Browsing by Author "Courtois, H. M."

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Euclid preparation XXXIV. The effect of linear redshift-space distortions in photometric galaxy clustering and its cross-correlation with cosmic shear
    (EDP Sciences, 2024-03-01) Tanidis, K.; Cardone, V. F.; Martinelli, M.; Tutusaus, I.; Camera, S.; Aghanim, N.; Amara, A.; Andreon, S.; Auricchio, N.; Baldi, M.; Bardelli, S.; Branchini, E.; Brescia, M.; Brinchmann, J.; Capobianco, V.; Carbone, C.; Carretero, J.; Casas, S.; Castellano, M.; Cavuoti, S.; Cimatti, A.; Cledassou, R.; Congedo, G.; Conversi, L.; Copin, Y.; Corcione, L.; Courbin, F.; Courtois, H. M.; Da Silvay, A.; Degaudenzi, H.; Dinis, J.; Dubath, F.; Dupac, X.; Dusini, S.; Farina, M.; Farrens, S.; Ferriol, S.; Fosalba, P.; Frailis, M.; Franceschi, E.; Fumana, M.; Galeotta, S.; Garilli, B.; Gillard, W.; Gillis, B.; Niemi, S. M.; Schneider, P.; Wang, Y.; Gozaliasl, G.; Sánchez, A. G.; , Euclid Collaboration; Department of Computer Science; Czech Academy of Sciences; Osservatorio Astronomico di Roma; IRAP; University of Turin; Université Paris-Saclay; University of Portsmouth; Osservatorio Astronomico di Brera; Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; University of Genoa; University of Naples Federico II; Universidade do Porto; National Institute for Astrophysics (INAF); Istituto Nazionale di Astrofisica (INAF); Institute for High Energy Physics; RWTH Aachen University; Osservatorio Astronomico di Capodimonte; Universitá di Bologna; Centre national d'études spatiales; University of Edinburgh; ESRIN - ESA Centre for Earth Observation; Université Claude Bernard Lyon 1; Swiss Federal Institute of Technology Lausanne; Institut national de physique nucléaire et de physique des particules; University of Lisbon; University of Geneva; Urbanización Villafranca Del Castillo; National Institute for Nuclear Physics; CSIC - Institute of Space Sciences; Osservatorio Astronomico di Trieste; Aix-Marseille Université; European Space Research and Technology Centre; University of Bonn; California Institute of Technology; Max Planck Institute for Extraterrestrial Physics
    Context. The cosmological surveys that are planned for the current decade will provide us with unparalleled observations of the distribution of galaxies on cosmic scales, by means of which we can probe the underlying large-scale structure (LSS) of the Universe. This will allow us to test the concordance cosmological model and its extensions. However, precision pushes us to high levels of accuracy in the theoretical modelling of the LSS observables, so that no biases are introduced into the estimation of the cosmological parameters. In particular, effects such as redshift-space distortions (RSD) can become relevant in the computation of harmonic-space power spectra even for the clustering of the photometrically selected galaxies, as has previously been shown in literature. Aims. In this work, we investigate the contribution of linear RSD, as formulated in the Limber approximation by a previous work, in forecast cosmological analyses with the photometric galaxy sample of the Euclid survey. We aim to assess their impact and to quantify the bias on the measurement of cosmological parameters that would be caused if this effect were neglected. Methods. We performed this task by producing mock power spectra for photometric galaxy clustering and weak lensing, as is expected to be obtained from the Euclid survey. We then used a Markov chain Monte Carlo approach to obtain the posterior distributions of cosmological parameters from these simulated observations. Results. When the linear RSD is neglected, significant biases are caused when galaxy correlations are used alone and when they are combined with cosmic shear in the so-called 3 × 2 pt approach. These biases can be equivalent to as much as 5σ when an underlying ΛCDM cosmology is assumed. When the cosmological model is extended to include the equation-of-state parameters of dark energy, the extension parameters can be shifted by more than 1σ.
