Lensing convergence in galaxy clustering in ΛCDM and beyond

Villa, Eleonora; Lepori, Francesca

doi:10.1088/1475-7516/2018/04/033

Cited by 26 publications

(33 citation statements)

References 125 publications

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“…As expected, standard tomography is very sensitive to lensing effects, because its wider redshift bins acquire a significant contribution from the integrated effect of lensing. On the other hand, the thinner the bin, the less important is lensing (see also Villa et al 2018). Thus, our hybrid approach, with its thin sub-bins, is almost insensitive to it, and we can therefore safely ignore the lensing contribution in the hybrid approach.…”

Section: Bias On Parameter Estimation From Neglecting Lensingmentioning

confidence: 99%

Optimized angular power spectra for spectroscopic galaxy surveys

Camera

Fonseca

Maartens

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The angular power spectrum C (z i , z j ) is a gauge-independent observable that is in principle the natural tool for analysing galaxy number counts. In practice, the problem is that the computational requirements for next-generation spectroscopic surveys such as Euclid and the Square Kilometre Array are currently unfeasible. We propose a new method to save computational time for spectroscopic angular power spectra. This hybrid method is modelled on the Fourier power spectrum approach of treating relatively thick redshift bins (∆z ∼ 0.1) as separate surveys. In the hybrid method, each thick bin is further subdivided into thin bins (δz ∼ 0.01); all the correlations within each thick bin are computed, while cross-bin correlations beyond the thick bins are neglected. Constraints on cosmological parameters from the hybrid method are comparable to those from the standard galaxy P g (k, z) analysis-but they have the advantage that cosmic evolution, wide-angle and lensing effects are naturally included, while no Alcock-Paczynski correction is needed. The hybrid method delivers much tighter constraints than a 2D tomographic approach that is typical for photometric surveys, which considers only thick bins and the correlations between them. Furthermore, for standard cosmological parameters our method is not biased by neglecting the effects of lensing on number counts, while the tomographic method is strongly biased.

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Section: Bias On Parameter Estimation From Neglecting Lensingmentioning

confidence: 99%

Optimized angular power spectra for spectroscopic galaxy surveys

Camera

Fonseca

Maartens

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…The inclusion of the lensing magnification in cross and auto-correlations of galaxy clustering and cosmic shear has been studied with Fisher analysis (Duncan et al 2013;Villa et al 2018;Thiele et al 2019), where it has already been suggested that the ignorance of the magnification bias may induce a bias in the cosmological parameter estimation. Here, we test this hypothesis by performing a full likelihood mock data analysis.…”

Section: Galaxy Number Counts and Magnification Biasmentioning

confidence: 99%

Developing a unified pipeline for large-scale structure data analysis with angular power spectra – II. A case study for magnification bias and radio continuum surveys

Tanidis

Camera

Parkinson

2019

Monthly Notices of the Royal Astronomical Society

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Following on our purpose of developing a unified pipeline for large-scale structure data analysis with angular (i.e. harmonic-space) power spectra, we now include the weak lensing effect of magnification bias on galaxy clustering in a publicly available, modular parameter estimation code. We thus forecast constraints on the parameters of the concordance cosmological model, dark energy, and modified gravity theories from galaxy clustering tomographic angular power spectra. We find that a correct modelling of magnification is crucial in order not to bias the estimation of cosmological parameters, especially in the case of deep galaxy surveys. Our case study adopts specifications of the Evolutionary Map of the Universe (EMU), which is a full-sky, deep radio-continuum survey, and is expected to probe the Universe up to redshift z ∼ 6. We assume the Limber approximation, and include magnification bias on top of density fluctuations and redshift-space distortions. By restricting our analysis to the regime where the Limber approximation holds true, we significantly minimise the computational time needed, compared to that of the exact calculation. We also show that there is a trend for more biased parameter estimates from neglecting magnification when the redshift bins are very wide. We conclude that this result implies a strong dependence on the lensing contribution, which is an integrated effect and becomes dominant when wide redshift bins are considered. Finally, we note that instead of being considered a contaminant, magnification bias encodes important cosmological information, and its inclusion leads leading to an alleviation of its degeneracy between the galaxy bias and the amplitude normalisation of the matter fluctuations.

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“…We derive constraints on the directions and amplitudes of anisotropies for both a Euclid-like and SKA2-like survey. The specifications for these surveys are taken from [53] and [54] respectively: the two redshift ranges are z ∈ [0.7, 2.0] for Euclid and z ∈ [0.1, 2.0] for SKA2 and we split them into 14 and 19 bins of thickness ∆z = 0.1 respectively, with L p = 2 Mpc/h. This choice of L p is motivated by the fact that this pixel size gives the best constraints in [25].…”

Section: A Model For Vector Perturbationsmentioning

confidence: 99%

Redshift-space distortions from vector perturbations. II. Anisotropic signal

et al. 2018

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We study the impact on the galaxy correlation function of the presence of a vector component in the tracers' peculiar velocities, in the case in which statistical isotropy is violated. We present a general framework -based on the bipolar spherical harmonics expansion -to study this effect in a model independent way, without any hypothesis on the origin or the properties of these vector modes. We construct six new observables, that can be directly measured in galaxy catalogs in addition to the standard monopole, quadrupole and hexadecapole, and we show that they completely describe any deviations from isotropy. We then perform a Fisher analysis in order to quantify the constraining power of future galaxy surveys. As an example, we show that the SKA2 would be able to detect anisotropic rotational velocities with amplitudes as low as 1% of that of the vorticity generated during shell-crossing in standard dark matter scenarios. CONTENTS

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Lensing convergence in galaxy clustering in ΛCDM and beyond

Cited by 26 publications

References 125 publications

Optimized angular power spectra for spectroscopic galaxy surveys

Optimized angular power spectra for spectroscopic galaxy surveys

Developing a unified pipeline for large-scale structure data analysis with angular power spectra – II. A case study for magnification bias and radio continuum surveys

Redshift-space distortions from vector perturbations. II. Anisotropic signal

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