The mass-metallicity relation of interacting galaxies

Leo Michel-Dansac, Diego G. Lambas, M. Sol Alonso, Patricia Tissera

Research output: Contribution to journalLetterpeer-review

79 Citations (Scopus)


We study the mass-metallicity relation of galaxies in pairs and in isolation taken from the Sloan Digital Sky Survey-Data Release 4 (SDSS-DR4) using the stellar masses and oxygen abundances derived by Tremonti et al. Close galaxy pairs, defined by projected separation rp < 25 kpc h-1 and radial velocity ΔV < 350 km s-1, are morphologically classified according to the strength of the interaction signs. We find that only for pairs showing signs of strong interactions, the mass-metallicity relation differs significantly from that of galaxies in isolation. In such pairs, the mean gas-phase oxygen abundances of galaxies with low stellar masses (M* ≲ 109 M h-1) exhibit an excess of 0.2 dex. Conversely, at larger masses (M* ≳ 1010 M h-1) galaxies have a systematically lower metallicity, although with a smaller difference (-0.05 dex). Similar trends are obtained if g-band magnitudes are used instead of stellar masses. In minor interactions, we find that the less massive member is systematically enriched, while a galaxy in interaction with a comparable stellar mass companion shows a metallicity decrement with respect to galaxies in isolation. We argue that metal-rich starbursts triggered by a more massive component, and inflows of low-metallicity gas induced by comparable or less massive companion galaxies, provide a natural scenario to explain our findings.

Original languageEnglish
Pages (from-to)L82-L86
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
Publication statusPublished - May 2008


  • Galaxies: abundances
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: interactions

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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