Constraints on the richness-mass relation and the optical-SZE positional offset distribution for SZE-selected clusters

• Published in: Monthly Notices of the Royal Astronomical Society
• Main Authors: Saro, A., Bocquet, S., Rozo, E., Benson, B. A., Mohr, J., Rykoff, E. S., Soares-Santos, M., Bleem, L., Dodelson, S., Melchior, P., Sobreira, F., Upadhyay, V., Weller, J., Abbott, T., Abdalla, F. B., Allam, S., Armstrong, R., Banerji, M., Bauer, A. H., Bayliss, M., Benoit-Levy, A., Bernstein, G. M., Bertin, E., Brodwin, M., Brooks, D., Buckley-Geer, E., Burke, D. L., Carlstrom, J. E., Capasso, R., Capozzi, D., Rosell, A. Carnero, Kind, M. Carrasco, Chiu, I., Covarrubias, R., Crawford, T. M., Crocce, M., D'Andrea, C. B., Costa, L. N. da, DePoy, D. L., Desai, S., Haan, T. de, Diehl, H. T., Dietrich, J. P., Doel, P., Cunha, C. E, Eifler, T. F., Evrard, A. E., Neto, A. Fausti, Fernandez, E., Flaugher, B., Fosalba, P., Frieman, J., Gangkofner, C., Gaztanaga, E., Gerdes, D., Gruen, D., Gruendl, R. A., Gupta, N., Hennig, C., Holzapfel, W. L., Honscheid, K., Jain, B., James, D., Kuehn, K., Kuropatkin, N., Lahav, O., Li, T. S., Lin, H., Maia, M. A. G., March, M., Marshall, J. L., Martini, Paul, McDonald, M., Miller, C. J., Miquel, R., Nord, B., Ogando, R., Plazas, A. A., Reichardt, C. L., Romer, A. K., Roodman, A., Sako, M., Sanchez, E., Schubnell, M., Sevilla, I., Smith, R. C., Stalder, B., Stark, A. A., Strazzullo, V., Suchyta, E., Swanson, M. E. C., Tarle, G., Thaler, J., Thomas, D., Tucker, D., Vikram, V., Linden, A. von der, Walker, A. R., Wechsler, R. H., Wester, W., Zenteno, A., Ziegler, K. E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: astro-ph.CO; catalogues; methods: data analysis; galaxies: abundances; galaxies: clusters: general; galaxies: haloes; galaxies: statistics; cosmology: miscellaneous; large-scale structure of Universe; RCUK; STFC; /dk/atira/pure/core/subjects/cosmology; Cosmology and Gravitation; South Pole; Lambda; South pole
• Online Access: https://doi.org/10.1093/mnras/stv2141; https://researchportal.port.ac.uk/portal/en/publications/constraints-on-the-richnessmass-relation-and-the-opticalsze-positional-offset-distribution-for-szeselected-clusters(53c55e3a-f4fd-4050-924a-8b2a907acc02).html; https://researchportal.port.ac.uk/ws/files/3318327/Constraints_on_the_richness_mass_relation.pdf

We cross-match galaxy cluster candidates selected via their Sunyaev-Zel'dovich effect (SZE) signatures in 129.1 deg$^2$ of the South Pole Telescope 2500d SPT-SZ survey with optically identified clusters selected from the Dark Energy Survey (DES) science verification data. We identify 25 clusters between $0.1\lesssim z\lesssim 0.8$ in the union of the SPT-SZ and redMaPPer (RM) samples. RM is an optical cluster finding algorithm that also returns a richness estimate for each cluster. We model the richness $\lambda$-mass relation with the following function $\langle\ln\lambda|M_{500}\rangle\propto B_\lambda\ln M_{500}+C_\lambda\ln E(z)$ and use SPT-SZ cluster masses and RM richnesses $\lambda$ to constrain the parameters. We find $B_\lambda= 1.14^{+0.21}_{-0.18}$ and $C_\lambda=0.73^{+0.77}_{-0.75}$. The associated scatter in mass at fixed richness is $\sigma_{\ln M|\lambda} = 0.18^{+0.08}_{-0.05}$ at a characteristic richness $\lambda=70$. We demonstrate that our model provides an adequate description of the matched sample, showing that the fraction of SPT-SZ selected clusters with RM counterparts is consistent with expectations and that the fraction of RM selected clusters with SPT-SZ counterparts is in mild tension with expectation. We model the optical-SZE cluster positional offset distribution with the sum of two Gaussians, showing that it is consistent with a dominant, centrally peaked population and a sub-dominant population characterized by larger offsets. We also cross-match the RM catalog with SPT-SZ candidates below the official catalog threshold significance $\xi=4.5$, using the RM catalog to provide optical confirmation and redshifts for additional low-$\xi$ SPT-SZ candidates.In this way, we identify 15 additional clusters with $\xi\in [4,4.5]$ over the redshift regime explored by RM in the overlapping region between DES science verification data and the SPT-SZ survey.