Astrophys. J., 882, 9-9 (2019/September-1)
Characterizing the local relation between star formation rate and gas-phase metallicity in MaNGA spiral galaxies.
SANCHEZ-MENGUIANO L., SANCHEZ ALMEIDA J., MUNOZ-TUNON C., SANCHEZ S.F., FILHO M., HWANG H.-C. and DRORY N.
Abstract (from CDS):
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.
© 2019. The American Astronomical Society. All rights reserved.
galaxies: abundances - galaxies: evolution - galaxies: formation - galaxies: star formation
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