REVIEW
An analytic model for the spatial clustering of dark matter haloes
Astrophysics · Submitted 19 Dec 1995
Pith's verdict: The Eulerian halo bias formula is the real contribution and it holds up; the 'entirely analytic autocorrelation' line in the abstract is an empirical regularity the authors themselves flag as underived.
T0 · AI review
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Referee report
The paper
The paper claims
Halo clustering can be computed from mass clustering times a single bias factor, and that factor comes from the Press-Schechter formalism plus spherical collapse.
The reading
What carries the argument
The bias function $b(M,z_1) = 1 + (6_1^2-1)/6_1$, with $6_1 = 6_1/7_1$ the peak height of the halo's smoothing scale. Its two additive pieces have distinct origins: the $1$ comes from the spherical contraction (or expansion) of the region between Lagrangian and Eulerian space, and the $(6_1^2-1)/6_1$ term is the peak-background split bias imprinted on the initial Gaussian field, the same combination that appears in earlier high-peak arguments. The machinery that produces it is the conditional Press-Schechter mass fraction $f(7_1,6_1|7_0,6_0)$ of Bond et al., which gives the mean number of $M_1$ haloes inside a sphere of radius $R_0$ and overdensity $6_0$, plus the spherical-collapse relations $R/R_0 = (3/10)(1-6_0)^{-1}$ and the interpolating formula $6_0(6)$ used to invert them. The paper also defines an averaged cross-correlation $7_{hm}$ over spheres of fixed radius and overdensity, which depends only on the mean halo count and so sidesteps the scatter problem that blocks the autocorrelation.
Extended reading notes
Core claim
The central claim is that the bias of dark haloes relative to the mass is computable analytically and is accurate. Halos of mass $M$ identified at redshift $z_1$ are defined, following Press-Schechter, as regions whose linearly extrapolated overdensity exceeds $6_1 = (1+z_1)6_c$; the fraction of the mass in a larger sphere of linear overdensity $6_0$ that sits in such haloes follows from the conditional probability of Bond et al. (1991). Combining that with a spherical-collapse map from Lagrangian $(R_0,6_0)$ to Eulerian $(R,6)$ gives a mean halo overdensity $6_h = b(M,z_1)6$ with $b = 1 + (6_1^2-1)/6_1$, where $6_1 = 6_1/7_1$ is the peak height. Halos with $6_1=1$, i.e. mass $M_*$, are predicted unbiased; more massive haloes are positively biased and rarer, and low-mass haloes are mildly antibiased. The authors verify this bias function, the Lagrangian cross-correlation, and the Eulerian halo–mass cross-correlation against P$^3$M simulations with $N=10^6$ particles and several power-law spectra, finding agreement well into the nonlinear regime. They are explicit that the average autocorrelation cannot be obtained this way, because halo exclusion makes count variances substantially sub-Poisson; instead they measure the standard two-point halo autocorrelation and find it proportional to the mass autocorrelation with the large-scale bias factor squared, which is what licenses an entirely analytic estimate of halo clustering.
Load-bearing premise
The claim that halo clustering can be estimated entirely analytically rests on the empirical finding that the ratio of halo to mass autocorrelation equals the large-scale bias factor squared even on nonlinear scales; the paper itself notes that the formalism does not directly produce a model for the halo autocorrelation, so this proportionality is read off the simulations rather than derived.
Editorial extensions
If this is right
- Halo clustering of any mass at any identification redshift can be predicted from the linear power spectrum alone, replacing a simulation with a formula for the bias factor.
- The same bias factor applied to a known nonlinear mass correlation function (e.g. the fitting formula of Jain, Mo & White) yields the halo autocorrelation analytically, including on scales where the mass correlation is well above unity.
- Because bias rises with identification redshift at fixed mass, galaxies formed at the centres of early low-mass haloes can be as strongly clustered today as much more massive haloes formed later, so a luminosity dependence of clustering is not a required feature of hierarchical models.
