Resolving a dusty, star-forming SHiZELS galaxy at z=2.2 with HST, ALMA and SINFONI on kiloparsec scales

R. K. Cochrane, P. N. Best, I. Smail, E. Ibar, C. Cheng, A. M. Swinbank, J. Molina, D. Sobral, U. Dudzeviciute

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We present ∼0.15 arcsec spatial resolution imaging of SHiZELS-14, a massive (⁠M∗∼1011M⊙⁠), dusty, star-forming galaxy at z = 2.24. Our rest-frame ∼1kpc-scale, matched-resolution data comprise four different widely used tracers of star formation: the Hα emission line (from SINFONI/VLT), rest-frame UV continuum (from HST F606W imaging), the rest-frame far-infrared (from ALMA), and the radio continuum (from JVLA). Although originally identified by its modest Hα emission line flux, SHiZELS-14 appears to be a vigorously star-forming (⁠SFR∼1000M⊙yr−1⁠) example of a submillimetre galaxy, probably undergoing a merger. SHiZELS-14 displays a compact, dusty central starburst, as well as extended emission in Hα and the rest-frame optical and FIR. The UV emission is spatially offset from the peak of the dust continuum emission, and appears to trace holes in the dust distribution. We find that the dust attenuation varies across the spatial extent of the galaxy, reaching a peak of at least AH α ∼ 5 in the most dusty regions, although the extinction in the central starburst is likely to be much higher. Global star-formation rates inferred using standard calibrations for the different tracers vary from ∼10−1000M⊙yr−1⁠, and are particularly discrepant in the galaxy’s dusty centre. This galaxy highlights the biased view of the evolution of star-forming galaxies provided by shorter wavelength data.
Original languageEnglish
Pages (from-to)2622-2638
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Early online date19 Feb 2021
Publication statusPublished - 1 May 2021


  • astro-ph.GA


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