Supernovae as probes of cosmic parameters: estimating the bias from under-dense lines of sight

Busti, V. C.; Holanda, R. F. L.; Clarkson, Chris

doi:10.1088/1475-7516/2013/11/020

Cited by 12 publications

(10 citation statements)

References 84 publications

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“…The physical relevance and the mathematical consistency of the DR approximation have been both questioned in the litterature [37,[52][53][54][55]. One of the criticisms, which lead to a "modified DR approximation" [37,56], relies on the argument that it is inconsistent to consider the Universe effectively underdense only in the focusing term, and not in the z(v) relation. In other words, hypotheses DR1 and DR3 would be incompatible.…”

Section: On the Physical Relevance Of The Approximationmentioning

confidence: 99%

Swiss-cheese models and the Dyer-Roeder approximation

Fleury

2014

J. Cosmol. Astropart. Phys.

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Abstract. In view of interpreting the cosmological observations precisely, especially when they involve narrow light beams, it is crucial to understand how light propagates in our statistically homogeneous, clumpy, Universe. Among the various approaches to tackle this issue, Swisscheese models propose an inhomogeneous spacetime geometry which is an exact solution of Einstein's equation, while the Dyer-Roeder approximation deals with inhomogeneity in an effective way. In this article, we demonstrate that the distance-redshift relation of a certain class of Swiss-cheese models is the same as the one predicted by the Dyer-Roeder approach, at a well-controlled level of approximation. Both methods are therefore equivalent when applied to the interpretation of, e.g., supernova obervations. The proof relies on completely analytical arguments, and is illustrated by numerical results.

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Section: On the Physical Relevance Of The Approximationmentioning

confidence: 99%

Swiss-cheese models and the Dyer-Roeder approximation

Fleury

2014

J. Cosmol. Astropart. Phys.

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“…Hence, possibility that a slightly evolving dark energy contribution can fuel the energy momentum-tensor, alleviating the problems related to the today tiny value 1 of Λ, is still valid. Thus, distinguishing dark energy from Λ and understanding whether the equation of state of the Universe is varying (Chevallier & Polarski 2001;Linder 2003;Padmanabhan 2010;Tsujikawa 2010; Aviles & Cervantes-Cota 2011; Clifton et al 2012;Bamba et al 2012;Luongo & Quevedo 2014a,b;Piedipalumbo et al 2014) have widely prompted the search for model-independent treatments and null-diagnostics (Harrison 1976;Visser 2005;Uzan, Clarkson & Ellis 2008;Clarkson, Bassett & Lu 2008;Zunckel & Clarkson 2008;Sahni, Shafieloo & Starobinsky 2008;Nesseris & Shafieloo 2010;Farooq & Ratra 2013;Busti, Holanda & Clarkson 2013;Aviles et al 2014;Escamilla-Rivera & Capozziello 2019; Escamilla-Rivera, Quintero & Capozziello 2020;…”

Section: Introductionmentioning

confidence: 99%

High-redshift cosmography: auxiliary variables versus Padé polynomials

Capozziello

D’Agostino

Luongo

2020

Monthly Notices of the Royal Astronomical Society

123

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Cosmography becomes non-predictive when cosmic data span beyond the red shift limit z ≃ 1. This leads to a strong convergence issue that jeopardizes its viability. In this work, we critically compare the two main solutions of the convergence problem, i.e. the y-parametrizations of the redshift and the alternatives to Taylor expansions based on Padé series. In particular, among several possibilities, we consider two widely adopted parametrizations, namely y 1 = 1 − a and y 2 = arctan(a −1 − 1), being a the scale factor of the Universe. We find that the y 2 -parametrization performs relatively better than the y 1 -parametrization over the whole redshift domain. Even though y 2 overcomes the issues of y 1 , we get that the most viable approximations of the luminosity distance d L (z) are given in terms of Padé approximations. In order to check this result by means of cosmic data, we analyze the Padé approximations up to the fifth order, and compare these series with the corresponding y-variables of the same orders. We investigate two distinct domains involving Monte Carlo analysis on the Pantheon Superovae Ia data, H(z) and shift parameter measurements. We conclude that the (2,1) Padé approximation is statistically the optimal approach to explain low and high-redshift data, together with the fifth-order y 2 -parametrization. At high redshifts, the (3,2) Padé approximation cannot be fully excluded, while the (2,2) Padé one is essentially ruled out.

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“…We are now at the stage where, to get accurate measurements of cosmological parameters, we need to take these inhomogeneities into account [e.g. [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Local gravitational redshifts can bias cosmological measurements

Wojtak

Davis

Wiis

2015

J. Cosmol. Astropart. Phys.

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Abstract. Measurements of cosmological parameters via the distance-redshift relation usually rely on models that assume a homogenous universe. It is commonly presumed that the large-scale structure evident in our Universe has a negligible impact on the measurement if distances probed in observations are sufficiently large (compared to the scale of inhomogeneities) and are averaged over different directions on the sky. This presumption does not hold when considering the effect of the gravitational redshift caused by our local gravitational potential, which alters light coming from all distances and directions in the same way. Despite its small magnitude, this local gravitational redshift gives rise to noticeable effects in cosmological inference using SN Ia data. Assuming conservative prior knowledge of the local potential given by sampling a range of gravitational potentials at locations of Milky-Waylike galaxies identified in cosmological simulations, we show that ignoring the gravitational redshift effect in a standard data analysis leads to an additional systematic error of ∼ 1% in the determination of density parameters and the dark energy equation of state. We conclude that our local gravitational field affects our cosmological inference at a level that is important in future observations aiming to achieve percent-level accuracy.

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Supernovae as probes of cosmic parameters: estimating the bias from under-dense lines of sight

Cited by 12 publications

References 84 publications

Swiss-cheese models and the Dyer-Roeder approximation

Swiss-cheese models and the Dyer-Roeder approximation

High-redshift cosmography: auxiliary variables versus Padé polynomials

Local gravitational redshifts can bias cosmological measurements

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