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Kiloparsec-scale Dust Disks in High-redshift Luminous Submillimeter Galaxies

Hodge, JA; Swinbank, AM; Simpson, JM; Smail, I; Walter, F; Alexander, DM; Bertoldi, F; ... van der Werf, P; + view all (2016) Kiloparsec-scale Dust Disks in High-redshift Luminous Submillimeter Galaxies. The Astrophysical Journal , 833 (1) 10.3847/1538-4357/833/1/103. Green open access

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Abstract

We present high-resolution (0 16) 870 μm Atacama Large Millimeter/submillimeter Array (ALMA) imaging of 16 luminous (LIR ~ ´4 10 L 12 ) submillimeter galaxies (SMGs) from the ALESS survey of the Extended Chandra Deep Field South. This dust imaging traces the dust-obscured star formation in these z ~ 2.5 galaxies on ∼1.3 kpc scales. The emission has a median effective radius of Re = 0 24 ± 0 02, corresponding to a typical physical size of Re= 1.8 ± 0.2 kpc. We derive a median Sérsic index of n = 0.9 ± 0.2, implying that the dust emission is remarkably disk-like at the current resolution and sensitivity. We use different weighting schemes with the visibilities to search for clumps on 0 12 (∼1.0 kpc) scales, but we find no significant evidence for clumping in the majority of cases. Indeed, we demonstrate using simulations that the observed morphologies are generally consistent with smooth exponential disks, suggesting that caution should be exercised when identifying candidate clumps in even moderate signal-to-noise ratio interferometric data. We compare our maps to comparable-resolution Hubble Space Telescope H160-band images, finding that the stellar morphologies appear significantly more extended and disturbed, and suggesting that major mergers may be responsible for driving the formation of the compact dust disks we observe. The stark contrast between the obscured and unobscured morphologies may also have implications for SED fitting routines that assume the dust is co-located with the optical/near-IR continuum emission. Finally, we discuss the potential of the current bursts of star formation to transform the observed galaxy sizes and light profiles, showing that the z ~ 0 descendants of these SMGs are expected to have stellar masses, effective radii, and gas surface densities consistent with the most compact massive ( * M ~ 1–2 × 1011 M) earlytype galaxies observed locally.

Type: Article
Title: Kiloparsec-scale Dust Disks in High-redshift Luminous Submillimeter Galaxies
Open access status: An open access version is available from UCL Discovery
DOI: 10.3847/1538-4357/833/1/103
Publisher version: http://doi.org/10.3847/1538-4357/833/1/103
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: galaxies: evolution – galaxies: formation – galaxies: high-redshift – galaxies: starburst – submillimeter: galaxies
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10038471
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