dc.contributor.author Heesen, V. dc.contributor.author E., Buie II dc.contributor.author Huff, C. J. dc.contributor.author Perez, L. A. dc.contributor.author Woolsey, J. G. dc.contributor.author Rafferty, D. A. dc.contributor.author Basu, A. dc.contributor.author Beck, R. dc.contributor.author Brinks, E. dc.contributor.author Horellou, C. dc.contributor.author Scannapieco, E. dc.contributor.author Brüggen, M. dc.contributor.author Dettmar, R. -J. dc.contributor.author Sendlinger, K. dc.contributor.author Nikiel-Wroczyński, B. dc.contributor.author Chyży, K. T. dc.contributor.author Best, P.N. dc.contributor.author Heald, George H. dc.contributor.author Paladino, R. dc.date.accessioned 2019-01-17T16:15:02Z dc.date.available 2019-01-17T16:15:02Z dc.date.issued 2018-10-15 dc.identifier.citation Heesen , V , E. , B II , Huff , C J , Perez , L A , Woolsey , J G , Rafferty , D A , Basu , A , Beck , R , Brinks , E , Horellou , C , Scannapieco , E , Brüggen , M , Dettmar , R -J , Sendlinger , K , Nikiel-Wroczyński , B , Chyży , K T , Best , P N , Heald , G H & Paladino , R 2018 , ' Calibrating the relation of low-frequency radio continuum to star formation rate at 1 kpc scale with LOFAR ' , Astronomy & Astrophysics . https://doi.org/10.1051/0004-6361/201833905 dc.identifier.issn 0004-6361 dc.identifier.other PURE: 15699439 dc.identifier.other PURE UUID: a445c726-7893-41c0-bba9-e27120195be0 dc.identifier.other ArXiv: http://arxiv.org/abs/1811.07968v1 dc.identifier.other ORCID: /0000-0002-7758-9699/work/54143418 dc.identifier.other Scopus: 85062047418 dc.identifier.uri http://hdl.handle.net/2299/20987 dc.description 9 figures, 6 tables and 17 pages. This paper is part of the LOFAR surveys data release 1 and has been accepted for publication in a special edition of A&A that will appear in Feb 2019, volume 622. The catalogues and images from the data release will be publicly available on lofar-surveys.org upon publication of the journal. Reproduced with permission from Astronomy & Astrophysics. © 2018 ESO. dc.description.abstract Radio continuum (RC) emission in galaxies allows us to measure star formation rates (SFRs) unaffected by extinction due to dust, of which the low-frequency part is uncontaminated from thermal (free-free) emission. We calibrate the conversion from the spatially resolved 140 MHz RC emission to the SFR surface density ($\Sigma_{\rm SFR}$) at 1 kpc scale. We used recent observations of three galaxies (NGC 3184, 4736, and 5055) from the LOFAR Two-metre Sky Survey (LoTSS), and archival LOw-Frequency ARray (LOFAR) data of NGC 5194. Maps were created with the facet calibration technique and converted to radio $\Sigma_{\rm SFR}$ maps using the Condon relation. We compared these maps with hybrid $\Sigma_{\rm SFR}$ maps from a combination of GALEX far-ultraviolet and Spitzer 24 $\mu\rm m$ data using plots tracing the relation at $1.2\times 1.2$-kpc$^2$ resolution. The RC emission is smoothed with respect to the hybrid $\Sigma_{\rm SFR}$ owing to the transport of cosmic-ray electrons (CREs). This results in a sublinear relation $(\Sigma_{\rm SFR})_{\rm RC} \propto [(\Sigma_{\rm SFR})_{\rm hyb}]^{a}$, where $a=0.59\pm 0.13$ (140 MHz) and $a=0.75\pm 0.10$ (1365 MHz). Both relations have a scatter of $\sigma = 0.3~\rm dex$. If we restrict ourselves to areas of young CREs ($\alpha > -0.65$; $I_\nu \propto \nu^\alpha$), the relation becomes almost linear at both frequencies with $a\approx 0.9$ and a reduced scatter of $\sigma = 0.2~\rm dex$. We then simulate the effect of CRE transport by convolving the hybrid $\Sigma_{\rm SFR}$ maps with a Gaussian kernel until the RC-SFR relation is linearised; CRE transport lengths are $l=1$-5 kpc. Solving the CRE diffusion equation, we find diffusion coefficients of $D=(0.13$-$1.5) \times 10^{28} \rm cm^2\,s^{-1}$ at 1 GeV. A RC-SFR relation at $1.4$ GHz can be exploited to measure SFRs at redshift $z \approx 10$ using $140$ MHz observations. en dc.language.iso eng dc.relation.ispartof Astronomy & Astrophysics dc.rights Open dc.subject astro-ph.GA dc.title Calibrating the relation of low-frequency radio continuum to star formation rate at 1 kpc scale with LOFAR en dc.contributor.institution School of Physics, Astronomy and Mathematics dc.contributor.institution Centre for Astrophysics Research dc.description.status Peer reviewed dc.relation.school School of Physics, Astronomy and Mathematics dc.description.versiontype Final Accepted Version dcterms.dateAccepted 2018-10-15 rioxxterms.version AM rioxxterms.versionofrecord https://doi.org/10.1051/0004-6361/201833905 rioxxterms.licenseref.uri Other rioxxterms.type Journal Article/Review herts.preservation.rarelyaccessed true herts.rights.accesstype Open
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