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1. Direct Optimal Mapping Image Power Spectrum and its Window Functions

Author

Zhilei Xu, Honggeun Kim, Jacqueline N. Hewitt, Kai-Feng Chen, Nicholas S. Kern, Eleanor Rath, Ruby Byrne, Adélie Gorce, Robert Pascua, Zachary E. Martinot, Joshua S. Dillon, Bryna J. Hazelton, Adrian Liu, Miguel F. Morales, Zara Abdurashidova, Tyrone Adams, James E. Aguirre, Paul Alexander, Zaki S. Ali, Rushelle Baartman, Yanga Balfour, Adam P. Beardsley, Gianni Bernardi, Tashalee S. Billings, Judd D. Bowman, Richard F. Bradley, Philip Bull, Jacob Burba, Steven Carey, Chris L. Carilli, Carina Cheng, David R. DeBoer, Eloy de Lera Acedo, Matt Dexter, Nico Eksteen, John Ely, Aaron Ewall-Wice, Nicolas Fagnoni, Randall Fritz, Steven R. Furlanetto, Kingsley Gale-Sides, Brian Glendenning, Deepthi Gorthi, Bradley Greig, Jasper Grobbelaar, Ziyaad Halday, Jack Hickish, Daniel C. Jacobs, Austin Julius, MacCalvin Kariseb, Joshua Kerrigan, Piyanat Kittiwisit, Saul A. Kohn, Matthew Kolopanis, Adam Lanman, Paul La Plante, Anita Loots, David Harold Edward MacMahon, Lourence Malan, Cresshim Malgas, Keith Malgas, Bradley Marero, Andrei Mesinger, Mathakane Molewa, Tshegofalang Mosiane, Steven G. Murray, Abraham R. Neben, Bojan Nikolic, Hans Nuwegeld, Aaron R. Parsons, Nipanjana Patra, Samantha Pieterse, Nima Razavi-Ghods, James Robnett, Kathryn Rosie, Peter Sims, Craig Smith, Hilton Swarts, Jianrong Tan, Nithyanandan Thyagarajan, Pieter van Wyngaarden, Peter K. G. Williams, Haoxuan Zheng, and HERA Collaboration

Subjects
H I line emission, Radio interferometry, Early universe, Reionization, Astrophysics, QB460-466
Abstract

The key to detecting neutral hydrogen during the epoch of reionization (EoR) is to separate the cosmological signal from the dominating foreground radiation. We developed direct optimal mapping (DOM) to map interferometric visibilities; it contains only linear operations, with full knowledge of point spread functions from visibilities to images. Here, we demonstrate a fast Fourier transform-based image power spectrum and its window functions computed from the DOM images. We use noiseless simulation, based on the Hydrogen Epoch of Reionization Array Phase I configuration, to study the image power spectrum properties. The window functions show

Published
2024
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2. Low-frequency Radio Recombination Lines Away from the Inner Galactic Plane

Author

Akshatha K. Vydula, Judd D. Bowman, David Lewis, Kelsie Crawford, Matthew Kolopanis, Alan E. E. Rogers, Steven G. Murray, Nivedita Mahesh, Raul A. Monsalve, Peter Sims, and Titu Samson

Subjects
Radio spectroscopy, Interstellar medium, the Milky Way, Reionization, Astronomy, QB1-991
Abstract

Diffuse radio recombination lines (RRLs) in the Galaxy are possible foregrounds for redshifted 21 cm experiments. We use EDGES drift scans centered at −26.°7 decl. to characterize diffuse RRLs across the southern sky. We find that RRLs averaged over the large antenna beam (72° × 110°) reach minimum amplitudes of R.A. = 2–6 hr. In this region, the C α absorption amplitude is 33 ± 11 mK (1 σ ) averaged over 50–87 MHz (27 ≳ z ≳ 15 for the 21 cm line) and increases strongly as frequency decreases. C β and H α lines are consistent with no detection with amplitudes of 13 ± 14 and 12 ± 10 mK (1 σ ), respectively. At 108–124.5 MHz ( z ≈ 11) in the same region, we find no evidence for carbon or hydrogen lines at the noise level of 3.4 mK (1 σ ). Conservatively assuming that observed lines come broadly from the diffuse interstellar medium, as opposed to a few compact regions, these amplitudes provide upper limits on the intrinsic diffuse lines. The observations support expectations that Galactic RRLs can be neglected as significant foregrounds for a large region of sky until redshifted 21 cm experiments, particularly those targeting cosmic dawn, move beyond the detection phase. We fit models of the spectral dependence of the lines averaged over the large beam of EDGES, which may contain multiple line sources with possible line blending, and find that including degrees of freedom for expected smooth, frequency-dependent deviations from local thermodynamic equilibrium (LTE) is preferred over simple LTE assumptions for C α and H α lines. For C α we estimate departure coefficients 0.79 < b _n β _n < 4.5 along the inner Galactic plane and 0 < b _n β _n < 2.3 away from the inner Galactic plane.

Published
2023
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3. Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations

Author

The HERA Collaboration: Zara Abdurashidova, Tyrone Adams, James E. Aguirre, Paul Alexander, Zaki S. Ali, Rushelle Baartman, Yanga Balfour, Rennan Barkana, Adam P. Beardsley, Gianni Bernardi, Tashalee S. Billings, Judd D. Bowman, Richard F. Bradley, Daniela Breitman, Philip Bull, Jacob Burba, Steve Carey, Chris L. Carilli, Carina Cheng, Samir Choudhuri, David R. DeBoer, Eloy de Lera Acedo, Matt Dexter, Joshua S. Dillon, John Ely, Aaron Ewall-Wice, Nicolas Fagnoni, Anastasia Fialkov, Randall Fritz, Steven R. Furlanetto, Kingsley Gale-Sides, Hugh Garsden, Brian Glendenning, Adélie Gorce, Deepthi Gorthi, Bradley Greig, Jasper Grobbelaar, Ziyaad Halday, Bryna J. Hazelton, Stefan Heimersheim, Jacqueline N. Hewitt, Jack Hickish, Daniel C. Jacobs, Austin Julius, Nicholas S. Kern, Joshua Kerrigan, Piyanat Kittiwisit, Saul A. Kohn, Matthew Kolopanis, Adam Lanman, Paul La Plante, David Lewis, Adrian Liu, Anita Loots, Yin-Zhe Ma, David H. E. MacMahon, Lourence Malan, Keith Malgas, Cresshim Malgas, Matthys Maree, Bradley Marero, Zachary E. Martinot, Lisa McBride, Andrei Mesinger, Jordan Mirocha, Mathakane Molewa, Miguel F. Morales, Tshegofalang Mosiane, Julian B. Muñoz, Steven G. Murray, Vighnesh Nagpal, Abraham R. Neben, Bojan Nikolic, Chuneeta D. Nunhokee, Hans Nuwegeld, Aaron R. Parsons, Robert Pascua, Nipanjana Patra, Samantha Pieterse, Yuxiang Qin, Nima Razavi-Ghods, James Robnett, Kathryn Rosie, Mario G. Santos, Peter Sims, Saurabh Singh, Craig Smith, Hilton Swarts, Jianrong Tan, Nithyanandan Thyagarajan, Michael J. Wilensky, Peter K. G. Williams, Pieter van Wyngaarden, and Haoxuan Zheng

Subjects
Astronomy data analysis, Radio interferometers, Intergalactic medium, Reionization, Galaxy formation, Cosmology, Astrophysics, QB460-466
Abstract

We report the most sensitive upper limits to date on the 21 cm epoch of reionization power spectrum using 94 nights of observing with Phase I of the Hydrogen Epoch of Reionization Array (HERA). Using similar analysis techniques as in previously reported limits, we find at 95% confidence that Δ ^2 ( k = 0.34 h Mpc ^−1 ) ≤ 457 mK ^2 at z = 7.9 and that Δ ^2 ( k = 0.36 h Mpc ^−1 ) ≤ 3496 mK ^2 at z = 10.4, an improvement by a factor of 2.1 and 2.6, respectively. These limits are mostly consistent with thermal noise over a wide range of k after our data quality cuts, despite performing a relatively conservative analysis designed to minimize signal loss. Our results are validated with both statistical tests on the data and end-to-end pipeline simulations. We also report updated constraints on the astrophysics of reionization and the cosmic dawn. Using multiple independent modeling and inference techniques previously employed by HERA Collaboration, we find that the intergalactic medium must have been heated above the adiabatic cooling limit at least as early as z = 10.4, ruling out a broad set of so-called “cold reionization” scenarios. If this heating is due to high-mass X-ray binaries during the cosmic dawn, as is generally believed, our result’s 99% credible interval excludes the local relationship between soft X-ray luminosity and star formation and thus requires heating driven by evolved low-metallicity stars.

Published
2023
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4. Effects of model incompleteness on the drift-scan calibration of radio telescopes

Author

Bharat K Gehlot, Daniel C Jacobs, Judd D Bowman, Nivedita Mahesh, Steven G Murray, Matthew Kolopanis, Adam P Beardsley, Zara Abdurashidova, James E Aguirre, Paul Alexander, Zaki S Ali, Yanga Balfour, Gianni Bernardi, Tashalee S Billings, Richard F Bradley, Phil Bull, Jacob Burba, Steve Carey, Chris L Carilli, Carina Cheng, David R DeBoer, Matt Dexter, Eloy de Lera Acedo, Joshua S Dillon, John Ely, Aaron Ewall-Wice, Nicolas Fagnoni, Randall Fritz, Steven R Furlanetto, Kingsley Gale-Sides, Brian Glendenning, Deepthi Gorthi, Bradley Greig, Jasper Grobbelaar, Ziyaad Halday, Bryna J Hazelton, Jacqueline N Hewitt, Jack Hickish, Austin Julius, Nicholas S Kern, Joshua Kerrigan, Piyanat Kittiwisit, Saul A Kohn, Adam Lanman, Paul La Plante, Telalo Lekalake, David Lewis, Adrian Liu, Yin-Zhe Ma, David MacMahon, Lourence Malan, Cresshim Malgas, Matthys Maree, Zachary E Martinot, Eunice Matsetela, Andrei Mesinger, Mathakane Molewa, Raul A Monsalve, Miguel F Morales, Tshegofalang Mosiane, Abraham R Neben, Bojan Nikolic, Aaron R Parsons, Robert Pascua, Nipanjana Patra, Samantha Pieterse, Jonathan C Pober, Nima Razavi-Ghods, Jon Ringuette, James Robnett, Kathryn Rosie, Mario G Santos, Peter Sims, Craig Smith, Angelo Syce, Max Tegmark, Nithyanandan Thyagarajan, Peter K G Williams, and Haoxuan Zheng

Published
2021
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5. New EoR power spectrum limits from MWA Phase II using the delay spectrum method and novel systematic rejection

Author

Matthew Kolopanis, Jonathan C Pober, Daniel C Jacobs, and Samantha McGraw

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present an analysis of Epoch of Reionization data from Phase II of the Murchison Widefield Array using the \texttt{simpleDS} delay spectrum pipeline. Prior work analyzed the same observations using the FHD/$\varepsilon$ppsilon imaging pipeline, and so the present analysis represents the first time that both principal types of 21 cm cosmology power spectrum estimation approaches have been applied to the same data set. Our limits on the 21 cm power spectrum amplitude span a range in $k$ space of $|k| < 1~h_{100}{\rm Mpc}^{-1}$ with a lowest measurement of $\Delta^2(k) \leq$ $4.58\times10^3$ mK$^2$ at $k = 0.190 h_{100}\rm{Mpc}^{-1}$ and $z = 7.14$. In order to achieve these limits, we need to mitigate a previously unidentified common mode systematic in the data set. If not accounted for, this systematic introduces an overall \emph{negative} bias that can make foreground contaminated measurements appear as stringent, noise-limited constraints on the 21 cm signal amplitude. The identification of this systematic highlights the risk in modeling systematics as positive-definite contributions to the power spectrum and in ``conservatively'' interpreting all measurements as upper limits., Comment: 19 pages, 12 figures, Accepted by MNRAS; Updated to match published version

