The BLUEDISK Survey: Thickness of H i Layers in Gas-rich Spiral Galaxies

Abstract

We use an empirical relation to measure the H i scale height of relatively H i -rich galaxies using 21 cm observations. The galaxies were selected from the BLUEDISK, THINGS, and VIVA surveys. We aim to compare the thickness of the H i layer of unusually H i- rich galaxies with that of normal spiral galaxies and find any correlation between the H i scale height and other galaxies’ properties. We found that on average the unusually H i- rich galaxies have H i disk thickness similar to that of the control sample and the galaxies selected from the THINGS and VIVA surveys within their uncertainties. Our results also show that the average thickness of the neutral hydrogen inside the optical disk is correlated with the atomic gas fraction inside the optical disk with a scatter of ∼0.22 dex. A correlation is also found between the H i scale height with the atomic-to-molecular hydrogen ratio, which indicates a link between star formation and the vertical distribution of H i, which is consistent with previous studies. This new scaling relation between the H i scale height and atomic gas fraction will allow us to predict the H i scale heights of a large number of galaxies, but a larger sample is needed to decrease the scatter.