Broken Isotropy from a Linear Modulation of the Primordial Perturbations
Abstract
A linear modulation of the primordial perturbations is proposed as an explanation for the observed asymmetry between the northern and southern hemispheres of the Wilkinson Microwave Anisotropy Probe (WMAP) data. A cut sky, reduced-resolution third-year ``internal linear combination'' (ILC) map was used to estimate the modulation parameters. A foreground template and a modulated plus unmodulated monopole and dipole were projected out of the likelihood. The effective χ2 was reduced by 9 for three extra parameters. The mean Galactic colatitude and longitude of the modulation, with 68%, 95%, and 99.7% confidence intervals were 56+17+36+65-17-35-51 and 63+28+59+105-26-58-213. The mean percentage change of the variance across the poles of the modulation was 62+18+35+57-18-35-47. Implications of these results and possible generating mechanisms are discussed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2007
- DOI:
- 10.1086/510511
- arXiv:
- arXiv:astro-ph/0607423
- Bibcode:
- 2007ApJ...656..636G
- Keywords:
-
- Cosmology: Cosmic Microwave Background;
- Cosmology: Early Universe;
- Cosmology: Large-Scale Structure of Universe;
- Astrophysics;
- High Energy Physics - Phenomenology
- E-Print:
- 15 pages, 3 figures