Next Generation Very Large Array Memo No. 7 Science Working Group 2: "Galaxy Ecosystems": The Matter Cycle in and Around Galaxies

TL;DR

The paper advocates for a next-generation Very Large Array (ngVLA) with enhanced sensitivity and resolution to revolutionize the study of galaxy ecosystems, matter cycles, and astrophysical processes in and around galaxies.

Contribution

It proposes specific design features and scientific applications of the ngVLA, emphasizing high brightness sensitivity and long baselines for advanced galaxy and ISM studies.

Findings

Potential for detailed microwave spectroscopy of the cold ISM

Ability to measure galaxy motions beyond the Local Group

Enhanced imaging of black hole feeding and protocluster formation

Abstract

This white paper discusses how a "next-generation" Very Large Array (ngVLA) operating in the frequency range 1-116 GHz could be a groundbreaking tool to study the detailed astrophysics of the "matter cycle" in the Milky Way and other galaxies. If optimized for high brightness sensitivity, the ngVLA would bring detailed microwave spectroscopy and modeling of the full radio spectral energy distribution into regular use as survey tools at resolutions of 0.1- 1 arcseconds. This wavelength range includes powerful diagnostics of density, excitation, and chemistry in the cold ISM, as well as multiple tracers of the rate of recent star formation, the magnetic field, shocks, and properties of the ionized ISM. We highlight design considerations that would make this facility revolutionary in this area, the foremost of which is a large amount of collecting area on ~km-length baselines. We also emphasize the strong case for harnessing the large proposed collecting area of the ngVLA for very long baseline applications as part of the core design. This would allow measurements of the three dimensional space motions of galaxies to beyond the Local Group and mapping of the Milky Way out to the far side of the disk. Finally, we discuss the gains from the proposed combination of very high resolution and sensitivity to thermal emission, which include observing the feeding of black holes and resolving forming protoclusters.