The Effect of Galactic Properties on the Escape Fraction of Ionizing Photons

Abstract

The escape fraction, fesc, of ionizing photons from early galaxies is a crucial parameter for determining whether the observed galaxies at z > 6 are able to reionize the high-redshift intergalactic medium. Previous attempts to measure fesc have found a wide range of values, varying from less than 0.01 to nearly 1. Rather than finding a single value of fesc, we clarify through modeling how internal properties of galaxies affect fesc through the density and distribution of neutral hydrogen within the galaxy, along with the rate of ionizing photons production. We find that the escape fraction depends sensitively on the covering factor of clumps, along with the density of the clumped and interclump medium. One must therefore be cautious when dealing with an inhomogeneous medium. Fewer, high-density clumps lead to a greater escape fraction than more numerous low-density clumps. When more ionizing photons are produced in a starburst, fesc increases, as photons escape more readily from the gas layers. Large variations in the predicted escape fraction, caused by differences in the hydrogen distribution, may explain the large observed differences in fesc among galaxies. Values of fesc must also be consistent with the reionization history. High-mass galaxies alone are unable to reionize the universe, because fesc > 1 would be required. Small galaxies are needed to achieve reionization, with greater mean escape fraction in the past.

arXiv comment27 pages, 8 figures. Accepted to ApJ. v2: Improvements based on referee's comments

