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

Delvecchio, I.; 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.; Prandoni, I.; 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.
Referencia bibliográfica

Astronomy and Astrophysics

Fecha de publicación:
3
2021
Número de autores
28
Número de autores del IAC
1
Número de citas
74
Número de citas referidas
64
Descripción
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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