Euclid preparation LX. The use of HST images as input for weak-lensing image simulations
Abstract
Data from the Euclid space telescope will enable cosmic shear measurements with very small statistical errors, requiring corresponding systematic error control level. A common approach to correct for shear biases involves calibrating shape measurement methods using image simulations with known input shear. Given their high resolution, Hubble Space Telescope (HST) galaxies can, in principle, be utilised to emulate Euclid observations. In this work, we employ a GalSim-based testing environment to investigate whether uncertainties in the HST point spread function (PSF) model or in data processing techniques introduce significant biases in weak-lensing (WL) shear calibration. We used single S\'ersic galaxy models to simulate both HST and Euclid observations. We then `Euclidised' our HST simulations and compared the results with the directly simulated Euclid-like images. For this comparison, we utilised a moment-based shape measurement algorithm and galaxy model fits. Through the Euclidisation procedure, we effectively reduced the residual multiplicative biases in shear measurements to sub-percent levels. This achievement was made possible by employing either the native pixel scales of the instruments, utilising the Lanczos15 interpolation kernel, correcting for noise correlations, and ensuring consistent galaxy signal-to-noise ratios between simulation branches. However, the Euclidisation procedure requires further analysis on the impact of the correlated noise, to estimate calibration bias. Additionally, we conducted an in-depth analysis of the accuracy of TinyTim HST PSF models using star fields observed in the F606W and F814W filters. We observe that F606W images exhibit a broader scatter in the recovered best-fit focus, compared to those in the F814W filter.
Cite
@article{arxiv.2501.08372,
title = {Euclid preparation LX. The use of HST images as input for weak-lensing image simulations},
author = {Euclid Collaboration and D. Scognamiglio and T. Schrabback and M. Tewes and B. Gillis and H. Hoekstra and E. M. Huff and O. Marggraf and T. Kitching and R. Massey and I. Tereno and C. S. Carvalho and A. Robertson and G. Congedo and N. Aghanim and B. Altieri and A. Amara and S. Andreon and N. Auricchio and C. Baccigalupi and M. Baldi and S. Bardelli and P. Battaglia and C. Bodendorf and D. Bonino and E. Branchini and M. Brescia and J. Brinchmann and S. Camera and V. Capobianco and C. Carbone and V. F. Cardone and J. Carretero and S. Casas and F. J. Castander and M. Castellano and G. Castignani and S. Cavuoti and A. Cimatti and C. Colodro-Conde and C. J. Conselice and L. Conversi and Y. Copin and F. Courbin and H. M. Courtois and M. Cropper and A. Da Silva and H. Degaudenzi and G. De Lucia and A. M. Di Giorgio and J. Dinis and F. Dubath and C. A. J. Duncan and X. Dupac and S. Dusini and M. Farina and S. Farrens and S. Ferriol and P. Fosalba and M. Frailis and E. Franceschi and S. Galeotta and C. Giocoli and P. Gómez-Alvarez and A. Grazian and F. Grupp and L. Guzzo and S. V. H. Haugan and W. Holmes and F. Hormuth and A. Hornstrup and P. Hudelot and K. Jahnke and B. Joachimi and E. Keihänen and S. Kermiche and A. Kiessling and M. Kilbinger and B. Kubik and M. Kümmel and M. Kunz and H. Kurki-Suonio and S. Ligori and P. B. Lilje and V. Lindholm and I. Lloro and G. Mainetti and E. Maiorano and O. Mansutti and K. Markovic and M. Martinelli and N. Martinet and F. Marulli and E. Medinaceli and S. Mei and Y. Mellier and M. Meneghetti and G. Meylan and M. Moresco and L. Moscardini and R. Nakajima and S. -M. Niemi and J. W. Nightingale and C. Padilla and S. Paltani and F. Pasian and K. Pedersen and S. Pires and G. Polenta and M. Poncet and L. A. Popa and L. Pozzetti and F. Raison and R. Rebolo and A. Renzi and J. Rhodes and G. Riccio and E. Romelli and M. Roncarelli and E. Rossetti and R. Saglia and Z. Sakr and A. G. Sánchez and D. Sapone and B. Sartoris and R. Scaramella and M. Schirmer and P. Schneider and A. Secroun and G. Seidel and S. Serrano and C. Sirignano and G. Sirri and J. Skottfelt and L. Stanco and J. -L. Starck and J. Steinwagner and P. Tallada-Crespí and A. N. Taylor and H. I. Teplitz and R. Toledo-Moreo and F. Torradeflot and I. Tutusaus and L. Valenziano and T. Vassallo and G. Verdoes Kleijn and A. Veropalumbo and Y. Wang and J. Weller and M. Wetzstein and G. Zamorani and E. Zucca and A. Biviano and M. Bolzonella and A. Boucaud and E. Bozzo and C. Burigana and M. Calabrese and J. A. Escartin Vigo and J. Gracia-Carpio and N. Mauri and A. Pezzotta and M. Pöntinen and C. Porciani and V. Scottez and M. Tenti and M. Viel and M. Wiesmann and Y. Akrami and V. Allevato and S. Anselmi and M. Ballardini and L. Blot and S. Borgani and S. Bruton and R. Cabanac and A. Calabro and A. Cappi and T. Castro and K. C. Chambers and S. Contarini and A. R. Cooray and S. Davini and B. De Caro and G. Desprez and A. Díaz-Sánchez and S. Di Domizio and H. Dole and S. Escoffier and A. G. Ferrari and I. Ferrero and F. Fornari and L. Gabarra and K. Ganga and J. García-Bellido and E. Gaztanaga and F. Giacomini and F. Gianotti and G. Gozaliasl and A. Hall and S. Hemmati and H. Hildebrandt and J. Hjorth and A. Jimenez Muñoz and J. J. E. Kajava and V. Kansal and D. Karagiannis and C. C. Kirkpatrick and J. Le Graet and L. Legrand and A. Loureiro and J. Macias-Perez and G. Maggio and M. Magliocchetti and F. Mannucci and R. Maoli and C. J. A. P. Martins and S. Matthew and L. Maurin and R. B. Metcalf and P. Monaco and C. Moretti and G. Morgante and Nicholas A. Walton and L. Patrizii and V. Popa and D. Potter and P. Reimberg and I. Risso and P. -F. Rocci and R. P. Rollins and M. Sahlén and A. Schneider and M. Sereno and P. Simon and A. Spurio Mancini and K. Tanidis and C. Tao and G. Testera and R. Teyssier and S. Toft and S. Tosi and A. Troja and M. Tucci and C. Valieri and J. Valiviita and D. Vergani and G. Verza},
journal= {arXiv preprint arXiv:2501.08372},
year = {2025}
}
Comments
Accepted by A&A. 23 pages, 20 figures, Euclid pre-launch key paper