References in corpus (66)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• A Universal Density Profile from Hierarchical Clustering
• Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• The Formation of Galactic Disks
• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
• Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
• In the Beginning: The First Sources of Light and the Reionization of the Universe
• Wilkinson Microwave Anisotropy Probe (WMAP) First Year Observations: TE Polarization
• On the properties of massive Population III stars and metal-free stellar populations
• Radiative Transfer in a Clumpy Universe: III. The Nature of Cosmological Ionizing Sources
• Early Star Formation and the Evolution of the Stellar Initial Mass Function in Galaxies
• Lyman Continuum Emission from Galaxies at z~3.4
• Early star-forming galaxies and the reionization of the Universe
• The Direct Detection of Lyman-Continuum Emission from Star-forming Galaxies at z~3
• Large Area Survey for z=7 Galaxies in SDF and GOODS-N: Implications for Galaxy Formation and Cosmic Reionization
• Ionizing Photon Escape Fractions from High Redshift Dwarf Galaxies
• The Star Formation Rate of the Universe at z~6 from the Hubble Ultra Deep Field
• The Stellar Mass Density and Specific Star Formation Rate of the Universe at z~7
• Escape of Ionizing Radiation from High Redshift Galaxies
• z~7 Galaxies in the HUDF: First Epoch WFC3/IR Results
• Very blue UV-continuum slopes of low luminosity z~7 galaxies from WFC3/IR: Evidence for extremely low metallicities?
• Galaxies at z = 6 - 9 from the WFC3/IR imaging of the HUDF
• The Contribution of High Redshift Galaxies to Cosmic Reionization: New Results from Deep WFC3 Imaging of the Hubble Ultra Deep Field
• Escape fraction of ionizing photons from high-redshift galaxies in cosmological SPH simulations
• The Escape of Ionizing Photons from the Galaxy
• Detections of Lyman Continuum from Star-forming Galaxies at z~3 Through Subaru/Suprime-Cam Narrow-band Imaging
• On the Escape of Ionizing Radiation from Starbursts
• H_alpha Emission from High-Velocity Clouds and their Distances
• The Escape of Ionizing Photons from OB Associations in Disk Galaxies: Radiation Transfer Through Superbubbles
• The Galaxy Luminosity Function during the Reionization Epoch
• New Constraints on the Lyman Continuum Escape Fraction at z~1.3
• A Deep HST Search for Escaping Lyman Continuum Flux at z~1.3: Evidence for an Evolving Ionizing Emissivity
• The Great Observatories Origins Deep Survey: Constraints on the Lyman Continuum Escape Fraction Distribution of Lyman--Break Galaxies at 3.4<z<4.5
• Candidates of z ~ 5.5--7 Galaxies in the HST Ultra Deep Field
• Ionizing radiation from z=4-10 galaxies
• The Diverse Properties of the Most Ultraviolet Luminous Galaxies Discovered by the Galaxy Evolution Explorer
• Escape of Ionizing Radiation from High-Redshift Galaxies
• Measuring the Sources of the Intergalactic Ionizing Flux
• The Influence of Supershells and Galactic Outflows on the Escape of Ionizing Radiation from Dwarf Starburst Galaxies
• Re-examining the Lyman Continuum in Starburst Galaxies Observed with the Hopkins Ultraviolet Telescope
• Luminous Lyman Break Galaxies at z>5 and the Source of Reionization
• Galactic porosity and a star formation threshold for the escape of ionising radiation from galaxies
• A Hubble & Spitzer Space Telescope Survey for Gravitationally-Lensed Galaxies: Further Evidence for a Significant Population of Low Luminosity Galaxies beyond Redshift Seven
• Feedback in the local LBG Analog Haro 11 as probed by far-UV and X-ray observations
• A New Constraint on the Escape Fraction in Distant Galaxies Using Gamma-ray Burst Afterglow Spectroscopy
• Constraints on the Lyman continuum radiation from galaxies: first results with FUSE on Mrk 54
• Feedback from Galaxy Formation: Escaping Ionizing Radiation from Galaxies at High Redshift
• The UDF05 Follow-up of the HUDF: II. Constraints on Reionization from z-dropout Galaxies
• A Low Upper Limit to the Lyman Continuum Emission of two galaxies at z 3
• A Spectroscopic Search for Leaking Lyman Continuum at z~0.7
• Mission: Impossible (Escape from the Lyman Limit)
• Escape of ionizing radiation from star forming regions in young galaxies
• The Cosmic Near Infrared Background: Remnant Light from Early Stars
• An HST Search for Lyman Continuum Emission From Galaxies at z=1.1--1.4
• VLT narrow-band photometry in the Lyman continuum of two galaxies at z~3: Limits to the escape of ionizing flux
• Possible Detection of Cosmological Reionization Sources
• Contamination on Lyman continuum emission at z >= 3: implication on the ionising radiation evolution
• Lyman Continuum Escape from Inhomogeneous ISM
• Are There Enough Ionizing Photons to Reionize the Universe by z=6?
• New HST Observations of the Halo Gas of NGC 3067: Limits on the Extragalactic Ionizing Background at Low Redshift and the Lyman Continuum Escape Fraction
• Determining the escape fraction of ionizing photons during reionization with the GRB derived star-formation rate
• The escape fraction of ionizing photons from high redshift galaxies
• A Multiwavelength Study on the Fate of Ionizing Radiation in Local Starbursts
• The Hubble Deep Field in the Far Ultraviolet

Cited by in corpus (55)

