Synergistic science with Euclid and SKA : the nature and history of Star Formation

TL;DR

This paper discusses how combining Euclid's infrared photometric and spectroscopic surveys with SKA's radio continuum surveys can significantly improve our understanding of cosmic star formation history up to redshift 5, by enabling dust-free SFR measurements.

Contribution

It demonstrates the synergy between Euclid and SKA surveys, showing how their combined data can accurately trace star formation rates and galaxy evolution up to high redshifts.

Findings

Euclid surveys will detect star-forming galaxies down to SFR ~1-10 M_sun/yr up to z~3.

SKA surveys will provide dust-free SFR estimates for about 85% of Euclid's star-forming galaxies.

The combined surveys will constrain the star formation history and galaxy evolution models up to z<5.

Abstract

We explored the impact of the synergy between the Euclid near-infrared photometric surveys and the SKA radio continuum surveys on the studies of the cosmic star formation. The Euclid satellite is expected to perform a Wide and Deep photometric surveys to an infrared limit of H ~ 24 and H ~ 26 respectively and a spectroscopy survey with a flux limit of $\sim 3 \times 10^{-16}$ erg cm$^{-2}$ s$^{-1}$ in the Halpha line. Combining the H band Euclid selected samples with the ground based ancillary data (fundamental for the SFR estimation) we will be able to detect the star forming galaxies down to SFRs of order of unit to z ~ 2 and down to SFR ~ 10 to z ~ 3, sampling the majority of the star forming galaxies up to z ~3 and beyond and placing definitive constraints on the star formation history of the universe at z<4-5 (is there a peak a z ~2 or a plateau at 1 <z <5 ?) and on the galaxies evolution models. The only tools able to provide a accurate dust-free calculation of their SFR are the SKA continuum surveys. The observational parameters of the Deep Tier SKA1 reference survey (a 0.2- 0.5 arcsec resolution and a 5 sigma detection limit of 1 microJy over 30 deg2 at Band 1/2 ) are the perfect complement of the Euclid survey. We showed, in fact, that with this kind of SKA survey we will be able to determine a dust unbiased SFR for a huge fraction (~85 %) of the Euclid SFG providing strong constraints on the star formation history of the Universe.