Predict the composition of dark matter

Predict the composition of dark matter

Shedding new light on dark matter

Artist’s rendering of the big bang nucleosynthesis, the first period in the universe in which protons “p” and neutrons “n” combine to form light elements. The presence of dark matter “χ” changes the amount of each element that will form. Credit: Cara Giovanetti/New York University

A new analysis by a team of physicists offers an innovative way to predict “cosmological signatures” for dark matter patterns.

A team of physicists has developed a method to predict the composition of dark matter, an invisible matter detected only by its gravitational pull on ordinary matter and whose discovery has long been sought by scientists.

His work, published in the journal Physical examination letters, focuses on the prediction of “cosmological signatures” for models of dark matter whose mass is between that of the electron and that of the proton. Previous methods had predicted similar signatures for simpler models of dark matter. This research establishes new ways to find these signatures in more complex patterns, which experiments continue to search for, the paper’s authors note.

“Experiments that search for dark matter are not the only way to learn more about this mysterious type of matter,” says Cara Giovanetti, who holds a doctorate. student in the Department of Physics at New York University and senior author of the paper.






This visualization from a computer simulation showcases the “cosmic web,” the large-scale structure of the universe. Each bright node is an entire galaxy, while the purple filaments indicate where matter is between galaxies. To the human eye, only the galaxies would be visible, and this visualization allows us to see the strands of matter connecting the galaxies and forming the cosmic web. This visualization is based on a scientific simulation of structure growth in the universe. Matter, dark matter and dark energy in a region of the universe are tracked from the earliest times of the universe to the present day using the equations of gravity, hydrodynamics and cosmology . Normal matter has been cut out to show only the densest regions, which are the galaxies, and is shown in white. Dark matter is shown in purple. The size of the simulation is a cube with a side length of 134 megaparsecs (437 million light years). Credit: Hubblesite; Visualization: Frank Summers, Space Telescope Science Institute; Simulation: Martin White and Lars Hernquist, Harvard University.

“Precision measurements of different parameters of the universe – for example, the amount of helium in the universe or the temperatures of different particles in the early universe – can also tell us a lot about dark matter,” adds Giovanetti, describing the method described in the Physical examination letters paper.

In the research, conducted with Hongwan Liu, an NYU postdoctoral fellow, Joshua Ruderman, an associate professor in NYU’s physics department, and Princeton physicist Mariangela Lisanti, Giovanetti and his co-authors focused on the nucleosynthesis of the big bang (BBN) – a process by which light forms of matter, such as helium, hydrogen and lithium, are created. The presence of invisible dark matter affects the formation of each of these elements. The cosmic microwave background (CMB) is also vital for these phenomena, that is, the electromagnetic radiation, generated by the combination of electrons and protons, which remained after the formation of the universe.

The team looked for a way to spot the presence of a specific category of dark matter – one whose mass falls between that of the electron and the proton – by creating models that take into account both the BBN and the CMB.

“Such dark matter can alter the abundance of certain elements produced in the early universe and leave an imprint in the cosmic microwave background by altering the expansion rate of the universe,” says Giovanetti.

In their research, the team made predictions of cosmological signatures related to the presence of certain forms of dark matter. These signatures are the result of dark matter altering the temperatures of different particles or altering the expansion rate of the universe.

Their results showed that dark matter that is too light will lead to different amounts of light elements than what astrophysical observations see.

“Lighter forms of dark matter could cause the universe to expand so rapidly that these elements have no chance of forming,” says Giovanetti, outlining one scenario.

“We learn from our analysis that some models of dark matter cannot have too small a mass, otherwise the universe would be different from the one we observe,” she adds.


New Theory Suggests Dark Matter Can Create New Dark Matter From Ordinary Matter


More information:
Cara Giovanetti et al, Joint Cosmic Microwave Background and Big Bang Nucleosynthesis Constraints on Light Dark Sectors with Dark Radiation, Physical examination letters (2022). DOI: 10.1103/PhysRevLett.129.021302

Provided by New York University

Quote: Predicting the composition of dark matter (2022, July 6) Retrieved July 7, 2022 from https://phys.org/news/2022-07-composition-dark.html

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