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 language | English |
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Pages (from-to) | 1281 |
Journal | Monthly Notices of the Royal Astronomical Society |
Publication status | Published - 1 May 2013 |
Keywords / Materials (for Non-textual outputs)
- galaxies: active
- galaxies: evolution
- galaxies: fundamental parameters
- galaxies: starburst
- infrared: galaxies