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Exploring Cosmic Origins with CORE: Cosmological Parameters

Eleonora Di Valentino, Thejs Brinckmann, Martina Gerbino, Vivian Poulin, François R. Bouchet, Julien Lesgourgues, Alessandro Melchiorri, Jens Chluba, Sebastien Clesse, Jacques Delabrouille, Cora Dvorkin, Francesco Forastieri, Silvia Galli, Deanna C. Hooper, Massimiliano Lattanzi, Carlos J. A. P. Martins, Laura Salvati, Giovanni Cabass, Andrea Caputo, Elena Giusarma, Eric Hivon, Paolo Natoli, Luca Pagano, Simone Paradiso, Jose Alberto Rubino-Martin, Ana Achucarro, Peter Ade, Rupert Allison, Frederico Arroja, Marc Ashdown, Mario Ballardini, A. J. Banday, Ranajoy Banerji, Nicola Bartolo, James G. Bartlett, Soumen Basak, Jochem Baselmans, Daniel Baumann, Paolo de Bernardis, Marco Bersanelli, Anna Bonaldi, Matteo Bonato, Julian Borrill, François Boulanger, Martin Bucher, Carlo Burigana, Alessandro Buzzelli, Zhen-Yi Cai, Martino Calvo, Carla Sofia Carvalho, Gabriella Castellano, Anthony Challinor, Ivan Charles, Ivan Colantoni, Alessandro Coppolecchia, Martin Crook, Giuseppe D'Alessandro, Marco De Petris, Gianfranco De Zotti, Josè Maria Diego, Josquin Errard, Stephen Feeney, Raul Fernandez-Cobos, Simone Ferraro, Fabio Finelli, Giancarlo de Gasperis, Ricardo T. Génova-Santos, Joaquin González-Nuevo, Sebastian Grandis, Josh Greenslade, Steffen Hagstotz, Shaul Hanany, Will Handley, Dhiraj K. Hazra, Carlos Hernández-Monteagudo, Carlos Hervias-Caimapo, Matthew Hills, Kimmo Kiiveri, Ted Kisner, Thomas Kitching, Martin Kunz, Hannu Kurki-Suonio, Luca Lamagna, Anthony Lasenby, Antony Lewis, Michele Liguori, Valtteri Lindholm, Marcos Lopez-Caniego, Gemma Luzzi, Bruno Maffei, Sylvain Martin, Enrique Martinez-Gonzalez, Silvia Masi, Darragh McCarthy, Jean-Baptiste Melin, Joseph J. Mohr, Diego Molinari, Alessandro Monfardini, Mattia Negrello, Alessio Notari, Alessandro Paiella, Daniela Paoletti, Guillaume Patanchon, Francesco Piacentini, Michael Piat, Giampaolo Pisano, Linda Polastri, Gianluca Polenta, Agnieszka Pollo, Miguel Quartin, Mathieu Remazeilles, Matthieu Roman, Christophe Ringeval, Andrea Tartari, Maurizio Tomasi, Denis Tramonte, Neil Trappe, Tiziana Trombetti, Carole Tucker, Jussi Väliviita, Rien van de Weygaert, Bartjan Van Tent, Vincent Vennin, Gérard Vermeulen, Patricio Vielva, Nicola Vittorio, Karl Young, Mario Zannoni

TL;DR

This paper assesses the CORE-M5 mission's capability to dramatically sharpen cosmological parameter constraints beyond Planck by forecasting using MCMC analyses across a suite of ΛCDM and extended models. It demonstrates substantial gains in precision for fundamental parameters (e.g., H_0, σ_8, Ω_b h^2, Ω_c h^2, N_eff, M_ν) and strong improvements in derived quantities, especially when CORE data are combined with BAO and weak lensing surveys like DESI and Euclid. The study also explores extended physics—curvature, extra relativistic relics, dark energy, recombination, dark matter properties, and modified gravity—showing CORE's power to break key degeneracies and constrain or detect new physics with unprecedented sensitivity. The findings underscore CORE's potential to probe the neutrino sector, early-universe processes, and fundamental constants, offering a path to resolving current cosmological tensions and guiding future experimental strategies. The results are framed within rigorous Monte Carlo forecasts, with explicit comparisons across configuration variants and external data combinations, highlighting CORE-M5 as a cost-effective yet physics-rich design closely approaching the capabilities of a larger mission like COrE+.

Abstract

We forecast the main cosmological parameter constraints achievable with the CORE space mission which is dedicated to mapping the polarisation of the Cosmic Microwave Background (CMB). CORE was recently submitted in response to ESA's fifth call for medium-sized mission proposals (M5). Here we report the results from our pre-submission study of the impact of various instrumental options, in particular the telescope size and sensitivity level, and review the great, transformative potential of the mission as proposed. Specifically, we assess the impact on a broad range of fundamental parameters of our Universe as a function of the expected CMB characteristics, with other papers in the series focusing on controlling astrophysical and instrumental residual systematics. In this paper, we assume that only a few central CORE frequency channels are usable for our purpose, all others being devoted to the cleaning of astrophysical contaminants. On the theoretical side, we assume LCDM as our general framework and quantify the improvement provided by CORE over the current constraints from the Planck 2015 release. We also study the joint sensitivity of CORE and of future Baryon Acoustic Oscillation and Large Scale Structure experiments like DESI and Euclid. Specific constraints on the physics of inflation are presented in another paper of the series. In addition to the six parameters of the base LCDM, which describe the matter content of a spatially flat universe with adiabatic and scalar primordial fluctuations from inflation, we derive the precision achievable on parameters like those describing curvature, neutrino physics, extra light relics, primordial helium abundance, dark matter annihilation, recombination physics, variation of fundamental constants, dark energy, modified gravity, reionization and cosmic birefringence. (ABRIDGED)

