Do stochastic inhomogeneities affect dark-energy precision measurements?

Ben-Dayan, Ido; Marozzi, Giovanni; Gasperini, Maurizio; Nugier, Fabien; Veneziano, Gabriele

doi:10.1103/PhysRevLett.110.021301

Article
Report number	arXiv:1207.1286 ; CERN-PH-TH-2012-188
Title	Do stochastic inhomogeneities affect dark-energy precision measurements?
Author(s)	Ben-Dayan, Ido (Canadian Inst. Theor. Astrophys. ; Perimeter Inst. Theor. Phys.) ; Gasperini, Maurizio (Bari U. ; INFN, Bari) ; Marozzi, Giovanni (College de France) ; Nugier, Fabien (Ecole Normale Superieure) ; Veneziano, Gabriele (College de France ; CERN)
Publication	2013
Imprint	06 Jul 2012
Number of pages	5
Note	Comments: 4 pages, 3 figures 5 pages, 3 figures. Comments and references added. Typos corrected. Version accepted for publication in Phys. Rev. Lett
In:	Phys. Rev. Lett. 110 (2013) 021301
DOI	10.1103/PhysRevLett.110.021301
Subject category	Astrophysics and Astronomy
Abstract	The effect of a stochastic background of cosmological perturbations on the luminosity-redshift relation is computed to second order through a recently proposed covariant and gauge-invariant light-cone averaging procedure. The resulting expressions are free from both ultraviolet and infrared divergences, implying that such perturbations cannot mimic a sizable fraction of dark energy. Different averages are estimated and depend on the particular function of the luminosity distance being averaged. The energy flux, being minimally affected by perturbations at large z, is proposed as the best choice for precision estimates of dark-energy parameters. Nonetheless, its irreducible (stochastic) variance induces statistical errors on \Omega_{\Lambda}(z) typically lying in the few-percent range.
Copyright/License	Preprint: © 2012-2025 CERN (License: CC-BY-3.0)

$The fractional correction $f_\Phi$ of Eq. (\ref{9}) (solid curve), compared with the same quantity given to leading order by Eq. (\ref{10}) (dashed curve), in the context of an inhomogeneous CDM model. We have used for ${\cal P}(k)$ the inflationary scalar spectrum with the WMAP parameters \cite{WMAP7} and the transfer function given in \cite{EH} (see also \cite{BGMNV1}). The plotted curve refers, as an illustrative example, to an UV cutoff $k_{UV}=1 {\rm Mpc}^{-1}$.$ $The fractional correction to the flux $f_\Phi$ of Eq. (\ref{7}) (thin curves) is compared with the fractional correction to the luminosity distance $f_d$ of Eq. (\ref{13}) (thick curves), for a $\La$CDM model with $\Om_\La=0.73$. We have used two different cutoff values: $k_{UV}=0.1 {\rm Mpc}^{-1}$ (dashed curves) and $k_{UV}=1 {\rm Mpc}^{-1}$ (solid curves); the spectrum is the same as that of Fig. \ref{f1}, adapted to $\La$CDM.$ $The averaged distance modulus $ \overline{\langle \mu \rangle} -\mu^M$ (thick solid curve), and its dispersion of Eq. (\ref{15}) (shaded region) are computed for $\Om_\La=0.73$ and compared with the homogeneous value for the unperturbed $\La$CDM models with $ \Om_\La= 0.69$, $0.71$, $0.73$, $0.75$, $0.77$ (dashed curves). We have used $k_{UV}=1\rm{Mpc}^{-1}$ and the same spectrum as in Fig. \ref{f2}.$ Show more plots

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Записът е създаден на 2012-07-07, последна промяна на 2017-03-25

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