Published
2023

6. A Real Time Processing system for big data in astronomy: Applications to HERA.

Author

Paul La Plante, Peter K. G. Williams, Matthew Kolopanis, Jesse Dillon, Adam P. Beardsley, Nicholas S. Kern, Michael Wilensky, Zaki S. Ali, Zara Abdurashidova, James E. Aguirre, Paul Alexander, Yanga Balfour, Gianni Bernardi, Tashalee S. Billings, Judd D. Bowman, Roxanne F. Bradley, Phil Bull, Jacob Burba, Steve Carey, Chris L. Carilli, Carina Cheng, David R. DeBoer, Matt Dexter, Eloy de Lera Acedo, John Ely, Aaron Ewall-Wice, Nicolas Fagnoni, Randall Fritz, Steven R. Furlanetto, Kingsley Gale-Sides, Brian Glendenning, Deepthi Gorthi, Bradley Greig, Jasper Grobbelaar, Ziyaad Halday, Bryna J. Hazelton, Jacqueline N. Hewitt, Jack Hickish, Daniel C. Jacobs, Austin Julius, Joshua Kerrigan, Piyanat Kittiwisit, Saul A. Kohn, Adam Lanman, Telalo Lekalake, David Lewis, Adrian Liu, David MacMahon, Lourence Malan, Cresshim Malgas, Matthys Maree, Zachary E. Martinot, Eunice Matsetela, Andrei Mesinger, Mathakane Molewa, Miguel F. Morales, Tshegofalang Mosiane, Steven G. Murray, Abraham R. Neben, Bojan Nikolic, Aaron R. Parsons, Robert Pascua, Nipanjana Patra, Samantha Pieterse, Jonathan C. Pober, Nima Razavi-Ghods, Jon Ringuette, James Robnett, Kathryn Rosie, Mario G. Santos, Peter H. Sims, Craig Smith, Angelo Syce, Nithyanandan Thyagarajan, and Haoxuan Zheng

Published
2021
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7. Optimization and Commissioning of the EPIC Commensal Radio Transient Imager for the Long Wavelength Array

Author

Harihanan Krishnan, Adam P Beardsley, Judd D Bowman, Jayce Dowell, Matthew Kolopanis, Greg Taylor, and Nithyanandan Thyagarajan

Subjects
Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract

Next-generation aperture arrays are expected to consist of hundreds to thousands of antenna elements with substantial digital signal processing to handle large operating bandwidths of a few tens to hundreds of MHz. Conventionally, FX correlators are used as the primary signal processing unit of the interferometer. These correlators have computational costs that scale as $\mathcal {O}(N^2)$ for large arrays. An alternative imaging approach is implemented in the E-field Parallel Imaging Correlator (EPIC) that was recently deployed on the Long Wavelength Array station at the Sevilleta National Wildlife Refuge (LWA-SV) in New Mexico. EPIC uses a novel architecture that produces electric field or intensity images of the sky at the angular resolution of the array with full or partial polarization and the full spectral resolution of the channelizer. By eliminating the intermediate cross-correlation data products, the computational costs can be significantly lowered in comparison to a conventional FX or XF correlator from $\mathcal {O}(N^2)$ to $\mathcal {O}(N \log N)$ for dense (but otherwise arbitrary) array layouts. EPIC can also lower the output data rates by directly yielding polarimetric image products for science analysis. We have optimized EPIC and have now commissioned it at LWA-SV as a commensal all-sky imaging back-end that can potentially detect and localize sources of impulsive radio emission on millisecond timescales. In this article, we review the architecture of EPIC, describe code optimizations that improve performance, and present initial validations from commissioning observations. Comparisons between EPIC measurements and simultaneous beam-formed observations of bright sources show spectral-temporal structures in good agreement.

Published
2023
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8. The correlation calibration of PAPER-64 data

Author

Tamirat G Gogo, Yin-Zhe Ma, Piyanat Kittiwisit, Jonathan L Sievers, Aaron R Parsons, Jonathan C Pober, Daniel C Jacobs, Carina Cheng, Matthew Kolopanis, Adrian Liu, Saul A Kohn, James E Aguirre, Zaki S Ali, Gianni Bernardi, Richard F Bradley, David R DeBoer, Matthew R Dexter, Joshua S Dillon, Pat Klima, David H E MacMahon, David F Moore, Chuneeta D Nunhokee, William P Walbrugh, Andre Walker, USA, and ZAF

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Space and Planetary Science, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Observation of redshifted 21-cm signal from the Epoch of Reionization (EoR) is challenging due to contamination from the bright foreground sources that exceed the signal by several orders of magnitude. The removal of this very high foreground relies on accurate calibration to keep the intrinsic property of the foreground with frequency. Commonly employed calibration techniques for these experiments are the sky model-based and the redundant baseline-based calibration approaches. However, the sky model-based and redundant baseline-based calibration methods could suffer from sky-modeling error and array redundancy imperfection issues, respectively. In this work, we introduce the hybrid correlation calibration ("CorrCal") scheme, which aims to bridge the gap between redundant and sky-based calibration by relaxing redundancy of the array and including sky information into the calibration formalisms. We demonstrate the slight improvement of power spectra, about $-6\%$ deviation at the bin right on the horizon limit of the foreground wedge-like structure, relative to the power spectra before the implementation of "CorrCal" to the data from the Precision Array for Probing the Epoch of Reionization (PAPER) experiment, which was otherwise calibrated using redundant baseline calibration. This small improvement of the foreground power spectra around the wedge limit could be suggestive of reduced spectral structure in the data after "CorrCal" calibration, which lays the foundation for future improvement of the calibration algorithm and implementation method., Comment: 18 pages, 12 figures, MNRAS in press

Published
2021

9. Constraining the 21 cm brightness temperature of the IGM at z = 6.6 around LAEs with the murchison widefield array

Author

Matthew Kolopanis, Adam P. Beardsley, Christopher H. Jordan, Nichole Barry, Q. Zheng, B. McKinley, Randall B. Wayth, E. Howard, Daniel A. Mitchell, Judd D. Bowman, J. S. B. Wyithe, Pratika Dayal, Cathryn M. Trott, Keisuke Hasegawa, Anne Hutter, Miguel F. Morales, Daniel C. Jacobs, Rachel L. Webster, Bradley Greig, Bryna J. Hazelton, A. Chokshi, S. Murray, M. Rahimi, J. L. B. Line, M. Wilensky, S. Yoshiura, Steven Tingay, Christene Lynch, B. Pindor, Keitaro Takahashi, Jonathan C. Pober, R. Byrne, and Astronomy

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), FOS: Physical sciences, Murchison Widefield Array, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Galaxy formation and evolution, instrumentation: interferometers, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Reionization, Astrophysics::Galaxy Astrophysics, Line (formation), Physics, methods: statistical, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Spectral density, Astronomy and Astrophysics, Redshift, Galaxy, Space and Planetary Science, Brightness temperature, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The locations of Ly-$\alpha$ emitting galaxies (LAEs) at the end of the Epoch of Reionisation (EoR) are expected to correlate with regions of ionised hydrogen, traced by the redshifted 21~cm hyperfine line. Mapping the neutral hydrogen around regions with detected and localised LAEs offers an avenue to constrain the brightness temperature of the Universe within the EoR by providing an expectation for the spatial distribution of the gas, thereby providing prior information unavailable to power spectrum measurements. We use a test set of 12 hours of observations from the Murchison Widefield Array (MWA) in extended array configuration, to constrain the neutral hydrogen signature of 58 LAEs, detected with the Subaru Hypersuprime Cam in the \textit{Silverrush} survey, centred on $z$=6.58. We assume that detectable emitters reside in the centre of ionised HII bubbles during the end of reionization, and predict the redshifted neutral hydrogen signal corresponding to the remaining neutral regions using a set of different ionised bubble radii. A prewhitening matched filter detector is introduced to assess detectability. We demonstrate the ability to detect, or place limits upon, the amplitude of brightness temperature fluctuations, and the characteristic HII bubble size. With our limited data, we constrain the brightness temperature of neutral hydrogen to $\Delta{\rm T}_B, Comment: 9 pages, 6 figures, accepted for publication in MNRAS

Published
2021

10. Bayesian jackknife tests with a small number of subsets: Application to HERA 21cm power spectrum upper limits

Author

Michael J Wilensky, Fraser Kennedy, Philip Bull, Joshua S Dillon, Zara Abdurashidova, Tyrone Adams, James E Aguirre, Paul Alexander, Zaki S Ali, Rushelle Baartman, Yanga Balfour, Adam P Beardsley, Gianni Bernardi, Tashalee S Billings, Judd D Bowman, Richard F Bradley, Jacob Burba, Steven Carey, Chris L Carilli, Carina Cheng, David R DeBoer, Eloy de Lera Acedo, Matt Dexter, Nico Eksteen, John Ely, Aaron Ewall-Wice, Nicolas Fagnoni, Randall Fritz, Steven R Furlanetto, Kingsley Gale-Sides, Brian Glendenning, Deepthi Gorthi, Bradley Greig, Jasper Grobbelaar, Ziyaad Halday, Bryna J Hazelton, Jacqueline N Hewitt, Jack Hickish, Daniel C Jacobs, Austin Julius, MacCalvin Kariseb, Nicholas S Kern, Joshua Kerrigan, Piyanat Kittiwisit, Saul A Kohn, Matthew Kolopanis, Adam Lanman, Paul La Plante, Adrian Liu, Anita Loots, David Harold Edward MacMahon, Lourence Malan, Cresshim Malgas, Keith Malgas, Bradley Marero, Zachary E Martinot, Andrei Mesinger, Mathakane Molewa, Miguel F Morales, Tshegofalang Mosiane, Steven G Murray, Abraham R Neben, Bojan Nikolic, Hans Nuwegeld, Aaron R Parsons, Nipanjana Patra, Samantha Pieterse, Nima Razavi-Ghods, James Robnett, Kathryn Rosie, Peter Sims, Hilton Swarts, Nithyanandan Thyagarajan, Pieter van Wyngaarden, Peter K G Williams, Haoxuan Zheng, Michael, J Wilensky, Fraser, Kennedy, Philip, Bull, Joshua, S Dillon, Zara, Abdurashidova, Tyrone, Adam, James, E Aguirre, Paul, Alexander, Zaki, S Ali, Rushelle, Baartman, Yanga, Balfour, Adam, P Beardsley, Bernardi, Gianni, Tashalee, S Billing, Judd, D Bowman, Richard, F Bradley, Jacob, Burba, Steven, Carey, Chris, L Carilli, Carina, Cheng, David, R DeBoer, Eloy de Lera Acedo, Matt, Dexter, Nico, Eksteen, John, Ely, Aaron, Ewall-Wice, Nicolas, Fagnoni, Randall, Fritz, Steven, R Furlanetto, Kingsley, Gale-Side, Brian, Glendenning, Deepthi, Gorthi, Greig, Bradley, Jasper, Grobbelaar, Ziyaad, Halday, Bryna, J Hazelton, Jacqueline, N Hewitt, Jack, Hickish, Daniel, C Jacob, Austin, Juliu, Maccalvin, Kariseb, Nicholas, S Kern, Joshua, Kerrigan, Piyanat, Kittiwisit, Saul, A Kohn, Matthew, Kolopani, Adam, Lanman, Paul La Plante, Liu, Adrian Chi-Yan, Anita, Loot, David Harold Edward MacMahon, Lourence, Malan, Cresshim, Malga, Keith, Malga, Bradley, Marero, Zachary, E Martinot, Mesinger, ANDREI ALBERT, Mathakane, Molewa, Miguel, F Morale, Tshegofalang, Mosiane, Steven, G Murray, Abraham, R Neben, Bojan, Nikolic, Hans, Nuwegeld, Aaron, R Parson, Nipanjana, Patra, Samantha, Pieterse, Nima, Razavi-Ghod, James, Robnett, Kathryn, Rosie, Peter, Sim, Hilton, Swart, Thyagarajan, Nithyanandan, Pieter van Wyngaarden, Peter K, G William, and Haoxuan, Zheng

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Settore FIS/05 - Astronomia e Astrofisica, Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present a Bayesian jackknife test for assessing the probability that a data set contains biased subsets, and, if so, which of the subsets are likely to be biased. The test can be used to assess the presence and likely source of statistical tension between different measurements of the same quantities in an automated manner. Under certain broadly applicable assumptions, the test is analytically tractable. We also provide an open-source code, chiborg, that performs both analytic and numerical computations of the test on general Gaussian-distributed data. After exploring the information theoretical aspects of the test and its performance with an array of simulations, we apply it to data from the Hydrogen Epoch of Reionization Array (HERA) to assess whether different sub-seasons of observing can justifiably be combined to produce a deeper 21 cm power spectrum upper limit. We find that, with a handful of exceptions, the HERA data in question are statistically consistent and this decision is justified. We conclude by pointing out the wide applicability of this test, including to CMB experiments and the H0 tension.

