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
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“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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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.
| Sentence | Role | The authors' own work | States the main conclusion | Strength |
|---|---|---|---|---|
| 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
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Not examined
- full text
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- references and citing sentences
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- P abstract
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- C citations
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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
- 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
What it cites · 55 sentences without a confident label
Builds on 2 papers
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Building on this, we develop a semi-cosmographic framework [ref] that incorporates the two-body decaying dark matter (DDM) scenario.
A semi-cosmographic approach to study cosmological evolution in phase space · Introduction · 0.84
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Building on this, we develop a semi-cosmographic framework [ref] that incorporates the two-body decaying dark matter (DDM) scenario.
2506.14275 · Introduction · 0.84
Uses the method or tool of 3 papers
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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
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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
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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
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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
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Among the Abellán et al. results [ref] , the closest agreement is found with their Planck full/lite and \(S_8\)-motivated solutions, for which both decay parameters remain within about \(1σ\).
Linear cosmological constraints on 2-body decaying dark matter scenarios and the $S_8$ tension · Results and discussion · 1.00
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When we compare our projections with Fuß & Garny [ref] , we find that the offset is higher when the comparison is made with their data BestFit1 (Planck+BAO+FS).
Decaying Dark Matter and Lyman-$\alpha$ forest constraints · Results and discussion · 1.00
Cites as background 11 papers
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This includes not only a diverse class of dark energy scenarios [ref] but also alternatives to cold dark matter, such as warm dark matter [ref] , decaying dark matter [ref] , and other non-standard dark sector frameworks [ref] .
Cosmological constraints to dark matter with two- and many-body decays · Introduction · 0.97
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In the post-reionisation regime ($z∼1$–$3$), the 21cm signal traces the large-scale distribution of dark matter [ref] .
How accurately can 21 cm tomography constrain cosmology? · The 21-cm Intensity Mapping · 0.86
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In the post-reionisation regime ($z∼1$–$3$), the 21cm signal traces the large-scale distribution of dark matter [ref] .
The 21cm Power Spectrum After Reionization · The 21-cm Intensity Mapping · 0.86
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