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Predicting the composition of dark matter

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An artist’s representation of Big Bang nucleosynthesis, a period in the early universe when protons “p” and neutrons “n” combine to form light elements. The presence of dark matter “χ” changes the amount of each element that will be formed. Credit: Kara Giovannetti/New York University.

A new analysis by a team of physicists offers an innovative means to predict the “cosmological signatures” of dark matter models.

A team of physicists has developed a method to predict the composition of dark matter, invisible matter only detectable due to its gravitational pull on ordinary matter, which scientists have long sought to discover.

His work that appears in the magazine Physical Review Letters, is focused on predicting “cosmological signatures” for dark matter models with a mass between an electron and a proton. Previous methods have predicted similar signatures for simpler models of dark matter. This study establishes new ways of finding these signatures in more complex models that experiments continue to seek, the authors of the article note.

“Experiments looking for dark matter are not the only way to learn more about this mysterious type of matter,” says Cara Giovannetti, Ph.D. physics student at New York University and lead author of the paper.






This visualization of a computer simulation demonstrates the “cosmic web”, the large-scale structure of the universe. Each bright knot is an entire galaxy, and the purple filaments show where the material is between the galaxies. Only galaxies will be visible to the human eye, and this visualization allows us to see the strands of material connecting the galaxies and forming the cosmic web. This visualization is based on scientific modeling of the growth of structure in the universe. Matter, dark matter and dark energy in a certain region of the universe are traced from the earliest 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, which are galaxies, and shown in white. Dark matter is shown in purple. The size of the simulation is a cube with a side of 134 megaparsecs (437 million light years). Credit: Hubblesite; Visualization: Frank Summers, Space Telescope Science Institute; Modeling: Martin White and Lars Hernquist, Harvard University.

“Precise measurements of various parameters of the universe — such as the amount of helium in the universe or the temperature of various particles in the early universe — can also tell us a lot about dark matter,” adds Giovanetti, describing the described method. in Physical Review Letters paper.

In a study with Hongwang Liu, an NYU postdoctoral fellow, Joshua Ruderman, an associate professor in the NYU Department of Physics, and Princeton physicist Mariangela Lisanti, Giovannetti and her co-authors focused on Big Bang Nucleosynthesis (BBN), a process that lighter forms of matter such as helium, hydrogen and lithium have been 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), the electromagnetic radiation generated by the union of electrons and protons that is left over from the formation of the universe.

The team was looking for a way to detect the presence of a particular category of dark matter — with a mass between an electron and a proton — by building models that account for both BBN and CMB.

“Such dark matter can change the abundance of certain elements produced in the early universe and leave an imprint on the cosmic microwave background, changing the expansion rate of the universe,” explains Giovanetti.

In their study, 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 the expansion rate of the universe.

Their results showed that too light dark matter would result in different amounts of light elements than what astrophysical observations see.

“Light forms of dark matter could cause the universe to expand so rapidly that these elements would not have a chance to form,” says Giovannetti, outlining one scenario.

“From our analysis, we learned that some models of dark matter cannot have too little mass, otherwise the universe would look different than the one we observe,” she adds.


New theory suggests dark matter can create new dark matter from ordinary matter


Additional Information:
Cara Giovannetti et al., Joint Cosmic Microwave Background and Limitations of Big Bang Nucleosynthesis on Light Dark Sectors with Dark Radiation, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.129.021302

Courtesy of New York University

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

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