Morphology of the dark matter contribution to the 511 keV gamma ray sky: constraints from INTEGRAL/SPI observations
Observations from the past 40 years show a clear, unambiguous detection of a 511 keV gamma-ray line originating in a spherically-symmetric region around the centre of the Milky Way, in addition to a fainter, disk-like component extending along the galactic plane. This implies the annihilation - and thus, the creation - of 1.5 x 10^43 electron-positron pairs every second. Known astrophysical positron sources mainly predict a bulge-to-disk (B/D) luminosity < 0.5, far below the B/D > 1.4 required by the most recent observations from the INTEGRAL/SPI space-borne experiment. I will introduce the 511 keV anomaly, and present a brief review of these sources. I will then show that interacting dark matter (DM) is an ideal candidate source which can produce the correct spectrum and morphology with minimal assumptions about the DM model. Indeed, DM can give a fit to the INTEGRAL/SPI data that is as good as the best phenomenological fits, but with six fewer degrees of freedom, when data from many-body DM simulations and gamma-ray observations of radioactive isotopes are included.
Date: Wednesday, 8 February 2012 Time: 14:30 Where: McGill University Ernest Rutherford Physics Building, R.E. Bell Conference Room (room 103) Contact: Robert Rutledge