  • Thumbnail Image
    Item
    Euclid preparation XXXVII. Galaxy colour selections with Euclid and ground photometry for cluster weak-lensing analyses
    (EDP Sciences, 2024-04-01) Lesci, G. F.; Sereno, M.; Radovich, M.; Castignani, G.; Bisigello, L.; Marulli, F.; Moscardini, L.; Baumont, L.; Covone, G.; Farrens, S.; Giocoli, C.; Ingoglia, L.; Miranda La Hera, S.; Vannier, M.; Biviano, A.; Maurogordato, S.; Aghanim, N.; Amara, A.; Andreon, S.; Auricchio, N.; Baldi, M.; Bardelli, S.; Bender, R.; Bodendorf, C.; Bonino, D.; Branchini, E.; Brescia, M.; Brinchmann, J.; Camera, S.; Capobianco, V.; Carbone, C.; Carretero, J.; Casas, S.; Castander, F. J.; Castellano, M.; Cavuoti, S.; Cimatti, A.; Congedo, G.; Conselice, C. J.; Conversi, L.; Copin, Y.; Corcione, L.; Courbin, F.; Courtois, H. M.; Niemi, S. M.; Schneider, P.; Starck, J. L.; Wang, Y.; Gozaliasl, G.; Sánchez, A. G.; , Euclid Collaboration; Department of Computer Science; Universitá di Bologna; Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; INAF - Osservatorio Astronomico di Padova; Université Paris-Saclay; University of Naples Federico II; Niels Bohr Institute; Université Côte d'Azur; Osservatorio Astronomico di Trieste; University of Portsmouth; Osservatorio Astronomico di Brera; Max Planck Institute for Extraterrestrial Physics; National Institute for Astrophysics (INAF); University of Genoa; Universidade do Porto; Istituto Nazionale di Astrofisica (INAF); Institute for High Energy Physics; RWTH Aachen University; CSIC - Institute of Space Sciences; Osservatorio Astronomico di Roma; Osservatorio Astronomico di Capodimonte; University of Edinburgh; University of Manchester; Urbanización Villafranca Del Castillo; Université Claude Bernard Lyon 1; Swiss Federal Institute of Technology Lausanne; Institut national de physique nucléaire et de physique des particules; European Space Research and Technology Centre; University of Bonn; California Institute of Technology
    Aims. We derived galaxy colour selections from Euclid and ground-based photometry, aiming to accurately define background galaxy samples in cluster weak-lensing analyses. These selections have been implemented in the Euclid data analysis pipelines for galaxy clusters. Methods. Given any set of photometric bands, we developed a method for the calibration of optimal galaxy colour selections that maximises the selection completeness, given a threshold on purity. Such colour selections are expressed as a function of the lens redshift. Results. We calibrated galaxy selections using simulated ground-based griz and Euclid YEJEHE photometry. Both selections produce a purity higher than 97%. The griz selection completeness ranges from 30% to 84% in the lens redshift range zl ∈ [0.2, 0.8]. With the full grizYEJEHE selection, the completeness improves by up to 25 percentage points, and the zl range extends up to zl = 1.5. The calibrated colour selections are stable to changes in the sample limiting magnitudes and redshift, and the selection based on griz bands provides excellent results on real external datasets. Furthermore, the calibrated selections provide stable results using alternative photometric aperture definitions obtained from different ground-based telescopes. The griz selection is also purer at high redshift and more complete at low redshift compared to colour selections found in the literature. We find excellent agreement in terms of purity and completeness between the analysis of an independent, simulated Euclid galaxy catalogue and our calibration sample, except for galaxies at high redshifts, for which we obtain up to 50 percentage points higher completeness. The combination of colour and photo-z selections applied to simulated Euclid data yields up to 95% completeness, while the purity decreases down to 92% at high zl. We show that the calibrated colour selections provide robust results even when observations from a single band are missing from the ground-based data. Finally, we show that colour selections do not disrupt the shear calibration for stage III surveys. The first Euclid data releases will provide further insights into the impact of background selections on the shear calibration.
