Weak lensing induced by second-order vector mode

Saga, Shohei; Yamauchi, Daisuke; Ichiki, Kiyotomo

doi:10.1103/physrevd.92.063533

Cited by 28 publications

(36 citation statements)

References 56 publications

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“…Although the gravitational lensing by density fluctuations in linear theory does not generate the curl mode under the Born approximation, the multiple-lens scattering employed in our simulation leads to a non-zero curl mode (Pratten & Lewis 2016). This curl mode is also generated by any vector or tensor metric perturbation (Namikawa et al 2012;Saga et al 2015). Figure 10 shows the power spectrum of the deflection angle for both modes: the upper (lower) curves correspond to the gradient (curl) mode.…”

Section: Power Spectra Of Cmb Anisotropiesmentioning

confidence: 90%

Full-sky Gravitational Lensing Simulation for Large-area Galaxy Surveys and Cosmic Microwave Background Experiments

Takahashi

Hamana

Shirasaki

et al. 2017

ApJ

182

248

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We present 108 full-sky gravitational lensing simulation data sets generated by performing multiplelens plane ray-tracing through high-resolution cosmological N -body simulations. The data sets include full-sky convergence and shear maps from redshifts z = 0.05 to 5.3 at intervals of 150 h −1 Mpc comoving radial distance (corresponding to a redshift interval of ∆z ≃ 0.05 at the nearby universe), enabling the construction of a mock shear catalog for an arbitrary source distribution up to z = 5.3. The dark matter halos are identified from the same N -body simulations with enough mass resolution to resolve the host halos of the Sloan Digital Sky Survey (SDSS) CMASS and luminous red galaxies (LRGs). Angular positions and redshifts of the halos are provided by a ray-tracing calculation, enabling the creation of a mock halo catalog to be used for galaxy-galaxy and cluster-galaxy lensing. The simulation also yields maps of gravitational lensing deflections for a source redshift at the last scattering surface, and we provide 108 realizations of lensed cosmic microwave background (CMB) maps in which the post-Born corrections caused by multiple light scattering are included. We present basic statistics of the simulation data, including the angular power spectra of cosmic shear, CMB temperature and polarization anisotropies, galaxy-galaxy lensing signals for halos, and their covariances. The angular power spectra of the cosmic shear and CMB anisotropies agree with theoretical predictions within 5% up to ℓ = 3000 (or at an angular scale θ > 0.5 arcmin). The simulation data sets are generated primarily for the ongoing Subaru Hyper Suprime-Cam survey, but are freely available for download at

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Section: Power Spectra Of Cmb Anisotropiesmentioning

confidence: 90%

Full-sky Gravitational Lensing Simulation for Large-area Galaxy Surveys and Cosmic Microwave Background Experiments

Takahashi

Hamana

Shirasaki

et al. 2017

ApJ

182

248

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“…Equation (10) means that the lensing signals, f and v, can be estimated through off-diagonal elements of the covariance matrix of the CMB Fourier modes (see Section 3.3 for details). Note that we do not include v in our simulations because its contribution is negligible in the standard ΛCDM model (e.g., Saga et al 2015;Pratten & Lewis 2016). We use the reconstructed curl mode as a null test in Section 5.…”

Section: Lensed Cmb Anisotropiesmentioning

confidence: 99%

Bicep2/KECK ARRAY VIII: MEASUREMENT OF GRAVITATIONAL LENSING FROM LARGE-SCALE B-MODE POLARIZATION

Ade¹,

Ahmed²,

Aikin³

et al. 2016

ApJ

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We present measurements of polarization lensing using the 150 GHz maps, which include all data taken by the BICEP2andKeck Array Cosmic Microwave Background polarization experiments up to and including the 2014 observing season (BK14). Despite their modest angular resolution (~ 0 . 5), the excellent sensitivity (∼3μK-arcmin) of these maps makes it possible to directly reconstruct the lensing potential using only information at larger angular scales (  ℓ 700). From the auto-spectrum of the reconstructed potential, we measure an amplitude of the spectrum to be) and reject the no-lensing hypothesis at s 5.8 , which is the highest significance achieved to date using an EB lensing estimator. Taking ). We perform a series of null tests and consistency checks to show that these results are robust against systematics and are insensitive to analysis choices. These results unambiguously demonstrate that the B modes previously reported by BICEP/Keck at intermediate angular scales350) are dominated by gravitational lensing. The good agreement between the lensing amplitudes obtained from the lensing reconstruction and B-mode spectrum starts to place constraints on any alternative cosmological sources of B modes at these angular scales.

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“…In this section, we quickly review 21cm physics [27], the second-order vector mode [16], and the weak lensing curl mode [20]. Throughout this paper, our calculation is based on a flat ΛCDM model with the standard six cosmological parameters constrained by Planck [4].…”

Section: Preliminarymentioning

confidence: 99%

“…The specific form of the source term S (2) λ (η, k) is given in Ref. [16]. The dominant part of the source term is the quadratic of the scalar potential, naively, S…”

Section: B Second-order Vector Modementioning

confidence: 99%

“…In our previous study [16], we discussed the detectability of the second-order curl mode in the CMB lensing and cosmic shear. Unfortunately, because the signal from the second-order curl mode is small, we concluded that we could not detect the second-order curl mode even with an ideal experiment for the full sky without the instrumental noise if we utilize the quadratic estimator method.…”

Section: Introductionmentioning

confidence: 99%

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Observable cosmological vector mode in the dark ages

Saga

2016

Phys. Rev. D

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The second-order vector mode is inevitably induced from the coupling of first-order scalar modes in cosmological perturbation theory and might hinder a possible detection of primordial gravitational waves from inflation through 21cm lensing observations. Here, we investigate the weak lensing signal in 21cm photons emitted by neutral hydrogen atoms in the dark ages induced by the second-order vector mode by decomposing the deflection angle of the 21cm lensing signal into the gradient and curl modes. The curl mode is a good tracer of the cosmological vector and tensor modes since the scalar mode does not induce the curl one. By comparing angular power spectra of the 21cm lensing curl mode induced by the second-order vector mode and primordial gravitational waves whose amplitude is parametrized by the tensor-to-scalar ratio r, we find that the 21cm curl mode from the second-order vector mode dominates over that from primordial gravitational waves on almost all scales if r 10 −5 . If we use the multipoles of the power spectrum up to ℓmax = 10 5 and 10 6 in reconstructing the curl mode from 21cm temperature maps, the signal-to-noise ratios of the 21cm curl mode from the second-order vector mode achieve S/N ≈ 0.46 and 73, respectively. Observation of 21cm radiation is, in principle, a powerful tool to explore not only the tensor mode but also the cosmological vector mode.

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Weak lensing induced by second-order vector mode

Cited by 28 publications

References 56 publications

Full-sky Gravitational Lensing Simulation for Large-area Galaxy Surveys and Cosmic Microwave Background Experiments

Full-sky Gravitational Lensing Simulation for Large-area Galaxy Surveys and Cosmic Microwave Background Experiments

Bicep2/KECK ARRAY VIII: MEASUREMENT OF GRAVITATIONAL LENSING FROM LARGE-SCALE B-MODE POLARIZATION

Observable cosmological vector mode in the dark ages

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