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

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Version 2 2023-06-12, 09:46
Version 1 2023-06-09, 23:25
journal contribution
posted on 2023-06-12, 09:46 authored by I Delvecchio, E Daddi, Mark Sargent, M J Jarvis, D Elbaz, S Jin, D Liu, I H Whittam, H Algera, R Carraro, C D’Eugenio, J Delhaize, B S Kalita, S Leslie, D Cs Molnár, others
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.

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Publication status

  • Published

File Version

  • Published version

Journal

Astronomy and Astrophysics

ISSN

0004-6361

Publisher

EDP Sciences

Volume

647

Page range

1-29

Article number

a123

Department affiliated with

  • Physics and Astronomy Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2021-03-24

First Open Access (FOA) Date

2021-03-24

First Compliant Deposit (FCD) Date

2021-03-23

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