Published
2022

11. Effects of model incompleteness on the drift-scan calibration of radio telescopes

Author

Phil Bull, David DeBoer, Adam P. Beardsley, Nipanjana Patra, Ziyaad Halday, Nima Razavi-Ghods, Nicholas S. Kern, Aaron R. Parsons, Piyanat Kittiwisit, Kingsley Gale-Sides, Robert Pascua, Max Tegmark, Judd D. Bowman, Adam Lanman, Samantha Pieterse, James Robnett, Peter Sims, Gianni Bernardi, Peter K. G. Williams, Miguel F. Morales, Chris Carilli, Saul A. Kohn, Zara Abdurashidova, Eloy de Lera Acedo, Zaki S. Ali, Steven R. Furlanetto, Abraham R. Neben, Eunice Matsetela, Randall Fritz, Bojan Nikolic, Aaron Ewall-Wice, Bryna J. Hazelton, Deepthi Gorthi, Richard F. Bradley, Matthew Kolopanis, Jon Ringuette, Brian Glendenning, Matt Dexter, Joshua S. Dillon, Carina Cheng, Paul La Plante, Austin Julius, S. H. Carey, Nithyanandan Thyagarajan, Haoxuan Zheng, David B. Lewis, Mario G. Santos, Daniel C. Jacobs, Joshua Kerrigan, Steven G. Murray, Cresshim Malgas, Jack Hickish, Adrian Liu, James E. Aguirre, Nicolas Fagnoni, Jacob Burba, Yanga Balfour, Lourence Malan, Craig Smith, Raul A. Monsalve, Bradley Greig, Jonathan C. Pober, Andrei Mesinger, Jasper Grobbelaar, Tashalee S. Billings, Zachary E. Martinot, Telalo Lekalake, Matthys Maree, B. K. Gehlot, David MacMahon, Yin-Zhe Ma, Mathakane Molewa, Paul Alexander, Kathryn Rosie, Tshegofalang Mosiane, Nivedita Mahesh, John Ely, Jacqueline N. Hewitt, Angelo Syce, Gehlot, B. K., Jacobs, D. C., Bowman, J. D., Mahesh, N., Murray, S. G., Kolopanis, M., Beardsley, A. P., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Ali, Z. S., Balfour, Y., Bernardi, G., Billings, T. S., Bradley, R. F., Bull, P., Burba, J., Carey, S., Carilli, C. L., Cheng, C., Deboer, D. R., Dexter, M., De Lera Acedo, E., Dillon, J. S., Ely, J., Ewall-Wice, A., Fagnoni, N., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Julius, A., Kern, N. S., Kerrigan, J., Kittiwisit, P., Kohn, S. A., Lanman, A., La Plante, P., Lekalake, T., Lewis, D., Liu, A., Ma, Y. -Z., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mesinger, A., Molewa, M., Monsalve, R. A., Morales, M. F., Mosiane, T., Neben, A. R., Nikolic, B., Parsons, A. R., Pascua, R., Patra, N., Pieterse, S., Pober, J. C., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Santos, M. G., Sims, P., Smith, C., Syce, A., Tegmark, M., Thyagarajan, N., Williams, P. K. G., Zheng, H., ITA, and USA

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010504 meteorology & atmospheric sciences, media_common.quotation_subject, statistical [methods], FOS: Physical sciences, 01 natural sciences, Radio telescope, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Calibration, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Reionization, 0105 earth and related environmental sciences, Remote sensing, media_common, Physics, COSMIC cancer database, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, interferometric [techniques], interferometer [instrumentation], Interferometry, Amplitude, 13. Climate action, Space and Planetary Science, Sky, data analysi [methods], dark ages, reionization, first star, Antenna (radio), Astrophysics - Instrumentation and Methods for Astrophysics, miscellaneou [instrumentation], Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Precision calibration poses challenges to experiments probing the redshifted 21-cm signal of neutral hydrogen from the Cosmic Dawn and Epoch of Reionization (z~30-6). In both interferometric and global signal experiments, systematic calibration is the leading source of error. Though many aspects of calibration have been studied, the overlap between the two types of instruments has received less attention. We investigate the sky based calibration of total power measurements with a HERA dish and an EDGES style antenna to understand the role of auto-correlations in the calibration of an interferometer and the role of sky in calibrating a total power instrument. Using simulations we study various scenarios such as time variable gain, incomplete sky calibration model, and primary beam model. We find that temporal gain drifts, sky model incompleteness, and beam inaccuracies cause biases in the receiver gain amplitude and the receiver temperature estimates. In some cases, these biases mix spectral structure between beam and sky resulting in spectrally variable gain errors. Applying the calibration method to the HERA and EDGES data, we find good agreement with calibration via the more standard methods. Although instrumental gains are consistent with beam and sky errors similar in scale to those simulated, the receiver temperatures show significant deviations from expected values. While we show that it is possible to partially mitigate biases due to model inaccuracies by incorporating a time-dependent gain model in calibration, the resulting errors on calibration products are larger and more correlated. Completely addressing these biases will require more accurate sky and primary beam models., Comment: 16 pages, 13 figures, 1 table; accepted for publication in MNRAS main journal

Published
2021

13. Characterization Of Inpaint Residuals In Interferometric Measurements of the Epoch Of Reionization

Author

Michael Pagano, Jing Liu, Adrian Liu, Nicholas S Kern, Aaron Ewall-Wice, Philip Bull, Robert Pascua, Siamak Ravanbakhsh, Zara Abdurashidova, Tyrone Adams, James E Aguirre, Paul Alexander, Zaki S Ali, Rushelle Baartman, Yanga Balfour, Adam P Beardsley, Gianni Bernardi, Tashalee S Billings, Judd D Bowman, Richard F Bradley, Jacob Burba, Steven Carey, Chris L Carilli, Carina Cheng, David R DeBoer, Eloy de Lera Acedo, Matt Dexter, Joshua S Dillon, Nico Eksteen, John Ely, Nicolas Fagnoni, Randall Fritz, Steven R Furlanetto, Kingsley Gale-Sides, Brian Glendenning, Deepthi Gorthi, Bradley Greig, Jasper Grobbelaar, Ziyaad Halday, Bryna J Hazelton, Jacqueline N Hewitt, Jack Hickish, Daniel C Jacobs, Austin Julius, MacCalvin Kariseb, Joshua Kerrigan, Piyanat Kittiwisit, Saul A Kohn, Matthew Kolopanis, Adam Lanman, Paul La Plante, Anita Loots, David Harold Edward MacMahon, Lourence Malan, Cresshim Malgas, Keith Malgas, Bradley Marero, Zachary E Martinot, Andrei Mesinger, Mathakane Molewa, Miguel F Morales, Tshegofalang Mosiane, Abraham R Neben, Bojan Nikolic, Hans Nuwegeld, Aaron R Parsons, Nipanjana Patra, Samantha Pieterse, Nima Razavi-Ghods, James Robnett, Kathryn Rosie, Peter Sims, Craig Smith, Hilton Swarts, Nithyanandan Thyagarajan, Pieter van Wyngaarden, Peter K G Williams, and Haoxuan Zheng

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Radio Frequency Interference (RFI) is one of the systematic challenges preventing 21cm interferometric instruments from detecting the Epoch of Reionization. To mitigate the effects of RFI on data analysis pipelines, numerous inpaint techniques have been developed to restore RFI corrupted data. We examine the qualitative and quantitative errors introduced into the visibilities and power spectrum due to inpainting. We perform our analysis on simulated data as well as real data from the Hydrogen Epoch of Reionization Array (HERA) Phase 1 upper limits. We also introduce a convolutional neural network that capable of inpainting RFI corrupted data in interferometric instruments. We train our network on simulated data and show that our network is capable at inpainting real data without requiring to be retrained. We find that techniques that incorporate high wavenumbers in delay space in their modeling are best suited for inpainting over narrowband RFI. We also show that with our fiducial parameters Discrete Prolate Spheroidal Sequences (DPSS) and CLEAN provide the best performance for intermittent ``narrowband'' RFI while Gaussian Progress Regression (GPR) and Least Squares Spectral Analysis (LSSA) provide the best performance for larger RFI gaps. However we caution that these qualitative conclusions are sensitive to the chosen hyperparameters of each inpainting technique. We find these results to be consistent in both simulated and real visibilities. We show that all inpainting techniques reliably reproduce foreground dominated modes in the power spectrum. Since the inpainting techniques should not be capable of reproducing noise realizations, we find that the largest errors occur in the noise dominated delay modes. We show that in the future, as the noise level of the data comes down, CLEAN and DPSS are most capable of reproducing the fine frequency structure in the visibilities of HERA data., Comment: 21 pages, 13 figures

Published
2022
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14. Foreground modelling via Gaussian process regression: an application to HERA data

Author

Max Tegmark, Aaron R. Parsons, Samavarti Gallardo, Angelo Syce, Jon Ringuette, Adam P. Beardsley, Gianni Bernardi, Richard F. Bradley, Matthew Kolopanis, Mario G. Santos, Adrian Liu, Kathryn Rosie, T. L. Grobler, Nicholas S. Kern, Brian Glendenning, Amy S. Igarashi, Siyanda Matika, Daniel C. Jacobs, Carina Cheng, Oleg Smirnov, Nithyanandan Thyagarajan, Haoxuan Zheng, Peter K. G. Williams, Matthys Maree, Roshan K. Benefo, Nathan Mathison, Lourence Malan, Austin Julius, Nima Razavi-Ghods, Cresshim Malgas, B. K. Gehlot, Nicolas Fagnoni, Bryna J. Hazelton, Andrei Mesinger, Chuneeta D. Nunhokee, Jasper Grobbelaar, David MacMahon, Deepthi Gorthi, Léon V. E. Koopmans, Joshua S. Dillon, Steve R. Furlanetto, Abraham R. Neben, Chris Carilli, Tashalee S. Billings, Zachary E. Martinot, Judd D. Bowman, Samantha Pieterse, Paul Alexander, Randall Fritz, James Robnett, Telalo Lekalake, Raddwine Sell, Saul A. Kohn, Eloy de Lera Acedo, Florent Mertens, Alec Josaitis, Bradley Greig, Nipanjana Patra, Craig Smith, Austin F. Fortino, David DeBoer, Miguel F. Morales, Zaki S. Ali, Bojan Nikolic, Aaron Ewall-Wice, Eunice Matsetela, MacCalvin Kariseb, Gcobisa Fadana, Paul M. Chichura, Jack Hickish, James E. Aguirre, Abhik Ghosh, Anita Loots, Ghosh, A., Mertens, F., Bernardi, G., Santos, M. G., Kern, N. S., Carilli, C. L., Grobler, T. L., Koopmans, L. V. E., Jacobs, D. C., Liu, A., Parsons, A. R., Morales, M. F., Aguirre, J. E., Dillon, J. S., Hazelton, B. J., Smirnov, O. M., Gehlot, B. K., Matika, S., Alexander, P., Ali, Z. S., Beardsley, A. P., Benefo, R. K., Billings, T. S., Bowman, J. D., Bradley, R. F., Cheng, C., Chichura, P. M., Deboer, D. R., Acedo, E. D. L., Ewall-Wice, A., Fadana, G., Fagnoni, N., Fortino, A. F., Fritz, R., Furlanetto, S. R., Gallardo, S., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Hickish, J., Josaitis, A., Julius, A., Igarashi, A. S., Kariseb, M., Kohn, S. A., Kolopanis, M., Lekalake, T., Loots, A., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Mathison, N., Matsetela, E., Mesinger, A., Neben, A. R., Nikolic, B., Nunhokee, C. D., Patra, N., Pieterse, S., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Sell, R., Smith, C., Syce, A., Tegmark, M., Thyagarajan, N., Williams, P. K. G., Zheng, H., Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), ITA, USA, ZAF, Astronomy, and Kapteyn Astronomical Institute

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), interferometers [instrumentation], first stars, statistical [methods], FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astronomy & Astrophysics, 01 natural sciences, Signal, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Coherence (signal processing), dark ages, reionization, first stars, dark ages, instrumentation: interferometers, 010306 general physics, 010303 astronomy & astrophysics, Reionization, Astrophysics::Galaxy Astrophysics, Physics, methods: statistical, COSMIC cancer database, Astrophysics::Instrumentation and Methods for Astrophysics, Spectral density, Astronomy and Astrophysics, White noise, observations [cosmology], Redshift, diffuse radiation, Periodic function, interferometer [instrumentation], Space and Planetary Science, cosmology: observations, astro-ph.CO, reionization, dark ages, reionization, first star, large-scale structure of Universe, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astronomical and Space Sciences, Astrophysics - Cosmology and Nongalactic Astrophysics, observation [cosmology]
Abstract

The key challenge in the observation of the redshifted 21-cm signal from cosmic reionization is its separation from the much brighter foreground emission. Such separation relies on the different spectral properties of the two components, although, in real life, the foreground intrinsic spectrum is often corrupted by the instrumental response, inducing systematic effects that can further jeopardize the measurement of the 21-cm signal. In this paper, we use Gaussian Process Regression to model both foreground emission and instrumental systematics in $\sim 2$ hours of data from the Hydrogen Epoch of Reionization Array. We find that a simple co-variance model with three components matches the data well, giving a residual power spectrum with white noise properties. These consist of an "intrinsic" and instrumentally corrupted component with a coherence-scale of 20 MHz and 2.4 MHz respectively (dominating the line of sight power spectrum over scales $k_{\parallel} \le 0.2$ h cMpc$^{-1}$) and a baseline dependent periodic signal with a period of $\sim 1$ MHz (dominating over $k_{\parallel} \sim 0.4 - 0.8$h cMpc$^{-1}$) which should be distinguishable from the 21-cm EoR signal whose typical coherence-scales is $\sim 0.8$ MHz., 15 pages, 15 figures, 1 table, Accepted to MNRAS

