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A Clash of Clusters Provides New Clue to Dark Matter
Cosmology Seminar: Brad Holden (UC Santa Cruz)
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Cosmology Seminar: Douglas Finkbeiner, Harvard
| What | cosmology |
|---|---|
| When |
15 October 07 from 11:00 am to 12:00 pm |
| Where | Varian room 355 |
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"Exciting" Dark Matter and the 511 keV line
Weakly-interacting massive particle (WIMP) dark matter has been
invoked to explain excess GeV gamma-rays, high-energy positrons, and
even excess microwaves in the inner Milky Way. Until now, however,
there has been no connection between these weak scale (mass of ~ 300
GeV) WIMPs and the 511 keV e+e- annihilation radiation from the inner
Milky Way.
Neal Weiner and I have proposed a WIMP candidate with an "excited
state" 1-2 MeV above the ground state (known as "exciting" dark
matter, eDM). This state may be collisionally excited and decays by
$e^+e^-$ pair emission. Such a particle converts WIMP kinetic energy
into pairs, which in turn could produce a substantial fraction of the
511 keV line observed by INTEGRAL/SPI in the inner Milky Way. Only a
small fraction of the WIMPs are above threshold, and that fraction
drops sharply with Galactocentric radius, naturally yielding a radial
cutoff, as observed. Even if the scattering probability in the inner
kpc is << 1% per Hubble time, enough power is available to produce the
number of pairs per second observed. I will specify the parameters
required to explain the INTEGRAL result, and discuss other
observational consequences of this model.
MASS: Lance Simms