- Expanding $6_h(6)$ to second order gives a calculable curvature $B_2$ in the bias relation, which feeds through to a predicted reduction in the skewness of halo counts relative to mass counts, potentially explaining the lower skewness measured for late-type galaxies.
- If the abundance of a class of haloes is known, the peak height $6_1$ can be inferred, the mass correlation function recovered from the observed halo correlation function, and $7_8$ extracted as a function of the assumed density parameter $\Omega_0$ — which is how the method is proposed as a measurement of $\Omega$.
Reading between the lines
- The proportionality $7_{hh} = b^2 7_m$ is the paper's most reusable export and its least derived one: it would be worth checking whether the ratio drifts with halo mass at fixed scale in simulations with larger boxes and better mass resolution than the ones available here.
- If $7_{hh}/7_m$ really is scale-independent down to the exclusion scale, then the shape of the galaxy correlation function carries almost no information about halo occupation — only its amplitude does — which would sharpen the degeneracy between $7_8$ and $\Omega_0$ in exactly the direction the authors want to exploit.
- The sub-Poisson count variance is treated as an obstacle; it could instead be treated as a signal, since the size of the deficit below Poisson measures the volume filling fraction of the excluded haloes and hence constrains their density profile.
- The double-epoch construction — haloes identified at $a_1$, positions followed to $a_2$ — is a template for any abundance-matching scheme in which a galaxy keeps the identity of the halo it formed in even after that halo has merged.
Original abstract
We develop a simple analytic model for the gravitational clustering of dark matter haloes to understand how their spatial distribution is biased relative to that of the mass. The statistical distribution of dark haloes within the initial density field (assumed Gaussian) is determined by an extension of the Press-Schechter formalism. Modifications of this distribution caused by gravitationally induced motions are treated using a spherical collapse approximation. We test this model against results from a variety of N-body simulations, and find that it gives an accurate description of a bias function. This bias function is sufficient to calculate the cross-correlation between dark haloes and mass, and again we find excellent agreement between simulation results and analytic predictions. Because haloes are spatially exclusive, the variance in the count of objects within spheres of fixed radius and overdensity is significantly smaller than the Poisson value. This seriously complicates any analytic calculation of the autocorrelation function of dark halos. Our simulation results show that this autocorrelation function is proportional to that of the mass over a wide range in $R$, even including scales where both functions are significantly greater than unity. The constant of proportionality is very close to that predicted on large scales by the analytic model. This result permits an entirely analytic estimate of the autocorrelation function of dark haloes. We use our model to study how the distribution of galaxies may be biased with respect to that of the mass. In conjunction with other data these techniques should make it possible to measure the amplitude of cosmic mass fluctuations and the density of the Universe.
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
We develop a simple analytic model for the gravitational clustering of dark matter haloes to understand how their spatial distribution is biased relative to that of the mass. The statistical distribution of dark haloes within the initial density field (assumed Gaussian) is determined by an extension of the Press-Schechter formalism. Modifications of this distribution caused by gravitationally induced motions are treated using a spherical collapse approximation. We test this model against results from a variety of N-body simulations, and find that it gives an accurate description of a bias function. This bias function is sufficient to calculate the cross-correlation between dark haloes and mass, and again we find excellent agreement between simulation results and analytic predictions. Because haloes are spatially exclusive, the variance in the count of objects within spheres of fixed radius and overdensity is significantly smaller than the Poisson value. This seriously complicates any analytic calculation of the autocorrelation function of dark halos. Our simulation results show that this autocorrelation function is proportional to that of the mass over a wide range in $R$, even including scales where both functions are significantly greater than unity. The constant of proportionality is very close to that predicted on large scales by the analytic model. This result permits an entirely analytic estimate of the autocorrelation function of dark haloes. We use our model to study how the distribution of galaxies may be biased with respect to that of the mass. In conjunction with other data these techniques should make it possible to measure the amplitude of cosmic mass fluctuations and the density of the Universe.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We develop a simple analytic model for the gravitational clustering of dark matter haloes to understand how their spatial distribution is biased relative to that of the mass. | contribution 0.99 | 0.95 | 0.07 | asserted 0.91 |
