Optimal galaxy survey for detecting the dipole in the cross-correlation with 21 cm Intensity Mapping

Lepori, Francesca; Villa, Eleonora; Viel, Matteo

doi:10.48550/arxiv.1709.03523

Cited by 6 publications

(10 citation statements)

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“…In our work we will neglect terms integrated along the line of sight like lensing magnification and Integrated Sachs-Wolf (ISW) effects, supported by results of previous work in terms of dipole of the correlation function [7,10,18].…”

Section: Number Countsmentioning

confidence: 83%

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The relativistic dipole and gravitational redshift on LSS

Dio¹,

Seljak²

2019

J. Cosmol. Astropart. Phys.

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We compute the dipole of the galaxy correlation function at 1-loop in perturbation theory by including all the relevant relativistic contributions. This provides a description and understanding of what the dipole truly measures, in particular in relation to the gravitational redshift effect in Large Scale Structure. In order to develop this perturbative approach we have computed for the first time the relevant relativistic corrections to third order in perturbation theory, including the corresponding non-linear galaxy bias model. This perturbative approach agrees on a wide range of scales with good accuracy with previous numerical results based on geodesic light tracing in N-body simulations. Previous claims of gravitational redshift detection may have neglected several relativistic effects which are comparable with the amplitude of gravitational redshift around 10 Mpc/h scales and which complicate the gravitational redshift interpretation of the measurement.

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Section: Number Countsmentioning

confidence: 83%

“…As shown in Refs. [8][9][10][11], beyond flat-sky approximation part of the quadrupole leaks into the dipole. Nevertheless the quadrupole, as any even multipole, is dominated by well-known Newtonian terms and we therefore do not need to derive further relativistic corrections.…”

Section: Number Countsmentioning

confidence: 99%

The relativistic dipole and gravitational redshift on LSS

Dio¹,

Seljak²

2019

J. Cosmol. Astropart. Phys.

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“…The lensing magnification contribution to number counts is itself a potentially important probe of gravity and dark matter [6][7][8][9][10][11], independent of weak lensing surveys. The Doppler contribution in the power spectrum [1,2,[12][13][14][15], and even more in the cross-power spectrum of two tracers [16][17][18][19][20][21][22] and in the bispectrum of a single tracer [23][24][25], is another powerful and independent probe of gravity. In order to realise the potential of these probes, it is necessary to include careful modelling of Q and b e .…”

Section: Introductionmentioning

confidence: 99%

Magnification and evolution biases in large-scale structure surveys

Maartens,

Fonseca,

Camera

et al. 2021

Preprint

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Measurements of the galaxy number density in upcoming surveys such as Euclid and the SKA will be sensitive to distortions from lensing magnification and Doppler effects, beyond the standard redshift-space distortions. The amplitude of these contributions depends sensitively on magnification bias and evolution bias in the galaxy number density. Magnification bias quantifies the change in the observed number of galaxies gained or lost by lensing magnification, while evolution bias quantifies the physical change in the galaxy number density relative to the conserved case. These biases are given by derivatives of the number density, and consequently are very sensitive to the form of the luminosity function. We give a careful derivation of the magnification and evolution biases, clarifying a number of results in the literature. We then examine the biases for a variety of surveys, encompassing optical/NIR, 21cm galaxy and 21cm intensity mapping surveys.

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“…primordial non-Gaussianity and relativistic lightcone effects as well as wide-angle effects, which are typically of the same magnitude as these other effects (see e.g. [15][16][17][18][19]).…”

Section: Introductionmentioning

confidence: 99%

The full-sky angular bispectrum in redshift space

Dio

Durrer

Maartens

et al. 2019

J. Cosmol. Astropart. Phys.

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We compute the redshift-dependent angular bispectrum of galaxy number counts at tree-level, including nonlinear clustering bias and estimating numerically for the first time the effect of redshift space distortions (RSD). We show that for narrow redshift bins the amplitude of nonlinear RSD is comparable with the matter density perturbations. While our numerical results only include terms relevant on sub-horizon scales, the formalism can readily be extended to the full tree-level bispectrum. Our approach does not rely on the flat-sky approximation and it can be easily generalized to different sources by including the appropriate bias expansion. We test the accuracy of Limber approximation for different z-bins. We highlight the subtle but relevant differences in the angular bispectrum of galaxy number counts with respect to CMB, due to the different scale dependence of perturbations. Our formalism can also be directly applied to the angular HI intensity mapping bispectrum. 1

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Optimal galaxy survey for detecting the dipole in the cross-correlation with 21 cm Intensity Mapping

Cited by 6 publications

References 0 publications

The relativistic dipole and gravitational redshift on LSS

The relativistic dipole and gravitational redshift on LSS

Magnification and evolution biases in large-scale structure surveys

The full-sky angular bispectrum in redshift space

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