Probing the infrared–radio correlation of the full IRAS revised bright galaxy sample with MeerKAT and the VLA

ABSTRACT We study the infrared–radio correlation of galaxies in the IRAS (Infrared Astronomical Satellite) revised bright galaxy sample using new MeerKAT observations at $\rm \nu = 1.28\, GHz$, complemented with Very Large Array data. We classify the objects by primary energy source (active galactic nuclei versus star forming) and take into account their merger status. With this, we aim to explore the effect of galaxy–galaxy interaction on the total infrared (TIR)/radio correlation ($q_\mathrm{TIR}$) of star-forming galaxies by comparing the $q_\mathrm{TIR}$ distribution between isolated and interacting/merging sources. We found the median $q_\mathrm{TIR}$ to be $2.61 \pm 0.01$ (scatter = 0.16) for isolated galaxies and $2.51 \pm 0.08$ (scatter = 0.26) for interacting/merging galaxies. Our analysis reveals that interacting/merging galaxies exhibit lower $q_\mathrm{TIR}$ and higher dispersion compared to isolated galaxies, and the difference is marginally significant. Interacting/merging galaxies have redder $W2-W3$ colours, higher star formation rates (SFR) and specific SFR compared to isolated objects. We observe a significant decrease in $q_\mathrm{TIR}$ with increasing radio luminosity for isolated galaxies. Additionally, we find the median ratio of TIR ($8 \, \mu {\rm m} < \lambda < 1000\, \mu {\rm m}$) to far-infrared (FIR; $40 \, \mu {\rm m} < \lambda < 120\, \mu {\rm m}$) luminosities to be $\left< L_\mathrm{TIR}/L_\mathrm{FIR}\right>\approx 2.29$. By examining the relation between $L_\mathrm{TIR}$ and the mid-infrared (MIR) SFR indicator ($L_\mathrm{12\, \mu m}$) employed for our interacting/merging sample, we note a strong and consistent (similar non-linear behaviour) relationship between the TIR/radio and TIR/MIR ratios. Finally, we show that already at $z<0.1$, $q_\mathrm{TIR}$ exhibits a dependence on stellar mass, with more massive galaxies displaying a lower $q_\mathrm{TIR}$.