Millimeter/submillimeter VLBI with a Next Generation Large Radio Telescope in the Atacama Desert

TL;DR

This paper discusses the development of two large 50-meter radio telescopes in Chile's Atacama Desert, designed to enhance millimeter/submillimeter VLBI imaging for the next-generation Event Horizon Telescope and other arrays.

Contribution

It introduces the LST and AtLAST projects, detailing their design, location, and potential to significantly improve high-resolution astronomical imaging capabilities.

Findings

Design of 50-meter telescopes for ngEHT frequencies

Enhanced sensitivity and multi-frequency VLBI observations

Potential to improve angular resolution of future VLBI arrays

Abstract

The proposed next generation Event Horizon Telescope (ngEHT) concept envisions the imaging of various astronomical sources on scales of microarcseconds in unprecedented detail with at least two orders of magnitude improvement in the image dynamic ranges by extending the Event Horizon Telescope (EHT). A key technical component of ngEHT is the utilization of large aperture telescopes to anchor the entire array, allowing the connection of less sensitive stations through highly sensitive fringe detections to form a dense network across the planet. Here, we introduce two projects for planned next generation large radio telescopes in the 2030s on the Chajnantor Plateau in the Atacama desert in northern Chile, the Large Submillimeter Telescope (LST) and the Atacama Large Aperture Submillimeter Telescope (AtLAST). Both are designed to have a 50-meter diameter and operate at the planned ngEHT frequency bands of 86, 230 and 345\,GHz. A large aperture of 50\,m that is co-located with two existing EHT stations, the Atacama Large Millimeter/Submillimeter Array (ALMA) and the Atacama Pathfinder Experiment (APEX) Telescope in the excellent observing site of the Chajnantor Plateau, will offer excellent capabilities for highly sensitive, multi-frequency, and time-agile millimeter very long baseline interferometry (VLBI) observations with accurate data calibration relevant to key science cases of ngEHT. In addition to ngEHT, its unique location in Chile will substantially improve angular resolutions of the planned Next Generation Very Large Array in North America or any future global millimeter VLBI arrays if combined. LST and AtLAST will be a key element enabling transformative science cases with next-generation millimeter/submillimeter VLBI arrays.