Spectroscopy of High Redshift Galaxies with the ngVLA

TL;DR

The paper demonstrates that the ngVLA will significantly outperform ALMA in imaging high-redshift galaxies, enabling detailed analysis of molecular gas structures and dynamics at high resolution and sensitivity.

Contribution

It provides simulations showing ngVLA's superior capabilities for high-resolution, sensitive imaging of molecular line emission in distant galaxies, surpassing current ALMA performance.

Findings

ngVLA is ~6 times more sensitive than ALMA at similar resolution

ngVLA can recover detailed velocity fields and sub-structures in high-redshift galaxies

enables analysis of cold gas and star formation processes at high redshift

Abstract

We present simulations of the capabilities of the ngVLA to image at $\sim 0.75$ kpc resolution ($0.085"$), molecular line emission from star forming disk galaxies at high redshift. The results are compared to the current capabilities of ALMA. ALMA can detect the integrated emission, and determine the velocity gradient and size across the brighter emission regions of the galaxy. The ngVLA is a factor $\sim 6$ more sensitive at the adopted spatial and velocity resolution. This sensitivity is needed to recover the detailed column density distribution, velocity field, and velocity dispersion at full resolution. The ngVLA will enable detailed analysis of spectral line profiles at $0.75$~kpc resolution, even in relatively faint regions. The ngVLA will trace the rotation curves to large radii, and recover sub-structure in the disks, such as clumps, spiral arms, bars, and rings. Detection of these features is crucial in order to assess how cold gas precipitates the formation of stars at high redshift.