Most submillimeter galaxies are major mergers

TY - JOUR

T1 - Most submillimeter galaxies are major mergers

AU - Engel...[et al.], H.

AU - Tacconi, L. J.

AU - Greve, Thomas Rodriguez

PY - 2010/11/20

Y1 - 2010/11/20

N2 - We analyze subarcsecond resolution interferometric CO line data for 12 submillimeter-luminous (S850μm ≥ 5 mJy) galaxies with redshifts between 1 and 3, presenting new data for 4 of them. Morphologically and kinematically, most of the 12 systems appear to be major mergers. Five of them are well-resolved binary systems, and seven are compact or poorly resolved. Of the four binary systems for which mass measurements for both separate components can be made, all have mass ratios of 1:3 or closer. Furthermore, comparison of the ratio of compact to binary systems with that observed in local ULIRGs indicates that at least a significant fraction of the compact submillimeter-luminous galaxies (SMGs) must also be late-stage mergers. In addition, the dynamical and gas masses we derive are most consistent with the lower end of the range of stellar masses published for these systems, favoring cosmological models in which SMGs result from mergers. These results all point to the same conclusion that most of the bright SMGs with LIR ≳ 5 × 1012 L⊙ are likely major mergers.

AB - We analyze subarcsecond resolution interferometric CO line data for 12 submillimeter-luminous (S850μm ≥ 5 mJy) galaxies with redshifts between 1 and 3, presenting new data for 4 of them. Morphologically and kinematically, most of the 12 systems appear to be major mergers. Five of them are well-resolved binary systems, and seven are compact or poorly resolved. Of the four binary systems for which mass measurements for both separate components can be made, all have mass ratios of 1:3 or closer. Furthermore, comparison of the ratio of compact to binary systems with that observed in local ULIRGs indicates that at least a significant fraction of the compact submillimeter-luminous galaxies (SMGs) must also be late-stage mergers. In addition, the dynamical and gas masses we derive are most consistent with the lower end of the range of stellar masses published for these systems, favoring cosmological models in which SMGs result from mergers. These results all point to the same conclusion that most of the bright SMGs with LIR ≳ 5 × 1012 L⊙ are likely major mergers.

U2 - 10.1088/0004-637X/724/1/233

DO - 10.1088/0004-637X/724/1/233

M3 - Journal article

SN - 0004-637X

VL - 724

SP - 233

EP - 243

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

ER -