  • Thumbnail Image
    Item
    Euclid preparation. XXXIX. The effect of baryons on the halo mass function
    (EDP Sciences, 2024-05-01) Castro, T.; Borgani, S.; Costanzi, M.; Dakin, J.; Dolag, K.; Fumagalli, A.; Ragagnin, A.; Saro, A.; Le Brun, A. M.C.; Aghanim, N.; Amara, A.; Andreon, S.; Auricchio, N.; Baldi, M.; Bardelli, S.; Bodendorf, C.; Bonino, D.; Branchini, E.; Brescia, M.; Brinchmann, J.; Camera, S.; Capobianco, V.; Carbone, C.; Carretero, J.; Casas, S.; Castellano, M.; Cavuoti, S.; Cimatti, A.; Congedo, G.; Conselice, C. J.; Conversi, L.; Copin, Y.; Corcione, L.; Courbin, F.; Courtois, H. M.; Cropper, M.; Da Silva, A.; Degaudenzi, H.; Di Giorgio, A. M.; Dinis, J.; Dubath, F.; Duncan, C. A.J.; Dupac, X.; Farina, M.; Niemi, S. M.; Schneider, P.; Starck, J. L.; Wang, Y.; Gozaliasl, G.; Sánchez, A. G.; , Euclid Collaboration; Department of Computer Science; Osservatorio Astronomico di Trieste; University of Zurich; Ludwig Maximilian University of Munich; University of Trieste; Observatoire de Paris; Université Paris-Saclay; University of Portsmouth; Osservatorio Astronomico di Brera; Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; Max Planck Institute for Extraterrestrial Physics; National Institute for Astrophysics (INAF); University of Genoa; University of Naples Federico II; Universidade do Porto; Istituto Nazionale di Astrofisica (INAF); Institute for High Energy Physics; RWTH Aachen University; Osservatorio Astronomico di Roma; Osservatorio Astronomico di Capodimonte; Universitá di Bologna; University of Edinburgh; University of Manchester; Urbanización Villafranca Del Castillo; Université Claude Bernard Lyon 1; Swiss Federal Institute of Technology Lausanne; Institut national de physique nucléaire et de physique des particules; University College London; University of Lisbon; University of Geneva; European Space Research and Technology Centre; University of Bonn; California Institute of Technology
    The Euclid photometric survey of galaxy clusters stands as a powerful cosmological tool, with the capacity to significantly propel our understanding of the Universe. Despite being subdominant to dark matter and dark energy, the baryonic component of our Universe holds substantial influence over the structure and mass of galaxy clusters. This paper presents a novel model that can be used to precisely quantify the impact of baryons on the virial halo masses of galaxy clusters using the baryon fraction within a cluster as a proxy for their effect. Constructed on the premise of quasi-adiabaticity, the model includes two parameters, which are calibrated using non-radiative cosmological hydrodynamical simulations, and a single large-scale simulation from the Magneticum set, which includes the physical processes driving galaxy formation. As a main result of our analysis, we demonstrate that this model delivers a remarkable 1% relative accuracy in determining the virial dark matter-only equivalent mass of galaxy clusters starting from the corresponding total cluster mass and baryon fraction measured in hydrodynamical simulations. Furthermore, we demonstrate that this result is robust against changes in cosmological parameters and against variation of the numerical implementation of the subresolution physical processes included in the simulations. Our work substantiates previous claims regarding the impact of baryons on cluster cosmology studies. In particular, we show how neglecting these effects would lead to biased cosmological constraints for a Euclid-like cluster abundance analysis. Importantly, we demonstrate that uncertainties associated with our model arising from baryonic corrections to cluster masses are subdominant when compared to the precision with which mass-observable (i.e. richness) relations will be calibrated using Euclid and to our current understanding of the baryon fraction within galaxy clusters.
