The Shaw Prize in Astronomy 2023 is awarded in equal shares to Matthew Bailes, Director of the Australian Research Council (ARC) Centre of Excellence for Gravitational Wave Discovery, Duncan Lorimer, Professor and Interim Chair of Physics and Astronomy and Associate Dean for Research at Eberly College of Arts and Sciences at West Virginia University, USA and Maura McLaughlin, Eberly Family Distinguished Professor at the Department of Physics and Astronomy, West Virginia University, USA, for the discovery of fast radio bursts (FRBs).

Fast radio bursts (FRBs) are among the most extreme and mysterious phenomena in astronomy; they are intense bursts of radio emission lasting only a few thousandths of a second that release as much energy as the Sun emits over several days. The sources of the bursts are smaller than the Earth but are as far away as distant galaxies. In a seminal research paper written in 2007, Bailes, Lorimer and McLaughlin (with collaborators Narkevic and Crawford) found the first FRB, deduced many of the properties of its source, in particular its extreme distance, small size, and enormous energy, estimated the cosmic rate of production of FRBs, and highlighted their potential as cosmological probes.

Despite initial scepticism about whether this unique event was a real astronomical source, the work by Bailes, Lorimer and McLaughlin inspired others to search for these elusive events. By now almost a thousand FRBs have been discovered. Telescopes based on novel technologies are being designed and built specifically to find FRBs and identify their host galaxies.

Although the nature of FRBs remains unknown, they are almost certainly associated with neutron stars, collapsed stellar remnants that contain the mass of the Sun within a diameter of only a few tens of kilometres. FRBs have the potential to provide a unique probe of physics in extreme conditions and of the distribution of matter in the Universe.

Matthew Bailes is on the faculty of Swinburne University of Technology in Melbourne, Australia. Duncan Lorimer and Maura McLaughlin are on the faculty at West Virginia University in Morgantown, West Virginia, USA. This award is also intended to recognise the other collaborators in this research, and the investigators who collected the original data for other purposes.

The 2023 Gruber Cosmology Prize recognises Richard Ellis of University College London for his pioneering work both studying galactic evolution dating back to the ‘cosmic dawn’ and designing innovative instruments with which to do so.

The Gruber Foundation today announced the recipient of this year’s Cosmology Prize. The prize is awarded annually to leading scientists and cosmologists who have made groundbreaking discoveries that change or challenge our understanding of the Universe.

The 2022 Gruber Cosmology Prize recognises Richard Ellis with the $500 000 award and a gold laureate pin at a ceremony that will take place in July at the ‘Shedding New Light on the First Billion Years of the Universe’ conference organised by the Galaxies, Etoiles et Cosmologie (GECO) team of the Laboratoire d'Astrophysique of Marseille, France. The citation highlights his “broad contributions in the fields of galaxy evolution” as well as his role as “the driver of many frontier instrumental developments in optical astronomy.”

His dual proficiency in observation and instrumentation alone would make Ellis unusual among astrophysicists. That his contributions in both areas have proved revolutionary might well make him unique.

As an observer, Ellis has redefined cosmology, the science that studies the growth of the Universe. Because the speed of light is finite, astronomers can trace the evolution of galactic structures in reverse, starting with the nearest and most mature and extending to the earliest and most primitive. Over the decades Ellis has repeatedly led surveys of galaxies farther and farther, and hence earlier and earlier, across the cosmic landscape.

In a series of landmark studies in the 1990s and 2000s he reconstructed the evolutionary processes that galaxies have undergone in the last seven billion years or so, or well more than halfway back to the Big Bang. In subsequent surveys he and his collaborators have probed two significant stages far earlier in the development of the Universe.

One was the era of reionisation, a period after the Big Bang when neutral hydrogen atoms were split into positively charged protons and free electrons. That process would have occurred during the emergence of the first galaxies from the gravitational collapse of primordial, opaque clouds of neutral hydrogen — a period of first light which cosmologists have come to call the cosmic dawn, and which Ellis and collaborators determined to have occurred about 250 million years after the Big Bang.

As “the leading authority on galaxy evolution,” as one Gruber nominator called him, Ellis has for decades been a fixture on astronomical projects requiring deep probes. In the mid‐1990s he was the sole Europe‐based member of the committee to outline the scientific goals for what was then called the Next Generation Space Telescope and is now the James Webb Space Telescope. He was a natural fit for the Supernova Cosmology Project team, one of the two teams that discovered evidence that the expansion of the Universe is accelerating (that led to the 2007 Gruber Prize; 2011 Nobel Prize). Ellis was also the principal investigator on the 2012 Hubble Ultra Deep Field campaign, which provided the first census of star‐forming galaxies less than a billion years after the Big Bang.

As Ellis’s observations have taken him farther and farther across the Universe into realms that were previously inaccessible, he has found himself needing to adopt or invent new tools.

One challenge was to observe the light from distant galaxies. In order to do so, Ellis was one of the first astronomers to use massive galaxy clusters as ‘gravitational lenses’ that (as Einstein’s general theory of relativity predicted) magnify the otherwise inaccessible light from objects beyond them.

Realising the challenges of efficiently studying faint galaxies, Ellis has devoted much of his career to promoting innovative instruments. He devised, funded, and oversaw the development of several forms of spectrographs that allow astronomers to study gas compositions in the earliest star‐forming galaxies. In turn, those instruments have helped other cosmologists make discoveries about the fundamental nature of the early Universe.

Ellis has also occupied many prestigious academic, research, or administrative positions, including: senior scientist at the European Southern Observatory; director of the Palomar Observatory (now Caltech Optical Observatories); director of the Institute of Astronomy at Cambridge University. In 2017 he returned, as a professor of astronomy, to University College London, from which he received his Bachelor of Science in astronomy in 1971.