Adam P. Beardsley

Hydrogen Epoch of Reionization Array (HERA)

The Hydrogen Epoch of Reionization Array (HERA http://reionization.org) is a staged experiment that uses the unique properties of the 21-cm line from neutral hydrogen to probe the Epoch of Reionization (EOR). During this epoch, roughly 0.3-1 billion years after the Big Bang, the first galaxies and black holes heated and reionized the early Universe. Direct observation of the large scale structure of reionization and its evolution with time will have a profound impact on our understanding of the birth of the first galaxies and black holes, their influence on the intergalactic medium (IGM), and cosmology. This paper will provide an overview of the project and describe the design of the HERA receiving element.

Parametrizing Epoch of Reionization foregrounds: a deep survey of low-frequency point-source spectra with the Murchison Widefield Array

Experiments that pursue detection of signals from the Epoch of Reionization (EoR) are relying on spectral smoothness of source spectra at low frequencies. This article empirically explores the effect of foreground spectra on EoR experiments by measuring high-resolution full-polarization spectra for the 586 brightest unresolved sources in one of the MWA EoR fields using 45 h of observation. A novel peeling scheme is used to subtract 2500 sources from the visibilities with ionospheric and beam corrections, resulting in the deepest, confusion-limited MWA image so far. The resulting spectra are found to be affected by instrumental effects, which limit the constraints that can be set on source-intrinsic spectral structure. The sensitivity and power-spectrum of the spectra are analysed, and it is found that the spectra of residuals are dominated by PSF sidelobes from nearby undeconvolved sources. We release a catalogue describing the spectral parameters for each measured source.

First limits on the 21 cm power spectrum during the Epoch of X-ray heating

This work was supported by NSF Grants AST-0457585, AST-0821321, AST-1105835, AST-1410719, AST-1410484, AST- 1411622, and AST-1440343, by the MIT School of Science, by the Marble Astrophysics Fund, and by generous donations from Jonathan Rothberg and an anonymous donor. AEW acknowledges support from the National Science Foundation Graduate Research Fellowship under Grant No. 1122374. AM acknowledges support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 638809 – AIDA). Support for the MWA comes from the U.S. National Science Foundation (grants AST-0457585, PHY-0835713, CAREER- 0847753, and AST-0908884), the Australian Research Council (LIEF grants LE0775621 and LE0882938), the U.S. Air Force Of- fice of Scientific Research (grant FA9550-0510247), and the Centre for All-sky Astrophysics (an Australian Research Council Centre of Excellence funded by grant CE110001020). Support is also provided by the Smithsonian Astrophysical Observatory, the Raman Research Institute, the Australian National University, and the Victoria University of Wellington (via grant MED-E1799 from the New Zealand Ministry of Economic Development and an IBM Shared University Research Grant). The Australian Federal government provides additional support via the Commonwealth Scientific and Industrial Research Organisation (CSIRO), National Collaborative Research Infrastructure Strategy, Education Investment Fund, and the Australia India Strategic Research Fund, and Astronomy Australia Limited, under contract to Curtin University.

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

Modern radio telescopes are favouring densely packed array layouts with large numbers of antennas (

DELAY SPECTRUM WITH PHASE-TRACKING ARRAYS: EXTRACTING THE H I POWER SPECTRUM FROM THE EPOCH OF REIONIZATION

N_\textrm{a}\gtrsim 1000

A Serendipitous MWA Search for Narrowband Signals from ‘Oumuamua

). Since the complexity of traditional correlators scales as

The Hydrogen Epoch of Reionization Array Dish III: Measuring Chromaticity of Prototype Element with Reflectometry

\mathcal{O}(N_\textrm{a}^2)

An Efficient Feedback Calibration Algorithm for Direct Imaging Radio Telescopes

, 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. It takes advantage of the multiplication-convolution theorem of Fourier transforms. Not only does it bring down the cost for dense layouts to

Sensitivity of the Hydrogen Epoch of Reionization Array and its build-out stages to one-point statistics from redshifted 21 cm observations

\mathcal{O}(N_\textrm{a}\log_2 N_\textrm{a})

Limits on radio emission from meteors using the MWA

but can also image from irregularly arranged heterogeneous antenna. EPIC is highly modular and parallelizable, implemented in object oriented Python, and publicly available. We have verified the images produced to be equivalent to those produced using traditional techniques to within a precision determined by coarseness of gridding. We have also validated our implementation on data observed with the Long Wavelength Array (LWA). Antenna layouts with a dense filling factor 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 EPIC. Inherent availability of calibrated time-domain images on digitizer writeout time-scales and vastly lower I/O bandwidth relative to visibility-based systems will make it a prime candidate for transient searches of Fast Radio Bursts (FRB) as well as planetary and exoplanetary phenomena.