Published
2020

15. Automated Detection of Antenna Malfunctions in Large-N Interferometers: A Case Study with the Hydrogen Epoch of Reionization Array

Author

Dara Storer, Joshua S. Dillon, Daniel C. Jacobs, Miguel F. Morales, Bryna J. Hazelton, Aaron Ewall‐Wice, Zara Abdurashidova, James E. Aguirre, Paul Alexander, Zaki S. Ali, Yanga Balfour, Adam P. Beardsley, Gianni Bernardi, Tashalee S. Billings, Judd D. Bowman, Richard F. Bradley, Philip Bull, Jacob Burba, Steven Carey, Chris L. Carilli, Carina Cheng, David R. DeBoer, Eloy Lera Acedo, Matt Dexter, Scott Dynes, John Ely, Nicolas Fagnoni, Randall Fritz, Steven R. Furlanetto, Kingsley Gale‐Sides, Brian Glendenning, Deepthi Gorthi, Bradley Greig, Jasper Grobbelaar, Ziyaad Halday, Jacqueline N. Hewitt, Jack Hickish, Tian Huang, Alec Josaitis, Austin Julius, MacCalvin Kariseb, Nicholas S. Kern, Joshua Kerrigan, Piyanat Kittiwisit, Saul A. Kohn, Matthew Kolopanis, Adam Lanman, Paul La Plante, Adrian Liu, Anita Loots, David MacMahon, Lourence Malan, Cresshim Malgas, Zachary E. Martinot, Andrei Mesinger, Mathakane Molewa, Tshegofalang Mosiane, Steven G. Murray, Abraham R. Neben, Bojan Nikolic, Chuneeta Devi Nunhokee, Aaron R. Parsons, Robert Pascua, Nipanjana Patra, Samantha Pieterse, Jonathan C. Pober, Nima Razavi‐Ghods, Daniel Riley, James Robnett, Kathryn Rosie, Mario G. Santos, Peter Sims, Saurabh Singh, Craig Smith, Jianrong Tan, Nithyanandan Thyagarajan, Peter K. G. Williams, Haoxuan Zheng, Storer, D., Dillon, J. S., Jacobs, D. C., Morales, M. F., Hazelton, B. J., Ewall-Wice, A., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Bernardi, G., Billings, T. S., Bowman, J. D., Bradley, R. F., Bull, P., Burba, J., Carey, S., Carilli, C. L., Cheng, C., Deboer, D. R., de Lera Acedo, E., Dexter, M., Dynes, S., Ely, J., Fagnoni, N., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hewitt, J. N., Hickish, J., Huang, T., Josaitis, A., Julius, A., Kariseb, M., Kern, N. S., Kerrigan, J., Kittiwisit, P., Kohn, S. A., Kolopanis, M., Lanman, A., La Plante, P., Liu, A., Loots, A., Macmahon, D., Malan, L., Malgas, C., Martinot, Z. E., Mesinger, A., Molewa, M., Mosiane, T., Murray, S. G., Neben, A. R., Nikolic, B., Nunhokee, C. D., Parsons, A. R., Pascua, R., Patra, N., Pieterse, S., Pober, J. C., Razavi-Ghods, N., Riley, D., Robnett, J., Rosie, K., Santos, M. G., Sims, P., Singh, S., Smith, C., Tan, J., Thyagarajan, N., Williams, P. K. G., and Zheng, H.

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, FOS: Physical sciences, interferometry, Condensed Matter Physics, 01 natural sciences, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, radio cosmology, reionization, General Earth and Planetary Sciences, flagging, Electrical and Electronic Engineering, Astrophysics - Instrumentation and Methods for Astrophysics, systematics, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present a framework for identifying and flagging malfunctioning antennas in large radio interferometers. We outline two distinct categories of metrics designed to detect outliers along known failure modes of large arrays: cross-correlation metrics, based on all antenna pairs, and auto-correlation metrics, based solely on individual antennas. We define and motivate the statistical framework for all metrics used, and present tailored visualizations that aid us in clearly identifying new and existing systematics. We implement these techniques using data from 105 antennas in the Hydrogen Epoch of Reionization Array (HERA) as a case study. Finally, we provide a detailed algorithm for implementing these metrics as flagging tools on real data sets., Comment: 31 pages, 17 figures

Published
2021

16. A new MWA limit on the 21 cm Power Spectrum at Redshifts $\sim$ 13 $-$ 17

Author

Eric Howard, Keitaro Takahashi, M. Wilensky, Bryna J. Hazelton, Christene Lynch, R. C. Joseph, B. Pindor, S. Yoshiura, M. Rahimi, J. L. B. Line, Matthew Kolopanis, Bradley Greig, B. McKinley, Daniel C. Jacobs, Steven Tingay, Jonathan C. Pober, Judd D. Bowman, Zheng Zhang, Randall B. Wayth, A. Chokshi, Christopher H. Jordan, R. Byrne, Rachel L. Webster, Nichole Barry, Adam P. Beardsley, J. S. B. Wyithe, Keisuke Hasegawa, Daniel A. Mitchell, Cathryn M. Trott, Miguel F. Morales, Qian Zheng, and Steven G. Murray

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Spectral density, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Interference (wave propagation), 01 natural sciences, 7. Clean energy, Radio spectrum, Redshift, Space and Planetary Science, 0103 physical sciences, Calibration, Range (statistics), Ionosphere, 010303 astronomy & astrophysics, Reionization, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Observations in the lowest MWA band between $75-100$ MHz have the potential to constrain the distribution of neutral hydrogen in the intergalactic medium at redshift $\sim 13-17$. Using 15 hours of MWA data, we analyse systematics in this band such as radio-frequency interference (RFI), ionospheric and wide field effects. By updating the position of point sources, we mitigate the direction independent calibration error due to ionospheric offsets. Our calibration strategy is optimized for the lowest frequency bands by reducing the number of direction dependent calibrators and taking into account radio sources within a wider field of view. We remove data polluted by systematics based on the RFI occupancy and ionospheric conditions, finally selecting 5.5 hours of the cleanest data. Using these data, we obtain two sigma upper limits on the 21 cm power spectrum in the range of $0.1\lessapprox k \lessapprox 1 ~\rm ~h~Mpc^{-1}$ and at $z$=14.2, 15.2 and 16.5, with the lowest limit being $6.3\times 10^6 ~\rm mK^2$ at $\rm k=0.14 \rm ~h~Mpc^{-1}$ and at $z=15.2$ with a possibility of a few \% of signal loss due to direction independent calibration., Comment: 17 pages, 18 figures, accepted to MNRAS

Published
2021
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17. Epoch of Reionization Power Spectrum Limits from Murchison Widefield Array Data Targeted at EoR1 Field

Author

Daniel C. Jacobs, Nichole Barry, Judd D. Bowman, Cathryn M. Trott, M. Wilensky, Miguel F. Morales, Bartosz Pindor, Eric Howard, Q. Zheng, Adam P. Beardsley, Rachel L. Webster, Randall B. Wayth, J. L. B. Line, Bradley Greig, Daniel A. Mitchell, Jonathan C. Pober, Benjamin McKinley, Bryna J. Hazelton, R. Byrne, J. S. B. Wyithe, Christopher H. Jordan, Kenji Hasegawa, Matthew Kolopanis, Steven Tingay, Masoud Rahimi, Shintaro Yoshiura, Keitaro Takahashi, Christene Lynch, R. C. Joseph, S. Murray, and A. Chokshi

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Field (physics), Radio galaxy, media_common.quotation_subject, Spectral density, Order (ring theory), FOS: Physical sciences, Astronomy and Astrophysics, Murchison Widefield Array, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Redshift, Space and Planetary Science, Sky, Astrophysics - Instrumentation and Methods for Astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics, media_common
Abstract

Current attempts to measure the 21cm Power Spectrum of neutral hydrogen during the Epoch of Reionization are limited by systematics which produce measured upper limits above both the thermal noise and the expected cosmological signal. These systematics arise from a combination of observational, instrumental, and analysis effects. In order to further understand and mitigate these effects, it is instructive to explore different aspects of existing datasets. One such aspect is the choice of observing field. To date, MWA EoR observations have largely focused on the EoR0 field. In this work, we present a new detailed analysis of the EoR1 field. The EoR1 field is one of the coldest regions of the Southern radio sky, but contains the very bright radio galaxy Fornax-A. The presence of this bright extended source in the primary beam of the interferometer makes the calibration and analysis of EoR1 particularly challenging. We demonstrate the effectiveness of a recently developed shapelet model of Fornax-A in improving the results from this field. We also describe and apply a series of data quality metrics which identify and remove systematically contaminated data. With substantially improved source models, upgraded analysis algorithms and enhanced data quality metrics, we determine EoR power spectrum upper limits based on analysis of the best $\sim$14-hours data observed during 2015 and 2014 at redshifts 6.5, 6.8 and 7.1, with the lowest $2\sigma$ upper limit at z=6.5 of $\Delta^2 \leq (73.78 ~\mathrm{mK)^2}$ at $k=0.13~\mathrm{h~ Mpc^{-1}}$, improving on previous EoR1 measurement results., Comment: 18 pages, 17 figures, Accepted for publication in MNRAS

Published
2021
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18. Methods of Error Estimation for Delay Power Spectra in $21\,\textrm{cm}$ Cosmology

Author

David MacMahon, Zara Abdurashidova, Bryna J. Hazelton, David DeBoer, Austin Julius, Jon Ringuette, Jacqueline N. Hewitt, Joshua Kerrigan, Adam Lanman, Jack Hickish, Richard F. Bradley, Matthew Kolopanis, Mathakane Molewa, Angelo Syce, Aaron Ewall-Wice, Jacob Burba, Kathryn Rosie, Daniel C. Jacobs, Judd D. Bowman, Samantha Pieterse, Tshegofalang Mosiane, Cresshim Malgas, Nicolas Fagnoni, James E. Aguirre, Yanga Balfour, Lourence Malan, Paul Alexander, Brian Glendenning, Carina Cheng, Deepthi Gorthi, Nithyanandan Thyagarajan, Joshua S. Dillon, Telalo Lekalake, Jonathan C. Pober, Steve R. Furlanetto, John Ely, Matt Dexter, Andrei Mesinger, Jasper Grobbelaar, Steven Carey, Haoxuan Zheng, Gianni Bernardi, Bradley Greig, Peter Sims, Chuneeta D. Nunhokee, Miguel F. Morales, Craig Smith, Chris Carilli, Matthys Maree, Eloy de Lera Acedo, Tashalee S. Billings, Zachary E. Martinot, Zaki S. Ali, Jianrong Tan, Eunice Matsetela, Adrian Liu, Philip Bull, Bojan Nikolic, Paul La Plante, Peter K. G. Williams, Nima Razavi-Ghods, James Robnett, Nicholas S. Kern, Abraham R. Neben, Randall Fritz, Aaron R. Parsons, Adam P. Beardsley, Saul A. Kohn, Saurabh Singh, Steven G. Murray, Piyanat Kittiwisit, Kingsley Gale-Sides, Nipanjana Patra, Ziyaad Halday, Tan, J., Liu, A., Kern, N. S., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Bernardi, G., Billings, T. S., Bowman, J. D., Bradley, R. F., Bull, P., Burba, J., Carey, S., Carilli, C. L., Cheng, C., Deboer, D. R., Dexter, M., De Lera Acedo, E., Dillon, J. S., Ely, J., Ewall-Wice, A., Fagnoni, N., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Jacobs, D. C., Julius, A., Kerrigan, J., Kittiwisit, P., Kohn, S. A., Kolopanis, M., Lanman, A., La Plante, P., Lekalake, T., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mesinger, A., Molewa, M., Morales, M. F., Mosiane, T., Murray, S. G., Neben, A. R., Nikolic, B., Nunhokee, C. D., Parsons, A. R., Patra, N., Pieterse, S., Pober, J. C., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Sims, P., Singh, S., Smith, C., Syce, A., Thyagarajan, N., Williams, P. K. G., and Zheng, H.

