Kavli Affiliate: Chihway Chang
| First 5 Authors: Meng-Xiang Lin, Bhuvnesh Jain, Marco Raveri, Eric J. Baxter, Chihway Chang
| Summary:
The $S_8$ tension between low-redshift galaxy surveys and the primary CMB
signals a possible breakdown of the $Lambda$CDM model. Recently differing
results have been obtained using low-redshift galaxy surveys and the higher
redshifts probed by CMB lensing, motivating a possible time-dependent
modification to the growth of structure. We investigate a simple
phenomenological model in which the growth of structure deviates from the
$Lambda$CDM prediction at late times, in particular as a simple function of
the dark energy density. Fitting to galaxy lensing, CMB lensing, BAO, and
Supernovae datasets, we find significant evidence – 2.5 – 3$sigma$, depending
on analysis choices – for a non-zero value of the parameter quantifying a
deviation from $Lambda$CDM. The preferred model, which has a slower growth of
structure below $zsim 1$, improves the joint fit to the data over
$Lambda$CDM. While the overall fit is improved, there is weak evidence for
galaxy and CMB lensing favoring different changes in the growth of structure.
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