Multimessenger Astrophysics
For thousands of years, astronomy relied solely on the observation of the night sky with the naked eye. The invention of the telescope during the Renaissance provided significant new opportunities for exploration. By the late 20th century, scientists had access to the complete electromagnetic spectrum, greatly enhancing their ability to study stars and galaxies. Astronomy now transcends light, thus over the last several decades, astronomers and physicists have collaborated to gather information from several different sources, or “messengers” to study the cosmos. Multimessenger astronomy focuses on high-energy particles that reach Earth while traveling through space, aiding our understanding of some of the universe's most extreme phenomena.
The sky is full of messengers
Photons
Cosmic Rays
Large part of our knowledge about the universe derives from the observation of electromagnetic signals: radio waves, infrared, visible light, ultra violet, X-rays and the powerful -rays.
Beyond the light, other astrophysical signals, as Cosmic Rays (CRs). In particular Ultra High Energy Cosmic Rays (UHECRs), arriving from directions roughly isotropic on the sky, could provide relevant information about the acceleration mechanisms that occur inside astrophysical sources.
Neutrinos
Neutrinos are particularly significant among the possible messengers due to their neutral charge, which allows them to remain unaffected by magnetic fields, thus enabling them to traverse vast distances before interacting, thanks to their small cross section. Moreover neutrinos can only be produced by hadronic processes, e quindi....
Gravitational waves
Gravitational waves are transient displacements in a gravitational field generated by the motion or acceleration of gravitating masses that radiate outward from their source at the speed of light.
The combination of high energy neutrino and gamma-ray astronomy can help in understanding the sources and the mechanisms of CR acceleration. The identification and investigation sources, able to accelerate protons to energies much larger than those reached in human built colliders, is one of the major purposes of astroparticle physics.