Euclid: Survey mask effects on clustering of galaxy clusters
Abstract
Wide-area cluster catalogues from Stage-IV surveys will substantially improve the precision of cluster clustering measurements, making the control of observational systematic effects essential for cosmological inference. In preparation for the first Euclid data release (DR1), we assess the impact of the survey mask and non-homogeneous sky coverage on the two-point correlation function of galaxy clusters and its covariance. Using DR1-like lightcone mocks, we confirm that the irregular footprint does not introduce appreciable changes in the two-point correlation function when the same mask is applied to the random catalogue. We also find that spatial inhomogeneities, implemented as variations of the cluster selection function in different patches of the sky, do not significantly bias the clustering amplitude, up to levels of variation well above those expected for DR1. When the degree of inhomogeneity is increased to the regime where the effect becomes significant, we show that its amplitude is related to the maximum variation of the selection function among different regions, rather than to the number of such regions. We further find that irregular mask geometry and non-uniform sky coverage both increase the clustering covariance, introducing small, nearly scale-independent offsets that can be captured by nuisance parameters in the covariance model. Our results consolidate the treatment of mask systematic errors for DR1 and inform the methodological refinements required for future \Euclid cluster cosmology.
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BibTeX
@misc{fumagalli2026euclid,
title = {{Euclid: Survey mask effects on clustering of galaxy clusters}},
author = {A. Fumagalli and R. Ingrao and M. Costanzi and T. Castro and S. Borgani and A. Saro and E. Tsaprazi and F. Marulli and M. Aguena and L. Baumont and N. Aghanim and B. Altieri and S. Andreon and N. Auricchio and C. Baccigalupi and M. Baldi and P. Battaglia and A. Biviano and E. Branchini and M. Brescia and J. Brinchmann and S. Camera and V. Capobianco and C. Carbone and M. Castellano and G. Castignani and S. Cavuoti and A. Cimatti and C. Colodro-Conde and G. Congedo and L. Conversi and Y. Copin and H. M. Courtois and H. Degaudenzi and S. de la Torre and G. De Lucia and H. Dole and F. Dubath and X. Dupac and S. Dusini and S. Escoffier and M. Farina and F. Faustini and S. Ferriol and F. Finelli and M. Frailis and E. Franceschi and M. Fumana and L. Gabarra and S. Galeotta and K. George and C. Giocoli and A. Grazian and F. Grupp and L. Guzzo and S. V. H. Haugan and S. Hemmati and W. Holmes and F. Hormuth and A. Hornstrup},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.06304},
eprint = {2611.06304},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.06304},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Euclid: Survey mask effects on clustering of galaxy clusters
AU - A. Fumagalli
AU - R. Ingrao
AU - M. Costanzi
AU - T. Castro
AU - S. Borgani
AU - A. Saro
AU - E. Tsaprazi
AU - F. Marulli
AU - M. Aguena
AU - L. Baumont
AU - N. Aghanim
AU - B. Altieri
AU - S. Andreon
AU - N. Auricchio
AU - C. Baccigalupi
AU - M. Baldi
AU - P. Battaglia
AU - A. Biviano
AU - E. Branchini
AU - M. Brescia
AU - J. Brinchmann
AU - S. Camera
AU - V. Capobianco
AU - C. Carbone
AU - M. Castellano
AU - G. Castignani
AU - S. Cavuoti
AU - A. Cimatti
AU - C. Colodro-Conde
AU - G. Congedo
AU - L. Conversi
AU - Y. Copin
AU - H. M. Courtois
AU - H. Degaudenzi
AU - S. de la Torre
AU - G. De Lucia
AU - H. Dole
AU - F. Dubath
AU - X. Dupac
AU - S. Dusini
AU - S. Escoffier
AU - M. Farina
AU - F. Faustini
AU - S. Ferriol
AU - F. Finelli
AU - M. Frailis
AU - E. Franceschi
AU - M. Fumana
AU - L. Gabarra
AU - S. Galeotta
AU - K. George
AU - C. Giocoli
AU - A. Grazian
AU - F. Grupp
AU - L. Guzzo
AU - S. V. H. Haugan
AU - S. Hemmati
AU - W. Holmes
AU - F. Hormuth
AU - A. Hornstrup
PY - 2026
DA - 2026/11/04
PB - arXiv
DO - 10.48550/arxiv.2611.06304
UR - https://arxiv.org/abs/2611.06304
AB - Wide-area cluster catalogues from Stage-IV surveys will substantially improve the precision of cluster clustering measurements, making the control of observational systematic effects essential for cosmological inference. In preparation for the first Euclid data release (DR1), we assess the impact of the survey mask and non-homogeneous sky coverage on the two-point correlation function of galaxy clusters and its covariance. Using DR1-like lightcone mocks, we confirm that the irregular footprint does not introduce appreciable changes in the two-point correlation function when the same mask is applied to the random catalogue. We also find that spatial inhomogeneities, implemented as variations of the cluster selection function in different patches of the sky, do not significantly bias the clustering amplitude, up to levels of variation well above those expected for DR1. When the degree of inhomogeneity is increased to the regime where the effect becomes significant, we show that its amplitude is related to the maximum variation of the selection function among different regions, rather than to the number of such regions. We further find that irregular mask geometry and non-uniform sky coverage both increase the clustering covariance, introducing small, nearly scale-independent offsets that can be captured by nuisance parameters in the covariance model. Our results consolidate the treatment of mask systematic errors for DR1 and inform the methodological refinements required for future \Euclid cluster cosmology.
ER -