Optimal void finders in weak lensing maps

Davies, Christopher T.; Paillas, Enrique; Cautun, Marius; Li, Baojiu

doi:10.1093/mnras/staa3262

Cited by 14 publications

(20 citation statements)

References 81 publications

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“…The error bars on the QCDM tangential shear profiles from the two algorithms are also similar in size, which suggests that both algorithms may offer similar constraining power, consistent with ref. [84] which finds roughly similar tangential shear signal-to-noise ratios between the two algorithms. The relative differences between the cvG models and their QCDM counterpart peak at the minimum of the profile, with a 10% difference for cvG with β 3 = 10 −6 , roughly the same as the relative difference found for tunnels in the same size range (which is the tunnel category for ν > 1).…”

Section: Watershedmentioning

confidence: 80%

“…In the final section we focus on the study of weak-lensing statistics. We start by analysing the lensing convergence field (κ) which can be used together with the matter power spectrum and bispectrum to circumvent the dependence on tracer bias (e.g., [82]), and end with an analysis of the abundances and tangential shear profiles of voids identified from WL maps [83,84].…”

Section: Weak Lensing Statisticsmentioning

confidence: 99%

“…In practice, the smoothing scale needs to be checked for different statistics from the lensing map, and for different noise levels (e.g., different surveys have different source galaxy number densities, which can lead to different levels of noise impact). In this paper, because the statistics we analyse and the survey specifications are the same as those of [84], we have applied the same filter as there. Note that in this plot we are showing statistics measured from an ideal lensing map without smoothing and a noisy map after smoothing, the former is just for theoretical interest.…”

Section: Weak Lensing Convergence and Peak Statisticsmentioning

confidence: 99%

“…Recently, it has been argued that void identification based on WL convergence maps can lead to the better constraints of certain modified gravity theories [97]. This has motivated us to use voids from the two dimensional convergence field through the tunnel and watershed algorithms as the resulting void catalogues have been shown to be amongst the most promising [84].…”

Section: Cosmic Voidsmentioning

confidence: 99%

“…All pixels connected to the same minimum in this way form one watershed basin, with ridges of local high κ values along the basin boundary. We could have used the WL peak catalogues to identify watershed voids, as is done for tunnels, but the results are generally very noisy [84]. To mitigate the impact of GSN, [84] found that the height of the basin boundary should have a minimum κ value of h boundary = σ GSN /2.…”

Section: Watershedmentioning

confidence: 99%

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Proca-stinated cosmology. Part II. Matter, halo, and lensing statistics in the vector Galileon

Becker¹,

Eggemeier²,

Davies³

et al. 2021

J. Cosmol. Astropart. Phys.

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The generalised Proca (GP) theory is a modified gravity model in which the acceleration of the cosmic expansion rate can be explained by self interactions of a cosmological vector field. In this paper we study a particular sub-class of the GP theory, with up to cubic order Lagrangian, known as the cubic vector Galileon (cvG) model. This model is similar to the cubic scalar Galileon (csG) in many aspects, including a fifth force and the Vainshtein screening mechanism, but with the additional flexibility that the strength of the fifth force depends on an extra parameter -interpolating between zero and the full strength of the csG model -while the background expansion history is independent of this parameter. It offers an interesting alternative to ΛCDM in explaining the cosmic acceleration, as well as a solution to the tension between early-and late-time measurements of the Hubble constant H 0 . To identify the best ways to test this model, in this paper we conduct a comprehensive study of the phenomenology of this model in the nonlinear regime of large-scale structure formation, using a suite of N-body simulations run with the modified gravity code ECOSMOG. By inspecting thirteen statistics of the dark matter field, dark matter haloes and weak lensing maps, we find that the fifth force in this model can have particularly significant effects on the large-scale velocity field and lensing potential at late times, which suggest that redshift-space distortions and weak lensing can place strong constraints on it.

