TY - JOUR
T1 - Exciting dark matter and the INTEGRAL/SPI 511 keV signal
AU - Finkbeiner, Douglas P.
AU - Weiner, Neal
PY - 2007/10/22
Y1 - 2007/10/22
N2 - We propose a dark matter candidate with an "excited state" 1-2 MeV above the ground state, which may be collisionally excited and deexcites by e+e- pair emission. By converting its kinetic energy into pairs, such a particle could produce a substantial fraction of the 511 keV line observed by the International Gamma-Ray Astrophysics Laboratory/SPI in the inner Milky Way. Only a small fraction of the dark matter candidates have sufficient energy to excite, 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 ∼3×1042 pairs per second observed in the galactic bulge. We specify the parameters of a pseudo-Dirac fermion designed to explain the positron signal, and find that it annihilates chiefly to e+e- and freezes out with the correct relic density. We discuss possible observational consequences of this model.
AB - We propose a dark matter candidate with an "excited state" 1-2 MeV above the ground state, which may be collisionally excited and deexcites by e+e- pair emission. By converting its kinetic energy into pairs, such a particle could produce a substantial fraction of the 511 keV line observed by the International Gamma-Ray Astrophysics Laboratory/SPI in the inner Milky Way. Only a small fraction of the dark matter candidates have sufficient energy to excite, 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 ∼3×1042 pairs per second observed in the galactic bulge. We specify the parameters of a pseudo-Dirac fermion designed to explain the positron signal, and find that it annihilates chiefly to e+e- and freezes out with the correct relic density. We discuss possible observational consequences of this model.
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U2 - 10.1103/PhysRevD.76.083519
DO - 10.1103/PhysRevD.76.083519
M3 - Article
AN - SCOPUS:35648998598
SN - 1550-7998
VL - 76
JO - Physical Review D - Particles, Fields, Gravitation and Cosmology
JF - Physical Review D - Particles, Fields, Gravitation and Cosmology
IS - 8
M1 - 083519
ER -