In this paper , we explore how the forthcoming generation of large-scale radio continuum surveys , with the inclusion of some degree of redshift information , can constrain cosmological parameters .
By cross-matching these radio surveys with shallow optical to near-infrared surveys , we can essentially separate the source distribution into a low- and a high-redshift sample , thus providing a constraint on the evolution of cosmological parameters such as those related to dark energy .
We examine two radio surveys , the Evolutionary Map of the Universe ( EMU ) and the Westerbork Observations of the Deep APERTIF Northern sky ( WODAN ) .
A crucial advantage is their combined potential to provide a deep , full-sky survey .
The surveys used for the cross-identifications are SkyMapper and SDSS , for the southern and northern skies , respectively .
We concentrate on the galaxy clustering angular power spectrum as our benchmark observable , and find that the possibility of including such low redshift information yields major improvements in the determination of cosmological parameters .
With this approach , and provided a good knowledge of the galaxy bias evolution , we are able to put strict constraints on the dark energy parameters , i.e . w _ { 0 } = -0.9 \pm 0.041 and w _ { a } = -0.24 \pm 0.13 , with type Ia supernovæ and CMB priors ( with a one-parameter bias in this case ) ; this corresponds to a Figure of Merit ( FoM ) > 600 , which is twice better than what is obtained by using only the cross-identified sources and greater than four time better than the case without any redshift information at all .