Overview

Dark matter and dark energy constitute two of the greatest mysteries of modern physics. Both populate the universe and are found in vast amounts on a large scale, agglutinating and separating the cosmologic structures. The great minds of modern science outline new and revolutionary ideas that help to understand the mysterious nature of these components. In this sense, an international team of researchers has proposed that part of the heat we observe in the cosmos could come from no less than a hypothetical dark matter component: dark photons.

The science and other stuff to know

Physicists must be extremely creative and resourceful in explaining the phenomena they observe simply and concisely. Dark matter is the most stealthy component of the cosmos, whose essence remains mysterious, although its effects are easily noticeable since none of the structures we see would exist without it.

We know dark matter exists because even though we can’t see it, we can ‘feel’ it. This is because it surrounds galaxies and clusters of galaxies providing enough gravity to hold them together. Otherwise, the centripetal energy of the rotation would push the farthest stars, and the galaxies would eventually break apart.

Now a new study proposes a novel way to detect dark matter and even some of its elusive components. The results have been recently published in the Physical Review Letters. In their paper, the specialists explore the possibility that a type of theoretical component of dark matter known as a dark photon is responsible for intergalactic heating clouds of gas.

By studying the light emitted by quasars — old and distant galaxies that emit large amounts of radio waves — the researchers found a model of dark matter in which some of the dark photons are excited and become ordinary photons can explain the observed heating of intergalactic gas clouds.

The spectrum is the light signature of an object. When physicists study the path of distant quasars through the intervening gas clouds, they see a pattern in the footprint called the Lyman-alpha Forest. The clouds closest to us show this effect amplified. The model proposes that nearby clouds heat up from interaction with dark matter, causing the effect observed in the absorption lines of the quasar spectrum.

“This may be an indication of a particular candidate of dark matter, which is called a dark photon. This dark photon can inject some energy and heat up the gas, making the lines a bit broader, in better agreement with the data,” lead author Andrea Caputo told APS.

So what?

The study suggests that dark photons could be the cornerstone in solving the dark matter puzzle. In addition, it provides a robust theoretical framework to explain certain phenomena, such as the Lyman-alpha anomalies observed in the quasar spectrum.

The authors communicated via email with Phys and commented: “Broadly speaking, we have shown that the Lyman-alpha forest is extremely useful for understanding dark matter models where energy can be converted from dark matter into heating. I think our study will encourage physicists interested in [dark matter] to pay more attention to the Lyman-alpha forest.”

What’s next?

Although dark photons are an exciting possibility and a strong candidate for a component of the elusive dark matter, many experts remain skeptical about it. Furthermore, they consider it prudent to be concerned with ruling out other possibilities, like the influence of active galactic nuclei.

However, the need to understand the structure of dark matter cannot be relegated. Cosmologist Sam Witte — who was not involved in the study — says: “Should future studies exclude conventional astrophysical explanations, it is compelling to consider the possibility that we might be observing the first nongravitational imprint of dark matter.”