The Next Generation Very Large Array

The next generation Very Large Array (ngVLA) is a transformational radio observatory being designed by the U.S. National Radio Astronomy Observatory (NRAO). It will provide order of magnitude improvements in sensitivity, resolution, and uv coverage over the current Jansky Very Large Array (VLA) at ~1.2-50 GHz and extend the frequency range up to 70-115 GHz. The ngVLA will consist of three arrays working in parallel: i) a Main Array of 214 x 18-m antennas clustered at the current VLA site but spread within and beyond New Mexico that will provide baselines of 0.01-1000 km; ii) a Short Baseline Array of 19 x 6-m antennas located at the Main Array centre (+ 4 MA antennas with total-power capabilities) for high sensitivity to low surface brightness emission, and; iii) a Long Baseline Array of 30 x 18-m antennas located across the U.S. from Hawaii to the Virgin Islands, as well as western Canada, for extremely high resolution imaging with a maximum ~8,800 km baseline. The ngVLA concept has been submitted for consideration to the U.S. Astro2020 decadal survey panel, and soon thereafter it will be submitted to the U.S. National Science Foundation's Major Research Equipment and Facility Construction program. The goal is to have early science with ngVLA as early as 2028 and full operations by 2034.

The ngVLA will be a PI-proposal driven observatory and will tackle a wide range of high-impact key science projects that shaped its overall design. For example, the ngVLA will probe the innermost "terrestrial" zones of nearby circumstellar disks for forming planets, search for interstellar signals from key prebiotic molecules such as simple amino acids, trace the evolution of gas within galaxies across cosmic time, plumb the Galactic Centre for pulsars that will test General Relativity in new regimes, and explore the growth and evolution of black holes within and beyond our Galaxy in the era of multi-messenger astronomy. The ngVLA's versatile design will also enable many other fundamental advances, as detailed in the recently published, topically diverse ngVLA Science Book.

NRAO is seeking international partnerships at the 25% level to build and operate the ngVLA. Since Canadians have been historically major users of the VLA and have been valued partners with NRAO for ALMA, our participation is welcome. Canadians have been actually involved in ngVLA discussions for the past five years, and have played leadership roles in the ngVLA Science and Technical Advisory Councils. Canadian technologies are also very attractive for the ngVLA, in particular our designs for radio antennas, receivers, correlators, and data archives, and our industrial capacities to realize them. Indeed, the Canadian designs for the ngVLA antennas and correlator/beamformer are presently the baseline models for the project. Five other countries have also expressed interest in participating in ngVLA.

Given the size of Canada's radio community and earlier use of the VLA (and ALMA), we recommend Canadian participation in the ngVLA at the 7% level. Such participation would be significant enough to allow Canadian leadership in ngVLA's construction and usage. Canada's participation in ngVLA should not preclude its participation in SKA; access to both facilities is necessary to meet Canada's radio astronomy needs. Indeed, ngVLA will fill the gap between those radio frequencies observable with the SKA and ALMA at high sensitivities and resolutions. Canada's partnership in ngVLA will make it a major player in global radio astronomy, with access to cutting-edge facilities together covering approximately three orders of magnitude in frequency.