A simulation-calibrated limit on the H i power spectrum from the GMRT Epoch of Reionization experiment

Paciga, Gregory; Albert, J. G.; Bandura, Kevin; Chang, Tzu-Ching; Gupta, Yashwant; Hirata, Christopher M.; Odegova, Julia; Pen, Ue-Li; Peterson, Jeffrey B.; Roy, Jayanta; Shaw, J. Richard; Sigurdson, Kris; Voytek, Tabitha

doi:10.1093/mnras/stt753

Cited by 324 publications

(315 citation statements)

References 53 publications

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“…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%

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: 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

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“…The foreground eigenvectors are spectral degrees of freedom that can be projected out of each line of sight. Determination of contaminated modes in the data themselves has been exploited in GBT data (Chang et al 2010;Masui et al 2013;Switzer et al 2013), GMRT (Paciga et al 2013), and most recently in PAPER (e.g., Ali et al 2015). Blind methods have been considered for SKA (Wolz et al 2014;Alonso et al 2015) and BINGO (Bigot-Sazy et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Interpreting the Unresolved Intensity of Cosmologically Redshifted Line Radiation

Switzer

Chang

Masui

et al. 2015

ApJ

107

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Intensity mapping experiments survey the spectrum of diffuse line radiation rather than detect individual objects at high signal-to-noise ratio. Spectral maps of unresolved atomic and molecular line radiation contain threedimensional information about the density and environments of emitting gasand efficiently probe cosmological volumes out to high redshift. Intensity mapping survey volumes also contain all other sources of radiation at the frequencies of interest. Continuum foregrounds are typically~10 2 -10 3 times brighter than the cosmological signal. The instrumental response to bright foregrounds will produce new spectral degrees of freedom that are not known in advance, nor necessarily spectrally smooth. The intrinsic spectra of foregrounds may also not be wellknown in advance. We describe a general class of quadratic estimators to analyze data from single-dish intensity mapping experimentsand determine contaminated spectral modes from the data themselves. The key attribute of foregrounds is not that they are spectrally smooth, but instead that they have fewer bright spectral degrees of freedom than the cosmological signal. Spurious correlations between the signal and foregrounds produce additional bias. Compensation for signal attenuation must estimate and correct this bias. A successful intensity mapping experiment will control instrumental systematics that spread variance into new modes, and it must observe a large enough volume that contaminant modes can be determined independently from the signal on scales of interest.

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“…The detection of signal is the major goal of a range of new low frequency radio telescopes: GMRT 1 (Paciga et al 2013), LOFAR 2 (van Haarlem et al 2013), MWA 3 (Tingay et al 2013), PAPER 4 (Parsons et al 2010) and 21CMA 5 . This signal maps out the distribution of neutral hydrogen on the largest scales in the IGM and its detection will reveal the progress of reionization in great detail.…”

Section: Introductionmentioning

confidence: 99%

Efficient photoheating algorithms in time-dependent photoionization simulations

Lee

Mellema

Lundqvist

2015

Mon. Not. R. Astron. Soc.

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We present an extension to the time-dependent photo-ionization code C 2 -RAY to calculate photo-heating in an efficient and accurate way. In C 2 -RAY, the thermal calculation demands relatively small time-steps for accurate results. We describe two novel methods to reduce the computational cost associated with small time-steps, namely, an adaptive time-step algorithm and an asynchronous evolution approach. The adaptive time-step algorithm determines an optimal time-step for the next computational step. It uses a fast ray-tracing scheme to quickly locate the relevant cells for this determination and only use these cells for the calculation of the time-step. Asynchronous evolution allows different cells to evolve with different timesteps. The asynchronized clocks of the cells are synchronized at the times where outputs are produced. By only evolving cells which may require short time-steps with these short timesteps instead of imposing them to the whole grid, the computational cost of the calculation can be substantially reduced. We show that our methods work well for several cosmologically relevant test problems and validate our results by comparing to the results of another timedependent photo-ionization code.

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A simulation-calibrated limit on the H i power spectrum from the GMRT Epoch of Reionization experiment

Cited by 324 publications

References 53 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

Interpreting the Unresolved Intensity of Cosmologically Redshifted Line Radiation

Efficient photoheating algorithms in time-dependent photoionization simulations

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