Science with the Murchison Widefield Array

Bowman, Judd D.; Cairns, Iver H.; Kaplan, David L.; Murphy, Tara; Oberoi, D.; Arcus, W.; Barnes, David G.; Bernardi, G.; Briggs, F.; Brown, Shea; Bunton, John D.; Burgasser, Adam J.; Cappallo, R. J.; Chatterjee, Shami; Corey, B. E.; Coster, A. J.; Deshpande, A. A.; deSouza, L.; Emrich, D.; Erickson, P. J.; Goeke, R.; Gaensler, B. M.; Greenhill, L. J.; Harvey-Smith, Lisa; Hazelton, B. J.; Herne, D.; Hewitt, Jacqueline N.; Johnston‐Hollitt, M.; Kasper, J. C.; Kincaid, B. B.; Koenig, R.; Kratzenberg, E.; Lonsdale, Colin J.; Lynch, M. J.; Matthews, L. D.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Ord, S. M.; Pathikulangara, J.; Prabu, T.; Remillard, Ronald A.; Robishaw, Timothy; Rogers, A. E. E.; Roshi, A.; Salah, J. E.; Sault, R. J.; Shankar, N. Udaya; Srivani, K. S.; Stevens, J.; Subrahmanyan, R.; Tingay, S. J.; Wayth, R. B.; Waterson, M.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, Christopher; Wyithe, J. Stuart B.

doi:10.1017/pas.2013.009

Cited by 318 publications

(186 citation statements)

References 285 publications

(438 reference statements)

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“…The array was thus designed with these programs in consideration and the layout was optimized using a pseudorandom antenna placement algorithm ) to obtain a well-behaved point-spread function (PSF) while retaining a dense core for EoR sensitivity Beardsley et al 2013). 32 A full description of the science capabilities of the array is found in Bowman et al (2013). The high imaging capability of the MWA enables us to calibrate and subtract foregrounds based on sky models, leveraging the full capability of the observatory for the EoR experiment.…”

Section: The Murchison Widefield Array and Observationsmentioning

confidence: 99%

“…(For reviews, see Furlanetto et al 2006;Morales & Wyithe 2010;Pritchard & Loeb 2012;Furlanetto 2013, andZaroubi 2013.) The first generation of instruments with primary science goals to detect the highly redshift 21 cm signal have been built, including the Giant Metrewave Radio Telescope (GMRT, Paciga et al 2013), LOw Frequency Array (LOFAR 28 Van Haarlem et al 2013;Yatawatta et al 2013), PAPER (Donald C. Backer Precision Array for Probing the Epoch of Reionization 29 , Parsons et al 2010), and the Murchison Widefield Array (MWA 30 , Bowman et al 2013;Tingay et al 2013). Due to arelatively low signal-to-noise ratio, these instruments aim for a statistical measurement of the EoR in the form of a cosmological power spectrum.…”

Section: Introductionmentioning

confidence: 99%

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First Season Mwa Eor Power Spectrum Results at Redshift 7

Beardsley

Hazelton

Sullivan

et al. 2016

ApJ

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The Murchison Widefield Array (MWA) has collected hundreds of hours of Epoch of Reionization (EoR) data and now faces the challenge of overcoming foreground and systematic contamination to reduce the data to a cosmological measurement. We introduce several novel analysis techniques, such as cable reflection calibration, hyper-resolution gridding kernels, diffuse foreground model subtraction, and quality control methods. Each change to the analysis pipeline is tested against a two-dimensional power spectrum figure of merit to demonstrate improvement. We incorporate the new techniques into a deep integration of 32 hoursof MWA data. This data set is used to place a systematic-limited upper limit on the cosmological power spectrum of  D2.7 10 2 4 mK 2 at k = 0.27 h Mpc −1 and z = 7.1, consistent with other published limits, and a modest improvement (factor of 1.4) over previous MWA results. From this deep analysis, we have identified a list of improvements to be made to our EoR data analysis strategies. These improvements will be implemented in the future and detailed in upcoming publications.

