Exploring cosmic origins with CORE: Cluster science

Abstract

We examine the cosmological constraints that can be achieved with a galaxy cluster survey with the future CORE space mission. Using realistic simulations of the millimeter sky, produced with the latest version of the Planck Sky Model, we characterize the CORE cluster catalogues as a function of the main mission performance parameters. We pay particular attention to telescope size, key to improved angular resolution, and discuss the comparison and the complementarity of CORE with ambitious future ground-based CMB experiments that could be deployed in the next decade. A possible CORE mission concept with a 150 cm diameter primary mirror can detect of the order of 50,000 clusters through the thermal Sunyaev-Zeldovich effect (SZE). The total yield increases (decreases) by 25% when increasing (decreasing) the mirror diameter by 30 cm. The 150 cm telescope configuration will detect the most massive clusters (> 10 14 M) at redshift z > 1.5 over the whole sky, although the exact number above this redshift is tied to the uncertain evolution of the cluster SZE flux-mass relation; assuming self-similar evolution, CORE will detect ∼ 500 clusters at redshift z > 1.5. This changes to 800 (200) when increasing (decreasing) the mirror size by 30 cm. CORE will be able to measure individual cluster halo masses through lensing of the cosmic microwave background anisotropies with a 1-σ sensitivity of 4 × 10 14 M , for a 120 cm aperture telescope, and 10 14 M for a 180 cm one. From the ground, we estimate that, for example, a survey with about 150,000 detectors at the focus of 350 cm telescopes observing 65% of the sky from Atacama would be shallower than CORE and detect about 11,000 clusters, while a survey from the South Pole with the same number of detectors observing 25% of sky with a 10 m telescope is expected to be deeper and to detect about 70,000 clusters. When combined with such a South Pole survey, CORE would reach a limiting mass of M 500 ∼ 2 − 3 × 10 13 M and detect 220,000 clusters (5 sigma detection limit). Cosmological constraints from CORE cluster counts alone are competitive with other scheduled large scale structure surveys in the 2020's for measuring the dark energy equation-of-state parameters w and w a (σ w 0 = 0.28, σ wa = 0.31). In combination with primary CMB constraints, CORE cluster counts can further reduce these error bars on w 0 and w a to 0.05 and 0.13 respectively, and constrain the sum of the neutrino masses, Σm ν , to 39 meV (1 sigma). The wide frequency coverage of CORE, 60-600 GHz, will enable measurement of the relativistic thermal SZE by stacking clusters. Contamination by dust emission from the clusters, however, makes constraining the temperature of the intracluster medium difficult. The kinetic SZE pairwise momentum will be extracted with S/N = 70 in the foreground-cleaned CMB map. Measurements of T CMB (z) using CORE clusters will establish competitive constraints on the evolution of the CMB temperature: (1 + z) 1−β , with an uncertainty of σ β 2.7 × 10 −3 at low redshift (z 1). The wide frequ...

Exploring cosmic origins with CORE: Gravitational lensing of the CMB

“…However, in some places we present parametric comparisons of different options to justify design choices made in the baseline. Lensing impacts much of CORE science; closely related papers in this series describe constraints on inflation [21] (where delensing is significant), cosmological parameters [22] (which combines the temperature, polarization, and lensing power spectra), and galaxy cluster science [23] (where mass calibration with CMB lensing of temperature anisotropies is discussed).…”

“…In section 7 we highlight the potential for CORE to self-calibrate the masses of its cluster catalogue via lensing of CMB polarization, extending the temperature-based forecasts presented in ref. [23]. While most of the forecasts throughout this paper assume that the 19 frequency channels of CORE will allow accurate cleaning of Galactic foreground emission, and so ignore potential Galactic residuals, in section 8 we relax this assumption.…”

“…The effects of dark energy are degenerate in the primary CMB fluctuations, which originate at much higher redshift than the onset of cosmic acceleration (z ≈ 1). However, through secondary effects in the CMB, CORE will provide several dark energy observables that complement other low-redshift probes: the cluster sample detected with CORE via the thermal Sunyaev-Zel'dovich (SZ) effect [23] (see also section 7); peculiar velocities as measured by the kinetic SZ effect [23]; and CMB lensing.…”

“…Such measurements will be significantly advanced with the diffuse tSZ map from CORE [23], which should be much cleaner than the equivalent from Planck [87], and the improved S/N of the CORE lensing map. As a final application, we note the recent constraints on the bias and hence halo masses of high-redshift quasar hosts from cross-correlation of CMB lensing with quasar catalogues [76,88].…”

In-Flight Performance of the LEKIDs of the OLIMPO Experiment

“…In the microwaves, KID technology has been already proven for ground-based experiments by NIKA [4] and NIKA2 [5]. OLIMPO [6] has qualified the KID technology in a representative near-space environment, relevant for TRL (Technology Readiness Level) advancement in view of future space missions [1,7,8,9,10,11,12,13,14,15]. In the past years, several efforts have been made to characterize KIDs in representative space conditions [16,17,18].…”