Galaxy Pairs in the Sloan Digital Sky Survey I: Star Formation, AGN Fraction, and the Luminosity-Mass-Metallicity Relation - AstrophysicsReportar como inadecuado




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Abstract: Abridged. We present a sample of 1716 galaxies with companions within Deltav < 500 km-s, r p < 80 kpc and stellar mass ratio 0.1 < M 1-M 2 < 10 from theSloan Digital Sky Survey SDSS Data Release 4 DR4. In agreement withprevious studies, we find an enhancement in the star formation rate SFR ofgalaxy pairs at projected separations < 30-40 kpc. In addition, we find thatthis enhancement is highest and extends to the greatest separations forgalaxies of approximately equal mass, the so-called `major- pairs. However, SFRenhancement can still be detected for a sample of galaxy pairs whose masses arewithin a factor of 10 of each other. In agreement with the one previous studyof the luminosity-metallicity LZ relation in paired galaxies, we find anoffset to lower metallicities by ~ 0.1 dex for a given luminosity forgalaxies in pairs compared to the control sample. We also present the firstmass-metallicity MZ relation comparison between paired galaxies and thefield, and again find an offset to lower metallicities by ~ 0.05 dex for agiven mass. The smaller offset in the MZ relation indicates that both higherluminosities and lower metallicities may contribute to the shift of pairsrelative to the control in the LZ relation. We show that the offset in the LZrelation depends on galaxy half light radius, r h. Galaxies with r h < 3 kpcand with a close companion show a 0.05-0.1 dex downwards offset in metallicitycompared to control galaxies of the same size. Finally, we study the AGNfraction in both the pair and control sample and find that whilst selectinggalaxies in different cuts of color and asymmetry yields different AGNfractions, the fraction for pairs and the control sample are consistent for agiven set of selection criteria.



Autor: Sara L. Ellison, David R. Patton, Luc Simard, Alan W. McConnachie

Fuente: https://arxiv.org/







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