The properties of (sub-)millimetre-selected galaxies as revealed by CANDELS HST WFC3/IR imaging in GOODS-South

T. A. Targett, J. S. Dunlop, M. Cirasuolo, R. J. McLure, V. A. Bruce, A. Fontana, A. Galametz, D. Paris, R. Davé, A. Dekel, S. M. Faber, H. C. Ferguson, N. A. Grogin, J. S. Kartaltepe, D. D. Kocevski, A. M. Koekemoer, P. Kurczynski, K. Lai, J. Lotz

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

We have exploited the Hubble Space Telescope (HST) Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) J and H-band Wide Field Camera 3 (WFC3)/infrared (IR) imaging to study the properties of (sub-)millimetre galaxies within the Great Observatories Origins Deep Survey South (GOODS-South) field. After using the deep radio (Very Large Array 1.4 GHz) and Spitzer (Infrared Array Camera 8 μm) imaging to identify galaxy counterparts for the (sub-)millimetre sources, we have then utilized the new CANDELS WFC3/IR imaging in two ways. First, the addition of new deep near-IR photometry from both HST and (at K band) the VLT to the existing GOODS-South data base has enabled us to derive improved photometric redshifts and stellar masses, confirming that the (sub-)millimetre sources are massive ( = 2.2 × 1011 ± 0.2 M⊙) galaxies at z ≃ 1-3. Secondly, we have exploited the depth and resolution of the WFC3/IR imaging to determine the sizes and morphologies of the galaxies at rest-frame optical wavelengths λrest > 4000 Å. Specifically, we have fitted two-dimensional axisymmetric galaxy models to the WFC3/IR images, varying luminosity, axial ratio, half-light radius r1/2 and Sérsic index n. Crucially, the wavelength and depth of the WFC3/IR imaging enables modelling of the mass-dominant galaxy, rather than the blue high surface-brightness features which often dominate optical (rest-frame ultraviolet) images of (sub-)millimetre galaxies, and can confuse visual morphological classification. As a result of this analysis, we find that >95 per cent of the rest-frame optical light in almost all of the (sub-)millimetre galaxies is well described by either a single exponential disc (n ≃ 1), or a multiple-component system in which the dominant constituent is disc like. We demonstrate that this conclusion is completely consistent with the results of recent high-quality ground-based K-band imaging sampling even longer rest-frame wavelengths, and explain why it is so. These massive disc galaxies are reasonably extended ( = 4.5 ± 0.5 kpc; median r1/2 = 4.0 kpc), consistent with the sizes of other massive star-forming discs at z ≃ 2. In many cases, we find evidence of blue clumps within the sources, with the mass-dominant disc component becoming more significant at longer wavelengths. Finally, only a minority of the sources show evidence for a major galaxy-galaxy interaction. Taken together, these results support the view that most (sub-)millimetre galaxies at z ≃ 2 are simply the most extreme examples of normal star-forming galaxies at that era. Interestingly, the only two bulge-dominated galaxies are also the two lowest redshift sources in the sample (z ≃ 1), a result which may reflect the structural evolution of high-mass galaxies in general.
Original languageEnglish
Pages (from-to)1281
JournalMonthly Notices of the Royal Astronomical Society
Publication statusPublished - 1 May 2013

Keywords / Materials (for Non-textual outputs)

  • galaxies: active
  • galaxies: evolution
  • galaxies: fundamental parameters
  • galaxies: starburst
  • infrared: galaxies


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