The Shaw Prize in Astronomy 2021 is shared equally by Victoria M. Kaspi, Professor of Physics, Director of McGill Space Institute and member of the Center for Research in Astrophysics of Quebec (CRAQ), and Chryssa Kouveliotou, Professor and Chair, Department of Physics at George Washington University, for their contributions to our understanding of magnetars, a class of highly magnetised neutron stars that are linked to a wide range of spectacular, transient astrophysical phenomena. This prestigious award is one way in which the Shaw Prize Foundation seeks to promote astronomy.
Through the development of new and precise observational techniques, Victoria M. Kaspi and Chryssa Kouvelioto confirmed the existence of neutron stars with ultra-strong magnetic fields and characterised their physical properties. Their work has established magnetars as a new and important class of astrophysical objects.
Neutron stars are the ultra-compact remnants of stellar explosions. Most are rapidly rotating with periods of milli-seconds to seconds and emit powerful beams of electromagnetic radiation (observed as pulsars). As such they are accurate ‘cosmic clocks’ that enable tests of fundamental physics in the presence of a gravitational field many billion times stronger than Earth’s. Reflecting their importance, the Nobel Prize in Physics has been awarded twice for work on pulsars (in 1974 and 1993).
Pulsars also have strong magnetic fields, since the magnetic field lines in the progenitor star are ‘frozen in’ in the stellar remnant as it collapses to become a neutron star. These magnetic fields funnel jets of particles along the magnetic poles, but classical radio pulsars are powered mainly by rotational energy and slowly spin down over their lifetimes.
The research carried out by Kaspi and Kouveliotou was motivated by the theoretical prediction that neutron stars with extreme magnetic fields up to a thousand times stronger than those in regular pulsars could form if dynamo action were efficient during the first few seconds after gravitational collapse in the core of the supernova. Such objects (termed magnetars) would be powered by their large reservoirs of magnetic energy, rather than by rotation, and were predicted to produce highly energetic bursts of gamma-rays through the generation of highly energetic ionised particle pairs at their centres.
From observations of a class of X-ray/gamma-ray sources called “soft gamma-ray repeaters” (SGRs) Chryssa Kouveliotou and her colleagues in 1998–99 established the existence of magnetars and provided a stunning confirmation of the magnetar model. Victoria Kaspi showed that a second class of rare X-ray emitting pulsars, the anomalous X-ray pulsars (AXPs), were also magnetars. She has also made fundamental contributions to the characterisation of magnetars as a population, through the elucidation of their physical properties and their relationship to the classical radio pulsars. Her work has cemented the recognition of magnetars as a distinct source class.
Today, magnetars are routinely invoked to explain the physics underlying a diverse range of astrophysical transients including gamma-ray bursts, superluminous supernovae and nascent neutron stars. Magnetars probe extreme physical conditions inaccessible on Earth, such as strong gravity, ultra-nuclear densities and the strongest magnetic fields in the Universe. In this high energy environment particle-antiparticle pairs are created from the vacuum, and unique tests of general relativity and quantum electrodynamics become possible.
About the Shaw Prize
The Shaw Prize is an international award to honour individuals who are currently active in their respective fields and who have recently achieved distinguished and significant advances, who have made outstanding contributions in academic and scientific research or applications, or who in other domains have achieved excellence. The award is dedicated to furthering societal progress, enhancing quality of life, and enriching humanity’s spiritual civilization.
Preference is given to individuals whose significant works were recently achieved and who are currently active in their respective fields.
The Shaw Prize consists of three annual awards: the Prize in Astronomy, the Prize in Life Science and Medicine, and the Prize in Mathematical Sciences. Each prize carries a monetary award of one million two hundred thousand US dollars.
The Shaw Prize, established under the auspices of Mr Run Run Shaw in November 2002, is managed and administered by The Shaw Prize Foundation based in Hong Kong.
Centre de recherche en astrophysique du Québec