Predicting the composition of dark matter

Shedding new light on dark matter

An artistic depiction of the big bang nucleosynthesis, the early period of the universe in which protons “p” and neutrons “n” come together to form light elements. The presence of dark matter “χ” changes how much of each element will be formed. 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 models.

A team of physicists has developed a method to predict the composition of dark matter – invisible matter that is only detected by its gravity On ordinary thing and whose discovery has long been sought after by scientists.

His work, which appears in the magazine Physical Assessment Letters, focuses on predicting “cosmological signatures” for models of dark matter with masses between that of the electron and 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 models, which experiments continue to look for, the paper authors note.

“Dark matter searching experiments aren’t the only way to learn more about this mysterious type of matter,” said Cara Giovanetti, a Ph.D. student in New York University’s Department of Physics and the lead author of the paper.






This visualization of a computer simulation shows the ‘cosmic web’, the large-scale structure of the universe. Each bright node is an entire galaxy, while the purple filaments show where there is material between the galaxies. To the human eye, only the galaxies would be visible, and this visualization allows us to see the strands of material that connect the galaxies and form the cosmic web. This visualization is based on a scientific simulation of the growth of structure in the universe. The matter, dark matter, and dark energy in an area of ​​the universe are tracked from the very early times of the universe to the present day using the equations of gravity, hydrodynamics, and cosmology. Normal matter has been cropped to show only the densest regions, namely the galaxies, and is shown in white. The 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: Hubble Site; Visualization: Frank Summers, Space Telescope Science Institute; Simulation: Martin White and Lars Hernquist, Harvard University.

“Precision measurements of various parameters of the universe, for example the amount of helium in the universe or the temperatures of different particles in the universe. early universe— can also teach us a lot about dark matter,” adds Giovanetti, who outlines the method described in the Physical Assessment Letters paper.

In the study, conducted with Hongwan Liu, a postdoctoral researcher at NYU, Joshua Ruderman, an associate professor in NYU’s Department of Physics, and Princeton physicist Mariangela Lisanti, Giovanetti and her co-authors focused on big bang nucleosynthesis (BBN) – a process in which light forms of matter, such as helium, hydrogen and lithium, are created. The presence of invisible dark matter affects how each of these elements will form. Also vital to these phenomena is the cosmic microwave background (CMB)—electromagnetic radiationgenerated by combining electrons and protons, which were left over from the formation of the universe.

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

“Such dark matter can alter the abundances of certain elements produced in the early universe and leave an imprint in the cosmic microwave background by altering how fast the universe is expanding,” explains Giovanetti.

In its research, the team made predictions of cosmological signatures associated with the presence of certain forms of dark matter. These signatures are the result of dark matter changing the temperature of various particles or changing how fast the universe is expanding.

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

“Lighter forms of dark matter could cause the universe to expand so quickly that these elements don’t have a chance to form,” says Giovanetti, who outlines a scenario.

“We learn from our analysis that some models of dark matter must not have a mass that is too small, otherwise the universe would look 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 Assessment Letters (2022). DOI: 10.1103/PhysRevLett.129.021302

Quote: Predicting Dark Matter Composition (2022, July 6), retrieved July 6, 2022 from https://phys.org/news/2022-07-composition-dark.html

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