Imprints of local lightcone projection effects on the galaxy bispectrum IV: second-order vector and tensor contributions

Jolicoeur, Sheean; Allahyari, Alireza; Clarkson, Chris; Larena, Julien; Umeh, Obinna; Maartens, Roy

doi:10.1088/1475-7516/2019/03/004

Cited by 16 publications

(18 citation statements)

References 90 publications

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“…The impact of vector modes on LSS observables is expected to be small relative to the scalar perturbations, both from perturbative (Lu et al 2009) and non-perturbative analyses (Bruni et al 2014;Adamek et al 2016b), although it can represent a new systematic which needs to be taken into account (Bonvin et al 2018). For instance, their effect on gravitational lensing seems to be not strong enough to be detectable by current observations (Thomas et al 2015a;Saga et al 2015;Gressel et al 2019), and the imprints of the vector potential in the angular power spectrum and bispectrum of galaxies are also weak (Durrer & Tansella 2016;Jolicoeur et al 2019), although a vector perturbation can be isolated from the full signal if it violates statistical isotropy and defines a preferred frame (see, e.g., Tansella et al 2018). On the other hand, the vector potential power spectrum is known to peak around the equality scale (Lu et al 2009), and its behaviour as well as impact on observables at highly nonlinear scales remains largely unexplored, although deviations from perturbation theory can be significant (Bruni et al 2014).…”

Section: Introductionmentioning

confidence: 94%

Vector modes in $Λ$CDM: the gravitomagnetic potential in dark matter haloes from relativistic $N$-body simulations

Barrera-Hinojosa,

Li,

Bruni

et al. 2020

Preprint

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We investigate the inherently nonlinear transverse modes of the gravitational and velocity fields in ΛCDM cosmology, based on a high-resolution simulation performed using the adaptive-mesh refinement general-relativistic N -body code GRAMSES. We study the generation of vorticity in the dark matter velocity field at low redshift, providing power-law fits to the shape and evolution of its power spectrum from large sub-horizon scales to deeply nonlinear scales. By analysing the gravitomagnetic vector potential, a purely relativistic vector mode of the gravitational field that is absent in Newtonian simulations of structure formation, in dark matter haloes with masses ranging from ∼ 10 12.5 h −1 M to ∼ 10 15 h −1 M , we find that the magnitude of this vector correlates with the halo mass, peaking in the inner regions and decreasing towards their outskirts. Nevertheless, on average, its ratio against the scalar gravitational potential remains fairly constant inside the haloes, below percent level, decreasing roughly linearly with redshift at z < 3 and showing a weak dependence on halo mass. Furthermore, we show that the gravitomagnetic acceleration in dark matter haloes peaks towards the core and reaches almost 10 −10 h cm/s 2 in the most massive halo of the simulation. However, regardless of the halo mass, the ratio between the magnitudes of the gravitomagnetic force and the standard gravitational force is typically at around the 10 −3 level in the innermost parts of the haloes and drops by up to one order of magnitude at the outskirts. This ratio shows a very weak dependence on redshift. This result confirms that the gravitomagnetic field has a negligible effect on cosmic structure formation, even for the most massive structures, although its behaviour in low density regions such as voids remains to be explored. In addition, its effects on photons and therefore observations remains to be understood in detail in the future.

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Section: Introductionmentioning

confidence: 94%

Vector modes in $Λ$CDM: the gravitomagnetic potential in dark matter haloes from relativistic $N$-body simulations

Barrera-Hinojosa,

Li,

Bruni

et al. 2020

Preprint

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“…Apart from RSD, the remaining 'projection' effects from observing in redshift space are ultra-large scale relativistic effects, which arise from Doppler, Sachs-Wolfe, integrated SW and time-delay terms, and their cross-correlations with each other and the dominant density and RSD terms (at first order, see [14][15][16] and at second-order see [11,13,[17][18][19][20][21][22][23][24][25][26]). These relativistic effects are all suppressed in Fourier space by factors (H/k) n , where n ≥ 2 in the power spectrum [14][15][16] and n ≥ 1 in the bispectrum [13,24,25], and we will neglect them.…”

Section: = ∆mentioning

confidence: 99%

Full-sky bispectrum in redshift space for 21cm intensity maps

Durrer,

Jalilvand,

Kothari

et al. 2020

Preprint

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We compute the tree-level bispectrum of 21cm intensity mapping after reionisation. We work in directly observable angular and redshift space, focusing on equal-redshift correlations and thin redshift bins, for which the lensing contribution is negligible. We demonstrate the importance of the contributions from redshift-space distortions which typically dominate the result. Taking into account the effects of telescope beams and foreground cleaning, we estimate the signal to noise, and show that the bispectrum is detectable by both SKA in single-dish mode and HIRAX in interferometer mode, especially at the lower redshifts in their respective ranges.

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“…(B.17) 31 Of course, this description holds only for the diffeomorphisms that are connected to the identity.…”

Section: Example: the Photon-electron-proton Fluidmentioning

confidence: 99%

“…The linear order perturbation theory around the homogeneous and isotropic solution is well understood and documented, but is often insufficient for matching the aforementioned precision requirements. This is why, in the last decade, the community has been actively investigating the impact of second-order effects in the CMB lensing [10][11][12][13][14][15][16][17][18][19][20][21], in galaxy number counts [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] and cosmological distances and weak lensing [37][38][39][40][41][42][43][44][45].…”

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confidence: 99%

Tetrad formalism for exact cosmological observables

Mitsou,

Yoo

2019

Preprint

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The standard description of cosmological observables is incomplete, because it does not take into account the correct angular parametrization of the sky, i.e. the one determined by the observer frame. The corresponding corrections must be taken into account for reliable results at non-linear orders. This can be accomplished by introducing an orthonormal basis, or "tetrad", at the observer point, representing the frame with respect to which observations are performed. In this paper we consider the tetrad formalism of General Relativity, thus associating tetrads to sources as well, and develop a new formalism for describing cosmological observables. It is based on a manifold which we call the "observer space-time", whose coordinates are the proper time, redshift and angles an observer uses to parametrize measurements, and on which the rest of the observables are defined. This manifold does not have to be diffeomorphic to the true space-time and allows us to resolve caustics in the latter, in contrast with similar coordinate-based formalisms. As a concrete example, we work out the definitions and equations for the angular diameter distance, weak lensing and number count observables. As for the observables associated to the CMB, they lie inside the phase space matrix distribution of the photon fluid evaluated at the observer point and pulled back on the observer sky. The second part of this paper is therefore devoted to general-relativistic matrix kinetic theory. Here too the tetrad formalism appears as the natural approach for relating the macroscopic dynamics to the microscopic QFT and therefore for constructing the matrix Boltzmann equations. Part of the presented material is known and is included for completeness, but we provide more detailed discussions over some subtle issues and we also consider an alternative construction of the collision term which deviates from the standard one at higher order in the loop corrections. In summary, the present paper contains all the required structures for computations in cosmology with exact and model-independent cosmological observables. The associated linear perturbation theory will be given in a companion paper.

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Imprints of local lightcone projection effects on the galaxy bispectrum IV: second-order vector and tensor contributions

Cited by 16 publications

References 90 publications

Vector modes in $Λ$CDM: the gravitomagnetic potential in dark matter haloes from relativistic $N$-body simulations

Vector modes in $Λ$CDM: the gravitomagnetic potential in dark matter haloes from relativistic $N$-body simulations

Full-sky bispectrum in redshift space for 21cm intensity maps

Tetrad formalism for exact cosmological observables

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