publication 26-September-2018 04:22:52

The nongravitational interactions of dark matter in colliding galaxy clusters

Publication date: 27 March 2015

Authors: Harvey, D., et al.

Journal: Science
Volume: 347
Issue: 6229
Page: 1462-1465
Year: 2015

Copyright: AAAS

Collisions between galaxy clusters provide a test of the nongravitational forces acting on dark matter. Dark matter's lack of deceleration in the "bullet cluster" collision constrained its self-interaction cross section σDM/m < 1.25 square centimeters per gram (cm2/g) [68% confidence limit (CL)] (σDM, self-interaction cross section; m, unit mass of dark matter) 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 7.6σ significance. The position of the dark mass has remained closely aligned within 5.8 ± 8.2 kiloparsecs 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.

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Last Update: 26 March 2015

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