Prospects of observing a quasar H ii region during the epoch of reionization with the redshifted 21-cm signal

Datta, Kanan K.; Friedrich, Martina M.; Mellema, Garrelt; Iliev, Ilian T.; Shapiro, Paul R.

doi:10.1111/j.1365-2966.2012.21268.x

Cited by 41 publications

(63 citation statements)

References 90 publications

(145 reference statements)

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“…Targeted observations of HII regions around known luminous QSOs will provide unique and more detailed information about their size and shape (Wyithe et al 2005;Datta et al 2008;Majumdar et al 2011;Datta et al 2012a). The anisotropy in the HII region shape which may arise due the rapidly expanding ionization font ) and finite light travel time (Wyithe et al 2005;Yu 2005;Majumdar et al 2011) can also be probed with SKA.…”

Section: Individual Qsosmentioning

confidence: 99%

“…The anisotropy in the HII region shape which may arise due the rapidly expanding ionization font ) and finite light travel time (Wyithe et al 2005;Yu 2005;Majumdar et al 2011) can also be probed with SKA. 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).…”

Section: Individual Qsosmentioning

confidence: 99%

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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%

Section: Individual Qsosmentioning

confidence: 99%

Reionization and the Cosmic Dawn with the Square Kilometre Array

et al. 2013

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“…To date, all C 2 -RAY simulations of reionization did not consider the thermal evolution and therefore those results remain valid (e.g. Iliev et al 2012;Datta et al 2012;Iliev et al 2014). Since the recombination rates only weakly depend on the temperature, the thermal state of the gas does not influence the reionization process much.…”

Section: Discussionmentioning

confidence: 99%

“…C 2 -RAY (Mellema et al 2006) is a time-dependent photoionization code which has been used extensively for reionization simulations (see for example Iliev et al 2006cIliev et al , 2011Datta et al 2012;Iliev et al 2014). Its efficiency is based partly on the use of an implicit method which allows the use of relatively large timesteps while retaining accuracy.…”

Section: Introductionmentioning

confidence: 99%

Efficient photoheating algorithms in time-dependent photoionization simulations

Lee

Mellema

Lundqvist

2015

Mon. Not. R. Astron. Soc.

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We present an extension to the time-dependent photo-ionization code C 2 -RAY to calculate photo-heating in an efficient and accurate way. In C 2 -RAY, the thermal calculation demands relatively small time-steps for accurate results. We describe two novel methods to reduce the computational cost associated with small time-steps, namely, an adaptive time-step algorithm and an asynchronous evolution approach. The adaptive time-step algorithm determines an optimal time-step for the next computational step. It uses a fast ray-tracing scheme to quickly locate the relevant cells for this determination and only use these cells for the calculation of the time-step. Asynchronous evolution allows different cells to evolve with different timesteps. The asynchronized clocks of the cells are synchronized at the times where outputs are produced. By only evolving cells which may require short time-steps with these short timesteps instead of imposing them to the whole grid, the computational cost of the calculation can be substantially reduced. We show that our methods work well for several cosmologically relevant test problems and validate our results by comparing to the results of another timedependent photo-ionization code.

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“…On much larger scales (box size of 425/h Mpc comoving) the same technique was used to perform the largestvolume, ray-tracing simulations of cosmic reionization to date, presented in Iliev et al (2014) and further explored in Datta et al (2012), Park et al (2013) and Shapiro et al (2013). This used the results in Section 4.2.2 to include the unresolved low-mass atomic cooling haloes (M = 10 8 − 10 9 M⊙).…”

Section: Introductionmentioning

confidence: 99%

Non-linear bias of cosmological halo formation in the early universe

Ahn

Iliev

Shapiro

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We present estimates of the nonlinear bias of cosmological halo formation, spanning a wide range in the halo mass from ∼ 10 5 M ⊙ to ∼ 10 12 M ⊙ , based upon both a suite of high-resolution cosmological N-body simulations and theoretical predictions. The halo bias is expressed in terms of the mean bias and stochasticity as a function of local overdensity (δ), under different filtering scales, which is realized as the density of individual cells in uniform grids. The sampled overdensities span a range wide enough to provide the fully nonlinear bias effect on the formation of haloes. A strong correlation between δ and halo population overdensity δ h is found, along with sizable stochasticity. We find that the empirical mean halo bias matches, with good accuracy, the prediction by the peak-background split method based on the excursion set formalism, as long as the empirical, globally-averaged halo mass function is used. Consequently, this bias formalism is insensitive to uncertainties caused by varying halo identification schemes, and can be applied generically. We also find that the probability distribution function of biased halo numbers has wider distribution than the pure Poisson shot noise, which is attributed to the sub-cell scale halo correlation. We explicitly calculate this correlation function and show that both overdense and underdense regions have positive correlation, leading to stochasticity larger than the Poisson shot noise in the range of haloes and halo-collapse epochs we study.

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Prospects of observing a quasar H ii region during the epoch of reionization with the redshifted 21-cm signal

Cited by 41 publications

References 90 publications

Reionization and the Cosmic Dawn with the Square Kilometre Array

Reionization and the Cosmic Dawn with the Square Kilometre Array

Efficient photoheating algorithms in time-dependent photoionization simulations

Non-linear bias of cosmological halo formation in the early universe

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