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Early cosmology constrained

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Title: Early cosmology constrained
Authors: Verde, L
Bellini, E
Pigozzo, C
Heavens, AF
Jimenez, R
Item Type: Journal Article
Abstract: We investigate our knowledge of early universe cosmology by exploring how much additional energy density can be placed in different components beyond those in the ΛCDM model. To do this we use a method to separate early- and late-universe information enclosed in observational data, thus markedly reducing the model-dependency of the conclusions. We find that the 95% credibility regions for extra energy components of the early universe at recombination are: non-accelerating additional fluid density parameter ΩMR < 0.006 and extra radiation parameterised as extra effective neutrino species 2.3 < Neff < 3.2 when imposing flatness. Our constraints thus show that even when analyzing the data in this largely model-independent way, the possibility of hiding extra energy components beyond ΛCDM in the early universe is seriously constrained by current observations. We also find that the standard ruler, the sound horizon at radiation drag, can be well determined in a way that does not depend on late-time Universe assumptions, but depends strongly on early-time physics and in particular on additional components that behave like radiation. We find that the standard ruler length determined in this way is rs = 147.4 ± 0.7 Mpc if the radiation and neutrino components are standard, but the uncertainty increases by an order of magnitude when non-standard dark radiation components are allowed, to rs = 150 ± 5 Mpc.
Issue Date: 13-Apr-2017
Date of Acceptance: 3-Apr-2017
URI: http://hdl.handle.net/10044/1/48091
DOI: https://dx.doi.org/10.1088/1475-7516/2017/04/023
ISSN: 1475-7516
Publisher: IOP PUBLISHING LTD
Journal / Book Title: JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
Volume: 2017
Issue: 4
Copyright Statement: © 2017 IOP Publishing Ltd and Sissa Medialab srl. This is an author-created, un-copyedited version of an article accepted for publication in Journal of Cosmology and Astroparticle Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at https://dx.doi.org/10.1088/1475-7516/2017/04/023
Sponsor/Funder: Imperial College Trust
Imperial College Trust
Science and Technology Facilities Council
Science and Technology Facilities Council (STFC)
Funder's Grant Number: N/A
NA
ST-N000838
ST/N000838/1
Keywords: Science & Technology
Physical Sciences
Astronomy & Astrophysics
Physics, Particles & Fields
Physics
cosmological parameters from CMBR
cosmological parameters from LSS
BARYON ACOUSTIC-OSCILLATIONS
DARK ENERGY
HUBBLE CONSTANT
PARAMETERS
PRODUCTS
Nuclear & Particles Physics
0201 Astronomical And Space Sciences
0202 Atomic, Molecular, Nuclear, Particle And Plasma Physics
Publication Status: Published
Open Access location: https://arxiv.org/abs/1611.00376
Article Number: ARTN 023
Appears in Collections:Physics
Astrophysics



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