Richard Saunders (1953-2026)

It is with great sadness that we announce the recent death of Richard Saunders, a valued colleague whose work over several decades made a lasting impact on radio astronomy and observational cosmology at the Cavendish. The following tribute by Emeritus Professor Paul Alexander and former Head of the Astrophysics Group reflects on his scientific achievements and lasting impact.

Richard Saunders joined what was then the Radio Astronomy (RA) Group (now the Astrophysics Group) in 1978, having completed his undergraduate degree in Bristol, an MSc in Space Sciences at University of Leicester and two years working for British Nuclear Fuels. At that time, new PhD students in the group began with general research and training before selecting a supervisor and topic. Richard chose to work with John Baldwin on giant radio galaxies– vast systems powered by active galactic nuclei that launch narrow, highly energetic jets extending far beyond their host galaxies. His analysis of the jet in the giant radio galaxy NGC6251 provided early quantitative support for the jet-beaming model proposed by Peter Scheuer.

The main thrust of his PhD was to find further giants. He did this by eye, meticulously examining contour map representations of the 6C 151-MHz survey laid out on the tables in Seminar Room B in the Rutherford building – low tech by today’s standard but highly effective!

One of Richard’s most influential contributions to the study of radio galaxies came a little later through a collaboration with Steve Rawlings, in which they showed a strong correlation between the [O III] emission from active galactic nuclei and the kinetic power of their jets. This result became foundational in the study of radio‑loud AGN.

After completing his PhD, Richard remained at the Cavendish as a SERC Research Fellow—a position that allowed him to change research direction completely. In 1984, after several years of work, Mark Birkinshaw and Steve Gull achieved the first detection of the so-called Sunyaev–Zeldovich (SZ) effect, a subtle distortion of the Cosmic Microwave Background (CMB) caused by hot gas in galaxy clusters. The experiment was exceptionally challenging, but the SZ effect’s unique independence from redshift made it a powerful probe of distant cosmic structure.

They suggested that the next step was a dedicated telescope to study the effect and Richard was appointed to lead a major upgrade of the 5‑km telescope at Lord’s Bridge, transforming it into the first dedicated SZ instrument. This comprehensive programme replaced nearly every component except the dishes themselves. The upgrade was successful and in 1993 the now renamed Ryle telescope produced the first-ever image of the SZ effect towards the cluster Abell 2218. This was soon followed by an unbiassed estimate of the Hubble constant.

Richard was appointed to the staff in 1990 as an Assistant Director of Research and was awarded the William Hopkins Prize of the Cambridge Philosophical Society in 1994 for the successful upgrade programme of the 5km telescope.

Richard’s later career remained centred on observations of the Cosmic Microwave Background radiation (CMB). He made important contributions to the design of the Cosmic Anisotropy Telescope (CAT), the first Cambridge instrument dedicated to imaging primordial CMB anisotropies, led by Peter Duffett-Smith. In particular, he led crucial surveys of background radio sources with the Ryle Telescope, enabling accurate subtraction of foreground objects from CAT data/ In 1996 the team made the first ever high-resolution image of primordial structure in the CMB – a landmark result in modern cosmology.

Appointed to a Lectureship in 2000 and promoted to Senior Lecturer in 2008, Richard continued to play a central role in the development and operation of two major CMB instruments built by the Cambridge group.

The Very Small Array, a joint Cambridge–Manchester project located in Tenerife, delivered key measurements of CMB anisotropy that complemented emerging space‑based missions. Richard was responsible for the complex logistics of shipping the instrument, after assembly and initial testing in Cambridge, and took great care also for the operational support of team members during commissioning and observing visits to Tenerife.

The Arcminute Microkelvin Imager (AMI), the final dedicated CMB telescope at Lord’s Bridge, was optimised for observing clusters through the SZ effect. AMI comprised a new compact array of ten dishes housed in a shielded enclosure, alongside a significant upgrade to the Ryle Telescope—including the long‑planned relocation of three of its original eight dishes, something Richard had long wanted to do.

Richard remained dedicated to mentoring and supervising research students, particularly those working with the AMI telescope, throughout his later years and into retirement. His support is affectionately acknowledged in the PhD theses of his students, several of whom remained in close contact with him after graduation.

His career spanned decades of transformative progress in observational cosmology, and his contributions played a vital role in shaping the Cavendish’s international reputation in radio and CMB astronomy.

We extend our heartfelt condolences to his family, friends and colleagues.