Subjects
Physics, Noise power, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Spectral density, FOS: Physical sciences, Astronomy and Astrophysics, Probability density function, 06 humanities and the arts, HERA, 0603 philosophy, ethics and religion, 01 natural sciences, Signal, Power (physics), Settore FIS/05 - Astronomia e Astrofisica, Space and Planetary Science, 060302 philosophy, 0103 physical sciences, Limit (mathematics), Astrophysics - Instrumentation and Methods for Astrophysics, 010303 astronomy & astrophysics, Reionization, Algorithm, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Precise measurements of the 21 cm power spectrum are crucial for understanding the physical processes of hydrogen reionization. Currently, this probe is being pursued by low-frequency radio interferometer arrays. As these experiments come closer to making a first detection of the signal, error estimation will play an increasingly important role in setting robust measurements. Using the delay power spectrum approach, we have produced a critical examination of different ways that one can estimate error bars on the power spectrum. We do this through a synthesis of analytic work, simulations of toy models, and tests on small amounts of real data. We find that, although computed independently, the different error bar methodologies are in good agreement with each other in the noise-dominated regime of the power spectrum. For our preferred methodology, the predicted probability distribution function is consistent with the empirical noise power distributions from both simulated and real data. This diagnosis is mainly in support of the forthcoming HERA upper limit, and also is expected to be more generally applicable., Comment: 35 Pages, 9 Figures, 4 Tables. Replaced with accepted ApJ version; some clarifying text added in response to referee comments with no changes to results

Published
2021
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19. A Real Time Processing System for Big Data in Astronomy: Applications to HERA

Author

Aaron Ewall-Wice, Daniel C. Jacobs, Craig Smith, Cresshim Malgas, Nicolas Fagnoni, Nipanjana Patra, James Robnett, Lourence Malan, Yanga Balfour, Joshua Kerrigan, Ziyaad Halday, Steve R. Furlanetto, M. Wilensky, Peter Sims, Paul Alexander, Judd D. Bowman, Samantha Pieterse, Nima Razavi-Ghods, Piyanat Kittiwisit, Angelo Syce, Richard F. Bradley, Matthew Kolopanis, Peter K. G. Williams, Jonathan C. Pober, Telalo Lekalake, Andrei Mesinger, Jasper Grobbelaar, Brian Glendenning, D. R. DeBoer, Kingsley Gale-Sides, John Ely, Gianni Bernardi, Tashalee S. Billings, Zachary E. Martinot, Mario G. Santos, Carina Cheng, Matthys Maree, Miguel F. Morales, Adrian Liu, Kathryn Rosie, Robert Pascua, Nithyanandan Thyagarajan, Zaki S. Ali, Nicholas S. Kern, Bryna J. Hazelton, Bojan Nikolic, Zara Abdurashidova, Jacqueline N. Hewitt, Chris Carilli, Austin Julius, P. La Plante, S. Murray, Mathakane Molewa, Bradley Greig, David B. Lewis, Tshegofalang Mosiane, Adam Lanman, Deepthi Gorthi, Joshua S. Dillon, Haoxuan Zheng, Eunice Matsetela, James E. Aguirre, Dave MacMahon, S. H. Carey, E. de Lera Acedo, Aaron R. Parsons, Matthew R. Dexter, Jon Ringuette, Abraham R. Neben, Randall Fritz, Jack Hickish, Jacob Burba, Adam P. Beardsley, Saul A. Kohn, Philip Bull, La Plante, P., Williams, P. K. G., Kolopanis, M., Dillon, J. S., Beardsley, A. P., Kern, N. S., Wilensky, M., Ali, Z. S., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Balfour, Y., Bernardi, G., Billings, T. S., Bowman, J. D., Bradley, R. F., Bull, P., Burba, J., Carey, S., Carilli, C. L., Cheng, C., Deboer, D. R., Dexter, M., de Lera Acedo, E., Ely, J., Ewall-Wice, A., Fagnoni, N., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Jacobs, D. C., Julius, A., Kerrigan, J., Kittiwisit, P., Kohn, S. A., Lanman, A., Lekalake, T., Lewis, D., Liu, A., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mesinger, A., Molewa, M., Morales, M. F., Mosiane, T., Murray, S., Neben, A. R., Nikolic, B., Parsons, A. R., Pascua, R., Patra, N., Pieterse, S., Pober, J. C., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Santos, M. G., Sims, P., Smith, C., Syce, A., Thyagarajan, N., Zheng, H., ITA, and USA

Subjects
Data analysis — Software, Astronomy — Software, Computer science, Real-time computing, Big data, FOS: Physical sciences, 0102 computer and information sciences, Development, Terabyte, Interference (wave propagation), 7. Clean energy, 01 natural sciences, Computer Science::Digital Libraries, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Methods, 010303 astronomy & astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), business.industry, SIGNAL (programming language), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, HERA, Computer Science Applications, 010201 computation theory & mathematics, Space and Planetary Science, Computer data storage, Data analysis — Physical sciences and engineering, Astrophysics - Instrumentation and Methods for Astrophysics, business, Raw data
Abstract

As current- and next-generation astronomical instruments come online, they will generate an unprecedented deluge of data. Analyzing these data in real time presents unique conceptual and computational challenges, and their long-term storage and archiving is scientifically essential for generating reliable, reproducible results. We present here the real-time processing (RTP) system for the Hydrogen Epoch of Reionization Array (HERA), a radio interferometer endeavoring to provide the first detection of the highly redshifted 21 cm signal from Cosmic Dawn and the Epoch of Reionization by an interferometer. The RTP system consists of analysis routines run on raw data shortly after they are acquired, such as calibration and detection of radio-frequency interference (RFI) events. RTP works closely with the Librarian, the HERA data storage and transfer manager which automatically ingests data and transfers copies to other clusters for post-processing analysis. Both the RTP system and the Librarian are public and open source software, which allows for them to be modified for use in other scientific collaborations. When fully constructed, HERA is projected to generate over 50 terabytes (TB) of data each night, and the RTP system enables the successful scientific analysis of these data., Comment: 15 pages, 3 figures, published in Astronomy and Computing

Published
2021
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20. Redundant-baseline calibration of the hydrogen epoch of reionization array

Author

Adrian Liu, Craig Smith, Paul Alexander, John Ely, Deepthi Gorthi, Nithyanandan Thyagarajan, Steven G. Murray, Joshua S. Dillon, Bryna J. Hazelton, Phil Bull, Nipanjana Patra, Jon Ringuette, Zara Abdurashidova, Ziyaad Halday, Aaron R. Parsons, Bradley Greig, Lourence Malan, Angelo Syce, Gianni Bernardi, Piyanat Kittiwisit, Austin Julius, Daniel C. Jacobs, Kingsley Gale-Sides, Jack Hickish, Yin-Zhe Ma, Jonathan C. Pober, Kathryn Rosie, Adam P. Beardsley, Robert Pascua, Peter K. G. Williams, Cresshim Malgas, S. H. Carey, Jacob Burba, Nicolas Fagnoni, David MacMahon, Andrei Mesinger, Jasper Grobbelaar, Yanga Balfour, Joshua Kerrigan, Max Tegmark, Richard F. Bradley, Matthew Kolopanis, David DeBoer, Abraham R. Neben, Mario G. Santos, Randall Fritz, Jacqueline N. Hewitt, Tashalee S. Billings, Zachary E. Martinot, Eunice Matsetela, Saul A. Kohn, David Lewis, Peter Sims, Mathakane Molewa, Naomi Orosz, Steven R. Furlanetto, Paul La Plante, Chuneeta D. Nunhokee, Matt Dexter, Tshegofalang Mosiane, Nicholas S. Kern, Judd D. Bowman, Samantha Pieterse, Max E. Lee, James E. Aguirre, Nima Razavi-Ghods, Miguel F. Morales, Zaki S. Ali, Bojan Nikolic, Aaron Ewall-Wice, Chris Carilli, Eloy de Lera Acedo, James Robnett, Brian Glendenning, Carina Cheng, Matthys Maree, Telalo Lekalake, Haoxuan Zheng, Adam Lanman, ITA, USA, ZAF, Dillon, J. S., Lee, M., Ali, Z. S., Parsons, A. R., Orosz, N., Nunhokee, C. D., La Plante, P., Beardsley, A. P., Kern, N. S., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Balfour, Y., Bernardi, G., Billings, T. S., Bowman, J. D., Bradley, R. F., Bull, P., Burba, J., Carey, S., Carilli, C. L., Cheng, C., Deboer, D. R., Dexter, M., de Lera Acedo, E., Ely, J., Ewall-Wice, A., Fagnoni, N., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Jacobs, D. C., Julius, A., Kerrigan, J., Kittiwisit, P., Kohn, S. A., Kolopanis, M., Lanman, A., Lekalake, T., Lewis, D., Liu, A., Ma, Y. -Z., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mesinger, A., Molewa, M., Morales, M. F., Mosiane, T., Murray, S., Neben, A. R., Nikolic, B., Pascua, R., Patra, N., Pieterse, S., Pober, J. C., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Santos, M. G., Sims, P., Smith, C., Syce, A., Tegmark, M., Thyagarajan, N., Williams, P. K. G., Zheng, H., Alexander, Paul [0000-0002-0292-9513], De Lera Acedo, Eloy [0000-0001-8530-6989], Nikolic, Bojan [0000-0001-7168-2705], Razavi-Ghods, Nima [0000-0003-2930-5396], and Apollo - University of Cambridge Repository

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), Calibration (statistics), interferometers [instrumentation], first stars, Degrees of freedom (statistics), FOS: Physical sciences, Astronomy & Astrophysics, 01 natural sciences, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Astronomical interferometer, dark ages, reionization, first stars, dark ages, instrumentation: interferometers, 010303 astronomy & astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, 010308 nuclear & particles physics, Noise (signal processing), Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, HERA, Interferometry, Dark ages, reionization, first star, Space and Planetary Science, astro-ph.CO, reionization, Antenna (radio), Astrophysics - Instrumentation and Methods for Astrophysics, Algorithm, Astronomical and Space Sciences, Astrophysics - Cosmology and Nongalactic Astrophysics, astro-ph.IM
Abstract

In 21 cm cosmology, precision calibration is key to the separation of the neutral hydrogen signal from very bright but spectrally-smooth astrophysical foregrounds. The Hydrogen Epoch of Reionization Array (HERA), an interferometer specialized for 21 cm cosmology and now under construction in South Africa, was designed to be largely calibrated using the self-consistency of repeated measurements of the same interferometric modes. This technique, known as "redundant-baseline calibration" resolves most of the internal degrees of freedom in the calibration problem. It assumes, however, on antenna elements with identical primary beams placed precisely on a redundant grid. In this work, we review the detailed implementation of the algorithms enabling redundant-baseline calibration and report results with HERA data. We quantify the effects of real-world non-redundancy and how they compare to the idealized scenario in which redundant measurements differ only in their noise realizations. Finally, we study how non-redundancy can produce spurious temporal structure in our calibration solutions--both in data and in simulations--and present strategies for mitigating that structure., Comment: 24 Pages, 19 Figures. Updated to match the accepted MNRAS version

Published
2020

21. Detection of cosmic structures using the bispectrum phase. II. First results from application to cosmic reionization using the Hydrogen Epoch of Reionization Array

Author

Kathryn Rosie, James E. Aguirre, Jonathan C. Pober, Andrei Mesinger, Jasper Grobbelaar, David MacMahon, Nipanjana Patra, Tashalee S. Billings, Zachary E. Martinot, Ziyaad Halday, Deepthi Gorthi, Joshua S. Dillon, S. H. Carey, Paul Alexander, Haoxuan Zheng, Eunice Matsetela, Piyanat Kittiwisit, Adam P. Beardsley, Saul A. Kohn, Jon Ringuette, Kingsley Gale-Sides, Joshua Kerrigan, John Ely, Siyanda Matika, Zara Abdurashidova, David DeBoer, Nithyanandan Thyagarajan, Aaron R. Parsons, Matt Dexter, Bryna J. Hazelton, Adrian Liu, Nicholas S. Kern, James Kent, Jack Hickish, Judd D. Bowman, Samantha Pieterse, James Robnett, Miguel F. Morales, Paul La Plante, Richard F. Bradley, Matthew Kolopanis, Austin Julius, Chris Carilli, Eloy de Lera Acedo, Peter K. G. Williams, Craig Smith, Jacob Burba, Zaki S. Ali, Brian Glendenning, Jacqueline N. Hewitt, Carina Cheng, Gianni Bernardi, David B. Lewis, Bojan Nikolic, Aaron Ewall-Wice, Abraham R. Neben, Randall Fritz, Steven R. Furlanetto, Mathakane Molewa, Tshegofalang Mosiane, Lourence Malan, Bradley Greig, Nima Razavi-Ghods, Adam Lanman, Peter Sims, Daniel C. Jacobs, Cresshim Malgas, Nicolas Fagnoni, Yanga Balfour, Angelo Syce, Telalo Lekalake, Matthys Maree, Thyagarajan, N., Carilli, C. L., Nikolic, B., Kent, J., Mesinger, A., Kern, N. S., Bernardi, G., Matika, S., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Billings, T. S., Bowman, J. D., Bradley, R. F., Burba, J., Carey, S., Cheng, C., Deboer, D. R., Dexter, M., Acedo, E. D. L., Dillon, J. S., Ely, J., Ewall-Wice, A., Fagnoni, N., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Jacobs, D. C., Julius, A., Kerrigan, J., Kittiwisit, P., Kohn, S. A., Kolopanis, M., Lanman, A., La Plante, P., Lekalake, T., Lewis, D., Liu, A., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Molewa, M., Morales, M. F., Mosiane, T., Neben, A. R., Parsons, A. R., Patra, N., Pieterse, S., Pober, J. C., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Sims, P., Smith, C., Syce, A., Williams, P. K. G., Zheng, H., Nikolic, Bojan [0000-0001-7168-2705], Kent, James [0000-0003-3331-2409], Alexander, Paul [0000-0002-0292-9513], Razavi-Ghods, Nima [0000-0003-2930-5396], Apollo - University of Cambridge Repository, ITA, USA, and ZAF

