Blazar neutrinos and gamma rays reaching Earth
Blazars are a type of active galaxy with one of its jets pointing toward Earth. In this artistic rendering, a blazar emits both neutrinos and gamma rays, like in the case of the IceCube-170922A event, recorded on 22 September 2017. On this occasion, the IceCube Neutrino Observatory at the South Pole detected a neutrino while at the same time gamma rays, coming from the same direction in the sky, were detected by other telescopes on Earth and in space.
ESA's INTEGRAL gamma-ray observatory was part of the international collaboration that observed this source. While it did not record any prompt burst of gamma rays from this blazar nor observed it to be in a flaring state, this non-detection provided important information to help constrain the properties of the source.