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**Dark energy properties from large future galaxy surveys.** / Basse, Tobias; Eggers Bjælde, Ole; Hamann, Jan; Hannestad, Steen; Wong, Yvonne Y. Y.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

Basse, T, Eggers Bjælde, O, Hamann, J, Hannestad, S & Wong, YYY 2014, 'Dark energy properties from large future galaxy surveys', *Journal of Cosmology and Astroparticle Physics*, vol. 05, 021. https://doi.org/10.1088/1475-7516/2014/05/021

Basse, T., Eggers Bjælde, O., Hamann, J., Hannestad, S., & Wong, Y. Y. Y. (2014). Dark energy properties from large future galaxy surveys. *Journal of Cosmology and Astroparticle Physics*, *05*, [021]. https://doi.org/10.1088/1475-7516/2014/05/021

Basse T, Eggers Bjælde O, Hamann J, Hannestad S, Wong YYY. 2014. Dark energy properties from large future galaxy surveys. Journal of Cosmology and Astroparticle Physics. 05. https://doi.org/10.1088/1475-7516/2014/05/021

Basse, Tobias et al. "Dark energy properties from large future galaxy surveys". *Journal of Cosmology and Astroparticle Physics*. 2014. 05. https://doi.org/10.1088/1475-7516/2014/05/021

Basse T, Eggers Bjælde O, Hamann J, Hannestad S, Wong YYY. Dark energy properties from large future galaxy surveys. Journal of Cosmology and Astroparticle Physics. 2014 May 1;05. 021. https://doi.org/10.1088/1475-7516/2014/05/021

Basse, Tobias ; Eggers Bjælde, Ole ; Hamann, Jan ; Hannestad, Steen ; Wong, Yvonne Y. Y. / **Dark energy properties from large future galaxy surveys**. In: Journal of Cosmology and Astroparticle Physics. 2014 ; Vol. 05.

@article{7415c537d38f4c4088bcc31e80aebb3d,

title = "Dark energy properties from large future galaxy surveys",

abstract = "We perform a detailed forecast on how well a Euclid-like survey will be able to constrain dark energy and neutrino parameters from a combination of its cosmic shear power spectrum, galaxy power spectrum, and cluster mass function measurements. We find that the combination of these three probes vastly improves the survey's potential to measure the time evolution of dark energy. In terms of a dark energy figure-of-merit defined as (σ(wp)σ(wa))‑1, we find a value of 690 for Euclid-like data combined with Planck-like measurements of the cosmic microwave background anisotropies in a 10-dimensional cosmological parameter space, assuming a ΛCDM fiducial cosmology. For the more commonly used 7-parameter model, we find a figure-of-merit of 1900 for the same data combination. We consider also the survey's potential to measure dark energy perturbations in models wherein the dark energy is parameterised as a fluid with a nonstandard non-adiabatic sound speed, and find that in an optimistic scenario in which w0 deviates from -1 by as much as is currently observationally allowed, models with hat cs2 = 10‑6 and hat cs2 = 1 can be distinguished from one another at more than 2σ significance. We emphasise that constraints on the dark energy sound speed from cluster measurements are strongly dependent on the modelling of the cluster mass function; significantly weaker sensitivities ensue if we modify our model to include fewer features of nonlinear dark energy clustering. Finally, we find that the sum of neutrino masses can be measured with a 1σ precision of 0.015 eV, even in complex cosmological models in which the dark energy equation of state varies with time. The 1σ sensitivity to the effective number of relativistic species Neffml is approximately 0.03, meaning that the small deviation of 0.046 from 3 in the standard value of Neffml due to non-instantaneous decoupling and finite temperature effects can be probed with 1σ precision for the first time.",

author = "Tobias Basse and {Eggers Bj{\ae}lde}, Ole and Jan Hamann and Steen Hannestad and Wong, {Yvonne Y. Y.}",

year = "2014",

month = "5",

day = "1",

doi = "10.1088/1475-7516/2014/05/021",

language = "English",

volume = "05",

journal = "Journal of Cosmology and Astroparticle Physics",

issn = "1475-7516",

publisher = "IOP Publishing",

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TY - JOUR

T1 - Dark energy properties from large future galaxy surveys

AU - Basse, Tobias

AU - Eggers Bjælde, Ole

AU - Hamann, Jan

AU - Hannestad, Steen

AU - Wong, Yvonne Y. Y.

