Multifrequency Analysis of 21 Centimeter Fluctuations from the Era of Reionization

By Mário G. Santos, A. Cooray, Lloyd Knox. 2004

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We study the prospects for extracting detailed statistical properties of the neutral hydrogen distribution during the era of reionization using the brightness temperature fluctuations from redshifted 21 cm line emission. Detection of this signal is complicated by contamination from foreground sources such as diffuse Galactic synchrotron and free-free emission at low radio frequencies, extragalactic free-free emission from ionized regions, and radio point sources. We model these foregrounds to determine the extent to which 21 cm fluctuations can be detected with upcoming experiments. We find that not only the level of correlation from one frequency to another but also the functional form of the foreground correlations has a substantial impact on foreground removal. We calculate how well the angular power spectra of the 21 cm fluctuations can be determined. We also show that the large-scale bias of the neutral hydrogen gas distribution with respect to the density field can be determined with high precision and used to distinguish between different reionization histories.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/879dfd2baf0145db9e50a2e0da5c17bf681a5def

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Citations in the corpus

THE PRECISION ARRAY FOR PROBING THE EPOCH OF RE-IONIZATION: EIGHT STATION RESULTS (2009, methodology): “However, at lower radio frequencies for ` < 100, we see a flattening of these spectra to a shallow, negative power-law that shows qualitative agreement with the C`,sync ∝ `−2.4 model adopted by Tegmark et al. (2000) and Santos et al. (2005).”
FOUR FUNDAMENTAL FOREGROUND POWER SPECTRUM SHAPES FOR 21 cm COSMOLOGY OBSERVATIONS (2012, background): “…than the EoR signal, and initial studies of the 21 cm foreground concentrated on identifying all of the potentially offending sources (e.g., Matteo et al. 2002; Oh & Mack 2003; Matteo et al. 2004; Gnedin & Shaver 2004; Santos et al. 2005; McQuinn et al. 2007; reviewed by Morales & Wyithe 2010).”
A SENSITIVITY AND ARRAY-CONFIGURATION STUDY FOR MEASURING THE POWER SPECTRUM OF 21 cm EMISSION FROM REIONIZATION (2011, background): “The brightness temperatures of these foregrounds can exceed the expected ∼ 10 mK amplitude of the 21cm EoR signal by up to five orders of magnitude (Zahn et al. 2007; Santos et al. 2005).”
Fast large volume simulations of the 21-cm signal from the reionization and pre-reionization epochs (2009, background): “…leading to a frequency selection for observations, the 21 cm data provides a tomographic view of the reionization and pre-reionization process (Santos et al. 2005; Furlanetto et al. 2004a) and can also be an exquisite cos- ⋆ Email: mgrsantos@ist.utl.pt (MGS); luis.ferramacho@ist.utl.pt…”
An Overview of CHIME, the Canadian Hydrogen Intensity Mapping Experiment (2022, background): “The main challenge associated with 21 cm intensity mapping is the very bright synchrotron foreground emission from the Milky Way and from other nearby galaxies (e.g. Santos et al. 2005; Liu & Tegmark 2012).”
ALL-SKY INTERFEROMETRY WITH SPHERICAL HARMONIC TRANSIT TELESCOPES (2013, methodology): “We base our models on Santos et al. (2005), although we will only include the galactic synchrotron and extragalactic point source contributions.”
OPENING THE 21 cm EPOCH OF REIONIZATION WINDOW: MEASUREMENTS OF FOREGROUND ISOLATION WITH PAPER (2013, background): “All 21cm cosmology experiments will need to separate bright galactic and extragalactic foregrounds from the neutral hydrogen signal, which can be fainter by as much as 5 orders of magnitude or more (see, e.g., Furlanetto et al. 2006 and Santos et al. 2005).”
FOREGROUND CONTAMINATION IN INTERFEROMETRIC MEASUREMENTS OF THE REDSHIFTED 21 cm POWER SPECTRUM (2008, methodology): “This corresponds to the principal scenarios addressed by previous efforts (Di Matteo et al. 2004; Zaldarriaga et al. 2004; Furlanetto & Briggs 2004; Gnedin & Shaver 2004; Santos et al. 2005; Wang et al. 2006; McQuinn et al. 2006; Gleser et al. 2008).”
LATE-TIME COSMOLOGY WITH 21 cm INTENSITY MAPPING EXPERIMENTS (2014, methodology): “(7)F X X n p m FG 2 p i X X The amplitude and index parameters for four representative foregrounds are given in Table 1, following Santos et al. (2005).”
PAPER-64 CONSTRAINTS ON REIONIZATION: THE 21 cm POWER SPECTRUM AT z = 8.4 (2015, background): “…where 21 cm reionization experiments operate, emission from these foregrounds is brighter than the predicted reionization signal by several orders of magnitude (Santos et al. 2005; Ali et al. 2008; de Oliveira-Costa et al. 2008; Jelić et al. 2008; Bernardi et al. 2009, 2010; Ghosh et al. 2011).”
Hydrogen Epoch of Reionization Array (HERA) (2016, methodology): “This was a conservative value based on estimates of power in spectrally smooth foreground sources (Santos et al. 2005; Ali et al. 2008; de Oliveira-Costa et al. 2008; Jelić et al. 2008; Bernardi et al. 2010) and experience with PAPER dealing with foreground systematics.”
21 cm Tomography with Foregrounds (2005, methodology): “…Di Matteo et al. 2002, 2004; Furlanetto et al. 2004a, 2004b; Gnedin & Shaver 2004; Iliev et al. 2002, 2003; Loeb & Zaldarriaga 2004; McQuinn et al. 2006; Morales 2005; Oh & Mack 2003; Pen et al. 2004; Santos et al. 2005; Shaver et al. 1999; Wyithe & Loeb 2004a, 2004b; Zaldarriaga et al. 2004).”
Observational Constraints on Cosmic Reionization (2006, methodology): “Santos et al. (2005), Bharadwaj & Ali (2005), Zaldariagga et al. (2004a) perform a similar analysis, only in the complementary Fourier space, meaning cross correlation of spectral channels.”
Science with the Murchison Widefield Array (2012, background): “All of these foregrounds are significantly stronger than the redshifted 21 cm signal and have considerable angular structure on the sky (see Figure 2 and Santos et al. 2005, their Figure 5).”
Reionization and the Cosmic Dawn with the Square Kilometre Array (2012, methodology): “This can be achieved by using polynomials (e.g., Santos et al. 2005; Wang et al. 2006; McQuinn et al. 2006; Bowman et al. 2006; Jelić et al. 2008, and references therein), or more advanced non-parametric methods (Harker et al. 2009a; Chapman et al. 2012, 2013).”
21-cm fluctuations from inhomogeneous X-ray heating before reionization (2006, methodology): “In the analysis that follows, we assume that foreground removal can be affected by exploiting the smoothness of foregrounds in frequency space (Morales & Hewitt 2004; Zaldarriaga et al. 2004; Morales 2005; Santos et al. 2005; McQuinn et al. 2006; Wang & Hu 2006).”