REVIEW
Nonlinear evolution of cosmological power spectra
Astrophysics · Submitted 8 Mar 1996 · 1 reference
Pith's verdict: The spectrum-dependent HKLM fit is the real deliverable and it holds up; the one untested claim is that the factor-2 index shift in Eq. (22) doesn't matter, which is asserted exactly where the (1+n/3) exponents bite hardest.
T0 · AI review
Why Pith says this
Highlight any text to comment on it.
Referee report
The paper
The paper claims
A single closed-form recipe, with one slope-dependent correction and one growth factor, converts a linear density power spectrum into its nonlinear counterpart across open, flat, and cosmological-constant universes.
The reading
What carries the argument
The carrying object is the generalized Hamilton–Kumar–Lu–Matthews mapping: nonlinear power at wavenumber $k_{NL}$ is read off linear power at a shifted, smaller wavenumber $k_L=[1+2_{NL}(k_{NL})]^{-1/3}k_{NL}$, and the two are related by a fitting function with a linear-growth term, a quasilinear power law, and a virialized $x^{3/2}$ asymptote, softened by a parameter $1$. The new ingredient is that the quasilinear coefficients $A$, $B$, $1$, $1$, $V$ are not constants but scale with $(1+n/3)$ raised to fitted powers, with $n$ taken from the tangent slope of the linear spectrum at $k_L/2$ — a factor-of-two shift the authors adopt because using the unshifted slope left the CDM results systematically below the power-law fits. The $g^3$ denominator on the virialized term is the only place the cosmological model appears.
Extended reading notes
Core claim
The central claim is that the nonlinear-to-linear mapping $f_{NL}$ is not universal, but is well described by a five-parameter family whose coefficients are simple power laws in $(1+n/3)$, where $n$ is the tangent spectral index of the linear spectrum evaluated at half the linear wavenumber: $n_L(k_L) 1 d1$ at $k=k_L/2$. Fitted globally to power-law and CDM simulations, this gives about 14 per cent rms in $f_{NL}(x)$ over $0.1<2.5$ in $1$, and about 7 per cent scatter in the direction that governs reconstructing a spectrum from nonlinear data. The cosmological dependence — open versus flat-with-$1$, and the value of $1$ — is carried entirely by the $g^3(1)$ factor that sets the amplitude of the stable-clustering asymptote $f_{NL}(x)1$. The qualitative result is that nonlinear effects boost small-scale power more strongly for more negative spectral indices and for lower densities, but that a cosmological constant softens the boost relative to an open universe of the same $1$.
Load-bearing premise
The load-bearing premise is that the tangent spectral index should be read at half the linear wavenumber being predicted; the paper asserts that the exact size of this shift is not critical, but never shows a sensitivity scan, and the whole cold-dark-matter branch of the fit depends on it.
Editorial extensions
If this is right
- Linearizing an observed nonlinear clustering spectrum to recover the underlying linear spectrum becomes a numerical iteration using a single formula, rather than a separate simulation campaign for each cosmology.
- The earlier conclusion that small-scale clustering data imply a linear spectral index near $-1.5$ survives: in the regime those data actually covered ($2_{NL}1$), the deduced linear power shifts by at most about 20 per cent.
- Because the quasilinear slope $f_{NL}1$ with $1$–$4.5$ is steeper than the stable-clustering answer, the predicted growth of nonlinear power with time is faster than linear growth, which bears on the weak angular clustering of faint galaxies.
- An observed nonlinear slope of about 1.8 would imply a linear index near $-2.2$ through the paper's relation between $1$ and $n$, rather than the $n=0$ that stable clustering alone would suggest.
- The method is proposed as general for any convex hierarchical spectrum, with hot or warm dark matter cutoffs explicitly excluded as needing separate treatment.
Reading between the lines
- The finding that cosmology enters only through $g(1)$ is close to a statement that quasilinear evolution is Zeldovich-like: if final positions are initial displacements scaled by a universal factor, then matching displacement amplitude should erase the cosmology. That suggests the residual cosmological dependence could be computed analytically from the known Zeldovich power spectrum rather than fi
- Reading the tangent index at a smaller scale than the one being predicted makes the mapping implicitly non-local in $k$. A spectrum with a sharp feature — a baryon oscillation, a mild cutoff — would then be mispredicted in a way a smooth CDM spectrum conceals, which is a testable weakness rather than a defect of the present fit.
