Observable cosmological vector mode in the dark ages
arXiv:1607.03973 · doi:10.1103/PhysRevD.94.063523
Abstract
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 , 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 . If we use the multipoles of the power spectrum up to and 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 and , respectively. Observation of 21cm radiation is, in principle, a powerful tool to explore not only the tensor mode but also the cosmological vector mode.
9 pages, 2 figures, Accepted for publication in PRD
References in corpus (34)
- Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results
- Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
- Cosmological Constraints from the SDSS Luminous Red Galaxies
- Weak Gravitational Lensing of the CMB
- Gravitational Wave Spectrum Induced by Primordial Scalar Perturbations
- The cosmological gravitational wave background from primordial density perturbations
- Reconstruction of lensing from the cosmic microwave background polarization
- Ray Tracing Simulations of Weak Lensing by Large-Scale Structure
- Power Spectra in Global Defect Theories of Cosmic Structure Formation
- CMB anisotropies from primordial inhomogeneous magnetic fields
- The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the full shape of the clustering wedges in the data release 10 and 11 galaxy samples
- The 21cm angular-power spectrum from the dark ages
- Cosmological Magnetic Field: a fossil of density perturbations in the early universe
- Second Order Corrections to Weak Lensing by Large-Scale Structure
- Constraints on primordial density perturbations from induced gravitational waves
- Vector field models of modified gravity and the dark sector
- Cosmic Microwave Background Anisotropies from Scaling Seeds: Global Defect Models
- Primordial gravity wave fossils and their use in testing inflation
- Computing General Relativistic effects from Newtonian N-body simulations: Frame dragging in the post-Friedmann approach
- CMB Bispectrum from Primordial Scalar, Vector and Tensor non-Gaussianities
- Full-sky lensing reconstruction of gradient and curl modes from CMB maps
- Lensing of 21-cm Fluctuations by Primordial Gravitational Waves
- Observable primordial vector modes
- The seed magnetic field generated during recombination
- Cosmic 21-cm Delensing of Microwave Background Polarization and the Minimum Detectable Energy Scale of Inflation
- Impact of anisotropic stress of free-streaming particles on gravitational waves induced by cosmological density perturbations
- Cosmic Shear from Scalar-Induced Gravitational Waves
- Weak lensing induced by second-order vector mode
- Weak lensing generated by vector perturbations and detectability of cosmic strings
- Magnetic field spectrum at cosmological recombination revisited
- Full-sky formulae for weak lensing power spectra from total angular momentum method
- Lensing signals from Spin-2 perturbations
- Generation of magnetic fields in Einstein-Aether gravity
- Primordial magnetic fields from self-ordering scalar fields