Predicting the composition of dark matter
An artist’s performance of big bang nucleosynthesis, the early period of the universe in which proton “p” and neutron “n” combined to form light elements. The presence of dark matter “χ” changes how much each element will form. Credit: Cara Giovanetti/University of New York
A new analysis by a team of physicists offers an innovative way to predict the “cosmological signature” for dark matter models.
A team of physicists has developed a method for predicting the composition of dark matter—the invisible matter detected only by its gravitational pull on ordinary matter and its discovery has long been sought after by scientists.
His work, which appeared in the journal Physical Review Letter, centered on predicting a “cosmological signature” for dark matter models with masses between electrons and protons. Previous methods have predicted similar signatures for simpler dark matter models. The research establishes a new way to find these signatures in more complex models, which experiments continue to seek, note the authors of the paper.
“Experiments looking for dark matter are not the only way to learn more about this mysterious type of matter,” says Cara Giovanetti, Ph.D. student in New York University’s Department of Physics and lead author of this paper.
“Precise measurements of various parameters of the universe—for example, the amount of helium in the universe, or the temperatures of various particles in the early universe—can also teach us a lot about dark matter,” adds Giovanetti, outlining the method described in Physical Review Letter paper.
In research conducted with Hongwan Liu, an NYU postdoctoral fellow, Joshua Ruderman, a professor in the NYU Department of Physics, and Princeton physicist Mariangela Lisanti, Giovanetti and his co-authors focused on big bang nucleosynthesis (BBN)—a process by which light matter forms, such as helium, hydrogen, and lithium, which is created. The presence of invisible dark matter affects how each of these elements will form. Also important to this phenomenon is the cosmic microwave background (CMB)—electromagnetic radiation, produced by combining electrons and protons, that remained after the formation of the universe.
The team looked for a way to discover the existence of a particular category of dark matter—which has a mass between electrons and protons—by creating a model that took BBN and CMB into account.
“Such dark matter can modify the abundance of certain elements that were produced in the early universe and leave traces in the cosmic microwave background by modifying how fast the universe is expanding,” Giovanetti explained.
In their research, the team made predictions about cosmological signs associated with the presence of certain forms of dark matter. This signature is the result of dark matter changing the temperature of different particles or changing how fast the universe is expanding.
Their results suggest that dark matter that is too bright will produce different amounts of light elements than what astrophysical observations see.
“Lighter forms of dark matter probably made the universe expand so fast that these elements didn’t have a chance to form,” Giovanetti said, outlining one scenario.
“We learned from our analysis that some models of dark matter cannot have too small a mass, otherwise the universe would look different from what we observe,” he added.
New theory suggests dark matter can create new dark matter out of ordinary matter
Cara Giovanetti et al, Cosmic Microwave Background and Big Bang Nucleosynthesis Constraints in the Light Dark Sector with Dark Radiation, Physical Review Letter (2022). DOI: 10.103/PhysRevLett.129.021302
Provided by New York University
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