A new study proposed a scenario that dark matter could be made from ultralight dark photons that warmed our universe.
The Cosmic Origin Spectrograph (COS) aboard the Hubble Space Telescope, which measures the “cosmic web,” the intricate and thin filaments that fill the space between galaxies, says this hypothesis lines up perfectly with observations. According to the data collected by COS, the hydrodynamic simulations of the traditional model of structure formation indicate that the cosmic intergalactic filaments are hotter than they are.
Scientists said, “Because dark photons can be converted into low-frequency photons and the cosmic structures can heat up. They could explain the experimental information well.”
Authors James S. Bolton (University of Nottingham), Andrea Caputo (CERN and Tel Aviv University), Hongwan Liu (New York University), and Matteo Viel (SISSA) explain: “Dark photons are hypothetical new particles that are the force carriers for a new one force in the dark sector, just as the photon is the force carrier for electromagnetism. However, unlike photons, they can have mass. In particular, the ultra-light dark photon – with a mass as small as twenty orders of magnitude less than the electron – is a good candidate for dark matter.”
Similar to how different types of neutrinos mix, dark and regular photons are expected to do the same, allowing ultralight dark photons to transform dark matter into low-frequency photons. The cosmic web is heated by these photons, but unlike other heating mechanisms based on astrophysical processes, such as star formation and galactic winds, this heating process is more diffuse and effective, even in places that are not very dense.
Matteo Viel explains: “Usually, cosmic filaments have been used to investigate small-scale properties of dark matter, while in this case we used for the first time the intergalactic low-redshift medium data as a calorimeter to check whether all the heating processes that we are aware of are sufficient to make the data We found that this is not the case: something is missing that we model as a contribution from the dark photon.”
- James S. Bolton, Andrea Caputo, Hongwan Liu and Matteo Viel. Comparison of low redshift Lyman-α forest observations and hydrodynamic simulations with Dark Photon Dark Matter. Physical assessment letters. DOI: 10.1103/PhysRevLett.129.211102