In the beginning: the first sources of light and the reionization of the universe

Barkana, Rennan; Loeb, Abraham

doi:10.1016/s0370-1573(01)00019-9

Cited by 1,365 publications

(1,559 citation statements)

References 391 publications

(443 reference statements)

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“…However, the mass range we cover is where the majority of ionizing photons during reionization is expected to be produced (Barkana & Loeb 2001). The stellar mass in the haloes lies between 1250 M M 2 × 10 8 M , where the minimum mass is given by the SPH particle mass.…”

Section: Massmentioning

confidence: 99%

The First Billion Years project: the escape fraction of ionizing photons in the epoch of reionization

Paardekooper

Khochfar

Vecchia

2015

Monthly Notices of the Royal Astronomical Society

251

280

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Proto-galaxies forming in low-mass dark matter haloes are thought to provide the majority of ionizing photons needed to reionize the Universe, due to their high escape fractions of ionizing photons. We study how the escape fraction in high-redshift galaxies relates to the physical properties of the halo in which the galaxies form, by computing escape fractions in more than 75000 haloes between redshifts 27 and 6 that were extracted from the First Billion Years project, high-resolution cosmological hydrodynamics simulations of galaxy formation. We find that the main constraint on the escape fraction is the gas column density in a radius of 10 pc around the stellar populations, causing a strong mass dependence of the escape fraction. The lower potential well in haloes with M 200 10 8 M results in low column densities that can be penetrated by radiation from young stars (age < 5 Myr). In haloes with M 200 10 8 M supernova feedback is important, but only ∼ 30% of the haloes in this mass range have an escape fraction higher than 1%. We find a large range of escape fractions in haloes with similar properties, caused by different distributions of the dense gas in the halo. This makes it very hard to predict the escape fraction on the basis of halo properties and results in a highly anisotropic escape fraction. The strong mass dependence, the large spread and the large anisotropy of the escape fraction may strongly affect the topology of reionization and is something current models of cosmic reionization should strive to take into account.

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Section: Massmentioning

confidence: 99%

The First Billion Years project: the escape fraction of ionizing photons in the epoch of reionization

Paardekooper

Khochfar

Vecchia

2015

Monthly Notices of the Royal Astronomical Society

251

280

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“…At the same time, the first stars and galaxies were forming from primordial gas clouds in the Universe. Although there is a clear connection between these two events (Barkana & Loeb 2001;Bromm & Yoshida 2011;Loeb & Furlanetto 2013;Robertson et al 2013), their detailed relation is unknown, thanks to uncertainties in the properties of the galaxy populations. Fortunately, understanding the epoch of reionization itself will also shed light on the formation and evolution of early galaxies.…”

Section: Introductionmentioning

confidence: 99%

Constraints on the star formation efficiency of galaxies during the epoch of reionization

Sun

Furlanetto

2016

Mon. Not. R. Astron. Soc.

178

157

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Reionization is thought to have occurred in the redshift range of 6 < z < 9, which is now being probed by both deep galaxy surveys and CMB observations. Using halo abundance matching over the redshift range 5 < z < 8 and assuming smooth, continuous gas accretion, we develop a model for the star formation efficiency f of dark matter halos at z > 6 that matches the measured galaxy luminosity functions at these redshifts. We find that f peaks at ∼ 30% at halo masses M ∼ 10 11 -10 12 M , in qualitative agreement with its behavior at lower redshifts. We then investigate the cosmic star formation histories and the corresponding models of reionization for a range of extrapolations to small halo masses. We use a variety of observations to further constrain the characteristics of the galaxy populations, including the escape fraction of UV photons. Our approach provides an empirically-calibrated, physically-motivated model for the properties of star-forming galaxies sourcing the epoch of reionization. In the case where star formation in low-mass halos is maximally efficient, an average escape fraction ∼ 0.1 can reproduce the optical depth reported by Planck, whereas inefficient star formation in these halos requires either about twice as many UV photons to escape, or an escape fraction that increases towards higher redshifts. Our models also predict how future observations with JWST can improve our understanding of these galaxy populations.

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“…Within the current ΛCDM paradigm, the first stars, the so-called Population III (Pop III), are predicted to have formed at redshifts z 20 − 30. Their emergence signals the rapid transformation of the universe into an increasingly complex, hierarchical system, due to the energy and heavy element input from Pop III stars and accreting black holes (Barkana & Loeb 2001;Bromm & Larson 2004;Ciardi & Ferrara 2005;Miralda-Escudé 2003). Currently, we can directly probe the state of the universe roughly a million years after the Big Bang by detecting the temperature anisotropies in the cosmic microwave background (CMB), thus providing us with the initial conditions for subsequent structure formation.…”

Section: Introductionmentioning

confidence: 99%

The Very First Stars: Formation and Reionization of the Universe

Bromm

2009

Proc. IAU

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Abstract. One of the key challenges for the next 10 years is to understand the first sources of light, the first stars and possibly accreting black holes. Their formation ended the cosmic dark ages at redshifts z 20 − 30, and signaled the transition from the simple initial state of the universe to one of ever increasing complexity. We here review recent progress in understanding the formation process of the first stars with numerical simulations, starting with cosmological initial conditions and modelling the detailed physics of accretion. Once formed, the first stars exerted crucial feedback on the primordial intergalactic medium, due to their input of radiation and of heavy chemical elements in the wake of supernova explosions. The current theoretical model posits that the first stars were predominantly very massive, typically ∼ 100M . Our predictions will be tested with upcoming near-infrared observatories, such as the James Webb Space Telecope, in the decade ahead.

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In the beginning: the first sources of light and the reionization of the universe

Cited by 1,365 publications

References 391 publications

The First Billion Years project: the escape fraction of ionizing photons in the epoch of reionization

The First Billion Years project: the escape fraction of ionizing photons in the epoch of reionization

Constraints on the star formation efficiency of galaxies during the epoch of reionization

The Very First Stars: Formation and Reionization of the Universe

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