The GMRT Epoch of Reionization experiment: a new upper limit on the neutral hydrogen power spectrum at z≈ 8.6

Paciga, Gregory; Chang, Tzu-Ching; Gupta, Yashwant; Nityanada, Rajaram; Odegova, Julia; Pen, Ue-Li; Peterson, Jeffrey B.; Roy, Jayanta; Sigurdson, Kris

doi:10.1111/j.1365-2966.2011.18208.x

Cited by 187 publications

(184 citation statements)

References 80 publications

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“…The predicted 2σ upper limit in the absence of the a celestial signal is shown in dashed cyan, assuming T K 500 sys = . The triangles indicate 2 σ upper limits from GMRT (Paciga et al 2011) (yellow) at z = 8.6, MWA ) at z = 9.5 (magenta), and the previous PAPER upper limit (P14) at z = 7.7 (green). The magenta curve shows a predicted model 21 cm power spectrum at 50% ionization (Lidz et al 2008). the error bars on the spherically averaged power spectrum P(k), where positive and negative k  measurements are kept separate for diagnostic purposes.…”

Section: Power Spectrum Constraintsmentioning

confidence: 99%

“…We take the conservative approach and do not correct for this effect, noting that the leakage of Q in to I will result in positive power, increasing our limits. Foreground removal techniques discussed in the literature include spectral polynomial fitting (Wang et al 2006;Bowman et al 2009a;Liu et al 2009a), principal component analysis (Liu & Tegmark 2011;Paciga et al 2011;Masui et al 2013;Paciga et al 2013), non-parametric subtractions (Harker et al 2009;Chapman et al 2013), and inverse covariance weighting (Liu & Tegmark 2011;Dillon et al 2013Dillon et al , 2014Liu et al 2014aLiu et al , 2014b, Fourier-mode filtering Petrovic & Oh (2011), and per-baseline delay filtering described in P12b. This delay-spectrum filtering technique is well-suited to the maximum redundancy PAPER configuration, which is not optimized for the other approaches where high fidelity imaging is a prerequisite.…”

Section: Wideband Delay Filteringmentioning

confidence: 99%

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PAPER-64 CONSTRAINTS ON REIONIZATION: THE 21 cm POWER SPECTRUM ATz= 8.4

Ali

Parsons

Zheng

et al. 2015

ApJ

265

224

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In this paper, we report new limits on 21 cm emission from cosmic reionization based on a 135 day observing campaign with a 64-element deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization in South Africa. This work extends the work presented in Parsons et al. with more collecting area, a longer observing period, improved redundancy-based calibration, improved fringe-rate filtering, and updated power-spectral analysis using optimal quadratic estimators. The result is a new 2σ upper limit on Δ 2 (k) of (22.4 mK) 2 in the range k h 0.15 0.5 Mpc 1 < < -at z = 8.4. This represents a three-fold improvement over the previous best upper limit. As we discuss in more depth in a forthcoming paper, this upper limit supports and extends previous evidence against extremely cold reionization scenarios. We conclude with a discussion of implications for future 21 cm reionization experiments, including the newly funded Hydrogen Epoch of Reionization Array.

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Section: Power Spectrum Constraintsmentioning

confidence: 99%

Section: Wideband Delay Filteringmentioning

confidence: 99%

PAPER-64 CONSTRAINTS ON REIONIZATION: THE 21 cm POWER SPECTRUM ATz= 8.4

Ali

Parsons

Zheng

et al. 2015

ApJ

265

224

View full text Add to dashboard Cite

show abstract

“…Pen et al (2009) have carried out 150 MHz GMRT observations at a high Galactic latitude to place an upper limit of 2 C /2π < 3K on the polarized foregrounds at < 1000. Paciga et al (2011) placed an upper limit on the 21-cm power spectrum during the EoR of (70 mK) 2 at wavenumbers of k = 0.65 h/Mpc which after a more careful handling of the foreground subtraction had to be increased to (248 mK) 2 for k = 0.50 h/Mpc (Paciga et al 2013). This shows how proper foreground removal remains a challenge.…”

Section: Selected Results From Ska Precursors and Pathfindersmentioning

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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“…We then subtract the wide-band deconvolved foreground model from the measured visibilities to suppress the scattering of foreground emission off of unsmooth sampling weights relating to RFI flagging. In essence, delay-space CLEAN is a direct analog of the image-domain modeling proposed for foreground removal (Paciga et al 2011;Datta et al 2009). The difference here is that it is acting per-baseline, and that, in addition to selecting CLEAN components in delay bins that map to imagedomain coordinates, delay-space CLEAN is also restricted to models that produce smooth spectral responses.…”

Section: Reducing Sidelobes Of Foregrounds Arising From Frequency-dommentioning

confidence: 99%

A PER-BASELINE, DELAY-SPECTRUM TECHNIQUE FOR ACCESSING THE 21 cm COSMIC REIONIZATION SIGNATURE

Parsons

Pober

Aguirre

et al. 2012

ApJ

303

458

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A critical challenge in measuring the power spectrum of 21 cm emission from cosmic reionization is compensating for the frequency dependence of an interferometer's sampling pattern, which can cause smooth-spectrum foregrounds to appear unsmooth and degrade the separation between foregrounds and the target signal. In this paper, we present an approach to foreground removal that explicitly accounts for this frequency dependence. We apply the delay transformation introduced in Parsons & Backer to each baseline of an interferometer to concentrate smooth-spectrum foregrounds within the bounds of the maximum geometric delays physically realizable on that baseline. By focusing on delay modes that correspond to image-domain regions beyond the horizon, we show that it is possible to avoid the bulk of smooth-spectrum foregrounds. We map the point-spread function of delay modes to k-space, showing that delay modes that are uncorrupted by foregrounds also represent samples of the three-dimensional power spectrum, and can be used to constrain cosmic reionization. Because it uses only spectral smoothness to differentiate foregrounds from the targeted 21 cm signature, this per-baseline analysis approach relies on spectrally and spatially smooth instrumental responses for foreground removal. For sufficient levels of instrumental smoothness relative to the brightness of interfering foregrounds, this technique substantially reduces the level of calibration previously thought necessary to detect 21 cm reionization. As a result, this approach places fewer constraints on antenna configuration within an array, and in particular, facilitates the adoption of configurations that are optimized for power-spectrum sensitivity. Under these assumptions, we demonstrate the potential for the Precision Array for Probing the Epoch of Reionization (PAPER) to detect 21 cm reionization at an amplitude of 10 mK 2 near k ∼ 0.2 h Mpc −1 with 132 dipoles in 7 months of observing.

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The GMRT Epoch of Reionization experiment: a new upper limit on the neutral hydrogen power spectrum at z≈ 8.6

Cited by 187 publications

References 80 publications

PAPER-64 CONSTRAINTS ON REIONIZATION: THE 21 cm POWER SPECTRUM ATz= 8.4

PAPER-64 CONSTRAINTS ON REIONIZATION: THE 21 cm POWER SPECTRUM ATz= 8.4

Reionization and the Cosmic Dawn with the Square Kilometre Array

A PER-BASELINE, DELAY-SPECTRUM TECHNIQUE FOR ACCESSING THE 21 cm COSMIC REIONIZATION SIGNATURE

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