Finding Passive Galaxies in HI-MaNGA: The Impact of Star-Formation Rate Indicator

TL;DR

This study compares different star-formation rate indicators in HI-rich galaxies from HI-MaNGA, revealing that various methods yield statistically similar low-sSFR samples when interpreted consistently, impacting understanding of galaxy evolution.

Contribution

It demonstrates that different SFR estimators produce comparable low-sSFR galaxy samples if W2-W3~<2 is properly interpreted, clarifying previous ambiguities.

Findings

Different SFR indicators yield similar low-sSFR galaxy samples.

Interpretation of W2-W3~<2 as sSFR<10^{-11.15} yr^{-1} is crucial.

Methodology impacts the understanding of HI-rich, low-SF galaxy populations.

Abstract

HI-rich galaxies typically have high star-formation rates (SFR), but there exist interesting HI-rich and low star-forming (low-SF) galaxies. Previous work on a sample of these galaxies identified from HI-MaNGA (HI follow-up to the MaNGA survey) using an infrared indicator of specific-SFR (sSFR; namely W2-W3~<2) could find no single physical process to explain their unusual behaviour. The method by which galaxies are identified as low sSFR may be important in this conclusion. In this Research Note, we explore how an HI-rich, low sSFR sample of HI-MaNGA galaxies differs using H alpha, single stellar population, and ultraviolet estimators of SFR. We find that samples are statistically similar to each other so long as W2-W3~<2 is interpreted as corresponding to sSFR<10^{-11.15} yr^{-1}.