Starship Asterisk*

In shaping the Universe, gravity builds a vast cobweb-like structure of filaments tying galaxies and clusters of galaxies together along invisible bridges hundreds of millions of light-years long. This is known as the cosmic web. ~ Credit: Volker Springel (MPA) et al.

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There’s some potentially big news on the hunt for dark matter. Astronomers may have a handle on what makes this mysterious cosmic stuff: strange particles called “axions.”

Rather than search directly for axions, however, a multinational team of researchers led by Keir Rogers from the University of Toronto looked for something else. They focused on the “clumpiness” of the Universe and found that cosmic matter is more evenly distributed than expected.

So, what role do axions play here? Quantum mechanics explains these ultra-light particles as “fuzzy” because they exhibit wave-like behavior. It turns out their wavelengths can be bigger than entire galaxies. Apparently, that fuzziness plays a role in smoothing out the Universe by influencing the formation and distribution of dark matter. If that’s true, then it goes a long way toward explaining why the matter in the cosmos is more evenly spread out. It implies that axions play a part in the distribution of matter in the cosmos.

It’s an interesting idea, and a big step forward if the team can test their theory through other means. “If confirmed with future telescope observations and lab experiments, finding axion dark matter would be one of the most significant discoveries of this century,” said Rogers. “At the same time, our results suggest an explanation for why the Universe is less clumpy than we thought, an observation that has become increasingly clear over the last decade or so, and currently leaves our theory of the Universe uncertain.” ...

• Cosmology and Astroparticle Physics 2023(06):023 (June 2023) DOI: 10.1088/1475-7516/2023/06/023
• arXiv > astro-ph > arXiv:2301.08361 > 19 Jan 2023 (v1), 18 May 2023 (v2)