dc.contributor.author Ramasawmy, J. dc.contributor.author Geach, J. E. dc.contributor.author Hardcastle, M. J. dc.contributor.author Best, P. N. dc.contributor.author Bonato, M. dc.contributor.author Bondi, M. dc.contributor.author Rivera, G. Calistro dc.contributor.author Cochrane, R. K. dc.contributor.author Conway, J. E. dc.contributor.author Coppin, K. dc.contributor.author Duncan, K. J. dc.contributor.author Dunlop, J. S. dc.contributor.author Franco, M. dc.contributor.author García-Vergara, C. dc.contributor.author Jarvis, M. J. dc.contributor.author Kondapally, R. dc.contributor.author McCheyne, I. dc.contributor.author Prandoni, I. dc.contributor.author Röttgering, H. J. A. dc.contributor.author Smith, D. J. B. dc.contributor.author Tasse, C. dc.contributor.author Wang, L. dc.date.accessioned 2021-07-30T13:06:59Z dc.date.available 2021-07-30T13:06:59Z dc.date.issued 2021-04-19 dc.identifier.citation Ramasawmy , J , Geach , J E , Hardcastle , M J , Best , P N , Bonato , M , Bondi , M , Rivera , G C , Cochrane , R K , Conway , J E , Coppin , K , Duncan , K J , Dunlop , J S , Franco , M , García-Vergara , C , Jarvis , M J , Kondapally , R , McCheyne , I , Prandoni , I , Röttgering , H J A , Smith , D J B , Tasse , C & Wang , L 2021 , ' Low-frequency radio spectra of submillimetre galaxies in the Lockman Hole ' , Astronomy & Astrophysics , vol. 648 , A14 . https://doi.org/10.1051/0004-6361/202039858 dc.identifier.issn 0004-6361 dc.identifier.other PURE: 24855158 dc.identifier.other PURE UUID: b17cd18c-2c74-44f7-b129-f60a9d68277c dc.identifier.other ArXiv: http://arxiv.org/abs/2103.09677v1 dc.identifier.other ORCID: /0000-0001-9708-253X/work/97834483 dc.identifier.other ORCID: /0000-0002-0729-2988/work/97834506 dc.identifier.other ORCID: /0000-0002-3560-8599/work/97834582 dc.identifier.other Scopus: 85104664496 dc.identifier.uri http://hdl.handle.net/2299/24932 dc.description © ESO 2021. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1051/0004-6361/202039858 dc.description.abstract We investigate the radio properties of a sample of 53 sources selected at 850 $\mu$m from the SCUBA-2 Cosmology Legacy Survey using new deep, low-frequency radio imaging of the Lockman Hole field from the Low Frequency Array. Combining these data with additional radio observations from the GMRT and the JVLA, we find a variety of radio spectral shapes and luminosities within our sample despite their similarly bright submillimetre flux densities. We characterise their spectral shapes in terms of multi-band radio spectral indices. Finding strong spectral flattening at low frequencies in ~20% of sources, we investigate the differences between sources with extremely flat low-frequency spectra and those with `normal' radio spectral indices. As there are no other statistically significant differences between the two subgroups of our sample as split by the radio spectral index, we suggest that any differences are undetectable in galaxy-averaged properties that we can observe with our unresolved images, and likely relate to galaxy properties that we cannot resolve, on scales $\lesssim$ 1 kpc. We attribute the observed spectral flattening in the radio to free-free absorption, proposing that those sources with significant low-frequency spectral flattening have a clumpy distribution of star-forming gas. We estimate an average spatial extent of absorbing material of at most several hundred parsecs to produce the levels of absorption observed in the radio spectra. This estimate is consistent with the highest-resolution observations of submillimetre galaxies in the literature, which find examples of non-uniform dust distributions on scales of ~100 pc, with evidence for clumps and knots in the interstellar medium. Additionally, we find two bright (> 6 mJy) submm sources undetected at all other wavelengths. We speculate that these objects may be very high redshift sources, likely residing at z > 4. en dc.format.extent 14 dc.language.iso eng dc.relation.ispartof Astronomy & Astrophysics dc.subject astro-ph.GA dc.title Low-frequency radio spectra of submillimetre galaxies in the Lockman Hole en dc.contributor.institution School of Physics, Engineering & Computer Science dc.contributor.institution Centre for Astrophysics Research dc.contributor.institution Centre of Data Innovation Research dc.contributor.institution Centre for Climate Change Research dc.contributor.institution Department of Physics, Astronomy and Mathematics dc.contributor.institution SPECS Deans Group dc.contributor.institution School of Physics, Astronomy and Mathematics dc.description.status Peer reviewed rioxxterms.version AM rioxxterms.versionofrecord https://doi.org/10.1051/0004-6361/202039858 rioxxterms.type Journal Article/Review herts.preservation.rarelyaccessed true
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