An ALMA survey of CO in submillimetre galaxies: companions, triggering, and the environment in blended sources

Autor: Wardlow, J. L., Simpson, J. M., Smail, Ian, Swinbank, A. M., Blain, A. W., Brandt, W. N., Chapman, S. C., Chen, Chian-Chou, Cooke, E. A., Dannerbauer, H., Gullberg, B., Hodge, J. A., Ivison, R. J., Knudsen, K. K., Scott, Douglas, Thomson, A. P., Weiss, A., van der Werf, P. P.
Rok vydání: 2018
Předmět:
Zdroj: 2018, MNRAS, 479, 3879
Druh dokumentu: Working Paper
DOI: 10.1093/mnras/sty1526
Popis: We present ALMA observations of the mid-J 12CO emission from six single-dish selected 870-micron sources in the Extended Chandra Deep Field-South (ECDFS) and UKIDSS Ultra-Deep Survey (UDS) fields. These six single-dish submillimetre sources were selected based on previous ALMA continuum observations, which showed that each comprised a blend of emission from two or more individual submillimetre galaxies (SMGs), separated on 5--10 arcsec scales. The six single-dish submillimetre sources targeted correspond to a total of 14 individual SMGs, of which seven have previously-measured robust optical/near-infrared spectroscopic redshifts, which were used to tune our ALMA observations. We detect CO(3-2) or CO(4-3) at z=2.3--3.7 in seven of the 14 SMGs, and in addition serendipitously detect line emission from three gas-rich companion galaxies, as well as identify four new 3.3-mm selected continuum sources in the six fields. Joint analysis of our CO spectroscopy and existing data suggests that 64 \pm 18% of the SMGs in blended submillimetre sources are unlikely to be physically associated. However, three of the SMG fields (50%) contain new, serendipitously-detected CO-emitting (but submillimetre-faint) sources at similar redshifts to the 870-micron selected SMGs we targeted. These data suggest that the SMGs inhabit overdense regions, but that these are not sufficiently overdense on ~100 kpc scales to influence the source blending given the short lifetimes of SMGs. We find that 21 \pm 12% of SMGs have spatially-distinct and kinematically-close companion galaxies (~8--150 kpc and <~300 km/s), which may have enhanced their star-formation via gravitational interactions.
Comment: MNRAS in press
Databáze: arXiv
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