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

A. Saro, S. Bocquet, E. Rozo, B. A. Benson, J. Mohr, E. S. Rykoff, M. Soares-Santos, L. Bleem, S. Dodelson, P. Melchior, F. Sobreira, V. Upadhyay, J. Weller, T. Abbott, F. B. Abdalla, S. Allam, R. Armstrong, M. Banerji, A. H. Bauer, M. BaylissA. Benoit-Levy, G. M. Bernstein, E. Bertin, M. Brodwin, D. Brooks, E. Buckley-Geer, D. L. Burke, J. E. Carlstrom, R. Capasso, D. Capozzi, A. Carnero Rosell, M. Carrasco Kind, I. Chiu, R. Covarrubias, T. M. Crawford, M. Crocce, C. B. D'Andrea, L. N. da Costa, D. L. DePoy, S. Desai, T. de Haan, H. T. Diehl, J. P. Dietrich, P. Doel, C. E Cunha, T. F. Eifler, A. E. Evrard, A. Fausti Neto, E. Fernandez, B. Flaugher, P. Fosalba, J. Frieman, C. Gangkofner, E. Gaztanaga, D. Gerdes, D. Gruen, R. A. Gruendl, N. Gupta, C. Hennig, W. L. Holzapfel, K. Honscheid, B. Jain, D. James, K. Kuehn, N. Kuropatkin, O. Lahav, T. S. Li, H. Lin, M. A. G. Maia, M. March, J. L. Marshall, Paul Martini, M. McDonald, C. J. Miller, R. Miquel, B. Nord, R. Ogando, A. A. Plazas, C. L. Reichardt, A. K. Romer, A. Roodman, M. Sako, E. Sanchez, M. Schubnell, I. Sevilla, R. C. Smith, B. Stalder, A. A. Stark, V. Strazzullo, E. Suchyta, M. E. C. Swanson, G. Tarle, J. Thaler, D. Thomas, D. Tucker, V. Vikram, A. von der Linden, A. R. Walker, R. H. Wechsler, W. Wester, A. Zenteno, K. E. Ziegler

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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.
Original languageEnglish
Pages (from-to)2305-2319
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - 11 Dec 2015


  • 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


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