Euclid: Constraining ensemble photometric redshift distributions with stacked spectroscopy
Abstract
The ESA Euclid mission will produce photometric galaxy samples over 15000 square degrees of the sky that will be rich for clustering and weak lensing statistics. The accuracy of the cosmological constraints derived from these measurements will depend on the knowledge of the underlying redshift distributions based on photometric redshift calibrations. A new approach is proposed to use the stacked spectra from Euclid slitless spectroscopy to augment broad-band photometric information to constrain the redshift distribution with spectral energy distribution fitting. The high spectral resolution available in the stacked spectra complements the photometry and helps to break the colour-redshift degeneracy and constrain the redshift distribution of galaxy samples. We modelled the stacked spectra as a linear mixture of spectral templates. The mixture may be inverted to infer the underlying redshift distribution using constrained regression algorithms. We demonstrate the method on simulated Vera C. Rubin Observatory and Euclid mock survey data sets based on the Euclid Flagship mock galaxy catalogue. We assess the accuracy of the reconstruction by considering the inference of the baryon acoustic scale from angular two-point correlation function measurements. We selected mock photometric galaxy samples at redshift z>1 using the self-organising map algorithm. Considering the idealised case without dust attenuation, we find that the redshift distributions of these samples can be recovered with 0.5% accuracy on the baryon acoustic scale. The estimates are not significantly degraded by the spectroscopic measurement noise due to the large sample size. However, the error degrades to 2% when the dust attenuation model is left free. We find that the colour degeneracies introduced by attenuation limit the accuracy considering the wavelength coverage of Euclid near-infrared spectroscopy.
Keywords
Cite
@article{arxiv.2109.07303,
title = {Euclid: Constraining ensemble photometric redshift distributions with stacked spectroscopy},
author = {M. S. Cagliari and B. R. Granett and L. Guzzo and M. Bolzonella and L. Pozzetti and I. Tutusaus and S. Camera and A. Amara and N. Auricchio and R. Bender and C. Bodendorf and D. Bonino and E. Branchini and M. Brescia and V. Capobianco and C. Carbone and J. Carretero and F. J. Castander and M. Castellano and S. Cavuoti and A. Cimatti and R. Cledassou and G. Congedo and C. J. Conselice and L. Conversi and Y. Copin and L. Corcione and M. Cropper and H. Degaudenzi and M. Douspis and F. Dubath and S. Dusini and A. Ealet and S. Ferriol and N. Fourmanoit and M. Frailis and E. Franceschi and P. Franzetti and B. Garilli and C. Giocoli and A. Grazian and F. Grupp and S. V. H. Haugan and H. Hoekstra and W. Holmes and F. Hormuth and P. Hudelot and K. Jahnke and S. Kermiche and A. Kiessling and M. Kilbinger and T. Kitching and M. Kummel and M. Kunz and H. Kurki-Suonio and S. Ligori and P. B. Lilje and I. Lloro and E. Maiorano and O. Mansutti and O. Marggraf and K. Markovic and R. Massey and M. Meneghetti and E. Merlin and G. Meylan and M. Moresco and L. Moscardini and S. M. Niemi and C. Padilla and S. Paltani and F. Pasian and K. Pedersen and W. J. Percival and V. Pettorino and S. Pires and M. Poncet and L. Popa and F. Raison and R. Rebolo and J. Rhodes and H. -W. Rix and M. Roncarelli and E. Rossetti and R. Saglia and R. Scaramella and P. Schneider and M. Scodeggio and A. Secroun and G. Seidel and S. Serrano and C. Sirignano and G. Sirri and D. Tavagnacco and A. N. Taylor and I. Tereno and R. Toledo-Moreo and E. A. Valentijn and L. Valenziano and Y. Wang and N. Welikala and J. Weller and G. Zamorani and J. Zoubian and M. Baldi and R. Farinelli and E. Medinaceli and S. Mei and G. Polenta and E. Romelli and T. Vassallo and A. Humphrey},
journal= {arXiv preprint arXiv:2109.07303},
year = {2022}
}
Comments
16 pages, 10 figures. Accepted by A&A (Jan. 18)