Subjects
Brightness, Cosmology and Nongalactic Astrophysics (astro-ph.CO), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Atomic, 01 natural sciences, Cosmology, Radio telescope, Particle and Plasma Physics, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Nuclear, Astrophysics - Cosmology and Nongalactic Astrophysic, 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Reionization, Physics, Quantum Physics, COSMIC cancer database, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Molecular, Nuclear & Particles Physics, Redshift, 5101 Astronomical Sciences, astro-ph.CO, Hydrogen line, Astrophysics - Instrumentation and Methods for Astrophysics, 51 Physical Sciences, Bispectrum, Astronomical and Space Sciences, astro-ph.IM, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Characterizing the epoch of reionization (EoR) at $z\gtrsim 6$ via the redshifted 21 cm line of neutral Hydrogen (HI) is critical to modern astrophysics and cosmology, and thus a key science goal of many current and planned low-frequency radio telescopes. The primary challenge to detecting this signal is the overwhelmingly bright foreground emission at these frequencies, placing stringent requirements on the knowledge of the instruments and inaccuracies in analyses. Results from these experiments have largely been limited not by thermal sensitivity but by systematics, particularly caused by the inability to calibrate the instrument to high accuracy. The interferometric bispectrum phase is immune to antenna-based calibration and errors therein, and presents an independent alternative to detect the EoR HI fluctuations while largely avoiding calibration systematics. Here, we provide a demonstration of this technique on a subset of data from the Hydrogen Epoch of Reionization Array (HERA) to place approximate constraints on the brightness temperature of the intergalactic medium (IGM). From this limited data, at $z=7.7$ we infer "$1\sigma$" upper limits on the IGM brightness temperature to be $\le 316$ "pseudo" mK at $\kappa_\parallel=0.33$ "pseudo" $h$ Mpc$^{-1}$ (data-limited) and $\le 1000$ "pseudo" mK at $\kappa_\parallel=0.875$ "pseudo" $h$ Mpc$^{-1}$ (noise-limited). The "pseudo" units denote only an approximate and not an exact correspondence to the actual distance scales and brightness temperatures. By propagating models in parallel to the data analysis, we confirm that the dynamic range required to separate the cosmic HI signal from the foregrounds is similar to that in standard approaches, and the power spectrum of the bispectrum phase is still data-limited (at $\gtrsim 10^6$ dynamic range) indicating scope for further improvement in sensitivity as the array build-out continues., Comment: 22 pages, 12 figures (including sub-figures). Published in PhRvD. Abstract may be slightly abridged compared to the actual manuscript due to length limitations on arXiv

Published
2020

22. Imaging and Modeling Data from the Hydrogen Epoch of Reionization Array

Author

Juan Mena Parra, Piyanat Kittiwisit, Kingsley Gale-Sides, Joshua Kerrigan, Honggeun Kim, Adrian Liu, Phil Bull, Nipanjana Patra, Ziyaad Halday, Matthys Maree, James E. Aguirre, Bryna J. Hazelton, Jacqueline N. Hewitt, Zara Abdurashidova, Saul A. Kohn, Judd D. Bowman, Matt Dexter, K. Gale-Sides, Samantha Pieterse, Paul La Plante, Mathakane Molewa, James Kent, Nithyanandan Thyagarajan, Eunice Matsetela, Nicolas Fagnoni, Adam P. Beardsley, Alec Josaitis, Kathryn Rosie, David MacMahon, Jonathan C. Pober, Andrei Mesinger, Jasper Grobbelaar, Tashalee S. Billings, Zachary E. Martinot, Tshegofalang Mosiane, Abraham R. Neben, Austin Julius, Randall Fritz, Siyanda Matika, Brian Glendenning, Carina Cheng, Peter Sims, Paul Alexander, Daniel C. Jacobs, Steve R. Furlanetto, Gianni Bernardi, Bradley Greig, Lourence Malan, Nima Razavi-Ghods, Cresshim Malgas, Yanga Balfour, Nicholas S. Kern, Telalo Lekalake, David DeBoer, Aaron R. Parsons, Richard F. Bradley, Matthew Kolopanis, Deepthi Gorthi, Peter K. G. Williams, James Robnett, Joshua S. Dillon, Chris Carilli, Eloy de Lera Acedo, Miguel F. Morales, Zaki S. Ali, Bojan Nikolic, Aaron Ewall-Wice, Jack Hickish, Jacob Burba, Angelo Syce, Haoxuan Zheng, Adam Lanman, ITA, USA, ZAF, Carilli, C. L., Thyagarajan, N., Kent, J., Nikolic, B., Gale-Sides, K., Kern, N. S., Bernardi, G., Mesinger, A., Matika, S., Abdurashidova, Zara, Aguirre, James E., Paul, Alexander Christian, Ali, Zaki S., Balfour, Yanga, Beardsley, Adam P., Billings, Tashalee S., Bowman, Judd D., Bradley, Richard F., Bull, Phil, Burba, Jacob, Cheng, Carina, Deboer, David R., Dexter, Matt, Acedo, Eloy de Lera, Dillon, Joshua S., Ewall-Wice, Aaron, Fagnoni, Nicola, Fritz, Randall, Furlanetto, Steve R., Gale-Sides, Kingsley, Glendenning, Brian, Gorthi, Deepthi, Greig, Bradley, Grobbelaar, Jasper, Halday, Ziyaad, Hazelton, Bryna J., Hewitt, Jacqueline N., Hickish, Jack, Jacobs, Daniel C., Josaitis, Alec, Julius, Austin, Kerrigan, Joshua, Kim, Honggeun, Kittiwisit, Piyanat, Kohn, Saul A., Kolopanis, Matthew, Lanman, Adam, Plante, Paul La, Lekalake, Telalo, Liu, Adrian, Macmahon, David, Malan, Lourence, Malgas, Cresshim, Maree, Matthy, Martinot, Zachary E., Matsetela, Eunice, Molewa, Mathakane, Morales, Miguel F., Mosiane, Tshegofalang, Neben, Abraham R., Parra, Juan Mena, Parsons, Aaron R., Patra, Nipanjana, Pieterse, Samantha, Pober, Jonathan C., Razavi-Ghods, Nima, Robnett, Jame, Rosie, Kathryn, Sims, Peter, Syce, Angelo, Williams, Peter K. G., Zheng, Haoxuan, Carilli, CL [0000-0001-6647-3861], Thyagarajan, N [0000-0003-1602-7868], Kern, NS [0000-0002-8211-1892], Bernardi, G [0000-0002-0916-7443], Aguirre, JE [0000-0002-4810-666X], Beardsley, AP [0000-0001-9428-8233], Bowman, JD [0000-0002-8475-2036], Bull, P [0000-0001-5668-3101], Dillon, JS [0000-0003-3336-9958], Ewall-Wice, A [0000-0002-0086-7363], Furlanetto, SR [0000-0002-0658-1243], Hazelton, BJ [0000-0001-7532-645X], Jacobs, DC [0000-0002-0917-2269], Kerrigan, J [0000-0002-1876-272X], Kittiwisit, P [0000-0003-0953-313X], Kohn, SA [0000-0001-6744-5328], Kolopanis, M [0000-0002-2950-2974], Liu, A [0000-0001-6876-0928], Morales, MF [0000-0001-7694-4030], Neben, AR [0000-0001-7776-7240], Patra, N [0000-0002-9457-1941], Pober, JC [0000-0002-3492-0433], Williams, PKG [0000-0003-3734-3587], and Apollo - University of Cambridge Repository

Subjects
Physics, Cosmological evolution, Hydrogen, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, chemistry.chemical_element, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Cosmology, Data modeling, chemistry, Reionization, Space and Planetary Science, 0103 physical sciences, Radio interferometry, Astrophysics - Instrumentation and Methods for Astrophysics, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract

We analyze data from the Hydrogen Epoch of Reionization Array. This is the third in a series of papers on the closure phase delay-spectrum technique designed to detect the HI 21cm emission from cosmic reionization. We present the details of the data and models employed in the power spectral analysis, and discuss limitations to the process. We compare images and visibility spectra made with HERA data, to parallel quantities generated from sky models based on the GLEAM survey, incorporating the HERA telescope model. We find reasonable agreement between images made from HERA data, with those generated from the models, down to the confusion level. For the visibility spectra, there is broad agreement between model and data across the full band of $\sim 80$MHz. However, models with only GLEAM sources do not reproduce a roughly sinusoidal spectral structure at the tens of percent level seen in the observed visibility spectra on scales $\sim 10$ MHz on 29 m baselines. We find that this structure is likely due to diffuse Galactic emission, predominantly the Galactic plane, filling the far sidelobes of the antenna primary beam. We show that our current knowledge of the frequency dependence of the diffuse sky radio emission, and the primary beam at large zenith angles, is inadequate to provide an accurate reproduction of the diffuse structure in the models. We discuss implications due to this missing structure in the models, including calibration, and in the search for the HI 21cm signal, as well as possible mitigation techniques., Comment: 17 pages, 10 figures, accepted for the ApJ Supplement

Published
2020

23. Mitigating Internal Instrument Coupling for 21 cm Cosmology. II. A Method Demonstration with the Hydrogen Epoch of Reionization Array

Author

Nipanjana Patra, Ziyaad Halday, Adrian Liu, Matt Dexter, Joshua Kerrigan, Judd D. Bowman, Samantha Pieterse, Chris Carilli, David DeBoer, Eloy de Lera Acedo, Peter K. G. Williams, Zara Abdurashidova, Haoxuan Zheng, Piyanat Kittiwisit, Nithyanandan Thyagarajan, Kathryn Rosie, Austin Julius, Adam P. Beardsley, Philip Bull, David MacMahon, Adam Lanman, Jack Hickish, Gianni Bernardi, James Robnett, Angelo Syce, Jacob Burba, Bryna J. Hazelton, Deepthi Gorthi, Joshua S. Dillon, Richard F. Bradley, Matthew Kolopanis, Brian Glendenning, Matthys Maree, Paul Alexander, Carina Cheng, Miguel F. Morales, Mathakane Molewa, Zaki S. Ali, Bradley Greig, Craig Smith, Aaron Ewall-Wice, Saul A. Kohn, Telalo Lekalake, Nima Razavi-Ghods, Tshegofalang Mosiane, Jon Ringuette, Steve R. Furlanetto, Lourence Malan, Jacqueline N. Hewitt, Aaron R. Parsons, Jonathan C. Pober, Andrei Mesinger, Jasper Grobbelaar, Nicholas S. Kern, Zachary E. Martinot, Paul La Plante, Steven G. Murray, Daniel C. Jacobs, Cresshim Malgas, Abraham R. Neben, Nicolas Fagnoni, Randall Fritz, Yanga Balfour, Eunice Matsetela, Peter Sims, James E. Aguirre, ITA, USA, ZAF, Kern, N. S., Parsons, A. R., Dillon, J. S., Lanman, A. E., Liu, A., Bull, P., Ewall-Wice, A., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Bernardi, G., Bowman, J. D., Bradley, R. F., Burba, J., Carilli, C. L., Chen, Cheng, Deboer, D. R., Dexter, M., De Lera Acedo, E., Fagnoni, N., Fritz, R., Furlanetto, S. R., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Jacobs, D. C., Julius, A., Kerrigan, J., Kittiwisit, P., Kohn, S. A., Kolopanis, M., La Plante, P., Lekalake, T., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mesinger, A., Molewa, M., Morales, M. F., Mosiane, T., Murray, S. G., Neben, A. R., Patra, N., Pieterse, S., Pober, J. C., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Sims, P., Smith, C., Syce, A., Thyagarajan, N., Williams, P. K. G., and Zheng, H.

