Astrophysics · arXiv:0708.3673 v2 · submitted 28 Aug 2007
Exploiting scale dependence in cosmological averaging
The paper says
“We also demonstrate that the running smoothing scale R(z) can mimic acceleration, suggesting it could be at least as important as the backreaction in explaining dark energy as an inhomogeneity induced illusion.”
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The paper
Abstract
We study the role of scale dependence in the Buchert averaging method, using the flat Lemaitre-Tolman-Bondi model as a testing ground. Within this model, a single averaging scale gives too coarse predictions, but by replacing it with the distance of the objects R(z) for each redshift z, we find an O(1%) precision at z<2 in the averaged luminosity and angular diameter distances compared to their exact expressions. At low redshifts, we show the improvement for generic inhomogeneity profiles, and our numerical computations further verify it up to redshifts z 2. At higher redshifts, the method breaks down due to its inability to capture the time evolution of the inhomogeneities. We also demonstrate that the running smoothing scale R(z) can mimic acceleration, suggesting it could be at least as important as the backreaction in explaining dark energy as an inhomogeneity induced illusion.
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abstract compiled · 2026-09-23 · no language-model review
How the main claim is stated: hedged possibility 0.90
What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.96 · human participants 0.01 · controlled comparison 0.44 · randomized assignment 0.01 · states quantitative result 0.98 · compares with prior results 0.81 · 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 |
|---|---|---|---|---|
| We study the role of scale dependence in the Buchert averaging method, using the flat Lemaitre-Tolman-Bondi model as a testing ground. | contribution 0.87 | 0.84 | 0.03 | asserted 0.71 |
| Within this model, a single averaging scale gives too coarse predictions, but by replacing it with the distance of the objects R(z) for each redshift z, we find an O(1%) precision at z<2 in the averaged luminosity and angular diameter distances compared to their exact expressions. | result 0.97 | 0.95 | 0.38 | asserted 1.00 |
| At low redshifts, we show the improvement for generic inhomogeneity profiles, and our numerical computations further verify it up to redshifts z~2. | result 0.93 | 0.95 | 0.10 | asserted 1.00 |
| At higher redshifts, the method breaks down due to its inability to capture the time evolution of the inhomogeneities. | limitation 0.98 | 0.76 | 0.09 | asserted 1.00 |
| We also demonstrate that the running smoothing scale R(z) can mimic acceleration, suggesting it could be at least as important as the backreaction in explaining dark energy as an inhomogeneity induced illusion. | interpretation 0.86 | 0.89 | 0.50 | hedged possibility 0.90 |
What kind of paper the classifier reports this is: method or tool 0.47 · evidence from simulation or computation 0.98
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-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 4,384 input tokens, $0.0002 reported.
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Cited by 2 Pith papers
Reviewed papers on Pith that cite this one. The full citation record
- Evaluating backreaction with the peak model of structure formation astro-ph · Jan 2008
- Dark Energy from structure: a status report gr-qc · Jul 2007
How the literature uses it
7 arXiv papers cite this in 10 sentences
Papers citing it · 7 sentences without a confident label
Cites it as support 1 paper
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Even approximations of this kind have proven to be accurate in calculating the distance-redshift relations [ref] .
Dark energy as a mirage · The generalized Dyer-Roeder method · 0.98
Cites it as background 2 papers
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In the years since, this “backreaction” and the impact of inhomogeneities on observables has been relatively well studied in a variety of models and remains an active field [ref] ; see also [ref] for a recent status report.
Cosmological Backreaction from Perturbations · Introduction · 0.94
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One school of thought attempts to explain it as the influence, sometimes called backreaction, of averaging inhomogeneities on the average expansion of the universe [ref] .
Supernovae data and perturbative deviation from homogeneity · Introduction · 0.92
What it cites · 43 sentences without a confident label
Uses the method or tool of 2 papers
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One of the most popular methods in cosmology is the Buchert averaging [ref] , which is also the one considered in this work.
Dark Energy from structure: a status report · Introduction · 0.92
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One of the most popular methods in cosmology is the Buchert averaging [ref] , which is also the one considered in this work.
On average properties of inhomogeneous fluids in general relativity I: dust cosmologies · Introduction · 0.92
Uses data or values from 2 papers
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In this section, we use the inhomogeneity profile found in Sect.3.2 of Ref. [ref] , that gives a good fit to the Riess et. al. gold sample of 157 supernovae [ref] .
Type Ia Supernova Discoveries at z>1 From the Hubble Space Telescope: Evidence for Past Deceleration and Constraints on Dark Energy Evolution · Acceleration without backreaction · 0.83
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In this section, we use the inhomogeneity profile found in Sect.3.2 of Ref. [ref] , that gives a good fit to the Riess et. al. gold sample of 157 supernovae [ref] .
The effect of inhomogeneous expansion on the supernova observations · Acceleration without backreaction · 0.83
Cites as support 1 paper
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Anyhow, as demonstrated in Ref. [ref] , a globally expanding dust universe can have average acceleration as well.
The Possibility of Cosmic Acceleration via Spatial Averaging in Lemaitre-Tolman-Bondi Models · Observations in the averaged LTB model · 0.98
Cites as background 9 papers
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A commonly presented conjecture in cosmological averaging is that the backreaction of inhomogeneities causes the acceleration of the average expansion and could thus account for the observations [ref] .
Accelerated expansion from structure formation · Introduction · 0.97
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A commonly presented conjecture in cosmological averaging is that the backreaction of inhomogeneities causes the acceleration of the average expansion and could thus account for the observations [ref] .
Dark Energy from structure: a status report · Introduction · 0.97
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A commonly presented conjecture in cosmological averaging is that the backreaction of inhomogeneities causes the acceleration of the average expansion and could thus account for the observations [ref] .
The Possibility of Cosmic Acceleration via Spatial Averaging in Lemaitre-Tolman-Bondi Models · Introduction · 0.97
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