On the halo-mass and radial scale dependence of the lensing is low effect

The canonical Lambda cold dark matter (ACDM) cosmological model makes precise predictions for the clustering and lensing properties of galaxies. It has been shown that the lensing amplitude of galaxies in the Baryon Oscillation Spectroscopic Survey (BOSS) is lower than expected given their clustering properties. We present new measurements and modelling of galaxies in the BOSS LOWZ sample. We focus on the radial and stellar mass dependence of the lensing amplitude mismatch. We find an amplitude mismatch of around 35 per cent when assuming ACDM with Planck Cosmological Microwave Background (CMB) constraints. This offset is independent of halo mass and radial scale in the range Mhalo similar to 10(13.3) - 10(13.9) h(-1) M-circle dot and r = 0.1-60h(-1) Mpc (k approximate to 0.05-20 h Mpc(-1)). The observation that the offset is both mass and scale independent places important constraints on the degree to which astrophysical processes (baryonic effects, assembly bias) can fully explain the effect. This scale independence also suggests that the 'lensing is low' effect on small and large radial scales probably have the same physical origin. Resolutions based on new physics require a nearly uniform suppression, relative to ACDM predictions, of the amplitude of matter fluctuations on these scales. The possible causes of this are tightly constrained by measurements of the CMB and of the low-redshift expansion history.

Automated summary

The study presents new measurements and modeling of galaxies in the BOSS LOWZ sample, showing a lensing amplitude mismatch that is relatively independent of halo mass and radial scale. This suggests that astrophysical processes may not fully explain the observed effect, and new physics requiring a uniform suppression of matter fluctuations on certain scales may be needed. The physical origin of the "lensing is low" effect on different radial scales is likely the same, according to the observations.