Cosmological parameter forecasts for a CMB-HD survey

Journal Article · 17 March 2024 · Physical Review. D.

DOI: https://doi.org/10.1103/physrevd.109.063527 · OSTI ID:2324778

MacInnis, Amanda  ^[1]; Sehgal, Neelima  ^[2]; Rothermel, Miriam ^[2]

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1. Stony Brook University, NY (United States); Stony Brook University
2. Stony Brook University, NY (United States)

We present forecasts on cosmological parameters for a CMB-HD survey. For a $$\Lambda$$CDM + $$N_{eff}$$ + $$\sum m_\nu$$ model, we find $$\sigma(n_s) = 0.0013$$ and $$\sigma(N_{eff}) = 0.014$$ using CMB and CMB lensing multipoles in the range of $$\ell \in [30, 20000]$$, after adding anticipated residual foregrounds, delensing the acoustic peaks, and adding DESI BAO data. This is about a factor of two improvement in ability to probe inflation via $$n_s$$ compared to precursor CMB surveys. The $$N_{eff}$$ constraint can rule out light thermal particles back to the end of inflation with 95% CL; for example, it can rule out the QCD axion in a model-independent way assuming the Universe's reheating temperature was high enough that the axion thermalized. We find that delensing the acoustic peaks and adding DESI BAO tightens parameter constraints. We also find that baryonic effects can bias parameters if not marginalized over, and that uncertainties in baryonic effects can increase parameter error bars; however, the latter can be mitigated by including information about baryonic effects from kinetic and thermal Sunyaev-Zel'dovich measurements by CMB-HD. The CMB-HD likelihood and Fisher estimation codes used here are publicly available; the likelihood is integrated with Cobaya to facilitate parameter forecasting.

• Research Organization: Stony Brook University, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF); National Science Foundation (NSF)
• Grant/Contract Number: SC0020441; AC02-05CH11231
• OSTI ID: 2324778
• Alternate ID(s): OSTI ID: 2337994; OSTI ID: 2339820; OSTI ID: 2439575
• Journal Information: Physical Review. D., Journal Name: Physical Review. D. Journal Issue: 6 Vol. 109; ISSN 2470-0010
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English