(GIST OF SCIENCE REPORTER) DARK MATTER

(FEBRUARY-2025)

Physicists have revised the minimum possible mass of a dark matter particle which is a significant update in the world of dark matter.

For decades scientists thought the minimum mass of dark matter particle was about 10-31 times the mass of a proton. This was based on theoretical models and observations of the universe.
But in May 2024, theoretical physicists revised the limit and pushed it up by an order of magnitude, to 2.3 × 10-30 proton masses. This is a significant increase, about ten times larger than the previous estimate.
Using data on how stars move in Leo II, a dwarf galaxy orbiting the Milky Way, scientists inferred the dark matter density in it as a function of the distance from its centre. This density profile isn’t unique due to measurement uncertainties, so they generate a set consistent with the stellar data.
Next, they numerically solved the Schrödinger equation after modifying it to account for gravity and obtained an ensemble of density profiles.
Finally, they carried out a statistical procedure to match the two sets of density profiles - the empirical one from observing Leo II and the theoretical one from solving the equation.
Their key finding here was that the inner regions of Leo II contained more invisible mass and which dark particles of 10-31 proton mass couldn’t account for. Thus, they surmised heavier particles are needed to accommodate the inner crowding.