Subjects
Coupling, Physics, 010504 meteorology & atmospheric sciences, Dynamic range, Spectral density, Astronomy and Astrophysics, Astrophysics, HERA, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Signal, Noise floor, Cosmology, Settore FIS/05 - Astronomia e Astrofisica, Space and Planetary Science, 0103 physical sciences, 010303 astronomy & astrophysics, Reionization, 0105 earth and related environmental sciences
Abstract

We present a study of internal reflection and cross-coupling systematics in Phase I of the Hydrogen Epoch of Reionization Array (HERA). In a companion paper, we outlined the mathematical formalism for such systematics and presented algorithms for modeling and removing them from the data. In this work, we apply these techniques to data from HERA’s first observing season as a method demonstration. The data show evidence for systematics that, without removal, would hinder a detection of the 21 cm power spectrum for the targeted Epoch of Reionization (EoR) line-of-sight modes in the range 0.2 h -1 Mpc-1 < {k}\parallel < 0.5 h -1 Mpc-1. In particular, we find evidence for nonnegligible amounts of spectral structure in the raw autocorrelations that overlaps with the EoR window and is suggestive of complex instrumental effects. Through systematic modeling on a single night of data, we find we can recover these modes in the power spectrum down to the integrated noise floor, achieving a dynamic range in the EoR window of 106 in power (mK2 units) with respect to the bright galactic foreground signal. Future work with deeper integrations will help determine whether these systematics can continue to be mitigated down to EoR levels. For future observing seasons, HERA will have upgraded analog and digital hardware to better control these systematics in the field.

Published
2020

24. Detectability of Galactic Faraday Rotation in multiwavelength CMB observations

Author

Judd D. Bowman, Matthew Kolopanis, and Philip Daniel Mauskopf

Subjects
Physics, Cosmic microwave background, Astrophysics::Instrumentation and Methods for Astrophysics, Cosmic background radiation, Spectral density, Estimator, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Polarization (waves), 01 natural sciences, symbols.namesake, Space and Planetary Science, 0103 physical sciences, Faraday effect, symbols, Millimeter, 010306 general physics, 010303 astronomy & astrophysics, Radio astronomy
Abstract

We introduce a new cross-correlation method to detect and verify the astrophysical origin of Faraday Rotation (FR) in multiwavelength surveys. FR is well studied in radio astronomy from radio point sources but the $\lambda^{2}$ suppression of FR makes detecting and accounting for this effect difficult at millimeter and sub-millimeter wavelengths. Therefore statistical methods are used to attempt to detect FR in the cosmic microwave background (CMB). Most estimators of the FR power spectrum rely on single frequency data. In contrast, we investigate the correlation of polarized CMB maps with FR measure maps from radio point sources. We show a factor of $\sim30$ increase in sensitivity over single frequency estimators and predict detections exceeding $10\sigma$ significance for a CMB-S4 like experiment. Improvements in observations of FR from current and future radio polarization surveys will greatly increase the usefulness of this method.

Published
2017

25. Optimizing sparse RFI prediction using deep learning

Author

Nithyanandan Thyagarajan, Adam Lanman, Kathryn Rosie, Angelo Syce, Gianni Bernardi, Deepthi Gorthi, Joshua S. Dillon, Peter Sims, Judd D. Bowman, Brian Glendenning, Carina Cheng, Samantha Pieterse, Craig Smith, Nicholas S. Kern, Eunice Matsetela, Joshua Kerrigan, Miguel F. Morales, Piyanat Kittiwisit, Mathakane Molewa, Zaki S. Ali, Paul Alexander, Tshegofalang Mosiane, Aaron Ewall-Wice, Daniel C. Jacobs, Jack Hickish, Haoxuan Zheng, David MacMahon, Telalo Lekalake, Matt Dexter, Cresshim Malgas, Nicolas Fagnoni, Jacob Burba, Yanga Balfour, Adam P. Beardsley, Bradley Greig, Abraham R. Neben, Steve R. Furlanetto, Matthys Maree, Julia Estrada, David DeBoer, Randall Fritz, James E. Aguirre, Nipanjana Patra, Peter K. G. Williams, Nima Razavi-Ghods, Ziyaad Halday, Richard F. Bradley, Matthew Kolopanis, Paul La Plante, Aaron R. Parsons, Lourence Malan, Adrian Liu, Zara Abdurashidova, Austin Julius, Eloy de Lera Acedo, Jon Ringuette, James Robnett, Jonathan C. Pober, Andrei Mesinger, Jasper Grobbelaar, Saul A. Kohn, Chris Carilli, Zachary E. Martinot, Bryna J. Hazelton, USA, Kerrigan, J., la Plante, P., Kohn, S., Pober, J. C., Aguirre, J., Abdurashidova, Z., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Bernardi, G., Bowman, J. D., Bradley, R. F., Burba, J., Carilli, C. L., Cheng, C., Deboer, D. R., Dexter, M., de Lera Acedo, E., Dillon, J. S., Estrada, J., Ewall-Wice, A., Fagnoni, N., Fritz, R., Furlanetto, S. R., Glendenning, B., Greig, B., Grobbelaar, J., Gorthi, D., Halday, Z., Hazelton, B. J., Hickish, J., Jacobs, D. C., Julius, A., Kern, N. S., Kittiwisit, P., Kolopanis, M., Lanman, A., Lekalake, T., Liu, A., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mesinger, A., Molewa, M., Morales, M. F., Mosiane, T., Neben, A. R., Parsons, A. R., Patra, N., Pieterse, S., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Sims, P., Smith, C., Syce, A., Thyagarajan, N., Williams, P. K. G., and Zheng, H.

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), FOS: Physical sciences, Context (language use), 02 engineering and technology, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, 01 natural sciences, Radio telescope, Settore FIS/05 - Astronomia e Astrofisica, 020204 information systems, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, data analysis [methods], 010303 astronomy & astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), Discrete mathematics, Physics, business.industry, Deep learning, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, HERA, interferometric [techniques], Amplitude, Space and Planetary Science, data analysis – Techniques: interferometric [Methods], astro-ph.CO, Artificial intelligence, Radio interferometer, Astrophysics - Instrumentation and Methods for Astrophysics, business, Astronomical and Space Sciences, Astrophysics - Cosmology and Nongalactic Astrophysics, astro-ph.IM
Abstract

Radio Frequency Interference (RFI) is an ever-present limiting factor among radio telescopes even in the most remote observing locations. When looking to retain the maximum amount of sensitivity and reduce contamination for Epoch of Reionization studies, the identification and removal of RFI is especially important. In addition to improved RFI identification, we must also take into account computational efficiency of the RFI-Identification algorithm as radio interferometer arrays such as the Hydrogen Epoch of Reionization Array grow larger in number of receivers. To address this, we present a Deep Fully Convolutional Neural Network (DFCN) that is comprehensive in its use of interferometric data, where both amplitude and phase information are used jointly for identifying RFI. We train the network using simulated HERA visibilities containing mock RFI, yielding a known "ground truth" dataset for evaluating the accuracy of various RFI algorithms. Evaluation of the DFCN model is performed on observations from the 67 dish build-out, HERA-67, and achieves a data throughput of 1.6$\times 10^{5}$ HERA time-ordered 1024 channeled visibilities per hour per GPU. We determine that relative to an amplitude only network including visibility phase adds important adjacent time-frequency context which increases discrimination between RFI and Non-RFI. The inclusion of phase when predicting achieves a Recall of 0.81, Precision of 0.58, and $F_{2}$ score of 0.75 as applied to our HERA-67 observations., Comment: 11 pages, 7 figures

Published
2019

26. Understanding the HERA Phase I receiver system with simulations and its impact on the detectability of the EoR delay power spectrum

Author

Richard F. Bradley, Matthew Kolopanis, Nithyanandan Thyagarajan, Adam Lanman, Lourence Malan, Saul A. Kohn, Alec Josaitis, Adrian Liu, Bryna J. Hazelton, Matt Dexter, Haoxuan Zheng, Piyanat Kittiwisit, Nicholas S. Kern, Kingsley Gale-Sides, Deepthi Gorthi, Joshua S. Dillon, Paul Alexander, Honggeun Kim, Craig Smith, Miguel F. Morales, Steve R. Furlanetto, Adam P. Beardsley, Mathakane Molewa, Zaki S. Ali, Bojan Nikolic, Aaron Ewall-Wice, Tshegofalang Mosiane, Phil Bull, Nipanjana Patra, Jacqueline N. Hewitt, Ziyaad Halday, Angelo Syce, Abraham R. Neben, Randall Fritz, Juan Mena Parra, Jack Hickish, Aaron R. Parsons, Joshua Kerrigan, Brian Glendenning, Carina Cheng, Paul La Plante, James Robnett, Jacob Burba, Chris Carilli, Eloy de Lera Acedo, Telalo Lekalake, Zara Abdurashidova, Kathryn Rosie, Gianni Bernardi, David MacMahon, Austin Julius, Daniel C. Jacobs, Nima Razavi-Ghods, Cresshim Malgas, Nicolas Fagnoni, Yanga Balfour, Matthys Maree, Peter Sims, Jonathan C. Pober, Andrei Mesinger, Jasper Grobbelaar, Tashalee S. Billings, Zachary E. Martinot, Bradley Greig, James E. Aguirre, Peter K. G. Williams, Eunice Matsetela, Judd D. Bowman, Samantha Pieterse, David DeBoer, ITA, USA, GBR, Fagnoni, N., De Lera Acedo, E., Deboer, D. R., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Bernardi, G., Billings, T. S., Bowman, J. D., Bradley, R. F., Bull, P., Burba, J., Carilli, C. L., Cheng, C., Dexter, M., Dillon, J. S., Ewall-Wice, A., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Jacobs, D. C., Josaitis, A., Julius, A., Kern, N. S., Kerrigan, J., Kim, H., Kittiwisit, P., Kohn, S. A., Kolopanis, M., Lanman, A., Plante, P. L., Lekalake, T., Liu, A., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mena Parra, J., Mesinger, A., Molewa, M., Morales, M. F., Mosiane, T., Neben, A. R., Nikolic, B., Parsons, A. R., Patra, N., Pieterse, S., Pober, J. C., Razavi-Ghods, N., Robnett, J., Rosie, K., Sims, P., Smith, C., Syce, A., Thyagarajan, N., Williams, P. K. G., and Zheng, H.

Subjects
interferometers [instrumentation], first stars, Phase (waves), FOS: Physical sciences, 02 engineering and technology, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, 01 natural sciences, law.invention, Radio telescope, Telescope, Optics, Settore FIS/05 - Astronomia e Astrofisica, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, dark ages, 010303 astronomy & astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Spectral density, 020206 networking & telecommunications, Astronomy and Astrophysics, numerical [methods], telescopes, HERA, interferometric [techniques], interferometer [instrumentation], Transmission (telecommunications), Space and Planetary Science, reionization, dark ages, reionization, first star, Antenna (radio), Astrophysics - Instrumentation and Methods for Astrophysics, business, Astronomical and Space Sciences, astro-ph.IM
Abstract

The detection of the Epoch of Reionization (EoR) delay power spectrum using a "foreground avoidance method" highly depends on the instrument chromaticity. The systematic effects induced by the radio-telescope spread the foreground signal in the delay domain, which contaminates the EoR window theoretically observable. Applied to the Hydrogen Epoch of Reionization Array (HERA), this paper combines detailed electromagnetic and electrical simulations in order to model the chromatic effects of the instrument, and quantify its frequency and time responses. In particular, the effects of the analogue receiver, transmission cables, and mutual coupling are included. These simulations are able to accurately predict the intensity of the reflections occurring in the 150-m cable which links the antenna to the back-end. They also show that electromagnetic waves can propagate from one dish to another one through large sections of the array due to mutual coupling. The simulated system time response is attenuated by a factor $10^{4}$ after a characteristic delay which depends on the size of the array and on the antenna position. Ultimately, the system response is attenuated by a factor $10^{5}$ after 1400 ns because of the reflections in the cable, which corresponds to characterizable ${k_\parallel}$-modes above 0.7 $h\;\rm{Mpc}^{-1}$ at 150 MHz. Thus, this new study shows that the detection of the EoR signal with HERA Phase I will be more challenging than expected. On the other hand, it improves our understanding of the telescope, which is essential to mitigate the instrument chromaticity., Comment: 13 pages, 17 figures - Submitted to MNRAS - 2nd revision

Published
2019
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27. A simplified, lossless re-analysis of PAPER-64

Author

Chuneeta D. Nunhokee, David MacMahon, Matthew Kolopanis, Joshua S. Dillon, Andre Walker, Joshua Kerrigan, William P. Walbrugh, Zaki S. Ali, Chris Carilli, Adrian Liu, Nithyanandan Thyagarajan, Gianni Bernardi, Pat Klima, Jonathan C. Pober, Carina Cheng, Saul A. Kohn, Aaron R. Parsons, Matthew R. Dexter, David DeBoer, James E. Aguirre, Richard F. Bradley, David F. Moore, Daniel C. Jacobs, ITA, and USA

