2018/04/30 by Xian Gao, Chao Kang · 1 citation
Physics and Astronomy · #Cosmological perturbation theory #Cosmology and Gravitation Theories #Curvature #Galaxies: Formation, Evolution, Phenomena #Gravitational wave #Inflation (cosmology) #Perturbation (astronomy) #Polarization (electrochemistry) #Primordial fluctuations #Pulsars and Gravitational Waves Research #Scalar (mathematics) #Wavenumber #astro-ph.CO #hep-th
paper · pdf · doi:10.1088/1475-7516/2018/09/013
published in Journal of Cosmology and Astroparticle Physics 2018(09), 013 (Institute of Physics) · 32 pages, 5 figures; v2, perturbative approach and gauge invariant variables clarified, citations added
openalex created_date 2018/04/24 · arxiv created 2018/08/08 · openalex publication_date 2018/09/10 · arxiv updated 2018/09/11 · openalex updated_date 2026/08/05
We investigate the inhomogeneous inflation, in which the space exponentially expands with inhomogeneities, and its cosmological perturbations. The inhomogeneous inflation is realized by introducing scalar fields with spacelike gradients that break the spatial symmetry. We find that the space can expand uniformly in different direction with the same rate. By using the perturbative method, we calculate the corrections to the power spectra of gravitational waves and curvature perturbation up to the linear order in the background inhomogeneities. Since the background is inhomogeneous, perturbations modes with different wave numbers get correlated. We show that generally the power spectra of perturbations depend on the ratio and the angle of wave numbers of the two correlated modes. In particular, the two circular polarization modes of the gravitational waves gain different powers when the background inhomogeneity is of vector or tensor type.