Searching for multi-messenger signals with the Pierre Auger Observatory

Abstract

The Pierre Auger Observatory [1], primarily designed for the detection of ultra-high energy (UHE) cosmic rays, has been proven to be also an excellent tool in multi-messenger searches. With its unprecedented exposure to UHE particles, it is exploited to set stringent upper limits on the diffuse flux of UHE photons and neutrinos and to look for neutral particles associated with steady sources and transient events, such as gravitational waves. All these searches can provide key information to investigate the most energetic phenomena in the Universe and answer some of the most important still-open questions in astrophysics.