• Gaseous Galaxy Halos
• The Birth of a Galaxy - III. Propelling reionisation with the faintest galaxies
• The mass evolution of the first galaxies: stellar mass functions and star formation rates at $4<z<7$ in the CANDELS GOODS-South field
• Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies
• The First Billion Years Project: The escape fraction of ionizing photons in the epoch of reionization
• CANDELS: The Contribution of the Observed Galaxy Population to Cosmic Reionization
• The spectral evolution of the first galaxies. II. Spectral signatures of Lyman continuum leakage from galaxies in the reionization epoch
• Observational constraints on the merger history of galaxies since $z\approx 6$: Probabilistic galaxy pair counts in the CANDELS fields
• The LyA-LyC Connection: Evidence for an Enhanced Contribution of UV-faint Galaxies to Cosmic Reionization
• Direct Detection of Lyman Continuum Escape from Local Starburst Galaxies with the Cosmic Origins Spectrograph
• Cosmic reionization after Planck
• The population of Milky Way satellites in the LambdaCDM cosmology
• Gas Clumping in Self-Consistent Reionisation Models
• The redshift evolution of escape fraction of hydrogen ionizing photons from galaxies
• New Insights on Ly-alpha and Lyman Continuum Radiative Transfer in the Greenest Peas
• The Luminosity Function at z~8 from 97 Y-band dropouts: Inferences About Reionization
• The escape fraction of ionizing photons from high redshift galaxies from data-constrained reionization models
• Evolution in the Escape Fraction of Ionizing Photons and the Decline in Strong Lya Emission from z>6 Galaxies
• The Evolution of O I over 3.2 < z < 6.5: Reionization of the Circumgalactic Medium
• The Efficiency of Stellar Reionization: Effects of Rotation, Metallicity, and Initial Mass Function
• Direct Numerical Simulation of Reionization II: Recombinations, Clumping Factors, and the Photon Budget for Reionization
• Runaway Stars and the Escape of Ionizing Radiation from High-Redshift Galaxies
• Intergalactic Lyman continuum photon budget in the past 5 billion years
• The impacts of ultraviolet radiation feedback on galaxies during the epoch of reionization
• Lyman continuum galaxies and the escape fraction of Lyman break galaxies
• Mrk 71/NGC 2366: The nearest Green Pea analog
• New Constraints on the Escape of Ionizing Photons From Starburst Galaxies Using Ionization-Parameter Mapping
• Properties of QSO Metal Line Absorption Systems at High Redshifts: Nature and Evolution of the Absorbers and New Evidence on Escape of Ionizing Radiation from Galaxies
• A suppressed contribution of low mass galaxies to reionization due to supernova feedback
• An Ionization Cone in the Dwarf Starburst Galaxy NGC 5253
• Dwarf Galaxies with Ionizing Radiation Feedback. I: Escape of Ionizing Photons
• Warm Ionized Gas Revealed in the Magellanic Bridge Tidal Remnant: Constraining the Baryon Content and the Escaping Ionizing Photons around Dwarf Galaxies
• Molecular gas and star formation in an absorption-selected galaxy: Hitting the bull's eye at z = 2.46
• Hubble Space Telescope Wide Field Camera 3 Observations of Escaping Lyman Continuum Radiation from Galaxies and Weak AGN at Redshifts $z$$\simeq$2.3-4.1
• Stellar feedback from HMXBs in cosmological hydrodynamical simulations
• Millimeter and Submillimeter Excess Emission in M33 revealed by Planck and LABOCA
• The Escape Fraction of Ionizing Radiation from Galaxies
• Statistical properties of mass, star formation, chemical content and rotational patterns in early z > 9 structures
• Effect of halo bias and Lyman Limit Systems on the history of cosmic reionization
• Lyman alpha emission from the first galaxies: Implications of UV backgrounds and the formation of molecules
• Stars and Reionization: The Cross-Correlation of the 21cm Line and the Near Infrared Background
• Constraining the Inflationary Equation of State
• The dust SED of dwarf galaxies I. The case of NGC 4214
• Impact of Population III homogeneous stellar evolution on early cosmic reionisation
• Global Correlations Between the Radio Continuum, Infrared and CO Emission in Dwarf Galaxies
• The End of an Era - The Population III to Population II Transition and the Near Infrared Background
• Non-parametric Reconstruction of Photon Escape Fraction from Reionization
• Formation and Radiative Feedback of First Objects and First Galaxies
• A Novel Approach to Constrain the Escape Fraction and Dust Content at High Redshift Using the Cosmic Infrared Background Fractional Anisotropy
• The near-infrared radiation background, gravitational wave background and star formation rate of Pop III and Pop II during cosmic reionization
• Modelling the escape of Lyman Continuum photons from galaxies in the Epoch of Reionization
• Diversity of the Lyman continuum escape fractions of high-$z$ galaxies and its origins
• The impact of cosmic ray feedback during the epoch of reionisation
• Model-independent Reconstruction of UV Luminosity Function and Reionization Epoch
• The haloes that reionized the Universe