JWST Study Challenges Dark Matter in 3.7-Billion-Light-Year Bullet Cluster, Backs 50% Cut
Updated
Updated · Universe Today · Jul 3
JWST Study Challenges Dark Matter in 3.7-Billion-Light-Year Bullet Cluster, Backs 50% Cut
3 articles · Updated · Universe Today · Jul 3
Summary
James Webb data led an international team to argue the Bullet Cluster’s lensing can be explained without dark matter, challenging one of the strongest long-standing pieces of evidence for its existence.
3.7 billion light-years from Earth, the Bullet Cluster formed when two galaxy clusters collided about 4 billion years ago at more than 2,500 km/s, separating hot X-ray gas from the galaxies and creating the lensing pattern under debate.
The researchers said Webb’s sharper counts of stars and heavy elements let them model enough ordinary compact remnants—such as neutron stars and black holes—to account for the observed gravitational effects.
That result strengthens Modified Newtonian Dynamics, or MOND, which the authors say fits the Bullet Cluster better than previously thought; even under standard dark-matter models, they argue the required dark matter would need to be cut by about half.
Did the Webb telescope just help dismantle one of science's biggest mysteries?
If the universe's 'missing mass' is found, must we rewrite cosmology textbooks?
JWST Data Halves Dark Matter Estimate in Bullet Cluster, Revives MOND Debate
Overview
The Bullet Cluster has long been seen as strong evidence for dark matter because its gravitational lensing did not match the visible mass from hot gas and galaxies. Traditionally, the strongest lensing was found around the galaxy clusters, even though most visible matter was in the gas clouds, leading scientists to believe there was hidden, undetectable matter—dark matter—within the galaxies. However, new observations, likely from the James Webb Space Telescope, have prompted a reassessment. By more accurately counting stars, neutron stars, and black holes, researchers now suggest that much of the lensing can be explained by ordinary matter and modified gravity, reducing the need for dark matter.