  We investigate the shock acceleration of particles in massive galaxy mergers
or collisions, and show that cosmic rays (CRs) can be accelerated up to the
second knee energy ~0.1-1 EeV and possibly beyond, with a hard spectral index
Gamma ~ 2. Such CRs lose their energy via hadronuclear interactions within a
dynamical timescale of the merger shock, producing gamma rays and neutrinos as
a by-product. If ~ 10 % of the shock dissipated energy goes into CR
acceleration, some local merging galaxies will produce gamma-ray counterparts
detectable by CTA. Also, based on the concordance cosmology, where a good
fraction of the massive galaxies experience a major merger in a cosmological
timescale, the neutrino counterparts can constitute ~ 20-60 % of the isotropic
background detected by IceCube.
