We investigate the null tests of spatial flatness and the flat ACDM model using the baryon acoustic oscillation (BAO) data measured by the Dark Energy Spectroscopic Instrument (DESI), the cosmic chronometers (CCH) H(z) data, and the Union3 and Pantheon Plus type Ia supernovae (SNe Ia) datasets. We propose a novel non-parametric reconstruction of FAP, DM/rd and D′M/rd from the DESI BAO data to perform the <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11433_2025_2682_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="24" /> </InlineMediaObject> <EquationSource Format="TEX">${\cal O}_{k}$</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msub> <mrow> <mi mathvariant="script">O</mi> </mrow> <mrow> <mi>k</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> diagnostic, and we also conduct the <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11433_2025_2682_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="24" /> </InlineMediaObject> <EquationSource Format="TEX">${\cal O}_{k}$</EquationSource> <EquationSource Format="MATHML"><math display="block"> <msub> <mrow> <mi mathvariant="script">O</mi> </mrow> <mrow> <mi>k</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> diagnostic using the combination of CCH and SNe Ia data. The novel method avoids the issue of the dependence on cosmological parameters such as the value of the Hubble constant. There is no evidence of deviation from the flat ΛCDM model, nor is there any indication of dynamical dark energy found in the observational data. Since we employ a non-parametric reconstruction method, all the conclusions drawn in this paper remain robust and agnostic to any cosmological model and gravitational theory.

Null tests with Gaussian process

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发表日期：

2025年6月27日

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Shengqing Gao,
Qing Gao,
Yungui Gong,
Xuchen Lu

摘要

We investigate the null tests of spatial flatness and the flat ACDM model using the baryon acoustic oscillation (BAO) data measured by the Dark Energy Spectroscopic Instrument (DESI), the cosmic chronometers (CCH) H(z) data, and the Union3 and Pantheon Plus type Ia supernovae (SNe Ia) datasets. We propose a novel non-parametric reconstruction of F_AP, D_M/r_d and D′_M/r_d from the DESI BAO data to perform the ${\cal O}_{k}$ $O_{k}$ diagnostic, and we also conduct the ${\cal O}_{k}$ $O_{k}$ diagnostic using the combination of CCH and SNe Ia data. The novel method avoids the issue of the dependence on cosmological parameters such as the value of the Hubble constant. There is no evidence of deviation from the flat ΛCDM model, nor is there any indication of dynamical dark energy found in the observational data. Since we employ a non-parametric reconstruction method, all the conclusions drawn in this paper remain robust and agnostic to any cosmological model and gravitational theory.