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arXiv · 0705.2266

Evolution of the Frequency of Luminous (\geq L_V*) Close Galaxy Pairs at z < 1.2 in the COSMOS Field

J. S. Kartaltepe·D. B. Sanders·N. Z. Scoville·D. Calzetti·P. Capak·A. Koekemoer·B. Mobasher·T. Murayama·M. Salvato·S. S. Sasaki·Y. Taniguchi
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Abstract

We measure the fraction of luminous galaxies in pairs at projected separations of 5-20 kpc out to z=1.2 in the COSMOS field using ACS images and photometric redshifts derived from an extensive multiwavelength dataset. Analysis of a complete sample of 106,188 galaxies more luminous than M_V=-19.8 (~ L_V*) in the redshift range 0.1 < z < 1.2 yields 1,749 galaxy pairs. These data are supplemented by a local z=0-0.1 value for the galaxy pair fraction derived from the Sloan Digital Sky Survey (SDSS). After statistically correcting the COSMOS pair sample for chance line-of-sight superpositions, the evolution in the pair fraction is fit by a power law \propto (1+z)^{n=3.1 \pm 0.1}. If this strongly evolving pair fraction continues out to higher redshift, ~ 50% of all luminous galaxies at z ~ 2 are in close pairs. This clearly signifies that galaxy mergers are a very significant and possibly dominant mechanism for galaxy evolution during the epoch of galaxy formation at z=1 to 3.

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J. S. Kartaltepe, D. B. Sanders, N. Z. Scoville, D. Calzetti, P. Capak, A. Koekemoer, B. Mobasher, T. Murayama, M. Salvato, S. S. Sasaki, Y. Taniguchi. 2007-05-16. Evolution of the Frequency of Luminous (\geq L_V*) Close Galaxy Pairs at z < 1.2 in the COSMOS Field. https://doi.org/10.1086/519953

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