Euclid Bypass end-to-end simulations for spectroscopic galaxy clustering performance assessment

@misc{collaboration2026euclid,
  title = {{Euclid Bypass end-to-end simulations for spectroscopic galaxy clustering performance assessment}},
  author = {Euclid Collaboration and B. R. Granett and S. de la Torre and M. Moresco and A. Farina and M. Bethermin and B. Zabelle and S. Bruton and K. Markovic and I. Risso and S. Lee and K. S. McCarthy and O. Ilbert and V. Le Brun and P. Monaco and K. V. Nedkova and C. Scarlata and L. Guzzo and W. J. Percival and Y. Wang and G. Cañas-Herrera and C. Sirignano and B. Altieri and S. Andreon and N. Auricchio and C. Baccigalupi and M. Baldi and S. Bardelli and P. Battaglia and A. Biviano and M. Bolzonella and E. Branchini and M. Brescia and J. Brinchmann and S. Camera and V. Capobianco and C. Carbone and J. Carretero and M. Castellano and G. Castignani and S. Cavuoti and P. -Y. Chabaud and A. Cimatti and C. Colodro-Conde and G. Congedo and L. Conversi and Y. Copin and A. Costille and F. Courbin and H. M. Courtois and H. Degaudenzi and G. De Lucia and H. Dole and F. Dubath and X. Dupac and S. Dusini and S. Escoffier and M. Farina and R. Farinelli and F. Faustini},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.26990},
  eprint = {2610.26990},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.26990},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Euclid Bypass end-to-end simulations for spectroscopic galaxy clustering performance assessment
AU  - Euclid Collaboration
AU  - B. R. Granett
AU  - S. de la Torre
AU  - M. Moresco
AU  - A. Farina
AU  - M. Bethermin
AU  - B. Zabelle
AU  - S. Bruton
AU  - K. Markovic
AU  - I. Risso
AU  - S. Lee
AU  - K. S. McCarthy
AU  - O. Ilbert
AU  - V. Le Brun
AU  - P. Monaco
AU  - K. V. Nedkova
AU  - C. Scarlata
AU  - L. Guzzo
AU  - W. J. Percival
AU  - Y. Wang
AU  - G. Cañas-Herrera
AU  - C. Sirignano
AU  - B. Altieri
AU  - S. Andreon
AU  - N. Auricchio
AU  - C. Baccigalupi
AU  - M. Baldi
AU  - S. Bardelli
AU  - P. Battaglia
AU  - A. Biviano
AU  - M. Bolzonella
AU  - E. Branchini
AU  - M. Brescia
AU  - J. Brinchmann
AU  - S. Camera
AU  - V. Capobianco
AU  - C. Carbone
AU  - J. Carretero
AU  - M. Castellano
AU  - G. Castignani
AU  - S. Cavuoti
AU  - P. -Y. Chabaud
AU  - A. Cimatti
AU  - C. Colodro-Conde
AU  - G. Congedo
AU  - L. Conversi
AU  - Y. Copin
AU  - A. Costille
AU  - F. Courbin
AU  - H. M. Courtois
AU  - H. Degaudenzi
AU  - G. De Lucia
AU  - H. Dole
AU  - F. Dubath
AU  - X. Dupac
AU  - S. Dusini
AU  - S. Escoffier
AU  - M. Farina
AU  - R. Farinelli
AU  - F. Faustini
PY  - 2026
DA  - 2026/10/19
PB  - arXiv
DO  - 10.48550/arxiv.2610.26990
UR  - https://arxiv.org/abs/2610.26990
AB  - We present a simulation framework for Euclid galaxy clustering measurements that reproduces the essential behaviour of the spectroscopic reduction chain, bypassing the computation required by full pixel-level simulations. The framework comprises two complementary tools, FastSpec, which simulates 1-dimensional slitless spectra with a simplified instrument and noise model, and Pypelid, which computes detection probabilities on input catalogues, accounting for the survey dithering sequence and spatially varying noise. We develop calibrated prescriptions for the survey selection function, redshift errors, and redshift interloper populations. Applied to the Euclid Wide Survey, the baseline selection yields a redshift purity of 74% and a sample completeness of 45%, which improves with the use of Euclid photometric colours. The redshift error distribution is found to have a Gaussian core of width σ_z = 9.4 × 10^−4, with no significant trend over 0.9 < z < 1.8. Emission lines [OIII]5008 and [SIII]9530 misidentified as Hα contribute a few to ten per cent depending on redshift, while catastrophic redshift measurement failures dominate at low signal-to-noise ratio. Simulating the Data Release 1 footprint, we find that complex survey selection effects can be corrected with a forward-modelled random catalogue, recovering the monopole and quadrupole of the galaxy 2-point correlation function. The simplified noise model does not include residual contamination from overlapping spectra, or other artefacts seen in early Euclid data; this will be revisited with DR1 data. The framework provides an efficient route for characterising the Euclid spectroscopic selection function at the precision required for galaxy clustering science, and is the basis for systematic error assessments in Euclid galaxy clustering analyses.
ER  -