The escape of ionising radiation from high-redshift dwarf galaxies

Paardekooper, Jan‐Pieter; Pelupessy, F. I.; Altay, Gabriel; Kruip, Chael

doi:10.1051/0004-6361/201116841

Cited by 58 publications

(76 citation statements)

References 86 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous studies have shown the importance of the porosity of the inter-stellar medium for the escape fraction (Ciardi et al 2002;Fernandez & Shull 2011), especially in the vicinity of the sources (Paardekooper et al 2011). Our results refine the study of Kimm & Cen (2014), who found that in galaxies of low escape fraction the optical depth in a radius of 100 pc is ∼ 2 − 4, large enough to absorb the majority of produced ionizing photons.…”

Section: Discussionsupporting

confidence: 87%

“…However, high resolution is essential for the computation of the escape fraction, since the main constraint on the escape fraction is the local environment of the sources (Paardekooper et al 2011). Furthermore, this high resolution is necessary to resolve star formation in the abundant low-mass proto-galaxies that are likely the main drivers of reionization (Paper I, Wise et al 2014).…”

Section: Computation Of the Escape Fraction Of Ionizing Photons From mentioning

confidence: 99%

“…Although the gas density is generally not uniformly distributed in galaxies, the gas density around the sites of star formation can be so high that the recombination rate of the gas prevents any photons from escaping. In idealised simulations of disc galaxies this prevents any ionizing photons from escaping except when feedback clears away (part of) this dense gas (Paardekooper et al 2011). In our much larger sample we can now study whether this is also the case for haloes in a cosmological simulation.…”

Section: Absorption Of the Ionizing Radiationmentioning

confidence: 99%

See 2 more Smart Citations

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

250

280

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionsupporting

confidence: 87%

Section: Computation Of the Escape Fraction Of Ionizing Photons From mentioning

confidence: 99%

Section: Absorption Of the Ionizing Radiationmentioning

confidence: 99%

See 1 more Smart Citation

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

250

280

View full text Add to dashboard Cite

show abstract

“…However, the value of f esc for an individual galaxy is strongly dependent on its chemical, structural, and kinematic properties, and there exists considerable theoretical and observational evidence to suggest that the average f esc does indeed vary with redshift, mass, and/or star formation rate (e.g. Gnedin et al 2008;Wise & Cen 2009;Paardekooper et al 2011;Yajima et al 2011;Kuhlen & Faucher-Giguère 2012;Mitra et al 2013;Paardekooper et al 2015). …”

Section: An Evolving Escape Fractionmentioning

confidence: 99%

Dark-ages reionization and galaxy formation simulation – III. Modelling galaxy formation and the epoch of reionization

Mutch

Geil

Poole

et al. 2016

Mon. Not. R. Astron. Soc.

141

160

View full text Add to dashboard Cite

We introduce Meraxes, a new, purpose-built semi-analytic galaxy formation model designed for studying galaxy growth during reionization. Meraxes is the first model of its type to include a temporally and spatially coupled treatment of reionization and is built upon a custom (100 Mpc) 3 N -body simulation with high temporal and mass resolution, allowing us to resolve the galaxy and star formation physics relevant to early galaxy formation. Our fiducial model with supernova feedback reproduces the observed optical depth to electron scattering and evolution of the galaxy stellar mass function between z=5 and 7, predicting that a broad range of halo masses contribute to reionization. Using a constant escape fraction and global recombination rate, our model is unable to simultaneously match the observed ionizing emissivity at z < ∼ 6. However, the use of an evolving escape fraction of 0.05-0.1 at z∼6, increasing towards higher redshift, is able to satisfy these three constraints. We also demonstrate that photoionization suppression of low mass galaxy formation during reionization has only a small effect on the ionization history of the inter-galactic medium. This lack of 'selfregulation' arises due to the already efficient quenching of star formation by supernova feedback. It is only in models with gas supply-limited star formation that reionization feedback is effective at regulating galaxy growth. We similarly find that reionization has only a small effect on the stellar mass function, with no observationally detectable imprint at M * >10 7.5 M . However, patchy reionization has significant effects on individual galaxy masses, with variations of factors of 2-3 at z=5 that correlate with environment.

show abstract

“…However, SNe may also open low-density channels in the ISM, e.g. by expelling gas in winds, through which ionizing photons may escape more easily (e.g., Dove, Shull, & Ferrara 2000;Fujita et al 2003;Wise & Cen 2009;Paardekooper et al 2011). This makes it easier for galaxies to reionize the Universe.…”

Section: Impact On Reionizationmentioning

confidence: 99%

Spatially adaptive radiation-hydrodynamical simulations of galaxy formation during cosmological reionization

Pawlik

Schaye

Vecchia

2015

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present a suite of cosmological radiation-hydrodynamical simulations of the assembly of galaxies driving the reionization of the intergalactic medium (IGM) at z 6. The simulations account for the hydrodynamical feedback from photoionization heating and the explosion of massive stars as supernovae (SNe). Our reference simulation, which was carried out in a box of size 25 h −1 comoving Mpc using 2 × 512 3 particles, produces a reasonable reionization history and matches the observed UV luminosity function of galaxies. Simulations with different box sizes and resolutions are used to investigate numerical convergence, and simulations in which either SNe or photoionization heating or both are turned off, are used to investigate the role of feedback from star formation. Ionizing radiation is treated using accurate radiative transfer at the high spatially adaptive resolution at which the hydrodynamics is carried out. SN feedback strongly reduces the star formation rates (SFRs) over nearly the full mass range of simulated galaxies and is required to yield SFRs in agreement with observations. Photoheating helps to suppress star formation in low-mass galaxies, but its impact on the cosmic SFR is small. Because the effect of photoheating is masked by the strong SN feedback, it does not imprint a signature on the UV galaxy luminosity function, although we note that our resolution is insufficient to model star-forming minihaloes cooling through molecular hydrogen transitions. Photoheating does provide a strong positive feedback on reionization because it smooths density fluctuations in the IGM, which lowers the IGM recombination rate substantially. Our simulations demonstrate a tight non-linear coupling of galaxy formation and reionization, motivating the need for the accurate and simultaneous inclusion of photoheating and SN feedback in models of the early Universe.

show abstract

The escape of ionising radiation from high-redshift dwarf galaxies

Cited by 58 publications

References 86 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

Dark-ages reionization and galaxy formation simulation – III. Modelling galaxy formation and the epoch of reionization

Spatially adaptive radiation-hydrodynamical simulations of galaxy formation during cosmological reionization

Contact Info

Product

Resources

About