The Phase II Murchison Widefield Array: Design overview

Wayth, R. B.; Tingay, S. J.; Trott, Cathryn M.; Emrich, D.; Johnston‐Hollitt, M.; McKinley, B.; Gaensler, B. M.; Beardsley, Adam P.; Booler, T.; Crosse, B.; Franzen, T. M. O.; Horsley, L.; Kaplan, D. L.; Kenney, D.; Morales, M. F.; Pallot, D.; Sleap, G.; Steele, Kim; Walker, M.; Williams, A.; Wu, Chen; Cairns, Iver H.; Filipović, Miroslav; Johnston, S.; Murphy, Tara; Quinn, Peter J.; Staveley‐Smith, L.; Webster, R. L.; Wyithe, J. Stuart B.

doi:10.1017/pasa.2018.37

Cited by 260 publications

(205 citation statements)

References 51 publications

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“…A Fourier Transform over the data to retrieve the line-of-sight spatial scales will contain a comb shape due to these missing channels, where the k = 0 mode is copied in harmonics of the coarse channel separation. There are several ways to handle this; in this implementation of CHIPS, we use an ordinary kriging (a Gaussian Process Regression) to provide an interpolate of these data that uses the covariance structure of the data (Rasmussen & Nickisch 2010;Wackernagel 2003). Kriging has been used to fit for foregrounds in LOFAR EoR datasets, using an optimised set of hyperparameters (Mertens et al 2018).…”

Section: Power Spectrum Methodologymentioning

confidence: 99%

Deep multiredshift limits on Epoch of Reionization 21 cm power spectra from four seasons of Murchison Widefield Array observations

Trott

Jordan

Midgley³

et al. 2020

Monthly Notices of the Royal Astronomical Society

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204

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We compute the spherically-averaged power spectrum from four seasons of data obtained for the Epoch of Reionisation (EoR) project observed with the Murchison Widefield Array (MWA). We measure the EoR power spectrum over k = 0.07 − 3.0 hMpc −1 at redshifts z = 6.5 − 8.7. The largest aggregation of 110 hours on EoR0 high-band (3,340 observations), yields a lowest measurement of (43 mK) 2 = 1.8×10 3 mK 2 at k=0.14 hMpc −1 and z = 6.5 (2σ thermal noise plus sample variance). Using the Real-Time System to calibrate and the CHIPS pipeline to estimate power spectra, we select the best observations from the central five pointings within the 2013-2016 observing seasons, observing three independent fields and in two frequency bands. This yields 13,591 2-minute snapshots (453 hours), based on a quality assurance metric that measures ionospheric activity. We perform another cut to remove poorly-calibrated data, based on power in the foreground-dominated and EoR-dominated regions of the twodimensional power spectrum, reducing the set to 12,569 observations (419 hours). These data are processed in groups of 20 observations, to retain the capacity to identify poor data, and used to analyse the evolution and structure of the data over field, frequency, and data quality. We subsequently choose the cleanest 8,935 observations (298 hours of data) to form integrated power spectra over the different fields, pointings and redshift ranges.

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Section: Power Spectrum Methodologymentioning

confidence: 99%

Deep multiredshift limits on Epoch of Reionization 21 cm power spectra from four seasons of Murchison Widefield Array observations

Trott

Jordan

Midgley³

et al. 2020

Monthly Notices of the Royal Astronomical Society

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204

139

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“…We assume a frequency dependence of Ae(ν)/Ae(ν = 150MHz) = (150/ν) 2 . ‡ The Phase II upgrade gives the MWA a total of 256 tiles, however with the existing receivers and correlator it is only possible to use 128 at any one time (Wayth et al 2018).…”

Section: Reionization Historiesmentioning

confidence: 99%

Probing delayed-end reionization histories with the 21-cm LAE cross-power spectrum

Weinberger

Kulkarni

Haehnelt

2020

Monthly Notices of the Royal Astronomical Society

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We model the 21-cm signal and LAE population evolution during the epoch of reionization in order to predict the 21cm-LAE cross-power spectrum. We employ highdynamic-range simulations of the IGM to create models that are consistent with constraints from the CMB, Lyman-α forest and LAE population statistics. Using these models we consider the evolution of the cross-power spectrum for a selection of realistic reionization histories and predict the sensitivity of current and upcoming surveys to measuring this signal. We find that the imprint of a delayed-end to reionization can be observed by future surveys, and that strong constraints can be placed on the progression of reionization as late as z = 5.7 using a Subaru-SKA survey. We make predictions for the signal-to-noise ratios achievable by combinations of Subaru/PFS with the MWA, LOFAR, HERA and SKA interferometers. We find that a Subaru-SKA survey could measure the cross-power spectrum for a late reionization at z = 6.6 with a total signal-to-noise greater than 5, making it possible to constrain both the timing and bubble size at the end of reionization. Furthermore, we find that expanding the current Subaru/PFS survey area and depth by a factor of three would double the total signal-to-noise.

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“…Such depths are now possible with the MWA phase 2 (Wayth et al 2018) which includes the addition of new tiles forming baselines up to ∼ 5.5 km, effectively doubling the resolution and decreasing both the natural and sidelobe confusion by more than an order of magnitude. Currently on-going is GLEAM-eXtended (GLEAM-X; Hurley-Walker et al in prep.…”

Section: Implications For Future Radio Continuum Surveysmentioning

confidence: 99%

Searching for dark matter signals from local dwarf spheroidal galaxies at low radio frequencies in the GLEAM survey

Cook

Seymour

Spekkens

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The search for emission from weakly interacting massive particle (WIMP) dark matter annihilation and decay has become a multi-pronged area of research not only targeting a diverse selection of astrophysical objects, but also taking advantage of the entire electromagnetic spectrum. The decay of WIMP particles into standard model particles has been suggested as a possible channel for synchrotron emission to be detected at low radio frequencies. Here, we present the stacking analysis of a sample of 33 dwarf spheroidal (dSph) galaxies with low-frequency (72 -231 MHz) radio images from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. We produce radial surface brightness profiles of images centred upon each dSph galaxy with background radio sources masked. We remove ten fields from the stacking due to contamination from either poorly subtracted, bright radio sources or strong background gradients across the field. The remaining 23 dSph galaxies are stacked in an attempt to obtain a statistical detection of any WIMP-induced synchrotron emission in these systems. We find that the stacked radial brightness profile does not exhibit a statistically significant detection above the 95% confidence level of ∼ 1.5 mJy beam −1 . This novel technique shows the potential of using low-frequency radio images to constrain fundamental properties of particle dark matter.

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The Phase II Murchison Widefield Array: Design overview

Cited by 260 publications

References 51 publications

Deep multiredshift limits on Epoch of Reionization 21 cm power spectra from four seasons of Murchison Widefield Array observations

Deep multiredshift limits on Epoch of Reionization 21 cm power spectra from four seasons of Murchison Widefield Array observations

Probing delayed-end reionization histories with the 21-cm LAE cross-power spectrum

Searching for dark matter signals from local dwarf spheroidal galaxies at low radio frequencies in the GLEAM survey

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