Dark matter is made up of dark photons that fill the space between galaxies.

Artistic representation of dark matter. (Credit: Tchaikovsky2, Deviant Art)

Dark matter may be made up of ultralight dark photons that have heated up our universe: this is a new scenario proposed in a study recently published in the scientific journal Physical Review Letters.

This hypothesis, the authors say, fits perfectly with observations made by the Cosmic Origin Spectrograph (COS) aboard the Hubble Space Telescope, which measures the “cosmic web,” the complex and sparse network of filaments that fills space. between galaxies.

Data collected by COS suggests that cosmic intergalactic filaments are hotter than predictions from hydrodynamic simulations of the Standard Structure Formation Model.

“Since dark photons could be converted into low-frequency photons and heat cosmic structures,” the scientists explain, “they could well explain the experimental information.” The study was conducted by SISSA researchers in collaboration with researchers from Tel Aviv, Nottingham and New York Universities.

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“Dark photons are a good candidate for dark matter”

“Dark photons are hypothetical new particles that are the force carriers for the new force in the dark sector, much like the photon is the force carrier for electromagnetism,” argue authors James S. Bolton (University of Notingham), Andrea Caputo (CERN and Tel Aviv University), Hongwang Liu (New York University) and Matteo Wil (SISSA).

“However, unlike a photon, they can have mass. In particular, the ultralight dark photon — with a mass only twenty orders of magnitude smaller than an electron — is a good candidate for dark matter.”

It is also expected that dark photons and ordinary photons will mix like different types of neutrinos, allowing ultralight dark matter photons to transform into low-frequency photons.

A two-dimensional projection of the cosmic web, obtained as a result of simulation on a supercomputer. (TEACHER: Dr. Ewald Puchwein and the Sherwood-Relics Collaboration)

These photons will heat the cosmic web, but unlike other heating mechanisms based on astrophysical processes such as star formation and galactic winds, this heating process is more diffuse and efficient even in low density regions.

missing element

Matteo Wiel explains: “Typically, cosmic filaments have been used to investigate the small-scale properties of dark matter, whereas in this case, for the first time, we used data from the low-redshift intergalactic medium as a calorimeter to check whether all the heating processes we observe are sufficient to play back the data.

The gray solid curves show the case of no dark photon heating, while the other curves illustrate the effect of changing ϵ (left) or mA0 (right). Bottom panel: Thermal history of baryons at a fixed excess density, Δb, assuming m−13 = 0.8 and ϵ−14 = 0.5. The gray curves again show the case of no heating by dark photons. (CREDIT: Physical Review Letters)

We found that this is not the case: something is missing, which we model as the contribution of the dark photon.”

The work determined the mass and mixing of a dark photon with a photon of the Standard Model, necessary to eliminate the discrepancy between observations and simulations; this effort could lead to further theoretical and observational studies to explore the exciting possibility that a dark photon could constitute dark matter.

For more science and technology news, visit our New Discoveries section at The bright side of the news.

Note: Materials courtesy of Scuola Internazionale Superiore di Studi Avanzati. Content can be edited for style and length.

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