Imaging the Epoch of Reionization: Limitations From Foreground Confusion and Imaging Algorithms

Vedantham, H. K.; Shankar, N. Udaya; Subrahmanyan, R.

doi:10.1088/0004-637x/745/2/176

Cited by 239 publications

(288 citation statements)

References 11 publications

Supporting

Mentioning

286

Contrasting

Order By: Relevance

“…This relationship, known colloquially as "the wedge," was derived analytically (P12b; Vedantham et al 2012;Thyagarajan et al 2013;Liu et al 2014aLiu et al , 2014b, and has been confirmed in simulations (Datta et al 2010;Hazelton et al 2013) and observationally Dillon et al 2014). As described in P12b, the wedge is the result of the delay between when a wavefront originating from foreground emission arrives at the two antennas in a baseline.…”

Section: Calibrationmentioning

confidence: 69%

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

Ali

Parsons

Zheng

et al. 2015

ApJ

262

224

View full text Add to dashboard Cite

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.

show abstract

Section: Calibrationmentioning

confidence: 69%

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

Ali

Parsons

Zheng

et al. 2015

ApJ

262

224

View full text Add to dashboard Cite

show abstract

“…The shape of the multi-baseline modemixing ripple is different in each uv pixel and depends on the details of the foregrounds and on the exact locations of the baselines contributing to each location, but unlike the mode mixing discussed in previous work Trott et al 2012;Vedantham et al 2012;Parsons et al 2012), the spatial frequency (k ) of this ripple is not limited by the field of view of the instrument so it can throw power into higher k modes, including into the EoR window.…”

Section: Multi-baseline Simulationmentioning

confidence: 95%

“…The lowest k mode shown is the flat-spectrum (k = 0) mode, which would contain all the foreground power if there were no mode mixing. Our simulations naturally include the single-baseline effects identified by Morales et al (2012), Trott et al (2012), Vedantham et al (2012), and Parsons et al (2012) because we form visibilities as described in Equation (1), but we find that the multi-baseline effects dominate the mode-mixed power throughout the uv plane. The contamination that is present in the EoR window is a signature of multi-baseline mode mixing which can produce contamination to arbitrarily high k .…”

Section: Power Spectramentioning

confidence: 99%

THE FUNDAMENTAL MULTI-BASELINE MODE-MIXING FOREGROUND IN 21 cm EPOCH OF REIONIZATION OBSERVATIONS

Hazelton

Morales

Sullivan

2013

ApJ

106

109

View full text Add to dashboard Cite

The primary challenge for experiments measuring the neutral hydrogen power spectrum from the epoch of reionization (EoR) is mode-mixing effects, where foregrounds from very bright astrophysical sources interact with the instrument to contaminate the EoR signal. In this paper, we identify a new type of mode mixing that occurs when measurements from non-identical baselines are combined for increased power spectrum sensitivity. This multi-baseline effect dominates the mode-mixing power in our simulations and can contaminate the EoR window, an area in Fourier space previously identified to be relatively free of foreground power.

show abstract

“…It is worth noting that the gridding scheme presented here for the delay-spectrum technique differs substantially for other schemes that have been recently presented in the literature (e.g., Bowman et al 2009;Vedantham et al 2012) in that within an 8 MHz sub-band, every frequency channel has been formed from the same weighted sum of constituent baselines. .…”

Section: Gridding and Integrationmentioning

confidence: 99%

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

Parsons

Pober

Aguirre

et al. 2012

ApJ

296

458

View full text Add to dashboard Cite

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.

show abstract

Imaging the Epoch of Reionization: Limitations From Foreground Confusion and Imaging Algorithms

Cited by 239 publications

References 11 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

THE FUNDAMENTAL MULTI-BASELINE MODE-MIXING FOREGROUND IN 21 cm EPOCH OF REIONIZATION OBSERVATIONS

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

Contact Info

Product

Resources

About