Euclid view of the dusty star-forming galaxies at ≳ detected in wide area submillimetre surveys

Abstract

ABSTRACT We investigate the constraints provided by the Euclid space observatory on the physical properties of dusty star-forming galaxies (DSFGs) at $z\gtrsim 1.5$ detected in wide area submillimetre surveys with Herschel. We adopt a physical model for the high-z progenitors of spheroidal galaxies, which form the bulk of DSFGs at $z\gtrsim 1.5$. We improve the model by combining the output of the equations of the model with a formalism for the spectral energy distribution (SED). After optimizing the SED parameters to reproduce the measured infrared luminosity function and number counts of DFSGs, we simulated a sample of DSFGs over 100 $\hbox{deg}^2$ and then applied a $5\, \sigma$ detection limit of $37\,$ mJy at 250 $\mu$m. We estimated the redshifts from the Euclid data and then fitted the Euclid+Herschel photometry with the code CIGALE to extract the physical parameters. We found that 100 per cent of the Herschel galaxies are detected in all 4 Euclid bands above $3\, \sigma$. For 87 per cent of these sources the accuracy on $1 + z$ is better than 15 per cent. The sample comprises mostly massive, i.e. $\log (M_{\star }/{\rm M}_{\odot })\sim 10.5{\!-\!}12.9$, highly star forming, i.e. $\log (\hbox{SFR}/{\rm M}_{\odot }\hbox{yr}^{-1})\sim 1.5{\!-\!}4$, dusty, i.e. $\log (M_{\rm dust}/{\rm M}_{\odot })\sim 7.5{\!-\!}9.9$, galaxies. The measured stellar masses have a dispersion of 0.19 dex around the true value, thus showing that Euclid will provide reliable stellar mass estimates for the majority of the bright DSFGs at $z\gtrsim 1.5$ detected by Herschel. We also explored the effect of complementing the Euclid photometry with that from the Vera C. Rubin Observatory/LSST.