The impact of a percolating IGM on redshifted 21-cm observations of quasar H ii regions

Geil, Paul M.; Wyithe, J. Stuart B.

doi:10.1111/j.1365-2966.2008.13159.x

Cited by 75 publications

(104 citation statements)

References 49 publications

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“…This information can further be used to calculate the QSO luminosity and age with higher accuracy, providing crucial parameters for understanding the formation of SMBHs during the EoR (Datta et al 2012a;Majumdar et al 2012). In addition, measurements of the contrast in 21cm emission between HII regions and the surrounding regions will provide measurements of the hydrogen neutral fraction of the outside IGM (Geil & Wyithe 2008). These measurements will be complementary to power spectrum measurements.…”

Section: Individual Qsosmentioning

confidence: 99%

Reionization and the Cosmic Dawn with the Square Kilometre Array

et al. 2013

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The Square Kilometre Array (SKA) will have a low frequency component (SKA-low) which has as one of its main science goals the study of the redshifted 21cm line from the earliest phases of star and galaxy formation in the Universe. This 21cm signal provides a new and unique window both on the time of the formation of the first stars and accreting black holes and the subsequent period of substantial ionization of the intergalactic medium. The signal will teach us fundamental new things about the earliest phases of structure formation, cosmology and even has the potential to lead to the discovery of new physical phenomena. Here we present a white paper with an Executive SummaryThe Square Kilometre Array (SKA) will have a low frequency component (AA-low/SKA-low 1 ) which has as one of its main science goals the study of the redshifted 21cm line from the earliest phases of star and galaxy formation in the Universe (see SKA Memo 125). It is during this phase that the first building blocks of the galaxies that we see around us today, including our own Milky Way, were formed. It is a crucial period for understanding the history of the Universe and one for which we have currently very little observational data.We divide the period into two different phases based on the physical processes which affect the Intergalactic Medium. The first period, which we call the Cosmic Dawn, saw the formation of the first stars and accreting black holes, which changed the quantum state of the still neutral Intergalactic Medium. The second period, known as the Epoch of Reionization, is the one during which large areas between the galaxies were photo-ionized by the radiation produced in galaxies and which ended when the Intergalactic Medium had become completely ionized.Observations of the redshifted 21-cm line with SKA will provide a new and unique window on the entire period of Cosmic Dawn and Reionization. The signal is sensitive to the emergence of the first stellar populations, radiation from growing massive black holes and the formation of larger groups of galaxies and bright quasars. At the same time it maps the distribution of most of the baryonic matter in the Universe. The study of the redshifted 21cm line will teach us fundamental new things about the earliest phases of structure formation and cosmology. It even has the potential to lead to the discovery of new physical phenomena. Here we present an overview of the science questions that SKA-low can address, how we plan to tackle these questions and what this implies for the basic design of the telescope.The redshifted 21cm signal will be analyzed with different techniques, which each come with their own requirements for the SKA: (i) Tomography, (ii) power-spectra and higher-order statistics, (iii) hydrogen absorption, (iv) global/total-intensity signal. Whereas all precursors/pathfinders aim to study the signal statistically through its power spectrum, SKA will be able to image the neutral hydrogen distribution directly and its focus will therefore be more on tomograph...

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Section: Individual Qsosmentioning

confidence: 99%

Reionization and the Cosmic Dawn with the Square Kilometre Array

et al. 2013

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“…For example, a compact core is not ideal for detecting the 21 cmYgalaxy crosspower spectrum: here one needs to balance the MWA's high sensitivity along the line of sight, but poor transverse sensitivity, with the galaxy survey's poor line-of-sight sensitivity, due to uncertainties in photometric redshifts, yet superior transverse sensitivity . The MWA program to image quasar H ii regions (Geil & Wyithe 2008) may also suffer from reduced angular resolution. In practice, the MWA might start with an r À2 configuration, or a slightly more compact arrangement, and gradually add antennae into a compact core.…”

Section: Array Configuration Trade-offsmentioning

confidence: 99%

Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array

Lidz

Zahn

McQuinn

et al. 2008

ApJ

176

280

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We forecast the sensitivity with which the Murchison Widefield Array (MWA) can measure the 21 cm power spectrum of cosmic hydrogen. The MWA is sensitive to roughly a decade in scale (wavenumbers of k $ 0:1Y1 h Mpc À1 ). This amounts primarily to constraints on two numbers: the amplitude and the slope of the 21 cm power spectrum on the scales probed. We find, however, that the redshift evolution in these quantities can yield important information about reionization. We examine a range of theoretical models, spanning uncertainties in the nature of the ionizing sources and the abundance of minihalos during reionization. Although the power spectrum differs substantially among these models, a generic prediction is that the amplitude of the 21 cm power spectrum on MWA scales (k $ 0:4 h Mpc À1 ) peaks near the epoch when the intergalactic medium (IGM) is %50% ionized. Moreover, the slope of the 21 cm power spectrum flattens as the ionization fraction increases and the sizes of the H ii regions grow. With regards to detection sensitivity, we show that the optimal MWA antenna configuration for power spectrum measurements would pack all 500 antenna tiles as closely as possible in a compact core. Detecting the characteristic redshift evolution of our models will help to confirm that observed 21 cm fluctuations originate from the IGM, and not from foregrounds, and will provide an indirect constraint on the evolution of the volume-filling factor of H ii regions during reionization. After two years of observations, the MWA can constrain the filling factor at an epoch when x i h i$ 0:5 to within roughly AE x i h i$ 0:1 at 2 confidence. Subject headingg s: cosmology: theory -intergalactic medium -large-scale structure of universe

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“…A radiative transfer method (for example ray-tracing algorithms) can then be used to calculate the ionization structure on large scales. In recent years, new hybrid, or semi-numerical models (Mesinger & Furlanetto 2007;Geil & Wyithe 2008;Kim et al 2013a) have been developed that combine N -body simulations with analytical methods to enable the calculation of reionization structure in very large volumes with high efficiency. These methods have elucidated the primary features of the ionization structure during reionization, but do not capture the physics of galaxy formation.…”

Section: Introductionmentioning

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.

Self Cite

144

160

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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.

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The impact of a percolating IGM on redshifted 21-cm observations of quasar H ii regions

Cited by 75 publications

References 49 publications

Reionization and the Cosmic Dawn with the Square Kilometre Array

Reionization and the Cosmic Dawn with the Square Kilometre Array

Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array

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

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