Complementing the ground-based CMB-S4 experiment on large scales with the PIXIE satellite

Calabrese, Erminia ORCID: https://orcid.org/0000-0003-0837-0068, Alonso, David and Dunkley, Jo 2017. Complementing the ground-based CMB-S4 experiment on large scales with the PIXIE satellite. Physical Review D 95 (6) , 063504. 10.1103/PhysRevD.95.063504

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Abstract

We present forecasts for cosmological parameters from future cosmic microwave background (CMB) data measured by the stage-4 (S4) generation of ground-based experiments in combination with large-scale anisotropy data from the PIXIE satellite. We demonstrate the complementarity of the two experiments and focus on science targets that benefit from their combination. We show that a cosmic-variance-limited measurement of the optical depth to reionization provided by PIXIE, with error σ(τ)=0.002, is vital for enabling a 5σ detection of the sum of the neutrino masses when combined with a CMB-S4 lensing measurement and with lower-redshift constraints on the growth of structure and the distance-redshift relation. Parameters characterizing the epoch of reionization will also be tightly constrained; PIXIE’s τ constraint converts into σ(zre)=0.2 for the mean time of reionization, and a kinematic Sunyaev-Zel’dovich measurement from S4 gives σ(Δzre)=0.03 for the duration of reionization. Both PIXIE and S4 will put strong constraints on primordial tensor fluctuations, vital for testing early-Universe models, and will do so at distinct angular scales. We forecast σ(r)≈5×10−4 for a signal with a tensor-to-scalar ratio r=10−3, after accounting for diffuse foreground removal and delensing. The wide and dense frequency coverage of PIXIE results in an expected foreground-degradation factor on r of only ≈25%. By measuring large and small scales PIXIE and S4 will together better limit the energy injection at recombination from dark matter annihilation, with pann<0.09×10−6  m3/s/kg projected at 95% confidence. Cosmological parameters measured from the damping tail with S4 will be best constrained by polarization, which has the advantage of minimal contamination from extragalactic emission.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	American Physical Society
ISSN:	2470-0010
Date of First Compliant Deposit:	6 June 2017
Date of Acceptance:	16 February 2017
Last Modified:	04 May 2023 23:08
URI:	https://orca.cardiff.ac.uk/id/eprint/101217

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