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 Revised Bright Galaxy Sample using new MeerKAT observations at $\hat{\mathrm{I}}½=1.28\mathrm{GHz}$, complemented with VLA data. We classify the objects by primary energy source (Active Galactic Nuclei vs. 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 ($8\hat{I}¼m<\hat{I}»<1000\hat{I}¼m$) to far-infrared (FIR; $40\hat{I}¼m<\hat{I}»<120\hat{I}¼m$) luminosities to be $⟨L_{\mathrm{TIR}}/L_{\mathrm{FIR}}⟩\approx 2.29$. By examining the relation between $L_{\mathrm{TIR}}$ and the mid-infrared (MIR) star-formation rate indicator ($L_{12\hat{\mathrm{I}}¼\mathrm{m}}$) 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 $q_{\mathrm{TIR}}$.

This manuscript is 26 pages long and contains 16 figures and 3 tables. The data are provided in machine-readable format on Zenodo at https://doi.org/10.5281/zenodo.16889781. The paper was accepted for publication in the Monthly Notices of the Royal Astronomical Society Main Journal on 26 August 2025, ref. MN-24-1207-MJ.R3