Meet the AAS Keynote Speakers: Prof. Nicholas Scoville

In this series of posts, we sit down with a few of the plenary speakers of the 240th AAS meeting to learn more about them and their research. You can see a full schedule of their talks here, and read our other interviews here!

Prof. Nicholas Scoville is a Professor of Astronomy, Emeritus, at Caltech and has spent much of his career as both an observer and a theorist, traversing across spectral regimes and redshifts to address some of the most major questions in our field.  For example, how do galaxies form and evolve?  How does their star formation rate change with time?  What is the large scale structure of our Universe?  To address these major questions, Prof. Scoville uses light emitted from interstellar gas and dust to infer properties of galaxies and the processes that govern their evolution.

Introduction to the Astronomy Field and Early Career Contributions

Prof. Scoville began his career in astronomy at Columbia University where he completed his bachelor’s degree, initially starting off in the engineering school before transferring to the physics department.  It was when he took his first astrophysics course as a junior that he became interested in the field.  “[Astronomy] seemed like a very fresh field, and the people at Columbia who were teaching it were extremely good people,” he recalls, “In astronomy, there were lots of unsolved problems, and that was the field where I knew I could actually contribute.”  Prof. Scoville continued on to complete his PhD from Columbia University as well, focusing on giant molecular clouds in the Milky Way.  

After earning his PhD, he spent a few years at the University of Minnesota working with his advisor and friend Prof. Phillip Soloman.  While there, Prof. Scoville attended a seminar where Prof. Peter Goldreich of Caltech was speaking on maser emission.  Prof. Scoville asked several questions throughout the talk, and at its conclusion, Prof. Goldreich approached Prof. Scoville and informed him that he thought his questions were brilliant.  In fact, he was so impressed by them that Prof. Goldreich offered Prof. Scoville to work as a postdoctoral scholar at Caltech, where he worked for two years.  “That is a good pointer to use, ask good questions,” Prof. Scoville emphasized to students.  He left Caltech to work at the University of Massachusetts, Amherst, where he continued his observational work on interstellar gas and giant molecular clouds.  In this early career stage, Prof. Scoville became one of the astronomers to pioneer the technique of using emission lines from the molecule carbon monoxide (CO) to not only trace the structure of individual molecular clouds but also infer the mass of gas in distant galaxies.  By the end of his appointment at the University of Massachusetts, Prof. Scoville served as the associate director of the Five College Radio Astronomy Observatory.  It was after this that he was once again hired by Caltech.

Founding the COSMOS Collaboration

For ten years, Prof. Scoville acted as director of Caltech’s Owens Valley Radio Observatory, where he conducted theoretical and observational research of high luminosity infrared galaxies.  He was appointed a professorship during this time, and in 2003, founded the Cosmic Evolution Survey (COSMOS).  The aim of this project is to connect astronomers across the world to study galaxy formation and evolution and large scale structure using telescopes that span every spectral regime, from the X-ray to the radio.  Starting off with just 38 astronomers in 2003, the collaboration grew to over 200 people.  When asked what it was like to lead such a massive project, Prof. Scoville emphasized, “I viewed it as a collaboration.”  Rather than acting as the sole decision maker in the collaboration, Prof. Scoville remarked, “I wanted to honor people’s intelligence.”  As PI of COSMOS, Prof. Scoville valued the involvement and leadership of young astronomers and found working with them to be some of the most rewarding aspects of the collaboration.  Since its inception, COSMOS has significantly advanced our understanding of star formation at early epochs and the distribution of dark matter through cosmic time.  Within the two square degree COSMOS field, astronomers have discovered and studied over one million galaxies across cosmic time, some of which allow us to peer back to when the Universe was less than a billion years old.

Since stepping down as leader of COSMOS, Prof. Scoville has continued his work on galaxy formation and evolution and large scale structure.  As of May 9, 2022, Prof. Scoville was elected to the National Academy of Sciences in recognition of his continuing achievements in research.

Probing the Gas Mass of Galaxies at High Redshifts using Dust Emission

In Prof. Scoville’s plenary talk, he will be presenting his latest work, which involves using a relatively simple technique that studies Rayleigh-Jeans tail (long wavelength) emission, popularized by Prof. Roger Hilldebrand in the 1980s, to probe the interstellar gas content of galaxies out to one billion years after the Big Bang (redshift ~6).  CO emission is an effective tracer of (invisible) neutral hydrogen and works well for estimating the gas mass of lower redshift, nearby galaxies.  However, when moving further away to higher redshifts, astronomers are limited to a higher frequency transition of CO, one which exclusively traces high temperature gas (T>60K).  It is not an effective tracer of low-temperature (T = 10-20 K) gas, which constitutes most of the gas mass of galaxies.  To combat this at higher redshifts, Prof. Scoville turns to Rayleigh-Jeans tail emission, which is long-wavelength emission from dust.  This technique is sensitive to low-temperature dust and leverages our understanding of the relationship between dust and gas in a galaxy.  As such, greater accuracy and precision can be achieved when estimating gas masses of high-redshift sources.  Prof. Scoville notes that this technique is rather simple while also being effective: “I tend to like doing things simply rather than overcomplicating them.”

A Scientist and an Artist

Outside of science, Prof. Scoville enjoys welding metals like steel and aluminum into art sculptures.  He first became interested in welding towards the end of his undergraduate education at Columbia University while helping his brother build a house in Vermont.  His mother worked as an artist, initially starting off as a painter, and Prof. Scoville inspired her to take up welding as well, which she continued to do well into her 80s.  Prof. Scoville’s father was an arms expert for the CIA and later on became an important figure in nuclear disarmament activism.  Remarking on what he finds uniquely rewarding about art, “I enjoy doing things where you have no idea where you’re going to.  In astronomy, and in my projects, there’s often some data you’re trying to explain.  I like how when you do art, you’re given a blank canvas to create whatever you want.”

Be sure to check out Prof. Scoville’s Plenary Talk, Evolution of Gas and Stars in Galaxies Over the Last 12 Billion Years, on Tuesday, June 14th from 3:40 PM PT – 4:30 PM PT to learn more about his work on probing the interstellar gas content of high redshift galaxies!

Astrobite Edited by: Olivia Cooper

Featured Image Credit: Robert Paz (Caltech)

About Catherine Manea

Catherine is a 3rd year PhD student at the University of Texas at Austin. Her research is in Galactic Archaeology, the practice of using the dynamical and chemical information of individual stars to study the evolution of our Milky Way. She is particularly interested in pushing chemical tagging, the practice of tracing stars back to their birth sites, to new limits.

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