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Riccardo Giovanelli (1946-2022)

Riccardo Giovanelli was a pioneer in the application of observations of the HI 21 cm line of atomic hydrogen to probe galaxy evolution, to map the filamentary structure of the distribution of galaxies, and to trace dark matter on large scales in the local Universe.

Published onMay 07, 2024
Riccardo Giovanelli (1946-2022)

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Photo credit: Arecibo Observatory/Cornell University

Riccardo Giovanelli, a leading authority on the study of galaxies in the local universe via the HI 21 cm line and the development of radio astronomical instrumentation and facilities, died at home in Ithaca, NY on Wednesday, December 14, 2022 after a long battle with Parkinson’s disease. He was 76.

Riccardo was born in Reggio Emilia, Italy and spent much of his childhood in Argentina before returning to Italy to attend university. He first attended the University of Parma but transferred to the University of Bologna to study astrophysics. He received his laurea cum laude in physics in 1969, presenting a thesis on lunar occultations of radio sources. He then received a Fullbright fellowship to pursue his Ph.D. studies in astronomy at Indiana University. A summer research internship at the National Radio Astronomy Observatory in 1971 led to a position as a visiting graduate student at NRAO under the guidance of Gerritt Verschuur. His thesis explored the nature and origin of HI high velocity clouds via observations and analysis of the cloud structures and properties. In 1972, though he had published much of his thesis research, he did not have enough residency credits to meet degree requirements at Indiana and had to fulfill his Italian military service obligation. In lieu of military service, he arranged an alternative posting to teach physics for two years as a civil volunteer at the National University of El Salvador. He returned to Indiana in 1975 for another year to complete his degree requirements. During that year, he teamed up with fellow graduate student Martha Haynes to undertake observations of high velocity clouds using telescopes in both Green Bank and Arecibo.

After a brief return to the University of Bologna, Riccardo took up a position as the Karcher Visiting Lecturer at the University of Oklahoma and eventually joined the scientific staff of the Arecibo Observatory in 1978. Arecibo had just had its surface upgraded allowing observations of atomic hydrogen in the 21 cm (1.4 GHz) band and, over the following years, Riccardo advocated for improvements in receiver and spectrometer capability. He played an important role in making the science case for the 1990s Gregorian upgrade of Arecibo that significantly increased the telescope’s sensitivity and available bandwidth at 21 cm. He wrote software for processing Arecibo spectral line data and assisted visiting astronomers in conducting their observations. A paper published in 1993 with Kildal, Johansson and Hagfors presented the feasibility of a seven-element cluster feed for Arecibo, later resulting in the 7-horn “ALFA” feed array installed in 2004. During his time at Arecibo, Riccardo served as Head of the Radio Astronomy Group and Director of the Observatory. In 1991, he left Arecibo to take up a faculty position at Cornell University where he remained until his transition to Professor Emeritus in 2017.

Over his career, Riccardo, usually in collaboration with Martha, used many different telescopes to explore the relative gas, stellar and dark matter contents of galaxies in the local universe and how their evolution might be impacted by processes driven by the local intergalactic environment. The early Arecibo galaxy surveys established the comparative HI deficiency in cluster galaxies, showed that low mass star forming galaxies are less clustered than higher mass ones, and confirmed that galaxies trace the dark matter distribution on supercluster scales. The HI line galaxy redshift surveys demonstrated “the first three-dimensional view of some of the remarkable large-scale filamentary structures of our visible universe” for which Giovanelli and Haynes were awarded the 1989 Henry Draper medal by the US National Academy of Sciences. Additionally, Riccardo received the honorific title of Knight of the Order of Merit of the Italian Republic. In his home village and region in Italy, Riccardo often gave talks to school groups, amateur astronomy clubs and the public. In recognition, he was awarded the “Tricolore” (“Flag of the Three Colors”) by the city of Reggio Emilia and the “Spiga d’Oro” (“Straw of Wheat”) award of the municipality of Gattatico. In 2024, the Gattatico government renamed its community auditorium the Riccardo Giovanelli Cultural Center.

With the advent of the ALFA receiver at Arecibo in 2004, the ALFALFA survey of galaxies across the Arecibo sky delivered the first census of gas-bearing galaxies over a cosmologically-significant volume. Led by Riccardo and Martha, the survey team engaged a large group of faculty, postdocs, graduate and undergraduate students in hands-on aspects of the survey including observations utilizing over 4400 hours of telescope time, pipeline development, data processing and science analysis. In an inversion of the usual norm, the last two years of data were processed by the more senior members of the team, led by Riccardo, while the paper writing was led by early career astronomers. Riccardo was an active member of the Undergraduate ALFALFA Team, a collaboration of faculty and undergraduate students from 20 principally undergraduate teaching institutions in the US and Puerto Rico. Over his career, Riccardo mentored many graduate and undergraduate students and young astronomers from Cornell and elsewhere.

While at Cornell, Riccardo spearheaded the development of the CCAT project to construct a submillimeter telescope at 18,400 feet above the ALMA site on Cerro Chajnantor in the Atacama region of northern Chile. He led early efforts to conduct site tests and developed concepts for a telescope and the partnership to construct it. His dream will come to fruition as the Fred Young Submillimeter Telescope scheduled for first light in 2025.

Riccardo was passionate about his astronomical research into the nature, distribution and evolution of galaxies, their use as probes of cosmology and the development of radio astronomy techniques and facilities. He was equally devoted to teaching non-scientists, mentoring early career astronomers and inspiring the public about the wonder of the universe. He has left a lasting imprint on the lives of many people all over the world whose paths he crossed.

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