The Massive and Distant Clusters of WISE Survey 2: Splashback Radii to z=1.65 from Galaxy Density Profiles

Abstract

The Massive and Distant Clusters of WISE Survey 2 (MaDCoWS2) is a WISE-selected catalog of galaxy clusters at $0.1<z<2$ covering an effective area of $>6000$ deg${}^2$. In this paper, we derive splashback radii for this cluster ensemble from galaxy density profiles and constrain the mass threshold of the survey as a function of redshift. We use MaDCoWS2 cluster candidates at $0.4\le z\le 1.65$ divided into subsamples with different signal-to-noise (S/N${}_{\mathrm{P}}$) and redshifts, cross-correlated with galaxies from the CatWISE2020 catalog, to obtain average surface density profiles. We perform a Markov Chain Monte Carlo analysis to derive parameter estimates for theoretical models consisting of orbiting and infalling terms. A distinct splashback feature is detected in all subsamples. The measured splashback radii span from $0.89_{-0.02}^{+0.02}{h}^{-1}$ comoving Mpc/cMpc ($0.61_{-0.02}^{+0.02}{h}^{-1}$ proper Mpc/pMpc) at $\overline{z}=0.45$ to $1.27_{-0.05}^{+0.05}{h}^{-1}$ cMpc ($0.53_{-0.04}^{+0.04}{h}^{-1}$ pMpc) at $\overline{z}=1.54$. We also find that splashback radii increase with $S/N_{\mathrm{P}}$ at fixed redshift. The resultant splashback radii constrain the redshift dependence of the mass of MaDCoWS2 clusters at fixed $S/N_{\mathrm{P}}$. We calculate $M_{200m}$ from the radii using a relation based on a cosmological simulation. MaDCoWS2 $M_{200m}$ values derived from the simulation-based relation are lower than the expected values based on weak-lensing observations. More robust mass constraints will come from calibrating splashback radii derived from galaxy density profiles with weak lensing shear profiles from facilities such as $\text{Euclid}$, Rubin, and $\text{Roman}$.

22 pages, 7 figures, 9 tables, submitted to ApJ