http://arxiv.org/abs/2305.01266
We present constraints on models of the galaxy distribution in the cosmic web using a magnitude limited sample from the Galaxy and Mass Assembly (GAMA) survey. We model the redshift-space behaviour of the 2-point correlation function (2pcf) and the recently proposed Voronoi volume function (VVF) — which includes information beyond 2-point statistics. We extend the standard halo occupation distribution model by introducing extra satellite degrees of freedom, and also by including two assembly bias parameters, $\alpha_{\rm cen}$ and $\alpha_{\rm sat}$, which respectively correlate the occupation numbers of central and satellite galaxies with their host halo’s tidal environment. We measure $\alpha_{\rm sat}=1.44^{+0.25}{-0.43}$ and $\alpha{\rm cen}=-0.79^{+0.29}_{-0.11}$ using a combination of 2pcf and VVF measurements. These represent a detection of assembly bias at the 3.3$\sigma$ (2.4$\sigma$) significance level for satellite (central) galaxies, a result that remains robust to possible anisotropies in the halo-centric distribution of satellites as well as technicalities of estimating the data covariance. We show that the growth rate ($f\sigma_8$) deduced using models with assembly bias is about 7\% (i.e. $1.5\sigma$) lower than if assembly bias is ignored. Projecting $f\sigma_8$ onto the $\Omega_m$-$\sigma_8$ plane, we find that the model constraints without assembly bias overlap with Planck expectations, but that allowing assembly bias introduces significant tension with Planck, preferring either a lower $\Omega_m$ or a lower $\sigma_8$. We also study the effect of assembly bias on the weak lensing signal. While the all-galaxy lensing signal is unaffected, both central and satellite sub-populations individually show significantly different signals in the presence of assembly bias. [abridged]
S. Alam, A. Paranjape and J. Peacock
Wed, 3 May 23
24/67
Comments: 17 pages, 14 figures, 2 tables, submitted for review