By Hamish Johnston Yesterday we reported that the excess number
of cosmic positrons seen by PAMELA and other detectors could be
coming from a nearby pulsar called Geminga — rather than from
annihilating dark matter. While the pulsar explanation is
significant, the direct detection of dark matter via cosmic rays
could bag someone a Nobel Prize. But alas, it is looking less
likely that the current generation of cosmic ray detectors are
up to the prize-winning task (assuming dark matter exists, and
annihilates to create cosmic rays!). One of the physicists
arguing the pulsar explanation is Todor Stanev of the University
of Delaware. Stanev has also teamed up with researchers in
Germany, Sweden and the US to show that electron and positron
excesses seen by PAMELA and other experiments can also be
attributed to the violent acceleration of matter that is
believed to occur in the polar caps of certain supernovae.
According to the team, the energy spectra of electrons and
positrons emitted in such a polar cap match w