CMB lensing reconstruction biases in cross-correlation with large-scale structure probes

Fabbian, Giulio; Lewis, Antony; Beck, Dominic

doi:10.1088/1475-7516/2019/10/057

Cited by 63 publications

(75 citation statements)

References 130 publications

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“…On small scales, we notice that ω suffers a power-loss due to finite grid resolution effects, similar to what we observe for the convergence and ellipticity spectra. The rotation power spectrum has been computed in previous works, based on Newtonian simulations, using a multiple-lensplane approximation (Becker 2012;Takahashi et al 2017;Fabbian, Lewis & Beck 2019). Our results qualitatively agree with previous results in the literature, where a few per cent agreement was found between the spectra extracted from Newtonian simulations and the second-order post-Born prediction.…”

Section: Angular Power Spectrasupporting

confidence: 89%

Weak-lensing observables in relativistic N-body simulations

Lepori

Adamek

Durrer

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Abstract We present a numerical weak-lensing analysis that is fully relativistic and non-perturbative for the scalar part of the gravitational potential and first-order in the vector part, frame dragging. Integrating the photon geodesics backwards from the observer to the emitters, we solve the Sachs optical equations and study in detail the weak-lensing convergence, ellipticity and rotation. For the first time, we apply such an analysis to a high-resolution relativistic N-body simulation, which consistently includes the leading-order corrections due to general relativity on both large and small scales. These are related to the question of gauge choice and to post-Newtonian corrections, respectively. We present the angular power spectra and one-point probability distribution functions for the weak-lensing variables, which we find are broadly in agreement with comparable Newtonian simulations. Our geometric approach, however, is more robust and flexible, and can therefore be applied consistently to non-standard cosmologies and modified theories of gravity.

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Section: Angular Power Spectrasupporting

confidence: 89%

Weak-lensing observables in relativistic N-body simulations

Lepori

Adamek

Durrer

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…The cancellations are depicted in the second column of Fig 5. In the last column we plot the relative size of the corrections to the signal. While being bigger than in the autocorrelation, the corrections still remain at the sub-percent level a result which is in agreement with estimates from ray-traced simulations [12].…”

Section: Additional Jacobian Termssupporting

confidence: 88%

Lensing corrections on galaxy-lensing cross correlations and galaxy-galaxy auto correlations

Böhm

Modi

Castorina

2020

J. Cosmol. Astropart. Phys.

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We study the impact of lensing corrections on modeling cross correlations between CMB lensing and galaxies, cosmic shear and galaxies, and galaxies in different redshift bins. Estimating the importance of these corrections becomes necessary in the light of anticipated high-accuracy measurements of these observables. While higher order lensing corrections (sometimes also referred to as post Born corrections) have been shown to be negligibly small for lensing auto correlations, they have not been studied for cross correlations. We evaluate the contributing four-point functions without making use of the Limber approximation and compute line-of-sight integrals with the numerically stable and fast FFTlog formalism. We find that the relative size of lensing corrections depends on the respective redshift distributions of the lensing sources and galaxies, but that they are generally small for high signal-to-noise correlations. We point out that a full assessment and judgement of the importance of these corrections requires the inclusion of lensing Jacobian terms on the galaxy side. We identify these additional correction terms, but do not evaluate them due to their large number. We argue that they could be potentially important and suggest that their size should be measured in the future with ray-traced simulations. We make our code publicly available under [4].

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“…The bias on cross-correlations between the lensing spectrum and low-redshift large-scale structure tracers could, however, be larger due to larger low-redshift LSS non-Gaussianity, and smaller opposite-sign post-Born contributions at low redshift. However, for Planck noise levels, following Fabbian et al (2019) we estimate that the crosscorrelation bias remains below 1% for tracers at z 0.2 where there is a useful cross-correlation signal, and hence should also be negligible compared to errors.…”

Section: Lensing Gaussianity Assumptionmentioning

confidence: 81%

Planck2018 results

Aghanim¹,

Akrami²,

Ashdown³

et al. 2020

A&A

523

170

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We present measurements of the cosmic microwave background (CMB) lensing potential using the final Planck 2018 temperature and polarization data. Using polarization maps filtered to account for the noise anisotropy, we increase the significance of the detection of lensing in the polarization maps from 5σ to 9σ. Combined with temperature, lensing is detected at 40σ. We present an extensive set of tests of the robustness of the lensing-potential power spectrum, and construct a minimum-variance estimator likelihood over lensing multipoles 8 ≤ L ≤ 400 (extending the range to lower L compared to 2015), which we use to constrain cosmological parameters. We find good consistency between lensing constraints and the results from the Planck CMB power spectra within the ΛCDM model. Combined with baryon density and other weak priors, the lensing analysis alone constrains σ8Ωm0.25 = 0.589 ± 0.020 (1σ errors). Also combining with baryon acoustic oscillation data, we find tight individual parameter constraints, σ8 = 0.811 ± 0.019, H0 = 67.9−1.3+1.2 km s−1 Mpc−1, and Ωm = 0.303−0.018+0.016. Combining with Planck CMB power spectrum data, we measure σ8 to better than 1% precision, finding σ8 = 0.811 ± 0.006. CMB lensing reconstruction data are complementary to galaxy lensing data at lower redshift, having a different degeneracy direction in σ8 − Ωm space; we find consistency with the lensing results from the Dark Energy Survey, and give combined lensing-only parameter constraints that are tighter than joint results using galaxy clustering. Using the Planck cosmic infrared background (CIB) maps as an additional tracer of high-redshift matter, we make a combined Planck-only estimate of the lensing potential over 60% of the sky with considerably more small-scale signal. We additionally demonstrate delensing of the Planck power spectra using the joint and individual lensing potential estimates, detecting a maximum removal of 40% of the lensing-induced power in all spectra. The improvement in the sharpening of the acoustic peaks by including both CIB and the quadratic lensing reconstruction is detected at high significance.

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CMB lensing reconstruction biases in cross-correlation with large-scale structure probes

Cited by 63 publications

References 130 publications

Weak-lensing observables in relativistic N-body simulations

Weak-lensing observables in relativistic N-body simulations

Lensing corrections on galaxy-lensing cross correlations and galaxy-galaxy auto correlations

Planck2018 results

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