetical particles that experts hypothesize on the basis of theoretical considerations.
In Physical Review Letters, the group shows an example of how dark photons can turn into ordinary photons. Assuming some mass for the alien particles, the resulting radiation could explain why the network of intergalactic filaments that criss-cross the universe is heating up more than expected.
The basic concept behind the search for dark matter is that there appears to be much more mass in the universe than is actually visible. So far, up to 85 percent of the case has evaded investigation. The currently accepted hypothesis is that the universe is filled with elementary particles that interact with visible matter almost exclusively through their mass. However, the nature of these “dark” particles is quite mysterious, especially since all attempts to detect them, for example in particle accelerators, have so far been unsuccessful. So some experts are looking for differences between theoretical values and measured data that could indicate interactions of visible matter with dark matter.
Some of these anomalies could indicate the existence of dark photons: particles that mediate another force of nature, just as photons are mediators of the electromagnetic force. Unlike photons, dark photons will have mass, but can only be detected indirectly, after decaying into electrons and positrons (the antiparticles of electrons). Furthermore, the theory predicts that these particles are a “mix” of photons and dark photons, that is, they morph into each other like different types of neutrinos. In this way, dark photons could be a hitherto unknown source of radiation. Bolton’s team reports that a source of radiation of this type could explain an observation by the Hubble Space Telescope.
According to data from the Cosmic Origin Spectrograph (COS) aboard the telescope, the largest structures in the universe are much hotter than theoretically expected. Cosmic filaments are structures made up of entire clusters of galaxies, which, due to their gravity, arrange themselves into filaments and “walls” and stretch out into the Universe for enormous distances. However, dark photons with some mass can provide the exact “warming” we’re looking for by converting them into photons.
But so little is known about the hypothetical “dark sector” of matter that the properties of these virtual particles can be calibrated—within certain limits—on almost any observation. Thus, the theory moves within the limits of possibility until it proves otherwise.
(The original of this article was Published in Spektrum der Wisseschaft on December 13, 2022. Translation and editing by “Le Scienze”. Reproduction is authorized, all rights reserved.)