Beyond Starlight: An Exploration of Multi-Messenger Astronomy

Abstract

For most of astronomy’s long history, it could have been defined as the careful study of light from above. Humans wielded ever-more advanced telescopes and techniques to do so, eventually turning to wavelengths we couldn’t see with our own eyes. But only recently have we begun to catch other signals from the universe. Neutrinos, gravitational waves, and cosmic rays arrive on Earth carrying information from celestial events, just like photons. Multi-messenger astronomy has developed to make use of these alternate cosmic messengers. We’re at the start of a new era, when astronomical observatories look different- they're nestled below mountains, frozen within the Antarctic ice sheet, and anchored at the bottom of the Mediterranean. All over the world, these "telescopes" are searching for the nearly imperceptible whispers of colliding black holes and supernovas, resembling ears and noses more than eyes, detecting miniscule vibrations and particles instead of light. This thesis is a journalistic overview of multi-messenger astronomy as a nascent field, delving into its historical milestones and future scientific potential. We begin with an overview of historical astronomy’s study of light. Then, we move on to the fundamental physics behind the new cosmic messengers. We dive into the long search for gravitational waves, before heading to LIGO to discuss the current state of detectors. We touch on Super-Kamiokande, its past discoveries and our ever-growing understanding of the nature of neutrinos. Then, we visit IceCube to discuss high-energy neutrino discoveries and future potential. We discuss proposals for future gravitational wave observatories, along with recent evidence for the low-frequency gravitational wave background. We conclude with some thoughts and reflections on the future of multi-messenger astronomy.