2015/03/31 by David Harvey, Richard Massey, Thomas Kitching +2 · 1 citation
Physics and Astronomy · #astro-ph.CO #hep-ph
paper · pdf · doi:10.1126/science.1261381
published as Science, Vol. 347 no. 6229 pp. 1462-1465 (2015) · 5 Pages, 4 Figures and 18 pages supplementary information
arxiv created 2015/04/13 · arxiv updated 2015/05/15
Collisions between galaxy clusters provide a test of the non-gravitational forces acting on dark matter. Dark matter's lack of deceleration in the `bullet cluster collision' constrained its self-interaction cross-section σDM/m < 1.25cm2/g (68% confidence limit) for long-ranged forces. Using the Chandra and Hubble Space Telescopes we have now observed 72 collisions, including both `major' and `minor' mergers. Combining these measurements statistically, we detect the existence of dark mass at 7.6σsignificance. The position of the dark mass has remained closely aligned within 5.8+/-8.2 kpc of associated stars: implying a self-interaction cross-section σDM/m < 0.47 cm2/g (95% CL) and disfavoring some proposed extensions to the standard model.