Distinctive rings in the 21 cm signal of the epoch of reionization

Vonlanthen, Patrick; Semelin, B.; Baek, Sunghye; Revaz, Yves

doi:10.1051/0004-6361/201116811

Cited by 22 publications

(40 citation statements)

References 35 publications

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“…Majumdar et al (2012) devised an anisotropic filter to detect individual ionised bubbles around bright quasars and study how the age and luminosity of the quasar can be constrained, see also section 3.8.1. Vonlanthen et al (2011) estimated the observability by the SKA of faint rings around ionizing sources created by the Wouthuysen-Field effect of upper Lyman lines. They emphasize how both resolution and the ability to stack a large number of objects, and thus a large FoV, are crucial factors for this type of analysis.…”

Section: Tomography and Its Analysismentioning

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: Tomography and Its Analysismentioning

confidence: 99%

Reionization and the Cosmic Dawn with the Square Kilometre Array

et al. 2013

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“…To compute the spin temperature of hydrogen, the local Lyman alpha flux is required. LICORICE computes the transfer in the resonant Lyman lines on a fixed grid, post-processing the radiative hydrodynamic simulations (Semelin et al 2007;Vonlanthen et al 2011). The radiative hydrodynamic part of LICORICE benefits from double MPI+OpenMP parallelization (briefly described in Semelin 2016), while the Lyman line transfer is OpenMP parallelized with a simple MPI overlay (no domain decomposition).…”

Section: The Licorice Codementioning

confidence: 99%

“…xα can be computed from the local Lyman-α flux Jα using the procedure described in Hirata (2006) that includes the backreaction of the gas on the shape of the spectrum near the Lyman-α line. To obtain the local Lyman-α flux, we perform the full radiative transfer computation in the Lyman lines (see Vonlanthen et al 2011). Then, the driving factor is the emissivity of the sources in the Lyman band.…”

Section: A Choice Of 3-parameter Spacementioning

confidence: 99%

21SSD: a public data base of simulated 21-cm signals from the epoch of reionization

Semelin

Eames

Bolgar

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The 21-cm signal from the Epoch of Reionization (EoR) is expected to be detected in the next few years, either with existing instruments or by the upcoming SKA and HERA projects. In this context there is a pressing need for publicly available highquality templates covering a wide range of possible signals. These are needed both for end-to-end simulations of the up-coming instruments, as well as to develop signal analysis methods. In this work we present such a set of templates, publicly available, for download at 21ssd.obspm.fr. The database contains 21-cm brightness temperature lightcones at high and low resolution, and several derived statistical quantities for 45 models spanning our choice of 3D parameter space. These data are the result of fully coupled radiative hydrodynamic high resolution (1024 3 ) simulations performed with the LICORICE code. Both X-ray and Lyman line transfer is performed to account for heating and Wouthuysen-Field coupling fluctuations. We also present a first exploitation of the data using the power spectrum and the Pixel Distribution Function (PDF) as functions of redshifts, computed from lightcone data. We analyse how these two quantities behave when varying the model parameters while taking into account the thermal noise expected of a typical SKA survey. Finally, we show that the power spectrum and the PDF have different -and to some extent complementary -abilities to distinguish between different models. This opens the door to formulating an optimal sampling of the parameter space, dependant on the chosen diagnostics.

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“…The 3D transfer through the IGM of Lyman-band photons produced by stars and their scattering in the Ly-α to Ly-ζ lines is computed using the (currently distinct) version of LICORICE described in Semelin et al (2007a) and Vonlanthen et al (2011). Estimating the local flux at Ly-α frequency everywhere in the simulation box is necessary to accurately compute the spin temperature of hydrogen and thus the brightness temperature of the 21-cm signal.…”

Section: The Ly-α Transfer Simulationmentioning

confidence: 99%

Imprints of quasar duty cycle on the 21-cm signal from the Epochof Reionization

Bolgar

Eames

Hottier

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Quasars contribute to the 21-cm signal from the Epoch of Reionization (EoR) primarily through their ionizing UV and X-ray emission. However, their radio continuum and Lyman-band emission also regulates the 21-cm signal in their direct environment, potentially leaving the imprint of their duty cycle.We develop a model for the radio and UV luminosity functions of quasars from the EoR, and constrain it using recent observations. Our model is consistent with the z ∼ 7.5 quasar from Bañados et al. (2017), and also predicts only a few quasars suitable for 21-cm forest observations (∼ 10 mJy) in the sky. We exhibit a new effect on the 21cm signal observed against the CMB: a radio-loud quasar can leave the imprint of its duty cycle on the 21-cm tomography. We apply this effect in a cosmological simulation and conclude that the effect of typical radio-loud quasars is most likely negligible in an SKA field of view. For a 1 − 10mJy quasar the effect is stronger though hardly observable at SKA resolution. Then we study the contribution of the lyman band Ly-α to Ly-β) emission of quasars to the Wouthuisen-Field coupling. The collective effect of quasars on the 21-cm power spectrum is larger than the thermal noise at low k, though featureless. However, a distinctive pattern around the brightest quasars in an SKA field of view may be observable in the tomography, encoding the duration of their duty cycle. This pattern has a high signal-to-noise ratio for the brightest quasar in a typical SKA shallow survey.

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Distinctive rings in the 21 cm signal of the epoch of reionization

Cited by 22 publications

References 35 publications

Reionization and the Cosmic Dawn with the Square Kilometre Array

Reionization and the Cosmic Dawn with the Square Kilometre Array

21SSD: a public data base of simulated 21-cm signals from the epoch of reionization

Imprints of quasar duty cycle on the 21-cm signal from the Epochof Reionization

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