Context : The Milagro experiment has announced the discovery of an excess flux of TeV cosmic rays from the general direction of the heliotail , also close to the Galactic anticenter .

Aims : We investigate the hypothesis that the excess cosmic rays were produced in the SN explosion that gave birth to the Geminga pulsar .

Methods : The assumptions underlying our proposed scenario are that the Geminga supernova occurred about 3.4 10 ^ { 5 } years ago ( as indicated by the spin down timescale ) , that a burst of cosmic rays was injected with total energy \sim 10 ^ { 49 } erg ( i.e. , about 1 % of a typical SN output ) , and that the Geminga pulsar was born with a positive radial velocity of 100–200 km s ^ { -1 } .

Results : We find that our hypothesis is consistent with the available information .
In a first variant ( likely oversimplified ) , the cosmic rays have diffused according to the Bohm prescription ( i.e. , with a diffusion coefficient on the order of c \times r _ { L } , with c the speed of light and r _ { L } the Larmor radius ) .
An alternative scheme assumes that diffusion only occurred initially , and the final propagation to the Sun was a free streaming in a diverging magnetic field .

Conclusions : If the observed cosmic ray excess does indeed arise from the Geminga SN explosion , the long–sought “ smoking gun ” connecting cosmic rays with supernovae would finally be at hand .
It could be said that , while looking for the “ smoking gun ” , we were hit by the bullets themselves .