Measuring the Metallicity of Early-type Galaxies. I. Composite Region

Abstract

We present the data of 9,739 early-type galaxies (ETGs), cross-matching the Galaxy Zoo 1 with our sample selected from the catalog of the Sloan Digital Sky Survey Data Release 7 of MPA-JHU emission-line measurements. We first investigate the divisor between ETGs with and without star formation (SF), and find the best separator of W2-W3=2.0. is added. We explore the ETG sample by refusing a varity of ionization sources, and derive 5376 ETGs with SF by utilizing a diagnostic tool of the division line of $W2-W3=2.0$. We measure their metallicities with four abundance calibrators. We find that our composite ETG sample has similar distributons of $M_{\ast }$ and star formation rate (SFR) as star-forming galaxies (SFGs) do, that most of them lie on the "main sequence", and that our fit is a slightly steeper slope than that derived in Renzini \& Peng. Compared with the distributions between different metallicities calibrated by four abundance indicators, we find that the Courti17 method is the most accurate calibrator for composite ETGs among the four abundance indicators. We present a weak positive correlation of SFR and metallicity only when the metallicity is calibrated by the PP04, Curti17, and T04 indicators. The correlation is not consistent with the negative correlation of both parameters in SFGs. We suggest that the weak correlation is due to the dilution effect of gas inflow driven by minor mergers.

Published in ApJS, 9 pages, 9 figures, 1 table

References in corpus (14)

• The Host Galaxies and Classification of Active Galactic Nuclei
• Star Formation in AEGIS Field Galaxies since z=1.1 : The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-Forming Galaxies
• UV Star Formation Rates in the Local Universe
• The SAURON project -- IX. A kinematic classification for early-type galaxies
• Galaxy Zoo 1 : Data Release of Morphological Classifications for nearly 900,000 galaxies
• An Objective Definition for the Main Sequence of Star-Forming Galaxies
• New fully empirical calibrations of strong-line metallicity indicators in star forming galaxies
• The role of minor mergers in the recent star formation history of early-type galaxies
• The Slow Death (or Rebirth?) of Extended Star Formation in z~0.1 Green Valley Early-Type Galaxies
• The MASSIVE survey - XI. What drives the molecular gas properties of early-type galaxies
• Metallicity calibrations for diffuse ionised gas and low ionisation emission regions
• The many faces of LINER-like galaxies: a WISE view
• GASS 3505: the prototype of HI-excess, passive galaxies
• The Metallicity measurement of Early-type Galaxies

Cited by in corpus (2)

• Gas phase metallicity determinations in nearby AGNs with SDSS-IV MaNGA: evidence of metal poor accretion
• Estimating The Metallicity of Star-forming Early-type Galaxies