Speaker: Jonathan Weintroub, Electrical Engineer and Scientist at Harvard-Smithsonian Center for Astrophysics
Title: Wideband Digital Signal Processing and the Event Horizon Telescope
Abstract: A broad international collaboration is building the Event Horizon Telescope (EHT), a global λ ∼ 1 mm Very Long Baseline Interferometry (VLBI) array with angular resolution comparable to the Schwarzschild Radius of nearby supermassive black holes (SMBH). The ultimate goal of the EHT is to make an image of emission in the region of the black hole, in a region strongly influenced by intense gravity. Thus the EHT has to potential to verify Einstein’s General Relativity theory in the strong field regime. Ultra-wide bandwidths improve sensitivity, which is crucial, and thus ultra fast analog-to-digital conversion and commensurately fast digital signal processing are technologies which enable the EHT. Sensitivity is also improved by using digital phased arrays to aggregate all the collecting area at telescopes such as the Submillimeter Array (SMA) and the Atacama Large mm/Submm Array (ALMA). Recent developments at the Submillimeter Array (SMA) demonstrate the feasibility and potential of ultrawide band sampling and digital signal processing with fine uniform spectral resolution combining both correlation and phased array capability. The EHT and the SMA both benefit from technology shared by the Collaboration for Astronomy Signal Processing and Electronics Research (CASPER). I will describe the road map for wideband EHT instrument development with reference to CASPER where appropriate.
Bio: Jonathan Weintroub is an electrical engineer and scientist at the Harvard-Smithsonian Center for Astrophysics. He leads the digital signal processing group for the Submillimeter
Array (SMA), an eight element open-skies radio interferometer located on Maunakea in Hawaii. The SMA operates at frequencies of 230 GHz and above, and thus demands very wideband signal processing. Dr. Weintroub led the group which designed and deployed the “SMA Wideband Astronomical ROACH2 Machine” (SWARM) a 32 GHz bandwidth correlator and phased array, which transformed the utility of the SMA when it was commissioned as the primary facility back end in 2017. He is also the lead engineer for the Event Horizon Telescope (EHT) a global VLBI interferometer, which includes the SMA as a station, and which aims to make the first image of a supermassive black hole on Schwarzschild radius scales.