Semi-analytic spectral fitting: simultaneously modelling the mass accumulation and chemical evolution in MaNGA spiral galaxies

Abstract

We develop a novel semi-analytic spectral fitting approach to quantify the star-formation histories (SFHs) and chemical enrichment histories (ChEHs) of individual galaxies. We construct simple yet general chemical evolution models that account for gas inflow and outflow processes as well as star formation, to investigate the evolution of merger-free star-forming systems. These models are fitted directly to galaxies' absorption-line spectra, while their emission lines are used to constrain current gas phase metallicity and star formation rate. We apply this method to spiral galaxies selected from the SDSS-IV MaNGA survey. By fitting the co-added absorption-line spectra for each galaxy, and using the emission-line constraints on present-day metallicity and star formation, we reconstruct both the SFHs and the ChEHs for all objects in the sample. We can use these reconstructions to obtain archaeological measures of derived correlations such as the mass--metallicity relation at any redshift, which compare favourably with direct observations. We find that both the SFHs and ChEHs have strong mass dependence: massive galaxies accumulate their stellar masses and become enriched earlier. This mass dependence causes the observed flattening of the mass--metallicity relation at lower redshifts. The model also reproduces the observed gas-to-stellar mass ratio and its mass dependence. Moreover, we are able to determine that more massive galaxies have earlier gas infall times and shorter infall time-scales, and that the early chemical enrichment of low-mass galaxies is suppressed by strong outflows, while outflows are not very significant in massive galaxies.

20 pages, 21 figures, MNRAS accepted

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Cited by in corpus (9)

• DEVILS: Cosmic evolution of SED-derived metallicities and their connection to star-formation histories
• Stochastic Modelling of Star Formation Histories III. Constraints from Physically-Motivated Gaussian Processes
• SDSS-IV MaNGA: the chemical co-evolution of gas and stars in spiral galaxies
• Are Milky-Way-like galaxies like the Milky Way? A view from SDSS-IV/MaNGA
• Age-Divided Mean Stellar Populations from Full Spectrum Fitting as the Simplified Star Formation and Chemical Evolution History of a Galaxy: Methodology and Reliability
• The impact of environment on the lives of disk galaxies as revealed by SDSS-IV MaNGA
• A spectroscopic study of 14 structures behind Holm15A: Detecting a galaxy group candidate at z=0.58
• From Halos to Galaxies. X: Decoding Galaxy SEDs with Physical Priors and Accurate Star Formation History Reconstruction
• Testing a New Star Formation History Model from Principal Component Analysis to Facilitate Spectral Synthesis Modeling