Isocurvature Fluctuations Induce Early Star Formation

Abstract

The early reionisation of the Universe inferred from the WMAP polarisation 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 reionisation. 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 reionise 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.

6 pages, 5 figures, submitted to MNRAS

References in corpus (17)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Preliminary Maps and Basic Results
• Wilkinson Microwave Anisotropy Probe (WMAP) First Year Observations: TE Polarization
• Simulations of Early Structure Formation: Primordial Gas Clouds
• Halo Substructure And The Power Spectrum
• The Production, Spectrum and Evolution of Cosmic Strings in Brane Inflation
• Primordial Black Holes as Dark Matter: The Power Spectrum and Evaporation of Early Structures
• The Reionization History at High Redshifts I: Physical Models and New Constraints from CMB Polarization
• Early Reionization by the First Galaxies
• Cosmic Reionisation by Stellar Sources: Population III Stars
• Cosmic Reionisation by Stellar Sources: Population II Stars
• Spectroscopic Gravitational Lensing and Limits on the Dark Matter Substructure in Q2237+0305
• The Epoch of Reionization in Models with Reduced Small Scale Power
• Early Structure Formation and Reionization in a Cosmological Model with a Running Primordial Power Spectrum
• The mass spectrum of metal-free Stars resulting from photodissociation feedback: A scenario for the formation of low-mass population III stars
• Star Formation at the Twilight of the Dark Ages: Which Stars Reionized the Universe?
• The Earliest Epoch of Reionisation in the Standard $\Lambda$CDM Model

Cited by in corpus (5)

• The early reionization with the primordial magnetic fields
• Squeezing the window on isocurvature modes with the Lyman-alpha forest
• Primordial Black Holes from CDM Isocurvature Perturbations
• Cosmological signatures of tilted isocurvature perturbations: reionization and 21cm fluctuations
• Modification of the halo mass function by kurtosis associated with primordial non-Gaussianity