Understand
We propose that observations of super-massive galaxies contain cosmological constraining power similar to conventional cluster cosmology, and we provide promising indications that the associated systematic errors are comparably easier to control.
- We consider a fiducial spectroscopic and stellar mass complete sample of galaxies drawn from the Dark Energy Spectroscopic Survey (DESI) and forecast how constraints on Omega_m-sigma_8 from this sample will compare with those from number counts of clusters based on richness.
- At fixed number density, we find that massive galaxies offer similar constraints to galaxy clusters.
- However, a mass-complete galaxy sample from DESI has the potential to probe lower halo masses than standard optical cluster samples (which are typically limited to richness above 20 and halo mass above 10^13.5); additionally, it is straightforward to cleanly measure projected galaxy clustering for such a DESI sample, which we show can substantially improve the constraining power on Omega_m.