A Pilot for a VLA HI Deep Field

TL;DR

This paper presents a pilot VLA HI deep field survey in the COSMOS region, demonstrating the VLA's capability to detect neutral hydrogen in diverse galaxies across a specific redshift range, paving the way for future large-scale HI surveys.

Contribution

It introduces the first VLA HI deep field pilot in the COSMOS region, showcasing the telescope's capabilities and providing a foundation for future HI surveys with SKA pathfinders.

Findings

Detected HI in 33 galaxies, including 3 without prior redshifts

Demonstrated VLA B-array's effectiveness for HI deep fields

Proved VLA's readiness for large-scale HI surveys

Abstract

High-resolution 21-cm HI deep fields provide spatially and kinematically resolved neutral gas maps at different redshifts, which are key to understanding galaxy evolution across cosmic time and testing predictions of cosmological simulations. Here we present results from a pilot for the COSMOS HI Large Extragalactic Survey (CHILES) done with the Karl G. Jansky Very Large Array (VLA). We take advantage of the newly expanded capabilities of the telescope to probe the redshift interval 0<z<0.193 in one observation. We observe the COSMOS field for 50 hours, which contains 413 galaxies with optical spectroscopic redshifts in the imaged field of view of 34' x 34' and the observed redshift interval. We have detected neutral hydrogen gas in 33 galaxies in different environments spanning the probed redshift range, including three without a previously known spectroscopic redshift. The detections have a range of HI and stellar masses, indicating the diversity of galaxies we are probing. We discuss the observations, data reduction, results and highlight interesting detections. We find that the VLA's B-array is the ideal configuration for HI deep fields since its long spacings mitigate RFI. This pilot shows that the VLA is ready to carry out such a survey, and serves as a test for future HI deep fields planned with other SKA pathfinders.