MRI: Track 1: Acquisition of Commercial Compact Rack Mount Iodine Optical Clock

Very-long-baseline interferometry (VLBI) uses many radio telescopes spread across the Earth. It makes the sharpest possible astronomical images. In 2019 the Event Horizon Telescope (EHT) used VLBI to take the first picture of a black hole at the center of a galaxy called M87. A picture of the black hole in our own galaxy, the Milky Way, followed in 2022. Synchronization of telescopes on different continents needs an extremely precise atomic clock. At the high frequencies needed to make the sharpest pictures the clock must be even more precise. The EHT uses the highest radio frequencies. By purchasing and installing a new product, a US designed and manufactured atomic clock, this program aims to improve the EHT. The new product has better stability than the complex hydrogen-based atomic clocks now used. It is also smaller, simpler, and more reliable. The first unit purchased will be installed at the Submillimeter Array (SMA) one of the main EHT telescopes. The SMA can be used by US scientists at no cost. Additional benefits of this program include validation of a new technology by long term monitoring in VLBI operation. Students will learn about this new clock by helping to install and monitor it. The VLBI frontier is pushing from 230 to 345 GHz but sensitivity is limited, in part, by the hydrogen maser (H-maser) devices used as frequency references, resulting in a 10% sensitivity loss at the higher frequency. A specialized commercial iodine optical clock, the EG-30 from the US company Vector Atomic, became available very recently. This device locks a laser’s frequency to the stable and precise quantum transition of molecular iodine. In addition to twofold superior stability compared to the H-maser the EG-30 is more compact, lighter weight and more reliable. This program proposes the acquisition of an EG-30 and then to integrate and to deploy it at the Submillimeter Array (SMA). It will be used for collaborative VLBI with the Event Horizon Telescope (EHT) making images of black holes. Broader impacts of the program include student training; students will be recruited for long term monitoring of the EG-30. The students will also benefit by experience operating the SMA, a science grade submillimeter interferometer. Also, long term field testing of the EG-30 will benefit both ground and space-based interferometry, setting the stage for the next generation of high-resolution movies of super-massive black hole event horizons in the center of the Milky Way and other galaxies. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2511063 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Jonathan Weintroub | Institution: Smithsonian Institution Astrophysical Observatory, CAMBRIDGE, MA | Award Amount: $579,171 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2511063 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2511063.html