Dark Energy Surveyed Year 1 results : calibration of cluster mis-centring in the redMaPPer catalogues

Zhang, Y. and Jeltema, T. and Hollowood, D. L. and Everett, S. and Rozo, E. and Farahi, A. and Bermeo, A. and Bhargava, S. and Giles, P. and Romer, A. K. and Wilkinson, R. and Rykoff, E. S. and Mantz, A. and Diehl, H. T. and Evrard, A. E. and Stern, C. and Gruen, D. and von der Linden, A. and Splettstoesser, M. and Costanzi, M. and Allen, S. and Collins, C. and Hilton, M. and Klein, M. and Mann, R. G. and Manolopoulou, M. and Morris, G. and Mayers, J. and Sahlen, M. and Stott, J. and Vergara Cervantes, C. and Viana, P. T. P. and Wechsler, R. H. and Allam, S. and Avila, S. and Bechtol, K. and Bertin, E. and Brooks, D. and Burke, D. L. and Carnero Rosell, A. and Carrasco Kind, M. and Carretero, J. and Castander, F. J. and da Costa, L. N. and De Vicente, J. and Desai, S. and Dietrich, J. P. and Doel, P. and Flaugher, B. and Fosalba, P. and Frieman, J. and García-Bellido, J. and Gaztanaga, E. and Gruendl, R. A. and Gschwend, J. and Gutierrez, G. and Hartley, W. G. and Honscheid, K. and Hoyle, B. and Krause, E. and Kuehn, K. and Kuropatkin, N. and Lima, M. and Maia, M. A. G. and Marshall, J. L. and Melchior, P. and Menanteau, F. and Miller, C. J. and Miquel, R. and Ogando, R. L. C. and Plazas, A. A. and Sanchez, E. and Scarpine, V. and Schindler, R. and Serrano, S. and Sevilla-Noarbe, I. and Smith, M. and Soares-Santos, M. and Suchyta, E. and Swanson, M. E. C. and Tarle, G. and Thomas, D. and Tucker, D. L. and Vikram, V. and Wester, W. and DES Collaboration (2019) Dark Energy Surveyed Year 1 results : calibration of cluster mis-centring in the redMaPPer catalogues. Monthly Notices of the Royal Astronomical Society, 487 (2). pp. 2578-2593. ISSN 0035-8711

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Abstract

The centre determination of a galaxy cluster from an optical cluster finding algorithm can be offset from theoretical prescriptions or N-body definitions of its host halo centre. These offsets impact the recovered cluster statistics, affecting both richness measurements and the weak lensing shear profile around the clusters. This paper models the centring performance of the redMaPPer cluster finding algorithm using archival X-ray observations of redMaPPer-selected clusters. Assuming the X-ray emission peaks as the fiducial halo centres, and through analysing their offsets to the redMaPPer centres, we find that {˜ } 75± 8 {{ per cent}} of the redMaPPer clusters are well centred and the mis-centred offset follows a Gamma distribution in normalized, projected distance. These mis-centring offsets cause a systematic underestimation of cluster richness relative to the well-centred clusters, for which we propose a descriptive model. Our results enable the DES Y1 cluster cosmology analysis by characterizing the necessary corrections to both the weak lensing and richness abundance functions of the DES Y1 redMaPPer cluster catalogue.