Exploring Cosmic Origins with CORE: Cosmological Parameters

TL;DR

This paper assesses the CORE-M5 mission's capability to dramatically sharpen cosmological parameter constraints beyond Planck by forecasting using MCMC analyses across a suite of ΛCDM and extended models. It demonstrates substantial gains in precision for fundamental parameters (e.g., H_0, σ_8, Ω_b h^2, Ω_c h^2, N_eff, M_ν) and strong improvements in derived quantities, especially when CORE data are combined with BAO and weak lensing surveys like DESI and Euclid. The study also explores extended physics—curvature, extra relativistic relics, dark energy, recombination, dark matter properties, and modified gravity—showing CORE's power to break key degeneracies and constrain or detect new physics with unprecedented sensitivity. The findings underscore CORE's potential to probe the neutrino sector, early-universe processes, and fundamental constants, offering a path to resolving current cosmological tensions and guiding future experimental strategies. The results are framed within rigorous Monte Carlo forecasts, with explicit comparisons across configuration variants and external data combinations, highlighting CORE-M5 as a cost-effective yet physics-rich design closely approaching the capabilities of a larger mission like COrE+.

Abstract

We forecast the main cosmological parameter constraints achievable with the CORE space mission which is dedicated to mapping the polarisation of the Cosmic Microwave Background (CMB). CORE was recently submitted in response to ESA's fifth call for medium-sized mission proposals (M5). Here we report the results from our pre-submission study of the impact of various instrumental options, in particular the telescope size and sensitivity level, and review the great, transformative potential of the mission as proposed. Specifically, we assess the impact on a broad range of fundamental parameters of our Universe as a function of the expected CMB characteristics, with other papers in the series focusing on controlling astrophysical and instrumental residual systematics. In this paper, we assume that only a few central CORE frequency channels are usable for our purpose, all others being devoted to the cleaning of astrophysical contaminants. On the theoretical side, we assume LCDM as our general framework and quantify the improvement provided by CORE over the current constraints from the Planck 2015 release. We also study the joint sensitivity of CORE and of future Baryon Acoustic Oscillation and Large Scale Structure experiments like DESI and Euclid. Specific constraints on the physics of inflation are presented in another paper of the series. In addition to the six parameters of the base LCDM, which describe the matter content of a spatially flat universe with adiabatic and scalar primordial fluctuations from inflation, we derive the precision achievable on parameters like those describing curvature, neutrino physics, extra light relics, primordial helium abundance, dark matter annihilation, recombination physics, variation of fundamental constants, dark energy, modified gravity, reionization and cosmic birefringence. (ABRIDGED)

Paper Structure

This paper contains 44 sections, 20 equations, 25 figures, 35 tables.

Table of Contents

  1. Introduction
  2. Experimental setup and fiducial model
  3. $\Lambda$CDM and derived parameters
  4. Future constraints from CORE
  5. Improvement with respect to the Planck 2015 release
  6. Comparison between the different CORE configurations
  7. Constraints from CORE-M5 and future BAO datasets
  8. Constraints on curvature
  9. Future constraints from CORE
  10. Future constraints from CORE+DESI
  11. Extra relativistic relics
  12. Constraints on the primordial Helium abundance
  13. Sensitivity to the helium abundance in a minimal extension of $\Lambda$CDM
  14. Sensitivity to the helium abundance in $\Lambda$CDM+ $N_\mathrm{eff}$
  15. Constraints on the neutron lifetime
  16. ...and 29 more sections

Figures (25)

  • Figure 1: Fiducial model and variance $C_l+N_l$ of each data point $a_{lm}$, given the sensitivity of each CORE configuration (Planck is also shown for comparison). As long as the variance traces the fiducial model, the data is cosmic variance limited. This happens down to different angular scales for the temperature (left) and E-mode polarisation (middle). For CMB lensing extraction (right), on all scales, there is a substantial difference between the noise level of the different configurations.
  • Figure 2: 2D posteriors in the $\sigma_8$ vs $H_0$ plane (left panel) and on the $\Omega_bh^2$ vs $\Omega_{c}h^2$ plane (right panel) from the recent Planck 2015 data release (temperature and anisotropy) and from the simulated LiteCORE-80, CORE-M5 and COrE+ experimental configurations. $\Lambda$CDM is assumed for the CORE simulations. The improvement of any CORE configuration in constraining parameters with respect to Planck is clearly visible.
  • Figure 3: 2D posteriors for several combinations of parameters for the LiteCORE-80, CORE-M5 and COrE+ experimental configurations. $\Lambda$CDM is assumed as the underlying fiducial model.
  • Figure 4: 2D posteriors in the $H_0$ vs $\sigma_8$ (left panel) and $\Omega_bh^2$ vs $\Omega_ch^2$ (right panel) planes from Planck (simulated), CORE-M5, and future BAO dataset from the DESI survey. $\Lambda$CDM is assumed as the underlying fiducial model.
  • Figure 5: Left Panel: Constraints on the $H_0$ vs $\Omega_k$ plane from different CORE configurations. Current constraints from Planck+CMB lensing are reported for comparison. Right Panel: Constraints on the $H_0$ vs $\Omega_k$ plane for the following (simulated) datasets: Planck+DESI, LiteCORE80+DESI, CORE-M5+DESI, COrE++DESI. A flat universe is assumed in the simulated data.
  • ...and 20 more figures