Euclid. A two-point correlation approach to diagnosing star-related systematics in the Euclid spectroscopic survey

@misc{risso2026euclid,
  title = {{Euclid. A two-point correlation approach to diagnosing star-related systematics in the Euclid spectroscopic survey}},
  author = {I Risso and B.R Granett and E Branchini and A Veropalumbo and B Kubik and P Monaco and J Comparat and A Hall and N Aghanim and B Altieri and A Amara and S Andreon and N Auricchio and C Baccigalupi and M Baldi and A Balestra and S Bardelli and P Battaglia and A Biviano and M Bolzonella and M Brescia and S Camera and G Cañas-Herrera and V Capobianco and C Carbone and J Carretero and F.J Castander 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 F Courbin and H.M Courtois and H Degaudenzi and S de la Torre and G de Lucia and Herve Dole and F Dubath and X Dupac and S Dusini and S Escoffier and M Farina and R Farinelli and S Ferriol and F Finelli and N Fourmanoit and M Frailis and E Franceschi and M Fumana and L Gabarra and S Galeotta and K George and W Gillard and B Gillis and C Giocoli and J Gracia-Carpio},
  howpublished = {HAL},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.05155},
  eprint = {2609.05155},
  archivePrefix = {arXiv},
  url = {https://hal.science/hal-05760436v1},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Euclid. A two-point correlation approach to diagnosing star-related systematics in the Euclid spectroscopic survey
AU  - I Risso
AU  - B.R Granett
AU  - E Branchini
AU  - A Veropalumbo
AU  - B Kubik
AU  - P Monaco
AU  - J Comparat
AU  - A Hall
AU  - N Aghanim
AU  - B Altieri
AU  - A Amara
AU  - S Andreon
AU  - N Auricchio
AU  - C Baccigalupi
AU  - M Baldi
AU  - A Balestra
AU  - S Bardelli
AU  - P Battaglia
AU  - A Biviano
AU  - M Bolzonella
AU  - M Brescia
AU  - S Camera
AU  - G Cañas-Herrera
AU  - V Capobianco
AU  - C Carbone
AU  - J Carretero
AU  - F.J Castander
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  - F Courbin
AU  - H.M Courtois
AU  - H Degaudenzi
AU  - S de la Torre
AU  - G de Lucia
AU  - Herve Dole
AU  - F Dubath
AU  - X Dupac
AU  - S Dusini
AU  - S Escoffier
AU  - M Farina
AU  - R Farinelli
AU  - S Ferriol
AU  - F Finelli
AU  - N Fourmanoit
AU  - M Frailis
AU  - E Franceschi
AU  - M Fumana
AU  - L Gabarra
AU  - S Galeotta
AU  - K George
AU  - W Gillard
AU  - B Gillis
AU  - C Giocoli
AU  - J Gracia-Carpio
PY  - 2026
DA  - 2026/09/04
PB  - HAL
DO  - 10.48550/arxiv.2609.05155
UR  - https://hal.science/hal-05760436v1
AB  - The Euclid spectroscopic survey will measure galaxy clustering with unprecedented precision, requiring stringent control of observational and instrumental systematics. Star-related effects may contaminate spectroscopic images through photometric persistence and imperfect masking of stars. We characterized their impact on galaxy clustering analyses, focusing on angular features identifiable in the data. We used angular and spatial auto- and cross-correlation statistics. For galaxies, we used mock spectroscopic catalogues from the EuclidLargeMocks in a 330 deg2 region of the Euclid Wide Survey (EWS). For stars, we used Gaia and 2MASS catalogues in the same area. To simulate photometric persistence, we implemented a simplified detector-level model calibrated on spectroscopic measurements and varied its strength to introduce different interloper fractions. For stellar masking, we modelled inconsistencies between the mask applied to the data and to the random catalogue. We measured star-star, galaxy-galaxy, and star-galaxy angular correlation functions using the Landy--Szalay estimator, and quantified deviations from the expected null star-galaxy correlation. We also evaluated the large-scale impact of such systematics through the three-dimensional two-point correlation function (2PCF). Photometric persistence produces a characteristic feature in the star-galaxy angular cross-correlation at scales of order 100", corresponding to the Euclid dithering pattern and grism dispersion geometry, and a spurious positive signal approximately constant up to 1°. Star-galaxy cross-correlation can detect residual persistence at contamination levels as low as 10% in a Data Release 1 spectroscopic catalogue. In contrast, stellar-mask mismatches produce strong small-scale angular signatures but have negligible impact on the large-scale 2PCF under realistic EWS conditions.
ER  -