Statistical Features of 21 Centimeter Emission from the Epoch between Reionization and the Gunn‐Peterson Transparency

He, Pinjia; Liu, Ji-Ren; Feng, Long-Long; Bi, Hongguang; Fang, Li‐Zhi

doi:10.1086/423663

Cited by 5 publications

(5 citation statements)

References 45 publications

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“…We concentrate solely on the redshifted 21 cm signal in the frequency domain, because, as has been shown before, foreground contamination is a severe limiting factor in observing the cosmological features in the angular domain on the sky (Di Matteo et al 2002;Oh & Mack 2004;Gnedin & Shaver 2004). Several recent papers have discussed elegant and sophisticated approaches to circumventing this contamination (Zaldarriaga, Furlanetto & Hernquist 2004;He et al 2004;Santos et al 2004, Loeb & Zaldarriaga 2004), but these approaches would require bigger telescopes than currently planned, so it is most likely that the first detections will be made in the frequency domain and attempts to de-contaminate the angular signal will require follow-on observations.…”

Section: Introductionmentioning

confidence: 99%

Redshifted 21 cm Emission from the Pre‐Reionization Era. II. HiiRegions around Individual Quasars

Kohler¹,

Gnedin²,

Miralda-Escudé³

et al. 2005

ApJ

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We use cosmological simulations of reionization to predict the effect of large H II regions around individual high-redshift quasars on the possible signal from the redshifted 21 cm line of neutral hydrogen in the pre-reionization era. We show that these H II regions appear as "spectral dips" in frequency space with equivalent widths in excess of 3 mK MHz or depths in excess of about 1.5 mK, and that they are by far the most prominent cosmological signals in the redshifted H I distribution.These spectral dips are expected to be present in almost every line of sight. If the spectral dips of a large enough sample of H II regions are well resolved in frequency space, the distribution of line depth and equivalent width in frequency with a known observing beamsize can be used to infer the H II region size distribution and the mean difference in neutral hydrogen density between the H II regions ( which may contain self-shielded neutral gas clumps) and the surrounding medium, providing a powerful test for models of reionization.

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Section: Introductionmentioning

confidence: 99%

Redshifted 21 cm Emission from the Pre‐Reionization Era. II. HiiRegions around Individual Quasars

Kohler¹,

Gnedin²,

Miralda-Escudé³

et al. 2005

ApJ

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“…The 21‐cm signal from the high‐redshift Universe has been studied in relation to minihaloes (MHs; Iliev et al 2002; Furlanetto & Oh 2006; Shapiro et al 2006) and the IGM (e.g. Tozzi et al 2000; Ciardi & Madau 2003; He et al 2004; Furlanetto, Sokasian & Hernquist 2004; Furlanetto, Zaldarriaga & Hernquist 2004; Mellema et al 2006; Santos et al 2008). Prior to the formation of radiation sources, the IGM is cold and neutral and the 21‐cm line is expected to be observed in absorption against the CMB.…”

Section: Introductionmentioning

confidence: 99%

The contribution of the IGM and minihaloes to the 21-cm signal of reionization

Yue¹,

Ciardi²,

Scannapieco³

et al. 2009

Monthly Notices of the Royal Astronomical Society

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We study the statistical properties of the cosmological 21‐cm signal from both the intergalactic medium (IGM) and minihaloes, using a reionization simulation that includes a self‐consistent treatment of minihalo photoevaporation. We consider two models for minihalo formation and three typical thermal states of the IGM – heating purely by ionization, heating from both ionizing and Lyα photons and a maximal ‘strong heating’ model. We find that the signal from the IGM is almost always dominant over that from minihaloes. In our calculation, the differential brightness temperature, δTb, of minihaloes is never larger than 2 mK. Although there are indeed some differences in the signals from the minihaloes and from the IGM, even with the planned generation of radio telescopes it will be unfeasible to detect them. However, minihaloes significantly affect the ionization state of the IGM and the corresponding 21‐cm flux.

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“…This approach has been considered in the context of lower redshifts (Bharadwaj, Nath & Sethi 2001; Bharadwaj & Sethi 2001; Bharadwaj & Pandey 2003; Bharadwaj & Srikant 2004). A similar formalism can also be applied at high redshifts to probe reionization and also the pre‐reionization era (Bharadwaj & Ali 2004, 2005; Furlanetto, Zaldarriaga & Hernquist 2004b; He et al 2004; Loeb & Zaldarriaga 2004; Morales & Hewitt 2004; Zaldarriaga, Furlanetto & Hernquist 2004; Ali, Bharadwaj & Pandey 2005, 2006; Bharadwaj & Pandey 2005). One of the main aims of epoch of reionization 21‐cm studies is to probe the size, spatial distribution and evolution of the ionized regions which has been addressed by several groups (Furlanetto, Zaldarriaga & Hernquist 2004a; Wyithe & Loeb 2004; Furlanetto, McQuinn & Hernquist 2006; Iliev et al 2006; Mellema et al 2006).…”

Section: Introductionmentioning

confidence: 99%

The multifrequency angular power spectrum of the epoch of reionization 21-cm signal

Datta

Choudhury

Bharadwaj

2007

Monthly Notices of the Royal Astronomical Society

110

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Observations of redshifted 21-cm radiation from neutral hydrogen (H I) at high redshifts is an important future probe of reionization. We consider the multifrequency angular power spectrum (MAPS) to quantify the statistics of the H I signal as a joint function of the angular multipole l and frequency separation ν. The signal at two different frequencies is expected to decorrelate as ν is increased, and quantifying this is particularly important in deciding the frequency resolution for future H I observations. This is also expected to play a very crucial role in extracting the signal from foregrounds as the signal is expected to decorrelate much faster than the foregrounds (which are largely continuum sources) with increasing ν.In this paper, we develop formulae relating MAPS to different components of the 3D H I power spectrum taking into account H I peculiar velocities. We show that the flat-sky approximation provides a very good representation over the angular scales of interest, and a final expression which is very simple to calculate and interpret. We present results for z = 10 assuming a neutral hydrogen fraction of 0.6 considering two models for the H I distribution, namely, (i) DM: where H I traces the dark matter and (ii) PR: where the effects of patchy reionization are incorporated through two parameters which are the bubble size and the clustering of the bubble centres relative to the dark matter (bias), respectively. We find that while the DM signal is largely featureless, the PR signal peaks at the angular scales of the individual bubbles where it is Poisson fluctuation dominated, and the signal is considerably enhanced for large bubble size. For most cases of interest at l ∼ 100 the signal is uncorrelated beyond ν ∼ 1 MHz or even less, whereas this occurs around ∼0.1 MHz at l ∼ 10 3 . The ν dependence also carries an imprint of the bubble size and the bias, and is expected to be an important probe of the reionization scenario. Finally, we find that the l range 10 3 -10 4 is optimum for separating out the cosmological H I signal from the foregrounds, while this will be extremely demanding at l < 100 where it is necessary to characterize the ν dependence of the foreground MAPS to an accuracy better than 1 per cent.

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Statistical Features of 21 Centimeter Emission from the Epoch between Reionization and the Gunn‐Peterson Transparency

Cited by 5 publications

References 45 publications

Redshifted 21 cm Emission from the Pre‐Reionization Era. II. HiiRegions around Individual Quasars

Redshifted 21 cm Emission from the Pre‐Reionization Era. II. HiiRegions around Individual Quasars

The contribution of the IGM and minihaloes to the 21-cm signal of reionization

The multifrequency angular power spectrum of the epoch of reionization 21-cm signal

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