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arXiv · 2112.10959

Bias of reconstructing the dark energy equation of state from the Pad$\acute{e}$ cosmography

Yang Liu·Zhengxiang Li·Hongwei Yu·Puxun Wu
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Abstract

Pad$\acute{e}$ cosmography has been widely used to probe the cosmic evolution and to investigate the nature of dark energy. In this paper, we find that the Pad$\acute{e}$ approximant can describe the cosmic evolution better than the standard cosmography, and if the luminosity distance $d_L(z)$ described by the Pad$\acute{e}$ approximant is used to reconstruct the dark energy equation of state $w(z)$, then the reconstructed $w(z)$ will approach a constant, i.e. $1/3$ or $0$, when the redshift is very high. This result is general since it is independent of the coefficients in the Pad$\acute{e}$ approximant and the value of the present dimensionless matter density parameter. This intrinsic character will bias the $w(z)$ reconstruction and lead to misconception of the property of dark energy. Therefore, one must exercise caution in investigating the property of dark energy from Pad$\acute{e}$ cosmography when the high redshift data, i.e. $z>2$, are included.

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Yang Liu, Zhengxiang Li, Hongwei Yu, Puxun Wu. 2021-12-21. Bias of reconstructing the dark energy equation of state from the Pad$\acute{e}$ cosmography. https://doi.org/10.1007/s10509-021-04020-7

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