The Dark Matter Mystery Just Took a Weird Turn

TL;DR

A new study suggests galaxy clusters contain twice as much mass in dead stars as previously thought, making MOND a more viable alternative to dark matter.

Key Points

• 1.Galaxy clusters have been the strongest evidence against MOND for decades. MOND modifies gravity at tiny accelerations and works well for individual galaxies, but has historically predicted cluster masses off by a factor of ~2, requiring dark matter as a patch.
• 2.A new study of 46 galaxy clusters finds we've been undercounting normal matter. By modeling stellar populations, including neutron stars and black holes left by massive supernovae, the authors conclude clusters hold nearly twice as much mass in stellar remnants as earlier estimates.
• 3.With revised mass estimates, MOND's predictions align far better with cluster observations. The authors state MOND (Milgrom's theory) matches the new data, while standard dark matter models now require only half the dark matter previously assumed — a poor fit by their analysis.
• 4.The host rates the paper 7/10 on her 'bullshit meter,' calling the MOND resolution premature. The stellar-remnant counts rely on theoretical star-formation assumptions, the sample covers only 46 clusters, and MOND still faces challenges from gravitational lensing, wide binaries, and dark-matter-free galaxies.