The GMRT archive atomic gas survey -- I. Survey definition, methodology, and initial results from the pilot sample

TL;DR

This paper introduces the GMRT archive atomic gas survey, defining its methodology and presenting initial results from a pilot sample of 11 galaxies, aiming to analyze HI data uniformly across a large galaxy sample.

Contribution

It constructs the largest HI galaxy sample from GMRT archives and demonstrates a methodology for uniform data analysis and phase decomposition in galaxies.

Findings

Data quality confirmed for the pilot sample.

Multi-Gaussian decomposition effectively separates cold and warm HI phases.

Establishes a framework for large-scale HI galaxy studies.

Abstract

Interferometric observations of HI in galaxies played a pivotal role in studies of nearby galaxies. Compared to single-dish observation, it provides resolved distribution of gas in galaxies with unprecedented resolution. Several extensive HI surveys of nearby galaxies have been performed in the past; however, most of them consist of less than 100 galaxies due to individual efforts. On the other hand, present-day archives of the radio telescopes include data for at least several hundred galaxies. To utilize these data sets to their full potential, we construct a sample including all galaxies observed by the Giant Meter wave Radio Telescope (GMRT) in HI. This results in a total of 515 galaxies, the largest sample to date. We intend to analyze all the data uniformly and carry out different exciting science. As a pilot project, we analyze data from 11 galaxies and present the data products in this paper. We further investigate the neutral ISM in these galaxies and extract cold and warm phases using a multi-Gaussian decomposition method. This pilot project assures the quality of the data, which will enable us to perform critical science investigations using the full sample.