Observing the Redshifted 21 cm Signal around a Bright QSO at z ∼ 10

Ma, Qing-Bo; Ciardi, B.; Kakiichi, Koki; Zaroubi, Saleem; Zhi, Qi‐Jun; Busch, Philipp

doi:10.3847/1538-4357/ab5b95

Cited by 13 publications

(8 citation statements)

References 59 publications

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“…Whenever the cell size is too large to resolve the sharp ionization front expected from stellar type sources, the cell containing the front appears partially ionized and warm, as in our simulations, while in reality part of the gas in the cell should be neutral and cold, and part fully ionized and hot. We discuss this issue more in detail in Ma et al (2020) and Ma et al (2020b, in prep).…”

Section: Reionization and Reheating Historymentioning

confidence: 93%

Large scale simulations of H and He reionization and heating driven by stars and more energetic sources

Eide,

Ciardi,

Graziani

et al. 2020

Preprint

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We present simulations of cosmic reionization and reheating from z = 18 to z = 5, investigating the role of stars (emitting soft UV-photons), nuclear black holes (BHs, with power-law spectra), X-ray binaries (XRBs, with hard X-ray dominated spectra), and the supernova-associated thermal bremsstrahlung of the diffuse interstellar medium (ISM, with soft X-ray spectra). We postprocess the hydrodynamical simulation Massive-Black II (MBII) with multifrequency ionizing radiative transfer. The source properties are directly derived from the physical environment of MBII, and our only real free parameter is the ionizing escape fraction f esc . We find that, among the models explored here, the one with an escape fraction that decreases with decreasing redshift yields results most in line with observations, such as of the neutral hydrogen fraction and the Thomson scattering optical depth. Stars are the main driver of hydrogen reionization and consequently of the thermal history of the intergalactic medium (IGM). We obtain x HII = 0.99998 at z = 6 for all source types, with volume averaged temperatures T ∼ 20, 000 K. BHs are rare and negligible to hydrogen reionization, but conversely they are the only sources which can fully ionize helium, increasing local temperatures by ∼ 10 4 K. The thermal and ionization state of the neutral and lowly ionized hydrogen differs significantly with different source combinations, with ISM and (to a lesser extent) XRBs, playing a significant role and, as a consequence, determining the transition from absorption to emission of the 21 cm signal from neutral hydrogen.

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Section: Reionization and Reheating Historymentioning

confidence: 93%

Large scale simulations of H and He reionization and heating driven by stars and more energetic sources

Eide,

Ciardi,

Graziani

et al. 2020

Preprint

Self Cite

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“…As in Ma21, we include redshift-space distortion effects with the approach of Mao et al (2012), as well as the temperature corrections necessary to overcome the impossibility of resolving the ionization front in such large scale simulations. Such technique has been introduced and described in Ma et al (2020b). As discussed in Ma21, the temperature correction not only changes the statistics of the 21 cm signal during the early stages of the EoR (e.g.…”

Section: CM Signalmentioning

confidence: 99%

A CRASH simulation of the contribution of binary stars to the epoch of reionization

Ma,

Fiaschi,

Ciardi

et al. 2022

Preprint

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We use a set of 3D radiative transfer simulations to study the effect that a large fraction of binary stars in galaxies during the epoch of reionization has on the physical properties of the intergalactic medium (i.e. the gas temperature and the ionization state of hydrogen and helium), on the topology of the ionized bubbles and on the 21 cm power spectra. Consistently to previous literature, we find that the inclusion of binary stars can speed up the reionization process of HI and HeI, while HeII reionization is still dominated by more energetic sources, especially accreting black holes. The earlier ionization attained with binary stars allows for more time for cooling and recombination, so that gas fully ionized by binary stars is typically colder than that ionized by single stars at any given redshift. With the same volume averaged ionization fraction, the inclusion of binary stars results in fewer small ionized bubbles and more large ones, with visible effects also on the large scales of the 21 cm power spectrum.

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“…Here we note that, as numerical simulations on large scales are not able to resolve the ionization front for short mean free path photons, such as in the case of the pure UV spectrum in the GAL scenario (Ross et al 2017), the cells that contain the front can falsely appear as partially ionized and warm (see also discussion in E18 and E20), leading to wrong predictions of the 21 cm signal. To correct for this effect, we adopted the post-processing technique described in Ma et al (2020). More specifically, each partially ionized cell is divided into 8 sub-cells that are either fully ionized or completely neutral, depending on their minimal distance from the fully ionized cells calculated with the Euclidean distance transform (Rosenfeld & Pfaltz 1966;Busch et al 2020).…”

Section: Simulations Of Cosmic Reionizationmentioning

confidence: 99%

Investigating X-ray sources during the epoch of reionization with the 21 cm signal

Ma,

Ciardi,

Eide

et al. 2021

Preprint

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Heating of neutral gas by energetic sources is crucial for the prediction of the 21 cm signal during the epoch of reionization (EoR). To investigate differences induced on statistics of the 21 cm signal by various source types, we use five radiative transfer simulations which have the same stellar UV emission model and varying combinations of more energetic sources, such as X-ray binaries (XRBs), accreting nuclear black holes (BHs) and hot interstellar medium emission (ISM). We find that the efficient heating from the ISM increases the average global 21 cm signal, while reducing its fluctuations and thus power spectrum. A clear impact is also observed in the bispectrum in terms of scale and timing of the transition between a positive and a negative value. The impact of XRBs is similar to that of the ISM, although it is delayed in time and reduced in intensity because of the less efficient heating. Due to the paucity of nuclear BHs, the behaviour of the 21 cm statistics in their presence is very similar to that of a case when only stars are considered, with the exception of the latest stages of reionization, when the effect of BHs is clearly visible. We find that differences between the source scenarios investigated here are larger than the instrumental noise of SKA1-low at z 7 − 8, suggesting that in the future it might be possible to constrain the spectral energy distribution of the sources contributing to the reionization process.

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Observing the Redshifted 21 cm Signal around a Bright QSO at z ∼ 10

Cited by 13 publications

References 59 publications

Large scale simulations of H and He reionization and heating driven by stars and more energetic sources

Large scale simulations of H and He reionization and heating driven by stars and more energetic sources

A CRASH simulation of the contribution of binary stars to the epoch of reionization

Investigating X-ray sources during the epoch of reionization with the 21 cm signal

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