On the basis of existing observations ( at the 4.5 \sigma level ) of TeV \gamma -ray outbursts from the Fanaroff-Riley I ( FRI ) radio galaxy Centaurus A , we estimate the accompanying neutrino flux in a scenario where both photons and neutrinos emerge from pion decay .
We find a neutrino flux on Earth dF _ { \nu } / dE _ { \nu } = 4.5 \times 10 ^ { -11 } ( E _ { \nu } / { TeV } ) ^ { -2 } { TeV } ^ { -1 } % { cm } ^ { -2 } { s } ^ { -1 } , equally spread in flavor as a result of maximal mixing .
Such a flux will trigger at the IceCube facility about 10 showers/burst , with negligible background from atmospheric muons , and primary neutrino energies in excess of 100 TeV .
The only other FRI radio galaxy observed in the TeV photon energy range at the 4 \sigma level is M87 .
The burst nature of this activity is not established ; however , we show that the intrinsic neutrino luminosity during the active period is the same as the Centaurus A burst .
On the assumption that Centaurus A typifies the FRI population , we show that IceCube should collect 10 showers ( all neutrino flavors ) in 3 years , attaining a 95 % CL sensitivity to the diffuse neutrino flux from FRI radio galaxies in one year of observation .