TeraHertz Astronomy from Antarctica - NOVAC May 2023
Channel: Northern Virginia Astronomy Club
Date: 2023-05-25

Over the past ~30 years there has been an Antarctic “Gold Rush”, not to mine the rich mineral deposits that are known to exist there, but to mine the ultra-high frequency, terahertz photons that rain down from the heavens. The terahertz (THz) portion of the electromagnetic spectrum ( ~ 1 to 10 THz; ) provides us with a powerful window into cosmic evolution. THz photons arriving at Earth can yield valuable insights into everything from the birth and death of stars to the cataclysmic events associated with the origin of galaxies and the Universe itself. Most of the THz photons we observe are emitted by the gas and dust between the stars, that is, the interstellar medium (ISM). At THz frequencies we can observe photons associated with the ISM of our own galaxy, the Milky Way, as well as from the ISM’s of distant galaxies. The evolution of THz astronomy has been driven largely by two factors; 1) atmospheric absorption of THz light and 2) the availability of detector technology. Water vapor in the Earth’s atmosphere is a very efficient absorber of THz photons. Therefore, THz observations are best conducted from space-based telescopes, balloon-borne telescopes, airborne observatories, or telescopes at high, dry, cold sites on Earth. In this presentation we will discuss what it is like to be a terahertz astronomer in Antarctica and what insights into our cosmic origins this branch of astronomy provides.

Professor Christopher Walker has over 30 years of experience designing, building, and using state-of-the-art receiver systems for terahertz astronomy. Prof. Walker has published numerous papers on star formation and protostellar evolution. He has served as dissertation director for seventeen Ph.D. students and been a Topical Editor for IEEE Transactions on TeraHertz Science and Technology. Prof. Walker has worked in industry (TRW Aerospace and JPL) as well as academia. As a Millikan Fellow in Physics at Caltech, he worked on the development of low-noise, SIS waveguide receivers above 400 GHz and performed observational and theoretical studies of star forming regions. On joining the University of Arizona faculty in 1991, he began the Steward Observatory Radio Astronomy Lab (SORAL), which has become a world leader in developing THz receiver systems for astronomy and other remote sensing applications. Instruments developed by Prof. Walker’s team have served as primary facility instruments at the Heinrich Hertz Telescope on Mt. Graham, AZ and the AST/RO telescope at the South Pole.  Prof. Walker led the effort to design and build the world’s largest (64 pixels) submillimeter-wave heterodyne array receiver. He was PI of the NASA long duration balloon project “The Stratospheric THz Observatory (STO)’’, which flew in Antarctica in 2012 and 2016. He is now PI of GUSTO, a balloon-borne mission under the auspices of the NASA Explorer Program. He was also PI of the “10 meter Suborbital Large Balloon Reflector (LBR)” project, which was selected by the NASA Innovative Advanced Concepts (NIAC) program for both a Phase I and II study. He authored Terahertz Astronomy, the first textbook in his field of study. His new book, Investigating Life in the Universe, will be available later this year.