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Section: Watershedmentioning

confidence: 80%

Section: Weak Lensing Statisticsmentioning

confidence: 99%

Section: Weak Lensing Convergence and Peak Statisticsmentioning

confidence: 99%

Section: Cosmic Voidsmentioning

confidence: 99%

Section: Watershedmentioning

confidence: 99%

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Proca-stinated cosmology. Part II. Matter, halo, and lensing statistics in the vector Galileon

Becker¹,

Eggemeier²,

Davies³

et al. 2021

J. Cosmol. Astropart. Phys.

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Secondary halo bias through cosmic time

Balaguera-Antolínez,

Montero-Dorta,

Favole

2024

A&A

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The spatial distribution of dark matter halos carries cosmological and astrophysical information. Cosmological information can be considered to be contained in the connection between halo main properties and the large-scale halo bias, while the astrophysical information would be encoded in the scaling relations between halo properties. The combination of these two contributions leads to the effect of secondary halo bias. Our goal is to measure the signal of secondary halo bias as a function of a variety of intrinsic and environmental halo properties and to characterize its statistical significance as a function of cosmological redshift. Using fixed and paired $N$-body simulations of dark-matter halos -- the UNIT simulation -- with masses above $ M_ odot h^ $ identified over a wide range of cosmological redshifts ($0<z<5$), we explored the behavior of the scaling relations among different halo properties. We included novel environmental properties based on the halo distribution as well as the underlying dark-matter field. We implemented an object-by-object estimator of large-scale effective bias and tested its validity against standard approaches. With a bias assigned to each tracer, we performed a statistical analysis aimed at characterizing the distribution of the bias and the signal of the secondary halo bias. We show how the halo scaling relations linking direct probes of the halo potential well do not depend on the environment. On the contrary, links between the halo mass and the so-called set of secondary halo properties are sensitive to the cosmological environment, mainly to under-dense regions. We show that the signal of secondary bias is derived statistically from secondary correlations beyond the standard link to the halo mass. We show that the secondary bias arises through nonlocal and/or environmental properties related either to the halo distribution or to the properties of the underlying dark-matter field. In particular, properties such as the tidal field (a measure of the anisotropy of the density field) and the local Mach number (a measure of the local kinetic temperature of the halo distribution) generate the signals of the secondary bias with the highest significance. We propose applications of the assignment of individual bias for the generation of mock catalogs containing the signal of secondary bias, as well as a series of cosmological analyses aimed at mining large galaxy datasets.

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Towards testing the theory of gravity with DESI: summary statistics, model predictions and future simulation requirements

Alam

Arnold

Avilés

et al. 2021

J. Cosmol. Astropart. Phys.

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Shortly after its discovery, General Relativity (GR) was applied to predict the behavior of our Universe on the largest scales, and later became the foundation of modern cosmology. Its validity has been verified on a range of scales and environments from the Solar system to merging black holes. However, experimental confirmations of GR on cosmological scales have so far lacked the accuracy one would hope for — its applications on those scales being largely based on extrapolation and its validity there sometimes questioned in the shadow of the discovery of the unexpected cosmic acceleration. Future astronomical instruments surveying the distribution and evolution of galaxies over substantial portions of the observable Universe, such as the Dark Energy Spectroscopic Instrument (DESI), will be able to measure the fingerprints of gravity and their statistical power will allow strong constraints on alternatives to GR. In this paper, based on a set of N-body simulations and mock galaxy catalogs, we study the predictions of a number of traditional and novel summary statistics beyond linear redshift distortions in two well-studied modified gravity models — chameleon f(R) gravity and a braneworld model — and the potential of testing these deviations from GR using DESI. These summary statistics employ a wide array of statistical properties of the galaxy and the underlying dark matter field, including two-point and higher-order statistics, environmental dependence, redshift space distortions and weak lensing. We find that they hold promising power for testing GR to unprecedented precision. The major future challenge is to make realistic, simulation-based mock galaxy catalogs for both GR and alternative models to fully exploit the statistic power of the DESI survey (by matching the volumes and galaxy number densities of the mocks to those in the real survey) and to better understand the impact of key systematic effects. Using these, we identify future simulation and analysis needs for gravity tests using DESI.

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Optimal void finders in weak lensing maps

Cited by 14 publications

References 81 publications

Proca-stinated cosmology. Part II. Matter, halo, and lensing statistics in the vector Galileon

Proca-stinated cosmology. Part II. Matter, halo, and lensing statistics in the vector Galileon

Secondary halo bias through cosmic time

Towards testing the theory of gravity with DESI: summary statistics, model predictions and future simulation requirements

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