| s1 | The statistical distribution of dark haloes within the initial density field (assumed Gaussian) is determined by an extension of the Press-Schechter formalism. | method 0.95 | 0.66 | 0.03 | asserted 1.00 |
| s2 | Modifications of this distribution caused by gravitationally induced motions are treated using a spherical collapse approximation. | method 0.99 | 0.77 | 0.03 | asserted 0.98 |
| s3 | We test this model against results from a variety of N-body simulations, and find that it gives an accurate description of a bias function. | result 0.86 | 0.96 | 0.25 | asserted 1.00 |
| s4 | This bias function is sufficient to calculate the cross-correlation between dark haloes and mass, and again we find excellent agreement between simulation results and analytic predictions. | result 1.00 | 0.96 | 0.15 | asserted 1.00 |
| s5 | Because haloes are spatially exclusive, the variance in the count of objects within spheres of fixed radius and overdensity is significantly smaller than the Poisson value. | result 0.71 | 0.58 | 0.06 | asserted 1.00 |
| s6 | This seriously complicates any analytic calculation of the autocorrelation function of dark halos. | background 0.44 | 0.23 | 0.03 | asserted 0.98 |
| s7 | Our simulation results show that this autocorrelation function is proportional to that of the mass over a wide range in $R$, even including scales where both functions are significantly greater than unity. | result 1.00 | 0.94 | 0.25 | asserted 1.00 |
| s8 | The constant of proportionality is very close to that predicted on large scales by the analytic model. | result 0.98 | 0.88 | 0.13 | asserted 1.00 |
| s9 | This result permits an entirely analytic estimate of the autocorrelation function of dark haloes. | interpretation 0.81 | 0.81 | 0.27 | asserted 0.72 |
| s10 | We use our model to study how the distribution of galaxies may be biased with respect to that of the mass. | contribution 0.75 | 0.90 | 0.06 | hedged possibility 0.77 |
| s11 | In conjunction with other data these techniques should make it possible to measure the amplitude of cosmic mass fluctuations and the density of the Universe. | future work 0.68 | 0.09 | 0.09 | hedged possibility 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
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- R cross-paper relations
Figures
Showing 2 of the paper's 4 figures. See all figures in the PDF ↗ Figures reproduced from arXiv:astro-ph/9512127 by the authors.
References
How later papers used it
243 later papers cite it
17 later papers by other authors are listed below: 1 built on it, 14 used its method or tool, 1 used its data or values and 1 compared its own results with it. 1 more paper by the same authors is listed: 1 used its method or tool.
Builds on it 1 paper
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Generalized this paper's standard formula for the time evolution of linear bias to the case where merging is important.
Gravity and Large-Scale Non-local Bias (2012) · 1.00 · paraphrased: the licence does not allow quoting
Uses its method or tool 15 of 28 papers with this label · 1 by the same authors
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According to the theory of density perturbation, we use the approximation for spherical collapse from the equation 18 in [ref] to the linear matter density $δ_L$.
Spectroscopic Confirmation of two Extremely Massive Protoclusters BOSS1244 and BOSS1542 at $z=2.24$ (2021) · Overdensity and Present-day Masses Estimate · 1.00
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In order to do that we first map each density element at $z_ini$ to a corresponding linear density contrast using the following parametric formulae from [ref] : 1+δ_NL =92 (θ- sin θ)^2(1-cos θ)^3 , δ_L=3 ×6^2/320 (θ-sin θ)^2/3 for $δ_NL > 0$,
Simulating the epoch of Helium Reionization in photon-conserving semi-numerical code SCRIPT (2024) · Subgrid Implementation of thermal history · 1.00
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Took the conditional mass function to be provided by the Extended Press-Schechter formalism of this paper.
Probing power spectrum enhancement at small scales with the SKA (2026) · 0.98 · paraphrased: the licence does not allow quoting
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Converted a real over-density to a linear over-density via this paper.
