Cagliari, MS;
Granett, BR;
Guzzo, L;
Bolzonella, M;
Pozzetti, L;
Tutusaus, I;
Camera, S;
... Wang, Y; + view all
(2022)
Euclid: Constraining ensemble photometric redshift distributions with stacked spectroscopy.
Astronomy and Astrophysics
, 660
, Article A9. 10.1051/0004-6361/202142224.
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Abstract
Context: The ESA Euclid mission will produce photometric galaxy samples over 15 000 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. Aims: 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. Methods: 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. Results: We selected mock photometric galaxy samples at redshift za>a1 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.
| Type: | Article |
|---|---|
| Title: | Euclid: Constraining ensemble photometric redshift distributions with stacked spectroscopy |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1051/0004-6361/202142224 |
| Publisher version: | https://doi.org/10.1051/0004-6361/202142224 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | methods: data analysis / methods: statistical / galaxies: distances and redshifts / large-scale structure of Universe |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10147576 |
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