A LOFAR-IRAS cross-match study: the far-infrared radio correlation and the 150 MHz luminosity as a star-formation rate tracer

Wang, L.; Gao, F.; Duncan, K.J.; Williams, W.L.; Rowan-Robinson, M.; Sabater, J.; Shimwell, T.W.; Bonato, M.; Calistro-Rivera, G.; Chyży, K.T.; Farrah, D.; Gürkan, G.; Hardcastle, M.J.; McCheyne, I.; Prandoni, I.; Read, S.C.; Röttgering, H.J.A.; Smith, D.J.B.

Aims: We aim to study the far-infrared radio correlation (FIRC) at 150 MHz in the local Universe (at a median redshift ⟨z⟩∼0.05) and improve the use of the rest-frame 150 MHz luminosity, L₁₅₀, as a star-formation rate (SFR) tracer, which is unaffected by dust extinction.
Methods: We cross-match the 60 μm selected Revised IRAS Faint Source Survey Redshift (RIFSCz) catalogue and the 150 MHz selected LOFAR value-added source catalogue in the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) Spring Field. We estimate L₁₅₀ for the cross-matched sources and compare it with the total infrared (IR) luminosity, L_IR, and various SFR tracers.
Results: We find a tight linear correlation between log L₁₅₀ and log L_IR for star-forming galaxies, with a slope of 1.37. The median q^IR value (defined as the logarithm of the L_IR to L₁₅₀ ratio) and its rms scatter of our main sample are 2.14 and 0.34, respectively. We also find that log L₁₅₀ correlates tightly with the logarithm of SFR derived from three different tracers, i.e., SFR_Hα based on the Hα line luminosity, SFR₆₀ based on the rest-frame 60 μm luminosity and SFR_IR based on L_IR, with a scatter of 0.3 dex. Our best-fit relations between L₁₅₀ and these SFR tracers are, log L₁₅₀ (L_☉) = 1.35(±0.06) × log SFR_Hα (M_☉ yr^-1) + 3.20(±0.06), log L₁₅₀ (L_☉) = 1.31(±0.05) × log SFR₆₀ (M_☉ yr^-1) + 3.14(±0.06), and log L₁₅₀ (L_☉) = 1.37 (±0.05) × log SFR_IR (M_☉ yr^-1) + 3.09(±0.05), which show excellent agreement with each other.