Open AccessIsocurvature fluctuations induce early star formation
Author(s) -
Sugiyama Naoshi,
Zaroubi Saleem,
Silk Joseph
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.08210.x
Subject(s) - physics , reionization , cmb cold spot , astrophysics , cosmic microwave background , star formation , adiabatic process , primordial fluctuations , spectral density , galaxy , gravitational lens , universe , cosmology , astronomy , redshift , quantum mechanics , anisotropy , statistics , mathematics
The early reionization of the Universe inferred from the WMAP polarization results, if confirmed, poses a problem for the hypothesis that scale‐invariant adiabatic density fluctuations account for large‐scale structure and galaxy formation. One can only generate the required amount of early star formation if extreme assumptions are made about the efficiency and nature of early reionization. We develop an alternative hypothesis that invokes an additional component of a non‐scale‐free isocurvature power spectrum together with the scale‐free adiabatic power spectrum for inflation‐motivated primordial density fluctuations. Such a component is constrained by the Lyman alpha forest observations, can account for the small‐scale power required by spectroscopic gravitational lensing, and yields a source of early star formation that can reionize the Universe at z ∼ 20 yet becomes an inefficient source of ionizing photons by z ∼ 10 , thereby allowing the conventional adiabatic fluctuation component to reproduce the late thermal history of the intergalactic medium.