Lyman-alpha Emitters in Ionized Bubbles: Constraining the Environment and Ionized Fraction (2022) · 0.98 · paraphrased: the licence does not allow quoting
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Used a spherical collapse model from this paper to relate a matter overdensity to a linear matter enhancement.
Probing the existence of a rich galaxy overdensity at z=5.2 (2021) · 0.96 · paraphrased: the licence does not allow quoting
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Used equation 18 of this paper to convert between delta over sigma and the nonlinear density.
Small-scale clumping of dark matter and the mean free path of ionizing photons at $z=6$ (2022) · 0.93 · paraphrased: the licence does not allow quoting
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Used the halo bias of this paper in writing the one-halo and two-halo components of the 21-cm power spectrum.
Prospects for measuring neutrino mass with 21-cm forest (2025) · 0.93 · paraphrased: the licence does not allow quoting
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To model this bias, the peak-background split formalism [ref] is usually adopted to calculate an approximate linear halo bias, particularly in the 2-halo term of Eq. [ref], which describes the influence of the large-scale power spectrum on halo formation.
Accelerating cosmological inference of interacting dark energy with neural emulators (2025) · Halo bias · 0.93
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Used the linear halo bias factor of this paper.
A Designer's Guide to Lunar Far-Side Interferometer Array: Power Spectrum Measurement and Cosmological Constraints from the Dark Ages (2026) · 0.91 · paraphrased: the licence does not allow quoting
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Employed the halo bias of this paper in its two-halo term.
Cosmological free-free emission from dark matter halos in the $\Lambda$CDM model (2022) · 0.90 · paraphrased: the licence does not allow quoting
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Used the halo bias of this paper, according to the Press-Schechter formalism, in its ionization fraction fluctuation model.
Cross-correlation between 21-cm radiation and CMB B modes from the cosmic birefringence in the presence of a light scalar field (2019) · 0.89 · paraphrased: the licence does not allow quoting
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In particular, it predicts the probability that matter in a spherical region of mass, $M_0$, at redshift, $z_0$, and linear overdensity, $δ_0$, is contained within dark matter haloes of mass in the interval $(M_1, M_1 + dM_1)$ at redshift $z_1$: [equation] where, for a virialized structure, $δ_1=δ_c/D(z)$, and $δ_0$ is given by [The accuracy of this formula in underdense regions is examined in Appendix [ref].]: [equation] as an approximate solution of Eqs. (16-17) of [ref] .
The abundance of dark matter haloes down to Earth mass (2023) · Theoretical halo mass functions · 0.81
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According to the spherical collapse model, the halo collapses when the linear density contrast $δ(z,M)$ exceeds the critical value $δ_c$, so the collapse redshift is expressed as [ref]
Anisotropies in Cosmological 21 cm Background by Oscillons/I-balls of Ultra-light Axion-like Particle (2021) · Minihalo Mass Function · 0.88
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Under the peak-background split ansatz including this paper, related the large-scale halo bias to the Sheth-Tormen halo mass function.
The mass-concentration relationship of virialized halos and its impact on cosmological observables (2011) · 0.80 · paraphrased: the licence does not allow quoting
By the same authors
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Followed this paper to define halo bias as the ratio between the halo-matter cross-correlation function and the matter-matter autocorrelation function.
Relating the structure of dark matter halos to their assembly and environment (2020) (same authors) · 0.99 · paraphrased: the licence does not allow quoting
Uses its data or values 1 paper
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Used the fitting function in this paper to convert a density contrast of 0.8 to a linearly extrapolated density contrast of -2.81.
Voids as a Precision Probe of Dark Energy (2010) · 0.88 · paraphrased: the licence does not allow quoting
Compares with it 1 of 10 papers with this label
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Showed the predictions of this paper for comparison.
First results from the IllustrisTNG simulations: matter and galaxy clustering (2017) · 1.00 · paraphrased: the licence does not allow quoting
How the literature uses it
108 arXiv papers cite this in 150 sentences
Papers citing it · 94 sentences without a confident label
Builds on it 1 paper
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Along the way, we generalized the standard formula of the time evolution of linear bias [ref] to the case where merging is important (see Eq. [ref]).
