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Cosmology and Nongalactic Astrophysics · arXiv:2603.23247 v2 · submitted 24 Mar 2026

Padé semi-cosmographic reconstruction of residual dark energy in decaying dark matter cosmology: DESI DR2 BAO constraints and mock 21 cm forecasts

Mohit Yadav, Pankaj Chavan, Tapomoy Guha Sarkar

The paper says

“The forecast serves as proof of concept to demonstrate a possible improvement in model constraints when measurements of the 21\,cm power spectrum complement the BAO background observables.”

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The paper

Abstract

Pure cosmographic reconstructions provide a model-agnostic approach towards constraining cosmic evolution.We develop a hybrid phenomenological semi-cosmographic framework that adopts a Padé-rational fraction parametrization of the luminosity distance, and incorporates a phenomenologically motivated two-body decaying dark matter (DDM) sector. In this framework, the effective residual dark-energy equation of state is obtained by subtracting the contributions of DDM, baryons, and radiation from the Padé approximation to the expansion history under the assumptions of flat FLRW cosmology and the standard Friedmann equations. Cosmological observables computed from these semi-cosmographic quantities are fitted to the data to reconstruct cosmological evolution. We present two separate analyses. First, we perform a data fit to the current DESI DR2 BAO measurements. Second, we report a forecast based on an optimistic mock 21\,cm intensity-mapping power spectrum at z ≃ 1.75 for a SKA1-MID-like instrument, used jointly with the DESI DR2 BAO data. The forecast serves as proof of concept to demonstrate a possible improvement in model constraints when measurements of the 21\,cm power spectrum complement the BAO background observables. Posterior constraints on the Padé and DDM parameters are obtained using Markov Chain Monte Carlo (MCMC) analysis, and we present the corresponding equations of state of the massive daughter and the effective reconstructed dark energy.

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abstract compiled · 2026-09-23 · no language-model review

How the main claim is stated: hedged possibility 0.66

What the abstract itself states, as probabilities: claims first 0.05 · states limitation 0.40 · human participants 0.01 · controlled comparison 0.08 · randomized assignment 0.01 · states quantitative result 0.10 · compares with prior results 0.14 · mentions code or data availability 0.02

The abstract, sentence by sentence

This table labels the abstract only (arXiv listing abstract v2). The number is the probability the classifier gave the label.

SentenceRoleThe authors' own workStates the main conclusionStrength
Pure cosmographic reconstructions provide a model-agnostic approach towards constraining cosmic evolution.We develop a hybrid phenomenological semi-cosmographic framework that adopts a Pad\'e-rational fraction parametrization of the luminosity distance, and incorporates a phenomenologically motivated two-body decaying dark matter (DDM) sector. contribution 0.81 0.79 0.05 asserted 1.00
In this framework, the effective residual dark-energy equation of state is obtained by subtracting the contributions of DDM, baryons, and radiation from the Pad\'e approximation to the expansion history under the assumptions of flat FLRW cosmology and the standard Friedmann equations. method 0.99 0.72 0.05 asserted 1.00
Cosmological observables computed from these semi-cosmographic quantities are fitted to the data to reconstruct cosmological evolution. method 0.98 0.65 0.05 asserted 0.98
We present two separate analyses. contribution 0.66 0.82 0.02 asserted 0.87
First, we perform a data fit to the current DESI DR2 BAO measurements. contribution 0.50 0.94 0.03 asserted 0.98
Second, we report a forecast based on an optimistic mock 21\,cm intensity-mapping power spectrum at $z\simeq 1.75$ for a SKA1-MID-like instrument, used jointly with the DESI DR2 BAO data. contribution 0.56 0.89 0.07 asserted 0.96
The forecast serves as proof of concept to demonstrate a possible improvement in model constraints when measurements of the 21\,cm power spectrum complement the BAO background observables. interpretation 0.83 0.69 0.18 hedged possibility 0.66
Posterior constraints on the Pad\'e and DDM parameters are obtained using Markov Chain Monte Carlo (MCMC) analysis, and we present the corresponding equations of state of the massive daughter and the effective reconstructed dark energy. method 0.63 0.95 0.11 asserted 1.00

What kind of paper the classifier reports this is: method or tool 0.92 · evidence from analysis of existing data 1.00

What was examined, and what was not

Sources read

  • arXiv listing abstract v2

Not examined

  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers

Levels run

  • P abstract

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  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

How the labels were made

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 6,506 input tokens.

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. This record as JSON

Cited by 1 Pith paper

Reviewed papers on Pith that cite this one. The full citation record

  1. When, Why, and How CMB Compression Fails astro-ph.CO · Oct 2026
How the literature uses it

1 arXiv paper cite this in 1 sentence

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

What it cites · 55 sentences without a confident label

Builds on 2 papers
Uses the method or tool of 3 papers
  • In linear theory, the redshift-space 21cm power spectrum at redshift $z$ is modelled as [ref] [equation] We have adopted the Alcock–Paczyński (AP) [ref] rescaling between the fiducial and trial cosmologies by defining [equation] where $H^f$ and $D_A^f$ are the Hubble parameter and Angular diameter distance in a fiducial cosmology, and the AP-remapped variables $(k̃,μ̃)$ are given by [equation] The redshift-space distortion parameter $β_T$ is given by [equation] Here $D_+(z)$ denotes the linear growing mode of density perturbations and $b_T(z)$ is the effective HI bias.

    Estimation of Cosmological Parameters from HI Observations of Post-reionization Epoch · The 21-cm Intensity Mapping · 0.98

  • In linear theory, the redshift-space 21cm power spectrum at redshift $z$ is modelled as [ref] [equation] We have adopted the Alcock–Paczyński (AP) [ref] rescaling between the fiducial and trial cosmologies by defining [equation] where $H^f$ and $D_A^f$ are the Hubble parameter and Angular diameter distance in a fiducial cosmology, and the AP-remapped variables $(k̃,μ̃)$ are given by [equation] The redshift-space distortion parameter $β_T$ is given by [equation] Here $D_+(z)$ denotes the linear growing mode of density perturbations and $b_T(z)$ is the effective HI bias.

    The CMBR fluctuations from HI perturbations prior to reionization · The 21-cm Intensity Mapping · 0.98

  • We model instrumental uncertainties with the standard thermal-noise power spectrum for an interferometric array [ref] .

    Cosmological Parameter Estimation Using 21 cm Radiation from the Epoch of Reionization · The 21-cm Intensity Mapping · 0.99

Uses data or values from 1 paper
  • Observations of Lyman-$α$ absorption systems also indicate that the mean neutral fraction remains roughly constant in the post-reionization era, with a fiducial value $x̅_HI≃2.45×10^-2$ that is commonly adopted in large-scale 21 cm forecasts [ref] .

    The SDSS Damped Lya Survey: Data Release 3 · The 21-cm Intensity Mapping · 0.87

Compares with 2 papers
Cites as background 11 papers

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