Harshnoor Kaur, T. Shanks, S. Bose, A. C. Edge

We present angular correlation and power spectral analyses of the clustering of VST ATLAS galaxies, LRGs and QSOs and their cross-correlations with the ACT DR6 CMB lensing map with its $\approx3\times$ higher resolution than Planck DR3. We first use $Λ$CDM Halofit models at linear scales to estimate galaxy, LRG and QSO bias, $b$, from the ratio of the 3-D power spectra, $b= P_{gg}/P_{gK}$ and hence the mass clustering amplitudes, $σ_8$. For galaxies we find $b_G(z=0.15)=1.22\pm0.07$, $σ_8(z=0)=0.71\pm0.06$ and for LRGs $b_{LRG}(z=0.26)=2.76\pm0.11$, $σ_8(z=0)=0.63\pm0.15$, both consistent with $Λ$CDM predictions. But for QSOs, we estimate a bias of $b_Q(z=1.7)=4.44\pm0.24$ and $σ_8(z=0)=0.49\pm0.06$, the latter significantly lower than expected for $Λ$CDM and leads to an observed $0.15<z<1.7$ gravitational growth rate faster than predicted for $Λ$CDM. At smaller non-linear scales, HOD model fits imply a broad halo mass distribution for $z\approx0.15$ galaxies but much narrower mass distributions for LRGs and QSOs. More surprisingly, the HOD fit for QSOs implies $M_{eff}=5\times10^{14}M_\odot$, $\approx10\times$ higher than expected. Finally, while the LRG and QSO HOD models fit $w_{gg}$ and $w_{gK}$ consistently, the same is not true for the $z\approx0.15$ galaxies unless we hypothesise anti-bias with $b_G\approx0.55$. This result supports previous QSO lensing analyses that also found anti-bias at $r<5$h$^{-1}$Mpc. We suggest that while HOD + NFW halo models may well describe LRG mass profiles and clustering, at intermediate scales the dominant galaxy population (and QSOs) may follow the alternative hierarchical clustering model of \cite{Peebles1974} where galaxies trace the mass more closely than in a halo model.