Growth history and quasar bias evolution at z < 3 from Quaia

Understand

We make use of the Gaia-Unwise quasar catalogue, Quaia, to constrain the growth history out to high redshifts from the clustering of quasars and their cross-correlation with maps of the Cosmic Microwave Background (CMB) lensing convergence.

• Considering three tomographic bins, centered at redshifts $\bar{z}_i = [0.69, 1.59, 2.72]$, we reconstruct the evolution of the amplitude of matter fluctuations $\sigma_8(z)$ over the last $\sim12$ billion years of cosmic history.
• In particular, we make one of the highest-redshift measurements of $\sigma_8$ ($\sigma_8(z=2.72)=0.22\pm 0.06$), finding it to be in good agreement (at the $\sim1\sigma$ level) with the value predicted by $\Lambda$CDM using CMB data from Planck.
• We also used the data to study the evolution of the linear quasar bias for this sample, finding values similar to those of other quasar samples, although with a less steep evolution at high redshifts.