The infrared-radio correlation of star-forming galaxies is strongly M⋆-dependent but nearly redshift-invariant since z ∼ 4

Journal
Date Issued
2021
Author(s)
•
Daddi, E.
•
Sargent, M. T.
•
Jarvis, M. J.
•
Elbaz, D.
•
Jin, S.
•
Liu, D.
•
Whittam, I. H.
•
Algera, H.
•
Carraro, R.
•
D'Eugenio, C.
•
Delhaize, J.
•
Kalita, B. S.
•
Leslie, S.
•
Molnár, D. Cs.
•
Novak, M.
•
•
Smolčić, V.
•
Ao, Y.
•
Aravena, M.
•
Bournaud, F.
•
Collier, J. D.
•
Randriamampandry, S. M.
•
Randriamanakoto, Z.
•
Rodighiero, G.
•
Schober, J.
•
White, S. V.
•
Zamorani, G.
DOI
Abstract
Over the past decade, several works have used the ratio between total (rest 8−1000 μm) infrared and radio (rest 1.4 GHz) luminosity in star-forming galaxies (qIR), often referred to as the infrared-radio correlation (IRRC), to calibrate the radio emission as a star formation rate (SFR) indicator. Previous studies constrained the evolution of qIR with redshift, finding a mild but significant decline that is yet to be understood. Here, for the first time, we calibrate qIR as a function of both stellar mass (M⋆) and redshift, starting from an M⋆-selected sample of > 400 000 star-forming galaxies in the COSMOS field, identified via (NUV − r)/(r − J) colours, at redshifts of 0.1 < z < 4.5. Within each (M⋆,z) bin, we stacked the deepest available infrared/sub-mm and radio images. We fit the stacked IR spectral energy distributions with typical star-forming galaxy and IR-AGN templates. We then carefully removed the radio AGN candidates via a recursive approach. We find that the IRRC evolves primarily with M⋆, with more massive galaxies displaying a systematically lower qIR. A secondary, weaker dependence on redshift is also observed. The best-fit analytical expression is the following: qIR(M⋆, z) = (2.646 ± 0.024) × (1 + z)( − 0.023 ± 0.008)-(0.148 ± 0.013) × (log M⋆/M⊙ − 10). Adding the UV dust-uncorrected contribution to the IR as a proxy for the total SFR would further steepen the qIR dependence on M⋆. We interpret the apparent redshift decline reported in previous works as due to low-M⋆ galaxies being progressively under-represented at high redshift, as a consequence of binning only in redshift and using either infrared or radio-detected samples. The lower IR/radio ratios seen in more massive galaxies are well described by their higher observed SFR surface densities. Our findings highlight the fact that using radio-synchrotron emission as a proxy for SFR requires novel M⋆-dependent recipes that will enable us to convert detections from future ultra-deep radio surveys into accurate SFR measurements down to low-M⋆ galaxies with low SFR.
Volume
647
Start page
A123
Uri
Url
Issn Identifier
0004-6361
Ads BibCode
2021A&A...647A.123D
Rights
open.access
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