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CMB distance priors revisited: effects of dark energy dynamics, spatial curvature, primordial power spectrum, and neutrino parameters

Zhai, Zhongxu and Park, Chan-Gyung and Wang, Yun and Ratra, Bharat (2020) CMB distance priors revisited: effects of dark energy dynamics, spatial curvature, primordial power spectrum, and neutrino parameters. Journal of Cosmology and Astroparticle Physics, 2020 (7). Art. No. JCAP07. ISSN 1475-7516. doi:10.1088/1475-7516/2020/07/009.

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As a physical and sufficient compression of the full CMB data, the CMB distance priors, or shift parameters, have been widely used and provide a convenient way to include CMB data when obtaining cosmological constraints. In this paper, we revisit this data vector and examine its stability under different cosmological models. We find that the CMB distance priors are an accurate substitute for the full CMB data when probing dark energy dynamics. This is true when the primordial power spectrum model is directly generalized from the power spectrum of the model used in the derivation of the distance priors from the CMB data. We discover a difference when a non-flat model with the untilted primordial inflation power spectrum is used to measure the distance priors. This power spectrum is a radical change from the more conventional tilted primordial power spectrum and violates fundamental assumptions for the reliability of the CMB shift parameters. We also investigate the performance of CMB distance priors when the sum of neutrino masses ∑m_ν and the effective number of relativistic species N_(eff) are allowed to vary. Our findings are consistent with earlier results: the neutrino parameters can change the measurement of the sound horizon from CMB data, and thus the CMB distance priors. We find that when the neutrino model is allowed to vary, the cold dark matter density ω_c and N_(eff) need to be included in the set of parameters that summarize CMB data, in order to reproduce the constraints from the full CMB data. We present an updated and expanded set of CMB distance priors which can reproduce constraints from the full CMB data within 1σ, and are applicable to models with massive neutrinos, as well as non-standard cosmologies.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Zhai, Zhongxu0000-0001-7984-5476
Additional Information:© 2020 IOP Publishing Ltd and Sissa Medialab. Received 19 February 2020; Accepted 8 June 2020; Published 3 July 2020. We acknowledge the use of the public softwares CAMB [26], Matplotlib [89], NumPy [90], SciPy [91], ChainConsumer [92], Scikit-learn [93] and Emcee [94]. This work is supported in part by NASA grant 15-WFIRST15-0008, Cosmology with the High Latitude Survey WFIRST Science Investigation Team (SIT). C.-G.P. was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. 2017R1D1A1B03028384). B.R. was supported in part by DOE grant de-sc0019038.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
National Research Foundation of Korea2017R1D1A1B03028384
Department of Energy (DOE)DE-SC0019038
Issue or Number:7
Record Number:CaltechAUTHORS:20200511-103351299
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Official Citation:Zhongxu Zhai et al JCAP07(2020)009
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103100
Deposited By: Tony Diaz
Deposited On:11 May 2020 17:39
Last Modified:12 Jul 2022 17:33

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