Kavli Affiliate: Eli Rykoff
| First 5 Authors: Matthew Kwiecien, Tesla Jeltema, Alexie Leauthaud, Song Huang, Eli Rykoff
| Summary:
The number density and redshift evolution of optically selected galaxy
clusters offer an independent measurement of the amplitude of matter
fluctuations, $S_8$. However, recent results have shown that clusters chosen by
the redMaPPer algorithm show richness-dependent biases that affect the weak
lensing signals and number densities of clusters, increasing uncertainty in the
cluster mass calibration and reducing their constraining power. In this work,
we evaluate an alternative cluster proxy, outskirt stellar mass,
$M_{textrm{out}}$, defined as the total stellar mass within a $[50,100]$ kpc
envelope centered on a massive galaxy. This proxy exhibits scatter comparable
to redMaPPer richness, $lambda$, but is less likely to be subject to
projection effects. We compare the Dark Energy Survey Year 3 redMaPPer cluster
catalog with a $M_{textrm{out}}$ selected cluster sample from the
Hyper-Suprime Camera survey. We use weak lensing measurements to quantify and
compare the scatter of $M_{textrm{out}}$ and $lambda$ with halo mass. Our
results show $M_{textrm{out}}$ has a scatter consistent with $lambda$, with a
similar halo mass dependence, and that both proxies contain unique information
about the underlying halo mass. We find $lambda$-selected samples introduce
features into the measured $Delta Sigma$ signal that are not well fit by a
log-normal scatter only model, absent in $M_{textrm{out}}$ selected samples.
Our findings suggest that $M_{textrm{out}}$ offers an alternative for cluster
selection with more easily calibrated selection biases, at least at the
generally lower richnesses probed here. Combining both proxies may yield a mass
proxy with a lower scatter and more tractable selection biases, enabling the
use of lower mass clusters in cosmology. Finally, we find the scatter and slope
in the $lambda-M_{textrm{out}}$ scaling relation to be $0.49 pm 0.02$ and
$0.38 pm 0.09$.
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