Home > Research > Publications & Outputs > Hemispherical power asymmetry from scale-depend...

Associated organisational unit

View graph of relations

Hemispherical power asymmetry from scale-dependent modulated reheating

Research output: Contribution to journalJournal article

Article number041
<mark>Journal publication date</mark>19/11/2013
<mark>Journal</mark>Journal of Cosmology and Astroparticle Physics
Issue number11
Number of pages15
Publication statusPublished
Original languageEnglish


We propose a new model for the hemispherical power asymmetry of the CMB based on modulated reheating. Non-Gaussianity from modulated reheating can be small enough to satisfy the bound from Planck if the dominant modulation of the inflaton decay rate is linear in the modulating field sigma. sigma must then acquire a spatially-modulated power spectrum with a red scale-dependence. This can be achieved if the primordial perturbation of sigma is generated via tachyonic growth of a complex scalar field. Modulated reheating due to sigma then produces a spatially modulated and scale-dependent sub-dominant contribution to the adiabatic density perturbation. We show that it is possible to account for the observed asymmetry while remaining consistent with bounds from quasar number counts, non-Gaussianity and the CMB temperature quadupole. The model predicts that the adiabatic perturbation spectral index and its running will be modified by the modulated reheating component.