Galilean Equivalence for Galactic Dark Matter
Satellite galaxies are tidally disrupted as they orbit the Milky Way. If dark matter (DM) experiences a stronger self-attraction than baryons, stars will preferentially gain rather than lose energy during tidal disruption, leading to an enhancement in the trailing compared to the leading tidal stream. The Sgr dwarf galaxy is seen to have roughly equal streams, challenging models in which DM and baryons accelerate differently by more than 10%. Future observations and a better understanding of DM distribution should allow detection of equivalence violation at the percent level.
Additional Information© 2006 The American Physical Society (Received 22 June 2006; revised 2 August 2006; published 28 September 2006) We wish to thank John Dubinski and Larry Widrow for assistance with the use of GALACTICS and Pat McDonanld, Neal Dalal, Christoph Pfrommer, and Jonathan Sievers for useful conversations. All computations were performed on CITA's McKenzie cluster , which was funded by the Canada Foundation for Innovation and the Ontario Innovation Trust. Kesden acknowledges support from the NASA Graduate Research Program, and NSERC of Canada. Kamionkowski acknowledges support from the DoE No. DE-FG03-92-ER40701, NASA No. NNG05GF69G, and the Gordon and Betty Moore Foundation.
Published - KESprl06.pdf