Rights statement: © 2018. The American Astronomical Society. All rights reserved.
Accepted author manuscript, 2.22 MB, PDF document
Available under license: CC BY-NC: Creative Commons Attribution-NonCommercial 4.0 International License
Final published version
Licence: Unspecified
Other version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - The Dust and [C II] Morphologies of Redshift ˜4.5 Sub-millimeter Galaxies at ˜200 pc Resolution
T2 - The Absence of Large Clumps in the Interstellar Medium at High-redshift
AU - Gullberg, B.
AU - Swinbank, A. M.
AU - Smail, I.
AU - Biggs, A. D.
AU - Bertoldi, F.
AU - De Breuck, C.
AU - Chapman, S. C.
AU - Chen, C.-C.
AU - Cooke, E. A.
AU - Coppin, K. E. K.
AU - Cox, P.
AU - Dannerbauer, H.
AU - Dunlop, J. S.
AU - Edge, A. C.
AU - Farrah, D.
AU - Geach, J. E.
AU - Greve, T. R.
AU - Hodge, J.
AU - Ibar, E.
AU - Ivison, R. J.
AU - Karim, A.
AU - Schinnerer, E.
AU - Scott, D.
AU - Simpson, J. M.
AU - Stach, S. M.
AU - Thomson, A. P.
AU - van der Werf, P.
AU - Walter, F.
AU - Wardlow, J. L.
AU - Weiss, A.
N1 - © 2018. The American Astronomical Society. All rights reserved.
PY - 2018/5/20
Y1 - 2018/5/20
N2 - We present deep, high-resolution (0.″03, 200 pc) ALMA Band 7 observations covering the dust continuum and [C II] λ157.7 μm emission in four z ˜ 4.4-4.8 sub-millimeter galaxies (SMGs) selected from the ALESS and AS2UDS surveys. The data show that the rest-frame 160 μm (observed 345 GHz) dust emission is consistent with smooth morphologies on kpc scales for three of the sources. One source, UDS 47.0, displays apparent substructure, but this is also consistent with a smooth morphology—as indicated by simulations showing that smooth exponential disks can appear clumpy when observed at the high angular resolution (0.″03) and depth of these observations ({σ }345{GHz}˜ 27{--}47 μJy beam-1). The four SMGs are bright [C II] emitters. We extract [C II] spectra from the high-resolution data, and recover ˜20%-100% of the [C II] flux and ˜40%-80% of the dust continuum emission, compared to the previous lower-resolution observations. When tapered to 0.″2 resolution, our maps recover ˜80%-100% of the continuum emission, indicating that ˜60% of the emission is resolved out on ˜200 pc scales. We find that the [C II] emission in high-redshift galaxies is more spatially extended than the rest-frame 160 μm dust continuum by a factor of 1.6 ± 0.4. By considering the {L}[{{C}{{II}}]}/{L}FIR} ratio as a function of the star formation rate surface density ({{{Σ }}}SFR}), we revisit the [C II] deficit and suggest that the decline in the {L}[{{C}{{II}}]}/{L}FIR} ratio as a function of {{{Σ }}}SFR} is consistent with local processes. We also explore the physical drivers that may be responsible for these trends and can give rise to the properties found in the densest regions of SMGs.
AB - We present deep, high-resolution (0.″03, 200 pc) ALMA Band 7 observations covering the dust continuum and [C II] λ157.7 μm emission in four z ˜ 4.4-4.8 sub-millimeter galaxies (SMGs) selected from the ALESS and AS2UDS surveys. The data show that the rest-frame 160 μm (observed 345 GHz) dust emission is consistent with smooth morphologies on kpc scales for three of the sources. One source, UDS 47.0, displays apparent substructure, but this is also consistent with a smooth morphology—as indicated by simulations showing that smooth exponential disks can appear clumpy when observed at the high angular resolution (0.″03) and depth of these observations ({σ }345{GHz}˜ 27{--}47 μJy beam-1). The four SMGs are bright [C II] emitters. We extract [C II] spectra from the high-resolution data, and recover ˜20%-100% of the [C II] flux and ˜40%-80% of the dust continuum emission, compared to the previous lower-resolution observations. When tapered to 0.″2 resolution, our maps recover ˜80%-100% of the continuum emission, indicating that ˜60% of the emission is resolved out on ˜200 pc scales. We find that the [C II] emission in high-redshift galaxies is more spatially extended than the rest-frame 160 μm dust continuum by a factor of 1.6 ± 0.4. By considering the {L}[{{C}{{II}}]}/{L}FIR} ratio as a function of the star formation rate surface density ({{{Σ }}}SFR}), we revisit the [C II] deficit and suggest that the decline in the {L}[{{C}{{II}}]}/{L}FIR} ratio as a function of {{{Σ }}}SFR} is consistent with local processes. We also explore the physical drivers that may be responsible for these trends and can give rise to the properties found in the densest regions of SMGs.
KW - galaxies: evolution
KW - galaxies: ISM
KW - submillimeter: galaxies
U2 - 10.3847/1538-4357/aabe8c
DO - 10.3847/1538-4357/aabe8c
M3 - Journal article
VL - 859
JO - The Astrophysical Journal
JF - The Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 12
ER -