The GALEX Arecibo SDSS Survey. VI. Second Data Release and Updated Gas Fraction Scaling Relations

TL;DR

This paper presents the second data release of the GASS survey, providing HI measurements for ~1000 galaxies, and updates the scaling relations between gas fraction and galaxy properties based on the expanded dataset.

Contribution

It offers new HI data for 240 galaxies, doubling the sample size, and refines the gas fraction scaling relations with this larger, more comprehensive dataset.

Findings

Updated gas fraction scaling relations with stellar mass and other properties.

New HI measurements for 240 galaxies, expanding the sample.

Revised understanding of the gas fraction plane in galaxy evolution.

Abstract

We present the second data release from the GALEX Arecibo SDSS Survey (GASS), an ongoing large Arecibo program to measure the HI properties for an unbiased sample of ~1000 galaxies with stellar masses greater than 10^10 Msun and redshifts 0.025<z<0.05. GASS targets are selected from the Sloan Digital Sky Survey (SDSS) spectroscopic and Galaxy Evolution Explorer (GALEX) imaging surveys, and are observed until detected or until a gas mass fraction limit of a few per cent is reached. This second data installment includes new Arecibo observations of 240 galaxies, and marks the 50% of the complete survey. We present catalogs of the HI, optical and ultraviolet parameters for these galaxies, and their HI-line profiles. Having more than doubled the size of the sample since the first data release, we also revisit the main scaling relations of the HI mass fraction with galaxy stellar mass, stellar mass surface density, concentration index, and NUV-r color, as well as the gas fraction plane introduced in our earlier work.