A multi-messenger search for the origin of high-energy astrophysical neutrinos with VERITAS and Fermi

The astrophysical flux of TeV-PeV neutrinos discovered by the IceCube observatory is likely to originate in hadronic interactions at or near cosmic-ray accelerators. While no point-sources of neutrinos have been identified so far, it may be possible to detect them indirectly by searching for the emission of pion-decay gamma rays produced in such interactions. The sensitivity of present gamma-ray instruments, such as the Fermi space telescope and the VERITAS air Cherenkov telescope array, can be used to search for a GeV-TeV gamma-ray signature from the neutrino directions. We present preliminary results from 2 years of VERITAS observations of muon-neutrino event positions detected by IceCube and discuss current plans to implement prompt follow-up observations of these events. We also report on the analysis of Fermi-LAT data for these events which enhances the sensitivity of this search to fast transient sources.