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TY - JOUR
T1 - An ALMA survey of CO in submillimetre galaxies
T2 - companions, triggering, and the environment in blended sources
AU - Wardlow, J. L.
AU - Simpson, J. M.
AU - Smail, Ian
AU - Swinbank, A. M.
AU - Blain, A. W.
AU - Brandt, W. N.
AU - Chapman, S. C.
AU - Chen, Chian-Chou
AU - Cooke, E. A.
AU - Dannerbauer, H.
AU - Gullberg, B.
AU - Hodge, J. A.
AU - Ivison, R. J.
AU - Knudsen, K. K.
AU - Scott, Douglas
AU - Thomson, A. P.
AU - Weiß, A.
AU - van der Werf, P. P.
N1 - This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2018 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
PY - 2018/9/1
Y1 - 2018/9/1
N2 - 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 our CO spectroscopy 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.
AB - 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 our CO spectroscopy 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.
KW - galaxies: evolution
KW - galaxies: ISM
KW - submillimetre: galaxies
U2 - 10.1093/mnras/sty1526
DO - 10.1093/mnras/sty1526
M3 - Journal article
VL - 479
SP - 3879
EP - 3891
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 3
ER -