The LOFAR Two-metre Sky Survey Deep fields. The mass dependence of the far-infrared radio correlation at 150 MHz using deblended Herschel fluxes

The far-infrared radio correlation (FIRC) is one of the strongest correlations in astronomy, yet a model that explains this comprehensively does not exist. The new LOFAR all Sky Survey (LoTSS) deep field, ELAIS-N1, allows exploration of this relation in previously unexplored regions of parameter space of radio frequency (150 MHz), luminosity (L₁₅₀ < 10^24.7), redshift (z ∼ 1), and stellar mass M_* < 10^11.4. We present accurate deblended far-infrared (FIR) flux measurements with robust errors at 24, 100, 160, 250, 350, and 500 μm from Spitzer and the Herschel Space Observatory using XID+. We find that the FIRC has a strong mass dependence, the evolution of which takes the form q_TIR(M_*) = (2.00 ± 0.01)+(−0.22 ± 0.02)(log(M/M_*)−10.05). This matches recent findings in regards to the star formation rate-radio luminosity relation at 150 MHz and results from radio observations in COSMOS at 1.4 GHz with the Jansky Very Large Array (JVLA). Our results provide tighter constraints on the low-redshift end of the FIRC and at lower frequency than the COSMOS observations. In addition, we find a mild evolution with redshift, with a best fit relation q_TIR(z) = (1.94 ± 0.01)(1 + z)^{−0.04 ± 0.01}. This evolution is shallower than that suggested by previous results at 150 MHz with the differences explained by the fact that previous studies did not account for the mass dependence. Finally, we present deblended FIR fluxes for 79 609 galaxies across the LoTSS deep fields: Boötes, ELAIS-N1, and Lockman Hole.