OA@INAFhttps://openaccess.inaf.itThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Sat, 21 May 2022 05:41:12 GMT2022-05-21T05:41:12Z5021Euclid: Constraining ensemble photometric redshift distributions with stacked spectroscopyhttp://hdl.handle.net/20.500.12386/31724Title: Euclid: Constraining ensemble photometric redshift distributions with stacked spectroscopy
Authors: Cagliari, M. S.; GRANETT, Benjamin Rudolph; GUZZO, Luigi; BOLZONELLA, MICOL; POZZETTI, Lucia; Tutusaus, I.; Camera, S.; Amara, A.; AURICCHIO, NATALIA; Bender, R.; Bodendorf, C.; BONINO, Donata; Branchini, Enzo; BRESCIA, Massimo; Capobianco, Vito; CARBONE, Carmelita; Carretero, J.; Castander, F. J.; CASTELLANO, MARCO; CAVUOTI, STEFANO; Cimatti, A.
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.
Sat, 01 Jan 2022 00:00:00 GMThttp://hdl.handle.net/20.500.12386/317242022-01-01T00:00:00ZThe Multi-Tracer Optimal Estimator applied to VIPERShttp://hdl.handle.net/20.500.12386/31731Title: The Multi-Tracer Optimal Estimator applied to VIPERS
Authors: Montero-Dorta, Antonio D; Raul Abramo, L; GRANETT, Benjamin Rudolph; de la Torre, Sylvain; GUZZO, Luigi
Abstract: We use mock galaxy data from the VIMOS Public Extragalactic Redshift Survey
(VIPERS) to test the performance of the Multi-Tracer Optimal Estimator (MTOE)
of Abramo et al. as a tool to measure the monopoles of the power spectra of
multiple tracers of the large-scale structure, $P^{(0)}_\alpha(k)$. We show
that MTOE provides more accurate measurements than the standard technique of
Feldman, Kaiser & Peacock (FKP), independently of the tracer-selection strategy
adopted, on both small and large scales. The largest improvements on individual
$P^{(0)}_\alpha(k)$ are obtained using a colour-magnitude selection on small
scales, due to MTOE being naturally better equipped to deal with shot noise: we
report an average error reduction with respect to FKP of $\sim$ 40$\%$ at $k \,
[h$ Mpc$^{-1}]\gtrsim 0.3$. On large scales ($k[h$ Mpc$^{-1}]\lesssim0.1$), the
gain in accuracy resulting from cosmic-variance cancellation is $\sim$ 10$\%$
for the ratios of $P^{(0)}_\alpha(k)$. We have carried out a Monte-Carlo Markov
Chain analysis to determine the impact of these gains on several quantities
derived from $P^{(0)}_\alpha(k)$. If we push the measurement to scales $0.3 < k
\, [h$ Mpc$^{-1}]< 0.5$, the average improvements are $\sim$ 30 $\%$ for the
amplitudes of the monopoles, $\sim$ 70 $\%$ for the monopole ratios, and $\sim$
20 $\%$ for the galaxy biases. Our results highlight the potential of MTOE to
shed light upon the physics that operate both on large and small cosmological
scales. The effect of MTOE on cosmological constraints using VIPERS data will
be addressed in a separate paper.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/20.500.12386/317312020-01-01T00:00:00Z