DEVILS/MIGHTEE/GAMA/DINGO: the impact of SFR time-scales on the SFR-radio luminosity correlation
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Date
2024
Journal Title
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Publisher
Oxford
Abstract
The tight relationship between infrared luminosity ( L TIR ) and 1.4 GHz radio continuum luminosity ( L 1 . 4 GHz ) has proven useful for understanding star formation free from dust obscuration. Infrared emission in star-forming galaxies typically arises from recently formed, dust-enshrouded stars, whereas radio synchrotron emission is expected from subsequent supernovae. By leveraging the wealth of ancillary far -ultra violet –far-infrared photometry from the Deep Extragalactic VIsible Legacy Survey and Galaxy and Mass Assembly surveys, combined with 1.4 GHz observations from the Meer Karoo Array Telescope International GHz Tiered Extragalactic Exploration survey and Deep Investigation of Neutral Gas Origin projects, we investigate the impact of time-scale differences between far -ultraviolet –far-infrared and radio-derived star formation rate (SFR) tracers. We examine how the spectral energy distribution (SED)-derived star formation histories (SFHs) of galaxies can be used to explain discrepancies in these SFR tracers, which are sensitive to different time scales. Galaxies exhibiting an increasing SFH have systematically higher L TIR and SED-derived SFRs than predicted from their 1.4 GHz radio luminosity. This indicates that insufficient time has passed for subsequent supernovae-driven radio emissions to accumulate. We show that backtracking the SFR(t) of galaxies along their SED-derived SFHs to a time several hundred mega years prior to their observed epoch will both linearize the SFR–L 1 . 4 GHz relation and reduce the overall scatter. The minimum scatter in the SFR(t)–L 1 . 4 GHz is reached at 200 –300 Myrprior, consistent with theoretical predictions for the time-scales required to disperse the cosmic ray electrons responsible for the synchrotron emission.
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Meer Karoo Array Telescope International
Citation
Cook, R.H., Davies, L.J., Rhee, J., Hale, C.L., Bellstedt, S., Thorne, J.E., Delvecchio, I., Collier, J.D., Dodson, R., Driver, S.P. and Holwerda, B.W., 2024. DEVILS/MIGHTEE/GAMA/DINGO: the impact of SFR time-scales on the SFR-radio luminosity correlation. Monthly Notices of the Royal Astronomical Society, 531(1), pp.708-727.