Characterizing the Local Relation between Star Formation Rate and Gas-phase Metallicity in MaNGA Spiral Galaxies

Characterizing the Local Relation between Star Formation Rate and Gas-phase Metallicity in MaNGA Spiral Galaxies

The role of gas accretion in galaxy evolution is still a matter of debate. The presence of inflows of metal-poor gas that trigger star formation bursts of low metallicity has been proposed as an explanation for the local anticorrelation between star formation rate (SFR) and gas-phase metallicity (Zg...

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Bibliographic Details
Published in:The Astrophysical journal 2019-09, Vol.882 (1), p.9
Main Authors: Sánchez-Menguiano, Laura, Almeida, Jorge Sánchez, Muñoz-Tuñón, Casiana, Sánchez, Sebastián F., Filho, Mercedes, Hwang, Hsiang-Chih, Drory, Niv
Format: Article
Language:eng
Subjects:
Accretion
Algorithms
Astrophysics
Correlation
Deposition
Galactic evolution
galaxies: abundances
galaxies: evolution
galaxies: formation
galaxies: star formation
Machine learning
Metallicity
Metals
Polynomials
Regression analysis
Slopes
Spiral galaxies
Star & galaxy formation
Star formation
Star formation rate
Stars & galaxies
Stellar age
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Summary:The role of gas accretion in galaxy evolution is still a matter of debate. The presence of inflows of metal-poor gas that trigger star formation bursts of low metallicity has been proposed as an explanation for the local anticorrelation between star formation rate (SFR) and gas-phase metallicity (Zg) found in the literature. In the present study, we show how the anticorrelation is also present as part of a diversified range of behaviors for a sample of more than 700 nearby spiral galaxies from the SDSS-IV MaNGA survey. We have characterized the local relation between SFR and Zg after subtracting the azimuthally averaged radial profiles of both quantities. Of the analyzed galaxies, 60% display an SFR-Zg anticorrelation, with the remaining 40% showing no correlation (19%) or positive correlation (21%). Applying a random forest machine-learning algorithm, we find that the slope of the correlation is mainly determined by the average gas-phase metallicity of the galaxy. Galaxy mass, g − r colors, stellar age, and mass density seem to play a less significant role. This result is supported by the performed second-order polynomial regression analysis. Thus, the local SFR-Zg slope varies with the average metallicity, with the more metal-poor galaxies presenting the lowest slopes (i.e., the strongest SFR-Zg anticorrelations), and reversing the relation for more metal-rich systems. Our results suggest that external gas accretion fuels star formation in metal-poor galaxies, whereas in metal-rich systems, the gas comes from previous star formation episodes.
ISSN:0004-637X
1538-4357