- The steep quasilinear slope offers a growth-rate probe: measuring the nonlinear slope at a fixed nonlinear amplitude across two epochs constrains the growth factor more sharply than linear growth alone, and this is checkable against existing simulations at earlier output times.
- The calibration used boxes of $100\,h^{-1}$ Mpc with final $1$ in the range 0.4–1, so applying the formula to very high normalizations or to much smaller boxes is an extrapolation the paper does not test.
Original abstract
Hamilton et al. have suggested an invaluable scaling formula which describes how the power spectra of density fluctuations evolve into the nonlinear regime of hierarchical clustering. This paper presents an extension of their method to low-density universes and universes with nonzero cosmological constant. We pay particular attention to models with large negative spectral indices, and give a spectrum-dependent fitting formula which is of significantly improved accuracy by comparison with an earlier version of this work. The tendency of nonlinear effects to increase power on small scales is stronger for spectra with more negative spectral indices, and for lower densities. However, for low-density models with a cosmological constant, the nonlinear effects are less strong than for an open universe of the same $\Omega$.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
Hamilton et al. have suggested an invaluable scaling formula which describes how the power spectra of density fluctuations evolve into the nonlinear regime of hierarchical clustering. This paper presents an extension of their method to low-density universes and universes with nonzero cosmological constant. We pay particular attention to models with large negative spectral indices, and give a spectrum-dependent fitting formula which is of significantly improved accuracy by comparison with an earlier version of this work. The tendency of nonlinear effects to increase power on small scales is stronger for spectra with more negative spectral indices, and for lower densities. However, for low-density models with a cosmological constant, the nonlinear effects are less strong than for an open universe of the same $\Omega$.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | Hamilton et al. have suggested an invaluable scaling formula which describes how the power spectra of density fluctuations evolve into the nonlinear regime of hierarchical clustering. | background 1.00 | 0.03 | 0.03 | asserted 0.67 |
| s1 | This paper presents an extension of their method to low-density universes and universes with nonzero cosmological constant. | contribution 1.00 | 0.86 | 0.07 | asserted 0.98 |
| s2 | We pay particular attention to models with large negative spectral indices, and give a spectrum-dependent fitting formula which is of significantly improved accuracy by comparison with an earlier version of this work. | contribution 0.95 | 0.94 | 0.15 | asserted 1.00 |
| s3 | The tendency of nonlinear effects to increase power on small scales is stronger for spectra with more negative spectral indices, and for lower densities. | result 0.99 | 0.83 | 0.35 | asserted 1.00 |
| s4 | However, for low-density models with a cosmological constant, the nonlinear effects are less strong than for an open universe of the same $\Omega$. | result 1.00 | 0.84 | 0.14 | asserted 1.00 |
What was examined, and what was not
- arXiv listing abstract v1
- full text
- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
- S sections
- T body sentences
- C citations
- R cross-paper relations
Figures
Showing 3 of the paper's 5 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:astro-ph/9603031 by the authors.
References
How later papers used it
46 later papers cite it
4 later papers by other authors are listed below: 3 used its method or tool and 1 compared its own results with it.
Uses its method or tool 3 of 7 papers with this label
-
Used the method of this paper to determine the non-linear matter power spectrum because of its simplicity and speed.
Building a Predictive Model of Galaxy Formation - I: Phenomenological Model Constrained to the $z=0$ Stellar Mass Function (2014) · 1.00 · paraphrased: the licence does not allow quoting
-
Used the fitting function from this paper to get the nonlinear density power spectrum from the linear power spectrum calculated with its modified CMBfast code.
Large Scale Structure as a Probe of Gravitational Slip (2008) · 0.99 · paraphrased: the licence does not allow quoting
-
Used the cosmology- and simulation-dependent fitting formula of this paper to make its plot of expansion coefficients versus nonlinear wavenumber.
Fitting functions on the cheap: the relative nonlinear matter power spectrum (2019) · 0.99 · paraphrased: the licence does not allow quoting
Compares with it 1 of 3 papers with this label
-
Compared its own MA99 and HALOFIT with this paper's formula to identify the origin of a discrepancy, using a smooth linear power spectrum without baryonic oscillations.
