Multi-messenger astronomy

• Main Author: Cottrell, Geoff
• Format: Book Part
• Language: unknown
• Published: Oxford University PressOxford 2023
• Subjects: Antarc*; Antarctic; Ice Shelf
• Online Access: http://dx.doi.org/10.1093/actrade/9780192849021.003.0006; https://academic.oup.com/book/46431/chapter/406285802

Abstract This chapter highlights the new and different types of astronomical messengers, neutrinos and gravitational waves. These messengers can be detected in regions of the Universe that are electromagnetically hidden from view, and so are highly informative. Neutrinos are produced in massive numbers in the core of the Sun and stars, and also in the most violent events in the Universe, such as in supernovae and the accretion discs around black holes and AGN. Because they interact so weakly with normal matter, neutrinos are difficult to detect, and astronomers look for the rare interactions with matter in large volume detectors, such as the one-km block of ice which forms part of the Antarctic ice-shelf in the IceCube neutrino telescope. The first important neutrino detections, from supernova SN1987A also heralded the first multi-messenger observations. These observations, the higher energy neutrino detections from AGN are described. Gravitational waves are oscillations of the fabric of spacetime, and, unlike electromagnetic waves, are not absorbed making them informative astronomical messengers. Gravitational wave sources involve movements of large amounts of mass and energy, such as conditions of the Big Bang, merging black holes and neutron stars, as well as in supernovae. The first gravitational waves ever detected were from a pair of merging black holes, a billion light years away, by the Laser Interferometer Gravitational wave Observatories. In 2017 multimessenger gravitational and electromagnetic waves were detected from a kilonova, the violent merger of two neutron stars in a distant galaxy.