Mapping the Milky Way in High-Energy Neutrinos

I will present observations of the Milky Way Galaxy via high-energy neutrinos detected with the IceCube Neutrino Observatory, a 1 km$^3$ neutrino detector located at the South Pole. The Milky Way, which is visible in the sky as a swath of stars, dust, and gas, has captivated astronomers for centuries. More recently, the Galactic plane of the Milky Way has been observed in every wavelength of the electromagnetic spectrum, from radio waves to infrared, optical, x-rays, and gamma rays. This work presents the first observation of the Galactic plane in high-energy neutrinos, marking the first observation in a particle other than light. Within our Galaxy, high-energy neutrinos can be produced when cosmic rays interact at their acceleration sites or while propagating through the interstellar medium. Using a new sample of cascade neutrino events, selected with machine-learning techniques, a test of a diffuse neutrino emission model from the Galactic plane finds a 4.5σ rejection of the background-only hypothesis.