Cosmic Microwave Background Bispectrum from the Lensing--Rees-Sciama Correlation Reexamined: Effects of Non-linear Matter Clustering (2012) · 0.91 · paraphrased: the licence does not allow quoting
How the literature uses it
37 arXiv papers cite this in 47 sentences
Papers citing it · 28 sentences without a confident label
Contests it 2 papers
-
[ref] ) are uncapable to reach the required level of accuracy [ref] .
Flowing with Time: a New Approach to Nonlinear Cosmological Perturbations · Introduction · contest 0.87
-
Although there are well-known methods [ref] to analytically transform the linear power spectrum into the non-linear power spectrum, we find that they do not yield reasonable results in this application.
Primordial Black Hole Reformation in the Early Universe · Power Spectrum · contest 0.77
Uses its method or tool 7 papers
-
Here we take into account the effect of uncorrelated large scale structure projected along the line of sight on the error covariance matrix $C^lss_ij$ as $C=C^stat+C^lss$, where $C^lss$ is given as [ref] [equation] Here $C^κκ(l)$ is the weak-lensing power spectrum as a function of angular multipole $l$ evaluated for a given source population and a cosmology, and $Ĵ_0(lθ_i)$ is the Bessel function of the first kind and order zero averaged over the $i$th annulus between $θ_i,1$ and $θ_i,2 (>θ_i,1)$, given as [equation] We will assume the concordance $Λ$CDM cosmological model of [ref] and use the fitting formula of [ref] to compute the nonlinear mass power spectrum that enters in equation ([ref]).
A Precise Cluster Mass Profile Averaged from the Highest-Quality Lensing Data · Combining Weak and Strong Lensing · 0.98
-
There are two approaches to compute the $P_δ^NL(k,z)$ that have been extensively tested and used in the literature: the more recent Halofit [ref] model, which is included in CAMB [ref] and the Peacock and Dodds (PD) [ref] method (generalized for dark energy cosmologies by [ref] ).
Non-Gaussianity and the CMB Bispectrum: confusion between Primordial and Lensing-Rees Sciama contribution? · Bispectrum calculation and expected signal-to-noise · 0.97
-
We demonstrate that by integrating the mapping approach recommended in [ref] , it is feasible to derive a concise expression for the nonlinear power spectrum based on its linear counterpart and several critical cosmological parameters.
$\texttt{SPINE}$: Symbolic Models to Predict the Evolution of the $\Lambda$CDM Nonlinear Power Spectrum · Introduction · 0.92
Compares with it 3 papers
-
Fig. [ref] shows the sum of the linear and non-linear contributions compared to the non-linear power spectrum derived by [ref] from numerical simulations.
Non-equilibrium statistical field theory for classical particles: Non-linear structure evolution with first-order interaction · Results · 0.99
-
In order to identify the origin of this discrepancy, we have also compared MA99 and HALOFIT with the formula by Peacock and Dodds (1996; PD96) [ref] (not shown in Figure 1; in order to use their formula, it is necessary to use the smooth linear power spectrum without baryonic oscillations; thus, we used the smooth power spectrum given in [ref] ).
Cosmic Microwave Background Bispectrum from the Lensing--Rees-Sciama Correlation Reexamined: Effects of Non-linear Matter Clustering · Comparing $P(k,z)$ · 0.91
-
In $δ$, the migration of power is qualitatively as in [ref] and [ref] : power moves from large to small scales.
Ringing the initial Universe: the response of overdensity and transformed-density power spectra to initial spikes · Results · 0.94
Cites it as background 6 papers
-
A different idea to address the issue is expressing the non-linear power spectrum (or correlation function) as a function of its linear counterpart, evaluated at a different scale [ref] .
An Optimally Weighted Estimator of the Linear Power Spectrum Disentangling the Growth of Density Perturbations Across Galaxy Surveys · Growth of Perturbations · 0.90
-
Cosmological inference has traditionally focused on analyzing 2-point correlations, typically the power spectrum $P(k)$ [ref] , on large, weakly non-linear scales, where it is amenable to analytical modeling using perturbation theory (PT) [ref] .
PatchNet: A hierarchical approach for neural field-level inference from Quijote Simulations · Introduction · 0.97
-
For flat cosmological models in particular, fitting formulae or emulators based on the predictions of $N$-body simulations have been developed [ref] .
Flat to nonflat: Calculating nonlinear power spectra of biased tracers for nonflat $\Lambda$CDM model · Introduction · 0.92
Discussion
Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.