SLAC, Kavli 3rd Floor Conf. Room
New frontiers of astroparticle physics have been opened by IceCube's discovery of high-energy cosmic neutrinos. Their origin is a new mystery in the field, and solving this problem may enable us not only to understand the physics of astrophysical sources but also to obtain important clues about the old mystery, the origin of cosmic rays, and to utilize neutrinos as probes of neutrino properties, dark matter, and fundamental physics. In this talk, I discuss implications of the latest results of IceCube observations, with emphases on multi-messenger approaches. I will review recent topics about high-energy cosmic neutrinos, including IceCube-170922A that coincided with a blazar flare, a grand-unified cosmic particle model we recently proposed, and some implications to physics beyond the Standard Model.