PY - 2014/5/1

Y1 - 2014/5/1

N2 - We perform a detailed forecast on how well a Euclid-like survey will be able to constrain dark energy and neutrino parameters from a combination of its cosmic shear power spectrum, galaxy power spectrum, and cluster mass function measurements. We find that the combination of these three probes vastly improves the survey's potential to measure the time evolution of dark energy. In terms of a dark energy figure-of-merit defined as (σ(wp)σ(wa))‑1, we find a value of 690 for Euclid-like data combined with Planck-like measurements of the cosmic microwave background anisotropies in a 10-dimensional cosmological parameter space, assuming a ΛCDM fiducial cosmology. For the more commonly used 7-parameter model, we find a figure-of-merit of 1900 for the same data combination. We consider also the survey's potential to measure dark energy perturbations in models wherein the dark energy is parameterised as a fluid with a nonstandard non-adiabatic sound speed, and find that in an optimistic scenario in which w0 deviates from -1 by as much as is currently observationally allowed, models with hat cs2 = 10‑6 and hat cs2 = 1 can be distinguished from one another at more than 2σ significance. We emphasise that constraints on the dark energy sound speed from cluster measurements are strongly dependent on the modelling of the cluster mass function; significantly weaker sensitivities ensue if we modify our model to include fewer features of nonlinear dark energy clustering. Finally, we find that the sum of neutrino masses can be measured with a 1σ precision of 0.015 eV, even in complex cosmological models in which the dark energy equation of state varies with time. The 1σ sensitivity to the effective number of relativistic species Neffml is approximately 0.03, meaning that the small deviation of 0.046 from 3 in the standard value of Neffml due to non-instantaneous decoupling and finite temperature effects can be probed with 1σ precision for the first time.

AB - We perform a detailed forecast on how well a Euclid-like survey will be able to constrain dark energy and neutrino parameters from a combination of its cosmic shear power spectrum, galaxy power spectrum, and cluster mass function measurements. We find that the combination of these three probes vastly improves the survey's potential to measure the time evolution of dark energy. In terms of a dark energy figure-of-merit defined as (σ(wp)σ(wa))‑1, we find a value of 690 for Euclid-like data combined with Planck-like measurements of the cosmic microwave background anisotropies in a 10-dimensional cosmological parameter space, assuming a ΛCDM fiducial cosmology. For the more commonly used 7-parameter model, we find a figure-of-merit of 1900 for the same data combination. We consider also the survey's potential to measure dark energy perturbations in models wherein the dark energy is parameterised as a fluid with a nonstandard non-adiabatic sound speed, and find that in an optimistic scenario in which w0 deviates from -1 by as much as is currently observationally allowed, models with hat cs2 = 10‑6 and hat cs2 = 1 can be distinguished from one another at more than 2σ significance. We emphasise that constraints on the dark energy sound speed from cluster measurements are strongly dependent on the modelling of the cluster mass function; significantly weaker sensitivities ensue if we modify our model to include fewer features of nonlinear dark energy clustering. Finally, we find that the sum of neutrino masses can be measured with a 1σ precision of 0.015 eV, even in complex cosmological models in which the dark energy equation of state varies with time. The 1σ sensitivity to the effective number of relativistic species Neffml is approximately 0.03, meaning that the small deviation of 0.046 from 3 in the standard value of Neffml due to non-instantaneous decoupling and finite temperature effects can be probed with 1σ precision for the first time.

U2 - 10.1088/1475-7516/2014/05/021

DO - 10.1088/1475-7516/2014/05/021

M3 - Journal article

VL - 05

JO - Journal of Cosmology and Astroparticle Physics

JF - Journal of Cosmology and Astroparticle Physics

SN - 1475-7516

M1 - 021

ER -