Modeling Reionization in a Bursty Universe

Abstract

We present semi-analytic models of the epoch of reionization focusing on the differences between continuous and bursty star formation (SF). Our model utilizes physically motivated analytic fits to 1D radiative transfer simulations of HII regions around dark matter halos in a representative cosmic volume. Constraining our simulations with observed and extrapolated UV luminosity functions of high redshift galaxies, we find that for a fixed halo mass, stellar populations forming in bursty models produce larger HII regions which leave behind long-lived relic HII regions which are able to maintain partial ionization in the intergalactic medium (IGM) in a manner similar to an early X-ray background. The overall effect is a significant increase in the optical depth of the IGM, ${\tau }_e$, and a milder increase of the redshift of reionization. To produce ${\tau }_e=0.066$ observed by Planck and complete reionization by redshift $z_{\mathrm{re}}\sim 6$, models with bursty SF require an escape fraction $f_{\mathrm{esc}}\sim 2\%-10\%$ that is 2-10 times lower than $f_{\mathrm{esc}}\sim 17\%$ found assuming continuous SF and is consistent with upper limits on $f_{\mathrm{esc}}$ from observations at $z=0$ and $z\sim 1.3-6$. The ionizing photon budget needed to reproduce the observed ${\tau }_e$ and $z_{\mathrm{re}}$ depends on the period and duty cycle of the bursts of SF and the temperature of the neutral IGM. These results suggest that the tension between observed and predicted ionizing photon budget for reionization can be alleviated if reionization is driven by short bursts of SF, perhaps relating to the formation of Population~III stars and compact star clusters such as proto-globular clusters.

17 pages, 11 figures, 1 table. Submitted to MNRAS

References in corpus (24)

• A luminous quasar at a redshift of z = 7.085
• A New Calculation of the Ionizing Background Spectrum and the Effects of HeII Reionization
• Model-independent evidence in favor of an end to reionization by z~6
• Reionization after Planck: The Derived Growth of the Cosmic Ionizing Emissivity now matches the Growth of the Galaxy UV Luminosity Density
• Effect of Primordial Black Holes on the Cosmic Microwave Background and Cosmological Parameter Estimates
• Escape fraction of ionizing photons during reionization: effects due to supernova feedback and runaway OB stars
• The morphology of HII regions during reionization
• The observed ionization rate of the intergalactic medium and the ionizing emissivity at z >5: Evidence for a photon starved and extended epoch of reionization
• The Direct Detection of Lyman-Continuum Emission from Star-forming Galaxies at z~3
• Evolution of the Intergalactic Opacity: Implications for the Ionizing Background, Cosmic Star Formation, and Quasar Activity
• Rapid Decline of Lyman-alpha Emission Toward the Reionization Era
• Cosmic Reionization On Computers I. Design and Calibration of Simulations
• New Constraints on the Lyman Continuum Escape Fraction at z~1.3
• The Difficulty of Getting High Escape Fractions of Ionizing Photons from High-redshift Galaxies: a View from the FIRE Cosmological Simulations
• Cosmic reionization after Planck
• Imprint of Inhomogeneous Hydrogen Reionization on the Temperature Distribution of the Intergalactic Medium
• Cosmic Reionization On Computers II. Reionization History and Its Back Reaction on Early Galaxies
• Relative Role of Stars and Quasars in Cosmic Reionization
• The Local Group as a time machine: studying the high-redshift Universe with nearby galaxies
• Spatially adaptive radiation-hydrodynamical simulations of galaxy formation during cosmological reionization
• Clues on the Missing Sources of Reionization from Self-consistent Modeling of Milky Way and Dwarf Galaxy Globular Clusters
• Quasar H II Regions During Cosmic Reionization
• Are There Enough Ionizing Photons to Reionize the Universe by z=6?
• Radiation-induced large-scale structure during the reionization epoch: the autocorrelation function

Cited by in corpus (13)

• Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies
• Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph
• The spectral evolution of the first Galaxies. III. Simulated James Webb Space Telescope spectra of reionization-epoch galaxies with Lyman continuum leakage
• Simulating Star Clusters Across Cosmic Time: I. Initial Mass Function, Star Formation Rates and Efficiencies
• Growth of First Galaxies: Impacts of Star Formation and Stellar Feedback
• Simulating Star Clusters Across Cosmic Time: II. Escape Fraction of Ionizing Photons from Molecular Clouds
• SPICE: the connection between cosmic reionisation and stellar feedback in the first galaxies
• Violent starbursts and quiescence induced by FUV radiation feedback in metal-poor galaxies at high-redshift
• Prospects for distinguishing galaxy evolution models with surveys at redshifts $z\gtrsim 4$
• The high-redshift tail of stellar reionization in LCDM is beyond the reach of the low-$\ell$ CMB
• Ghostly Stellar Haloes and their Relationship to Ultra-faint Dwarfs
• Identifying reionization-epoch galaxies with extreme levels of Lyman continuum leakage in James Webb Space Telescope surveys
• ARC: Adaptive Ray-tracing with CUDA, a New Ray Tracing Code for Parallel GPUs