Copacabana: a probabilistic membership assignment method for galaxy clusters

Esteves, J. H.; Pereira, M. E. S.; Soares-Santos, M.; Annis, J.; Welch, B.; Wu, H. -Y.; Palmese, A.; Farahi, A.; Andrade-Oliveira, F.; Lin, H.; García-Bellido, J.; Aguena, M.; Alves, O.; Bacon, D.; Bocquet, S.; Brooks, D.; Carnero Rosell, A.; Carretero, J.; Costanzi, M.; da Costa, L. N.; De Vicente, J.; Doel, P.; Everett, S.; Flaugher, B.; Frieman, J.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Hinton, S. R.; Hollowood, D. L.; Honscheid, K.; James, D. J.; Kuehn, K.; Lidman, C.; Lima, M.; Marshall, J. L.; Mena-Fernández, J.; Miquel, R.; Myles, J.; Ogando, R. L. C.; Pieres, A.; Plazas Malagón, A. A.; Romer, A. K.; Sanchez, E.; Sanchez Cid, D.; Santiago, B.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Suchyta, E.; Swanson, M. E. C.; Weaverdyck, N.; Wiseman, P.; Yamamoto, M.; DES Collaboration
Referencia bibliográfica

Monthly Notices of the Royal Astronomical Society

Fecha de publicación:
1
2025
Número de autores
55
Número de autores del IAC
1
Número de citas
1
Número de citas referidas
0
Descripción
Cosmological analyses using galaxy clusters in optical/near-infrared photometric surveys require robust characterization of their galaxy content. Precisely determining which galaxies belong to a cluster is crucial. In this paper, we present the COlor Probabilistic Assignment of Clusters And BAyesiaNAnalysis (Copacabana) algorithm. Copacabana computes membership probabilities for all galaxies within an aperture centred on the cluster using photometric redshifts, colours, and projected radial probability density functions. We use simulations to validate Copacabana and we show that it achieves up to 89 per cent membership accuracy with a mild dependence on photometric redshift uncertainties and choice of aperture size. We find that the precision of the photometric redshifts has the largest impact on the determination of the membership probabilities followed by the choice of the cluster aperture size. We also quantify how much these uncertainties in the membership probabilities affect the stellar mass-cluster mass scaling relation, a relation that directly impacts cosmology. Using the sum of the stellar masses weighted by membership probabilities ($\rm \mu _{\star }$) as the observable, we find that Copacabana can reach an accuracy of 0.06 dex in the measurement of the scaling relation at low redshift for a Legacy Survey of Space and Time type survey. These results indicate the potential of Copacabana and $\rm \mu _{\star }$ to be used in cosmological analyses of optically selected clusters in the future.