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Section: The Murchison Widefield Array and Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

First Season Mwa Eor Power Spectrum Results at Redshift 7

Beardsley

Hazelton

Sullivan

et al. 2016

ApJ

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193

207

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“…They usually started after sunset or even later during the night and persisted until early morning (not later than 9 am). During the entire time period we observed 19 strong, 20 moderate and 59 weak tropospheric ducting events (overall almost 20% of analyzed nights) 1 . Typically, good and very good TD conditions persist for 2-3 nights.…”

Section: Seasonal and Daily Patterns In Tropospheric Ductingmentioning

confidence: 87%

“…Hence, it is possible that extremely weak TD events have been missed. Therefore, we would like to better understand seasonal and daily patters of tropospheric ducting events and possibly develop an additional data quality criteria (based on upper 1 The list of all TD events observed in the analyzed time period is available on request. atmosphere meteorology data).…”

Section: Seasonal and Daily Patterns In Tropospheric Ductingmentioning

confidence: 99%

Advanced, efficient primary beam modeling for the Murchison Widefield Array radio telescope

Wayth¹,

Colegate²,

Sokołowski³

et al. 2016

2016 International Conference on Electromagnetics in Advanced Applications (ICEAA)

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BIGHORNS is a total power radiometer developed to identify the signal from the Epoch of Reionisation in the all-sky averaged radio spectrum at low frequencies (70-300 MHz). In October 2014, the system with a conical log spiral antenna was deployed at the Murchison Radio-astronomy Observatory (MRO) and has been collecting data since then. The system has been monitoring the radio frequency interference (RFI) environment at the future site of the low-frequency component of the Square Kilometre Array. We have analyzed almost two years of data (October 2014 -August 2016 inclusive) in search for events of long distance propagation of the RFI in FM and digital TV bands due to tropospheric ducting and reflections (of the meteor trails or aircraft). We present statistics of tropospheric ducting events observed in the digital TV band over nearly two years, which shows seasonal changes. We also present a system using upper atmosphere data (temperature, humidity and pressure as a function of altitude) from all stations in Western Australia to calculate the modified refractive index and make predictions of tropospheric ducting events. Preliminary tests indicate that the system can be very useful in predicting tropospheric ducting events (even with limited amount of available upper atmosphere data).

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“…Similarly, the search for transient objects and regular monitoring of the time-dependent sky is driving instruments in the same direction with the added requirement of fast read-outs. A number of new telescopes around ⋆ E-mail: t nithyanandan@asu.edu the world are based on this new paradigm, including the Hydrogen Epoch of Reionization Array 1 (HERA; DeBoer et al 2016), the Murchison Widefield Array (MWA; Tingay et al 2013;Bowman et al 2013), the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER; Parsons et al 2010), the LOw Frequency ARray (LOFAR; van Haarlem et al 2013), the Canadian Hydrogen Intensity Mapping Experiment (CHIME; Bandura et al 2014), the Long Wavelength Array (LWA; Ellingson et al 2013), and the low frequency Square Kilometer Array (SKA1-Low; Mellema et al 2013).…”

Section: Introductionmentioning

confidence: 99%

A Generic and Efficient E-field Parallel Imaging Correlator for Next-Generation Radio Telescopes

Thyagarajan¹,

Beardsley²,

Bowman³

et al. 2017

Mon. Not. R. Astron. Soc.

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Modern radio telescopes are favouring densely packed array layouts with large numbers of antennas (N A 1000). Since the complexity of traditional correlators scales as O(N 2 A ), there will be a steep cost for realizing the full imaging potential of these powerful instruments. Through our generic and efficient E-field Parallel Imaging Correlator (EPIC), we present the first software demonstration of a generalized direct imaging algorithm, namely, the Modular Optimal Frequency Fourier (MOFF) imager. Not only does it bring down the cost for dense layouts to O(N A log 2 N A ) but can also image from irregular layouts and heterogeneous arrays of antennas. EPIC is highly modular, parallelizable, implemented in object-oriented Python, and publicly available. We have verified the images produced to be equivalent to those from traditional techniques to within a precision set by gridding coarseness. We have also validated our implementation on data observed with the Long Wavelength Array (LWA1). We provide a detailed framework for imaging with heterogeneous arrays and show that EPIC robustly estimates the input sky model for such arrays. Antenna layouts with dense filling factors consisting of a large number of antennas such as LWA, the Square Kilometre Array, Hydrogen Epoch of Reionization Array, and Canadian Hydrogen Intensity Mapping Experiment will gain significant computational advantage by deploying an optimized version of EPIC. The algorithm is a strong candidate for instruments targeting transient searches of Fast Radio Bursts (FRB) as well as planetary and exoplanetary phenomena due to the availability of high-speed calibrated time-domain images and low output bandwidth relative to visibility-based systems.

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Science with the Murchison Widefield Array

Cited by 318 publications

References 285 publications

First Season Mwa Eor Power Spectrum Results at Redshift 7

First Season Mwa Eor Power Spectrum Results at Redshift 7

Advanced, efficient primary beam modeling for the Murchison Widefield Array radio telescope

A Generic and Efficient E-field Parallel Imaging Correlator for Next-Generation Radio Telescopes

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