Weak lensing generated by vector perturbations and detectability of cosmic strings

Abstract

We study the observational signature of vector metric perturbations through the effect of weak gravitational lensing. In the presence of vector perturbations, the non-vanishing signals for B-mode cosmic shear and curl-mode deflection angle, which have never appeared in the case of scalar metric perturbations, naturally arise. Solving the geodesic and geodesic deviation equations, we drive the full-sky formulas for angular power spectra of weak lensing signals, and give the explicit expressions for E-/B-mode cosmic shear and gradient-/curl-mode deflection angle. As a possible source for seeding vector perturbations, we then consider a cosmic string network, and discuss its detectability from upcoming weak lensing and CMB measurements. Based on the formulas and a simple model for cosmic string network, we calculate the angular power spectra and expected signal-to-noise ratios for the B-mode cosmic shear and curl-mode deflection angle. We find that the weak lensing signals are enhanced for a smaller intercommuting probability of the string network, $P$, and they are potentially detectable from the upcoming cosmic shear and CMB lensing observations. For $P\sim 10^{-1}$, the minimum detectable tension of the cosmic string will be down to $G\mu \sim 5\times 10^{-8}$. With a theoretically inferred smallest value $P\sim 10^{-3}$, we could even detect the string with $G\mu \sim 5\times 10^{-10}$.

39 pages, 5 figures, v2: references added, minor corrections, v3: matches version published in JCAP

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Cited by in corpus (22)

• Bias-Hardened CMB Lensing
• Impact of post-Born lensing on the CMB
• Wave Effect in Gravitational Lensing by the Ellis Wormhole
• Bias-Hardened CMB Lensing with Polarization
• Equivalence of solutions between the four-dimensional novel and regularized EGB theories in a cylindrically symmetric spacetime
• Weak lensing induced by second-order vector mode
• Full-sky formulae for weak lensing power spectra from total angular momentum method
• Rotation of the cosmic microwave background polarization from weak gravitational lensing
• Lensing signals from Spin-2 perturbations
• CMB Mode Coupling with Isotropic Polarization Rotation
• Intensity mapping of the 21cm emission: lensing
• Constraining cosmic string parameters with curl mode of CMB lensing
• Cosmology with the Square Kilometre Array by SKA-Japan
• Imprints of primordial magnetic fields on intrinsic alignments of galaxies
• Probing the Cosmological Principle with weak lensing shear
• Unified approach to secondary effects on the CMB B-mode polarization
• A new observable for cosmic shear
• Observable cosmological vector mode in the dark ages
• Primordial gravitational waves and curvature perturbations induced energy density perturbation
• An Estimator for the lensing potential from galaxy number counts
• CMB ISW-lensing bispectrum from cosmic strings
• Weak lensing from self-ordering scalar fields