Gravity and Large-Scale Non-local Bias · Conclusions · 1.00
Uses its method or tool 17 papers
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We derive the void bias in PNG using the peak-background split formalism [ref] .
Constraint of Void Bias on Primordial non-Gaussianity · Theory · 0.94
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The collapse fraction can then be calculated with the extended Press-Schechter method [ref] .
Reionization in the Warm Dark Matter Model · Method of Calculation · 1.00
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Following [ref] , an application of the peak-background split approximation enables one to calculate $b(M)$ from a given mass function.
Nonlinear clustering in models with primordial non-Gaussianity: the halo model approach · Halo bias · 0.94
Uses its data or values 1 paper
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In order to estimate the number of voids of a particular size at a particular redshift, we use the Press-Schechter formalism to determine the number density of voids in a redshift bin centered at $z,$ with Eulerian comoving radius between $R_E$ and $R_E + d R_E.$ Simulations indicate that the number density of voids peaks at a density contrast of $δ≈-0.85$ [ref] , we shall consider all the voids to have a density contrast of 0.8, which can be seen to correspond to a linearly extrapolated density contrast of -2.81 using the fitting function in [ref] .
Voids as a Precision Probe of Dark Energy · Estimate of Voids to be found from a survey · 0.88
Compares with it 5 papers
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In particular, we compare against the fitting formulae from: * the predictions of spherical collapse [ref] : [equation] * the fit from [ref] (hereafter SMT01), motivated by the ellipsoidal collapse model and calibrated using simulations: [equation] with $a=0.707,b=0.5,c=0.6$. * the fit in [ref] (hereafter T10, see also Ref. [ref] ), also calibrated against simulations, with a more flexible form: [equation] where the parameters ($A,B,C,a,b,c$) are dependent on the virial overdensity, $Δ$, with respect to the mean density of the Universe, as detailed in Table 2 of T10.
An Improved Fit for Linear Halo Bias at High Redshift · Comparison to existing fits · 1.00
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In other words, references [ref] and [ref] derive an effect on the halo/galaxy bias that, for the local model, can be shown to be equivalent, at large scales, to the one described by Eq. ([ref]), and they actually coincide if one considers as well the high-peak limit $ν/σ_R≫1$ since, in this case [b_h,1-1]δ_c≃b_2σ_R^2≃ν^2=δ_c^2/σ_R^2, once one assumes an expression such as the one derived by [ref] for the galaxy quadratic bias parameter.
Constraining Running Non-Gaussianity · Halo bias and primordial non-Gaussianity · 0.92
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This differs from the more general Press-Schechter expression, $b_0,L=(ν^2-1)/δ_c$ [ref] , only by the term $-1/δ_c$, which is negligible for the massive halos considered here.
Tracing Primordial Gravitational Waves via non-Gaussian Signatures of Halo Bias · Halo Bias Correction · 0.98
Cites it as background 30 papers
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The theoretical framework underlying such clustering analysis, based on the Press-Schechter theory and cosmological $N$-body simulations, have shown that galaxies are biased tracers of the dark matter distribution, with their properties determined by the halos in which they form [ref] .
ODIN: Clustering Properties of Ly$\alpha$ Blobs at $z$ $\sim$ 2.4 and 3.1 · Introduction · 0.93
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In this perspective, the two main approaches are the excursion-set formalism [ref] and the theory of Lagrangian density peaks [ref] , which have been widely explored to provide theoretical models for the dark matter (DM) halo mass function (HMF), bias, halo correlation functions [ref] , and cosmic void size functions (VSF) [ref] , hereafter , [ref] .
The universal multiplicity function: counting halos and voids · Introduction · 0.94
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The excursion set formalism predicts the abundance of objects crossing a critical density threshold as a consequence of hierarchical structure formation in an initially linear Gaussian field [ref] .
VERSUS: An excursion-set-inspired void-finder for the Stage-IV era · Voids in the matter field · 0.95
Discussion
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