Abstract
ABSTRACT We study the star formation rate (SFR), stellar mass (M⋆), and the gas metallicity (Z) for 4636 galaxy pairs using the Galaxy And Mass Assembly (GAMA) survey. Our galaxy pairs lie in a redshift range of 0 < z < 0.35, mass range of 7.5 < log(M⋆/M⊙) < 11.5 and ΔV < 1000 km s−1. We explore variations in SFR and Z from three point of views: multiplicity, pair separation, and dynamics. We define multiplicity as the number of galaxies paired with a single galaxy, and analyzed for the first time variations in SFR and Z for both, single pairs and pairs with higher multiplicity. For the latter, we find SFR enhancements from 0.025–0.15 dex, that would shift the M–SFR relation of single pairs by 27${{\ \rm per\ cent}}$ to higher SFRs. The effect of Z, on the other hand, is of only 4${{\ \rm per\ cent}}$. We analyse the most and least massive galaxy of major/minor pairs as a function of the pair separation. We define major pairs those with mass ratios of 0.5 < M1/M2 < 2, while pairs with more discrepant mass ratios are classified as minor pairs. We find SFR enhancements of up to two and four times with respect to their control sample, for major and minor pairs. For the case of Z, we find decrements of up to 0.08 dex for the closest pairs. When we focus on dynamics, Z enhancements are found for minor pairs with high-velocity dispersion $(\sigma _p \gt 250 \,\, \mathrm{km\, s ^{-1}})$ and high multiplicity.
Highlights
The evolution of galaxies is influenced by the environment in which they reside and with the level of interaction they have with their neighbours
We present an analysis of star formation rate (SFR) and metallicity for a sample of 4636 SF galaxy pairs using the Galaxy And Mass Assembly (GAMA) survey
Our pairs were taken from the G3C and all our spectroscopic information from the SpecLineSFRv05 GAMA catalogue
Summary
The evolution of galaxies is influenced by the environment in which they reside (filaments, clusters, groups, pairs, or voids) and with the level of interaction they have with their neighbours. The gas metallicity in galaxy pairs was studied by Ellison et al (2008), who found decrements of metallicity for close projected separations. Di Matteo et al (2007), Scudder et al (2012b), and Scudder et al (2015) agree with the idea that the first pericenter passage could affect the quantity of gas in the disc of galaxies and the first episodes of SF This means that different samples of galaxy pairs must be explored in detail in order to determine which stage of interaction they are in. We analyse simultaneously the SFR and gas metallicity variations of galaxy pairs in the Galaxy And Mass Assembly (GAMA) survey (Driver et al 2011; Liske et al 2015), which is two orders of magnitude deeper than SDSS. Deeper surveys with higher completeness such as GAMA report ∼ 20 per cent of galaxy pairs at high multiplicity (see Section 2 of this paper).
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