An ALMA survey of CO in submillimetre galaxies: Companions, triggering, and the environment in blended sources
Journal article, 2018
We present ALMA observations of the mid-J 12CO emission from six single-dish selected 870-μm sources in the Extended Chandra Deep Field-South and UKIDSS Ultra-Deep Survey 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 7 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 ourCOspectroscopy and existing data suggests that 64(±18) per cent of the SMGs in blended submillimetre sources are unlikely to be physically associated. However, three of the SMG fields (50 per cent) contain new, serendipitously detected CO-emitting (but submillimetre-faint) sources at similar redshifts to the 870 μm 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 ± 12 per cent of SMGs have spatially distinct and kinematically close companion galaxies (∼8-150 kpc and ≲ 300 km s-1), which may have enhanced their star formation via gravitational interactions.
Galaxies: evolution
Galaxies: ism
Submillimetre: galaxies
Author
J. L. Wardlow
Durham University
J. M. Simpson
Academia Sinica
I. Smail
Durham University
A.M. Swinbank
Durham University
A. Blain
University Of Leicester
W. N. Brandt
Pennsylvania State University
S. C. Chapman
Dalhousie University
C. C. Chen
European Southern Observatory (ESO)
E. A. Cooke
Durham University
H. Dannerbauer
University of La Laguna
Instituto de Astrofísica de Canarias
B. Gullberg
Durham University
J. Hodge
Leiden University
R. J. Ivison
European Southern Observatory (ESO)
University of Edinburgh
Kirsten Kraiberg Knudsen
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
D. Scott
University of British Columbia (UBC)
A. P. Thomson
Durham University
University of Manchester
A. Weiß
Max Planck Society
P. van der Werf
Leiden University
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 479 3 3879-3891Subject Categories
Meteorology and Atmospheric Sciences
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
DOI
10.1093/mnras/sty1526