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Halo assembly bias and the tidal anisotropy of the local halo environment

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TLDR
In this article, the role of the local tidal environment in determining the assembly bias of dark matter haloes was studied, using correlations between the large-scale and small-scale environments of simulated haloes at z = 0 with masses between 10^11.6 and 10^14.9.
Abstract
We study the role of the local tidal environment in determining the assembly bias of dark matter haloes. Previous results suggest that the anisotropy of a halo's environment (i.e. whether it lies in a filament or in a more isotropic region) can play a significant role in determining the eventual mass and age of the halo. We statistically isolate this effect, using correlations between the large-scale and small-scale environments of simulated haloes at z = 0 with masses between 10^11.6 ≲ (m/h^−1 M_⊙) ≲ 10^14.9. We probe the large-scale environment, using a novel halo-by-halo estimator of linear bias. For the small-scale environment, we identify a variable α_R that captures the tidal anisotropy in a region of radius R = 4R_200b around the halo and correlates strongly with halo bias at fixed mass. Segregating haloes by α_R reveals two distinct populations. Haloes in highly isotropic local environments (α_R ≲ 0.2) behave as expected from the simplest, spherically averaged analytical models of structure formation, showing a negative correlation between their concentration and large-scale bias at all masses. In contrast, haloes in anisotropic, filament-like environments (α_R ≳ 0.5) tend to show a positive correlation between bias and concentration at any mass. Our multiscale analysis cleanly demonstrates how the overall assembly bias trend across halo mass emerges as an average over these different halo populations, and provides valuable insights towards building analytical models that correctly incorporate assembly bias. We also discuss potential implications for the nature and detectability of galaxy assembly bias.

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Citations
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Journal ArticleDOI

How does the cosmic web impact assembly bias

TL;DR: In this article, the mass, accretion rate, and formation time of dark matter halos near protofilaments are analytically predicted using a conditional version of the excursion set approach in its so-called upcrossing approximation.
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Cosmic web anisotropy is the primary indicator of halo assembly bias

TL;DR: In this paper, it was shown that the internal properties of dark matter haloes correlate with the large-scale halo clustering strength at fixed halo mass, and are also strongly affected by the local, non-linear cosmic web.
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The three causes of low-mass assembly bias

TL;DR: In this paper, the authors present a detailed analysis of the physical processes that cause halo assembly bias and show that splashback subhaloes are responsible for two thirds of the assembly bias signal, but do not account for the entire effect.
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Efficient computation of galaxy bias with neutrinos and other relics

TL;DR: ReliefFast as discussed by the authors finds that the bias induced by light relics partially compensates the suppression of power, and should be accounted for in any search for relics with galaxy data, at little computational cost.
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The multidimensional dependence of halo bias in the eye of a machine: a tale of halo structure, assembly, and environment

TL;DR: In this article, the bias is a multivariate function of halo properties that falls into three regimes: early-forming, low-mass and late-forming haloes, and the bias depends sensitively on the recent mass accretion history.
References
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Journal ArticleDOI

Gravity and Large-Scale Nonlocal Bias

TL;DR: In this paper, it was shown that the bias becomes nonlocal and nonlinear at large scales, due to the breaking of the Galilean invariance of the bias relation, a dipole field being the signature at second order.
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On the environmental dependence of halo formation

TL;DR: In this paper, the authors present a novel test of this assumption which uses thestatistics of weighted or "marked" correlations, which prove to be particularly well-suited to detecting and quantifying weak correlations with environment.
Journal ArticleDOI

Evidence for quadratic tidal tensor bias from the halo bispectrum

TL;DR: In this article, it was shown that there is a non-vanishing coefficient for the tidal tensor bias in the initial conditions of the Eulerian bias model in the Lagrangian space.
Journal ArticleDOI

Bayesian physical reconstruction of initial conditions from large-scale structure surveys

TL;DR: In this article, a fully probabilistic, physical model of the non-linearly evolved density field, as probed by realistic galaxy surveys, is presented, which is valid in the linear and mildly non-linear regimes and uses second order Lagrangian perturbation theory to connect the initial conditions with the final density field.
Journal ArticleDOI

Halo Assembly Bias in Hierarchical Structure Formation

TL;DR: In this article, the authors investigate the origin of halo assembly bias, the dependence of clustering on assembly history, and the extent of assembly bias found in N-body simulations of rare halos.
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