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The infrared-radio correlation (IRRC) underpins many commonly used radio luminosity–star formation rate (SFR) calibrations. In preparation for the new generation of radio surveys, we revisit the IRRC of low- z galaxies by (a) drawing on the best currently available infrared (IR) and 1.4 GHz radio photometry, plus ancillary data over the widest possible area, and (b) carefully assessing potential systematics. We compile a catalogue of ∼9500, z  < 0.2 galaxies and derive their 1.4 GHz radio (L 1.4), total IR, and monochromatic IR luminosities in up to seven bands, allowing us to parametrize the wavelength dependence of monochromatic IRRCs from 22–500 µm. For the first time for low- z samples, we quantify how poorly matched IR and radio survey depths bias measured median IR/radio ratios, |$\overline{q}_{\mathrm{TIR}}$|⁠ , and discuss the level of biasing expected for low-z IRRC studies in ASKAP/MeerKAT fields. For our subset of ∼2000 high-confidence star-forming galaxies, we find a median |$\overline{q}_{\mathrm{TIR}}$| of 2.54 (scatter: 0.17 dex). We show that |$\overline{q}_{\mathrm{TIR}}$| correlates with L 1.4, implying a non-linear IRRC with slope 1.11 ± 0.01. Our new L 1.4–SFR calibration, which incorporates this non-linearity, reproduces SFRs from panchromatic SED fits substantially better than previous IRRC-based recipes. Finally, we match the evolutionary slope of recently measured |$\overline{q}_{\mathrm{TIR}}$| –redshift trends without having to invoke redshift evolution of the IRRC. In this framework, the redshift evolution of |$\overline{q}_{\mathrm{TIR}}$| reported at GHz frequencies in the literature is the consequence of a partial, redshift-dependent sampling of a non-linear IRRC obeyed by low- z and distant galaxies. [ABSTRACT FROM AUTHOR]

Using infrared data from the Herschel Space Observatory and Karl G. Jansky Very Large Array 3 GHz observations in the COSMOS field, we investigate the redshift evolution of the infrared-radio correlation (IRRC) for star-forming galaxies (SFGs) we classify as either spheroid- or disc-dominated based on their morphology. The sample predominantly consists of disc galaxies with stellar mass ≳ 1010M☉, and residing on the star-forming main sequence (MS). After the removal ofAGNusing standard approaches, we observe a significant difference between the redshift evolution of the median IR/radio ratio qTIR of (i) a sample of ellipticals, plus discs with a substantial bulge component ('spheroid-dominated' SFGs) and, (ii) virtually pure discs and irregular systems ('disc-dominated' SFGs). The spheroid-dominated population follows a declining qTIR versus z trend similar to that measured in recent evolutionary studies of the IRRC. However, for disc-dominated galaxies, where radio and IR emission should be linked to star formation in the most straightforward way, we measure very little change in qTIR. This suggests that low-redshift calibrations of radio emission as a star formation rate (SFR) tracer may remain valid out to at least z ≃ 1-1.5 for pure star-forming systems. We find that the different redshift evolution of qTIR for the spheroid- and disc-dominated sample is mainly due to an increasing radio excess for spheroid-dominated galaxies at z≳ 0.8, hinting at some residual AGN activity in these systems. This finding demonstrates that in the absence of AGN, the IRRC is independent of redshift, and that radio observations can therefore be used to estimate SFRs at all redshifts for genuinely star-forming galaxies. [ABSTRACT FROM AUTHOR]