  • Thumbnail Image
    Item
    Euclid preparation: XL. Impact of magnification on spectroscopic galaxy clustering
    (EDP Sciences, 2024-05-01) Jelic-Cizmek, G.; Sorrenti, F.; Lepori, F.; Bonvin, C.; Camera, S.; Castander, F. J.; Durrer, R.; Fosalba, P.; Kunz, M.; Lombriser, L.; Tutusaus, I.; Viglione, C.; Sakr, Z.; Aghanim, N.; Amara, A.; Andreon, S.; Baldi, M.; Bardelli, S.; Bodendorf, C.; Bonino, D.; Branchini, E.; Brescia, M.; Brinchmann, J.; Capobianco, V.; Carbone, C.; Cardone, V. F.; Carretero, J.; Casas, S.; Castellano, M.; Cavuoti, S.; Cimatti, A.; Congedo, G.; Conselice, C. J.; Conversi, L.; Copin, Y.; Corcione, L.; Courbin, F.; Courtois, H. M.; Cropper, M.; Degaudenzi, H.; Di Giorgio, A. M.; Dinis, J.; Dubath, F.; Dupac, X.; Niemi, S. M.; Schneider, P.; Starck, J. L.; Wang, Y.; Gozaliasl, G.; Sánchez, A. G.; , Euclid Collaboration; Department of Computer Science; University of Geneva; University of Zurich; University of Turin; CSIC - Institute of Space Sciences; Institute of Space Studies of Catalonia; IRAP; Université Paris-Saclay; University of Portsmouth; Osservatorio Astronomico di Brera; Universitá di Bologna; Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; Max Planck Institute for Extraterrestrial Physics; National Institute for Astrophysics (INAF); University of Genoa; University of Naples Federico II; Universidade do Porto; Istituto Nazionale di Astrofisica (INAF); Osservatorio Astronomico di Roma; Institute for High Energy Physics; RWTH Aachen University; Osservatorio Astronomico di Capodimonte; University of Edinburgh; University of Manchester; Urbanización Villafranca Del Castillo; Université Claude Bernard Lyon 1; Swiss Federal Institute of Technology Lausanne; Institut national de physique nucléaire et de physique des particules; University College London; University of Lisbon; European Space Research and Technology Centre; California Institute of Technology
    In this paper we investigate the impact of lensing magnification on the analysis of Euclid's spectroscopic survey using the multipoles of the two-point correlation function for galaxy clustering. We determine the impact of lensing magnification on cosmological constraints as well as the expected shift in the best-fit parameters if magnification is ignored. We considered two cosmological analyses: (i) a full-shape analysis based on the δ cold dark matter (CDM) model and its extension w0waCDM and (ii) a model-independent analysis that measures the growth rate of structure in each redshift bin. We adopted two complementary approaches in our forecast: the Fisher matrix formalism and the Markov chain Monte Carlo method. The fiducial values of the local count slope (or magnification bias), which regulates the amplitude of the lensing magnification, have been estimated from the Euclid Flagship simulations. We used linear perturbation theory and modelled the two-point correlation function with the public code coffe. For a δ CDM model, we find that the estimation of cosmological parameters is biased at the level of 0.4- 0.7 standard deviations, while for a w0waCDM dynamical dark energy model, lensing magnification has a somewhat smaller impact, with shifts below 0.5 standard deviations. For a model-independent analysis aimed at measuring the growth rate of structure, we find that the estimation of the growth rate is biased by up to 1.2 standard deviations in the highest redshift bin. As a result, lensing magnification cannot be neglected in the spectroscopic survey, especially if we want to determine the growth factor, one of the most promising ways to test general relativity with Euclid. We also find that, by including lensing magnification with a simple template, this shift can be almost entirely eliminated with minimal computational overhead.