2014/11/30 by Samir Salim, Janice C. Lee, Chun Ly +5 · 3 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Metallicity #Offset (computer science) #Relation (database) #Spurious relationship #Star formation #Stellar mass #astro-ph.GA
paper · pdf · doi:10.1088/0004-637x/797/2/126
ApJ. Several minor corrections
openalex publication_date 2014/12/08 · arxiv created 2014/12/20 · arxiv updated 2014/12/23 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
It has been proposed that the (stellar) mass–(gas) metallicity relation of galaxies exhibits a secondary dependence on star formation rate (SFR), and that the resulting M * – Z –SFR relation may be redshift-invariant, i.e., "fundamental." However, conflicting results on the character of the SFR dependence, and whether it exists, have been reported. To gain insight into the origins of the conflicting results, we (1) devise a non-parametric, astrophysically motivated analysis framework based on the offset from the star-forming ("main") sequence at a given M * (relative specific SFR); (2) apply this methodology and perform a comprehensive re-analysis of the local M * – Z –SFR relation, based on SDSS, GALEX , and WISE data; and (3) study the impact of sample selection and of using different metallicity and SFR indicators. We show that metallicity is anti-correlated with specific SFR regardless of the indicators used. We do not find that the relation is spurious due to correlations arising from biased metallicity measurements or fiber aperture effects. We emphasize that the dependence is weak/absent for massive galaxies (log M * > 10.5), and that the overall scatter in the M * – Z –SFR relation does not greatly decrease from the M * – Z relation. We find that the dependence is stronger for the highest SSFR galaxies above the star-forming sequence. This two-mode behavior can be described with a broken linear fit in 12+log(O/H) versus log (SFR/ M * ), at a given M * . Previous parameterizations used for comparative analysis with higher redshift samples that do not account for the more detailed behavior of the local M * – Z –SFR relation may incorrectly lead to the conclusion that those samples follow a different relationship.