Year: 2018
Type: article
Abstract: We investigate the metallicity dependence of H i surface densities in star-forming regions along many lines of sight within 70 nearby galaxies, probing kiloparsec to 50 pc scales. We employ H i, SFR, stellar mass, and metallicity (gradient) measurements from the literature, spanning a wide range (5 dex) in stellar and gas mass and (1.6 dex) in metallicity. We consider metallicities as observed, or rescaled to match the mass–metallicity relation determined for SDSS galaxies. At intermediate to high metallicities (0.3–2 times solar), we find that the H i surface densities saturate at sufficiently large total gas surface density. The maximal H i columns vary approximately inversely with metallicity, and show little variation with spatial resolution, galactocentric radius, or among galaxies. In the central parts of massive spiral galaxies, the H i gas is depressed by factors of ∼ 2. The observed behavior is naturally reproduced by metallicity dependent shielding theories for the H i-to-H2 transitions in star-forming galaxies. We show that the inverse scaling of the maximal H i columns with metallicity suggests that the area filling fraction of atomic-molecular complexes in galaxies is of the order of unity, and weakly dependent on metallicity.
Source: The Astrophysical Journal
Authors: Andreas Schruba, Shmuel Bialy, Amiel Sternberg
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funder: Deutsche Forschungsgemeinschaft
Awards: G185239677, G2270942707, G37593186, G6803454950
OpenAlex ID: W2803181153