Subjects
Physics, Lossless compression, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Space and Planetary Science, 0103 physical sciences, Dark Ages, 010303 astronomy & astrophysics, Reionization, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present limits on the 21cm power spectrum from the Epoch of Reionization (EoR) using data from the 64 antenna configuration of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) analyzed through a power spectrum pipeline independent from previous PAPER analyses. Previously reported results from PAPER have been found to contain significant signal loss (Cheng et al. 2018, arxiv:1810.05175). Several lossy steps from previous PAPER pipelines have not been included in this analysis, namely: delay-based foreground filtering, optimal fringe-rate filtering, and empirical covariance-based estimators. Steps which remain in common with previous analyses include redundant calibration and local sidereal time (LST) binning. The power spectra reported here are effectively the result of applying a linear Fourier transform analysis to the calibrated, LST binned data. This analysis also uses more data than previous publications, including the complete available redshift range of $z \sim 7.5$ to $11$. In previous PAPER analyses, many power spectrum measurements were found to be detections of noncosmological power at levels of significance ranging from two to hundreds of times the theoretical noise. Here, excess power is examined using redundancy between baselines and power spectrum jackknives. The upper limits we find on the 21cm power spectrum from reionization are ($1500$ mK)$^{2}$, ($1900$ mK)$^{2}$, ($280$ mK)$^{2}$, ($200$ mK)$^{2}$, ($380$ mK)$^{2}$, ($300$ mK)$^{2}$ at redshifts $z=10.87,\ 9.93,\ 8.68,\ 8.37,\ 8.13,$ and $7.48$, respectively. For reasons described in Cheng et al. 2018 (arxiv:1810.05175), these limits supersede all previous PAPER results (Ali et al. 2018, arxiv:1502.06016)., Comment: 28 Pages, 17 Pages, Accepted to APJ

Published
2019
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28. Measuring HERA's Primary Beam in Situ: Methodology and First Results

Author

Richard F. Bradley, Matthew Kolopanis, Jonathan C. Pober, Andrei Mesinger, Daniel C. Jacobs, Bradley Greig, Jasper Grobbelaar, Cresshim Malgas, Craig Smith, Nicolas Fagnoni, Peter Sims, Yanga Balfour, Joshua Kerrigan, Angelo Syce, Tashalee S. Billings, Zachary E. Martinot, Piyanat Kittiwisit, Aaron R. Parsons, Chuneeta D. Nunhokee, Chris Carilli, Kingsley Gale-Sides, Nicholas S. Kern, Eloy de Lera Acedo, Peter K. G. Williams, Paul Alexander, Eunice Matsetela, Saul A. Kohn, Adam Lanman, Paul La Plante, David DeBoer, Nima Razavi-Ghods, David MacMahon, Bryna J. Hazelton, Nipanjana Patra, Adam P. Beardsley, Jon Ringuette, Matt Dexter, Ziyaad Halday, Deepthi Gorthi, Adrian Liu, Brian Glendenning, Nithyanandan Thyagarajan, Abraham R. Neben, Joshua S. Dillon, Gianni Bernardi, Zara Abdurashidova, Carina Cheng, Lourence Malan, Judd D. Bowman, Randall Fritz, Samantha Pieterse, Jacob Burba, Miguel F. Morales, Austin Julius, Zaki S. Ali, Bojan Nikolic, Aaron Ewall-Wice, James Robnett, Jacqueline N. Hewitt, James E. Aguirre, Kathryn Rosie, Steve R. Furlanetto, Mathakane Molewa, Haoxuan Zheng, Tshegofalang Mosiane, Matthys Maree, Telalo Lekalake, ITA, USA, CAF, Nunhokee, C. D., Parsons, A. R., Kern, N. S., Nikolic, B., Pober, J. C., Bernardi, G., Carilli, C. L., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Billings, T. S., Bowman, J. D., Bradley, R. F., Burba, J., Cheng, C., Deboer, D. R., Dexter, M., Acedo, E. D. L., Dillon, J. S., Ewall-Wice, A., Fagnoni, N., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Hewitt, J. N., Jacobs, D. C., Julius, A., Kerrigan, J., Kittiwisit, P., Kohn, S. A., Kolopanis, M., Lanman, A., Plante, P. L., Lekalake, T., Liu, A., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mesinger, A., Molewa, M., Morales, M. F., Mosiane, T., Neben, A. R., Patra, N., Pieterse, S., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Sims, P., Smith, C., Syce, A., Thyagarajan, N., Williams, P. K. G., and Zheng, H.

Subjects
In situ, Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, HERA, 01 natural sciences, Cosmology, Nuclear physics, Settore FIS/05 - Astronomia e Astrofisica, Space and Planetary Science, Primary (astronomy), 0103 physical sciences, H I line emission, Radio astronomy, Astrophysics - Instrumentation and Methods for Astrophysics, 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Beam (structure), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The central challenge in 21~cm cosmology is isolating the cosmological signal from bright foregrounds. Many separation techniques rely on the accurate knowledge of the sky and the instrumental response, including the antenna primary beam. For drift-scan telescopes such as the Hydrogen Epoch of Reionization Array \citep[HERA, ][]{DeBoer2017} that do not move, primary beam characterization is particularly challenging because standard beam-calibration routines do not apply \citep{Cornwell2005} and current techniques require accurate source catalogs at the telescope resolution. We present an extension of the method from \citet{Pober2012} where they use beam symmetries to create a network of overlapping source tracks that break the degeneracy between source flux density and beam response and allow their simultaneous estimation. We fit the beam response of our instrument using early HERA observations and find that our results agree well with electromagnetic simulations down to a -20~dB level in power relative to peak gain for sources with high signal-to-noise ratio. In addition, we construct a source catalog with 90 sources down to a flux density of 1.4~Jy at 151~MHz., 22 pages, 22 figures, accepted for publication in ApJ

Published
2020

29. The HERA-19 Commissioning Array: Direction-dependent Effects

Author

Judd D. Bowman, Samantha Pieterse, Daniel C. Jacobs, Gcobisa Fadana, Paul M. Chichura, C. H. Smith, Jacqueline N. Hewitt, Richard F. Bradley, Matthew Kolopanis, Joshua S. Dillon, Jon Ringuette, Cresshim Malgas, Jonathan C. Pober, Andrei Mesinger, Nicolas Fagnoni, Jasper Grobbelaar, Chris Carilli, Nima Razavi-Ghods, Tashalee S. Billings, Zachary E. Martinot, Eloy de Lera Acedo, David DeBoer, Chuneeta D. Nunhokee, Miguel F. Morales, Roshan K. Benefo, Haoxuan Zheng, Brian Glendenning, Austin Julius, Amy S. Igarashi, Gianni Bernardi, Carina Cheng, Zaki S. Ali, Nipanjana Patra, Bojan Nikolic, Aaron Ewall-Wice, Anita Loots, Angelo Syce, Peter Williams, Paul Alexander, Lourence Malan, Eunice Matsetela, Nithyanandan Thyagarajan, Steven R. Furlanetto, James E. Aguirre, Raddwine Sell, MacCalvin Kariseb, Telalo Lekalake, Max Tegmark, Matthys Maree, Bryna J. Hazelton, Bradley Greig, Adrian Liu, Jack Hickish, Nicholas S. Kern, Paul La Plante, Abraham R. Neben, Randall Fritz, Aaron R. Parsons, Samavarti Gallardo, Austin F. Fortino, Philip Bull, James Robnett, David MacMahon, Adam P. Beardsley, Saul A. Kohn, Kathryn Rosie, Nathan Mathison, ITA, USA, Kohn, SA [0000-0001-6744-5328], Aguirre, JE [0000-0002-4810-666X], La Plante, P [0000-0002-4693-0102], Nunhokee, CD [0000-0002-5445-6586], Kern, NS [0000-0002-8211-1892], Liu, A [0000-0001-6876-0928], Beardsley, AP [0000-0001-9428-8233], Bernardi, G [0000-0002-0916-7443], Bowman, JD [0000-0002-8475-2036], Carilli, CL [0000-0001-6647-3861], Dillon, JS [0000-0003-3336-9958], Ewall-Wice, A [0000-0002-0086-7363], Furlanetto, SR [0000-0002-0658-1243], Hazelton, BJ [0000-0001-7532-645X], Jacobs, DC [0000-0002-0917-2269], Kolopanis, M [0000-0002-2950-2974], Morales, MF [0000-0001-7694-4030], Neben, AR [0000-0001-7776-7240], Patra, N [0000-0002-9457-1941], Tegmark, M [0000-0001-7670-7190], Thyagarajan, N [0000-0003-1602-7868], Williams, PKG [0000-0003-3734-3587], Apollo - University of Cambridge Repository, Kohn, S. A., Aguirre, J. E., La Plante, P., Billings, T. S., Chichura, P. M., Fortino, A. F., Igarashi, A. S., Benefo, R. K., Gallardo, S., Martinot, Z. E., Nunhokee, C. D., Kern, N. S., Bull, P., Liu, A., Alexander, P., Ali, Z. S., Beardsley, A. P., Bernardi, G., Bowman, J. D., Bradley, R. F., Carilli, C. L., Cheng, C., Deboer, D. R., Acedo, E. D. L., Dillon, J. S., Ewall-Wice, A., Fadana, G., Fagnoni, N., Furlanetto, S. R., Glendenning, B., Greig, B., Grobbelaar, J., Hazelton, B. J., Hewitt, J. N., Hickish, J., Jacobs, D. C., Julius, A., Kariseb, M., Kolopanis, M., Lekalake, T., Loots, A., Macmahon, D., Malan, L., Malgas, C., Maree, M., Mathison, N., Matsetela, E., Mesinger, A., Morales, M. F., Neben, A. R., Nikolic, B., Parsons, A. R., Patra, N., Pieterse, S., Pober, J. C., Randall, F., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Sell, R., Smith, C., Syce, A., Tegmark, M., Thyagarajan, N., Williams, P. K. G., and Zheng, H.

Subjects
010504 meteorology & atmospheric sciences, interferometers [instrumentation], Atomic, Physical Chemistry, 7. Clean energy, 01 natural sciences, Spectral line, Particle and Plasma Physics, Astronomical interferometer, Stokes parameters, dark ages, instrumentation: interferometers, 010303 astronomy & astrophysics, Physics, Linear polarization, Astrophysics::Instrumentation and Methods for Astrophysics, HERA, Polarization (waves), observations [cosmology], interferometric [techniques], interferometer [instrumentation], Amplitude, techniques: interferometric, symbols, reionization, dark ages, reionization, first star, Astrophysics - Instrumentation and Methods for Astrophysics, Astronomical and Space Sciences, observation [cosmology], Physical Chemistry (incl. Structural), first stars, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, symbols.namesake, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Nuclear, dark ages, reionization, first stars, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, polarization, 010308 nuclear & particles physics, Molecular, Astronomy and Astrophysics, Computational physics, Space and Planetary Science, 13. Climate action, cosmology: observations, astro-ph.IM
Abstract

Foreground power dominates the measurements of interferometers that seek a statistical detection of highly-redshifted HI emission from the Epoch of Reionization (EoR). The chromaticity of the instrument creates a boundary in the Fourier transform of frequency (proportional to $k_\parallel$) between spectrally smooth emission, characteristic of the strong synchrotron foreground (the "wedge"), and the spectrally structured emission from HI in the EoR (the "EoR window"). Faraday rotation can inject spectral structure into otherwise smooth polarized foreground emission, which through instrument effects or miscalibration could possibly pollute the EoR window. Using data from the HERA 19-element commissioning array, we investigate the polarization response of this new instrument in the power spectrum domain. We perform a simple image-based calibration based on the unpolarized diffuse emission of the Global Sky Model, and show that it achieves qualitative redundancy between the nominally-redundant baselines of the array and reasonable amplitude accuracy. We construct power spectra of all fully polarized coherencies in all pseudo-Stokes parameters. We compare to simulations based on an unpolarized diffuse sky model and detailed electromagnetic simulations of the dish and feed, confirming that in Stokes I, the calibration does not add significant spectral structure beyond the expected level. Further, this calibration is stable over the 8 days of observations considered. Excess power is seen in the power spectra of the linear polarization Stokes parameters which is not easily attributable to leakage via the primary beam, and results from some combination of residual calibration errors and actual polarized emission. Stokes V is found to be highly discrepant from the expectation of zero power, strongly pointing to the need for more accurate polarized calibration., Comment: 21 pages, 12 figures, submitted to ApJ

Published
2018
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30. Improved 21 cm Epoch Of Reionization Power Spectrum Measurements with a Hybrid Foreground Subtraction and Avoidance Technique

Author

Jonathan C. Pober, Aaron R. Parsons, Nichole Barry, Wenyang Li, Adrian Liu, Carina Cheng, Matthew Kolopanis, Ian Sullivan, James E. Aguirre, Joshua S. Dillon, Gianni Bernardi, Saul A. Kohn, Richard F. Bradley, Daniel C. Jacobs, Joshua Kerrigan, David DeBoer, Adam Lanman, Adam P. Beardsley, Chris Carilli, Zaki S. Ali, and USA

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Subtraction, Astrophysics::Instrumentation and Methods for Astrophysics, Spectral density, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Space and Planetary Science, Computer Science::Computer Vision and Pattern Recognition, 0103 physical sciences, Dark Ages, Astrophysics - Instrumentation and Methods for Astrophysics, 010303 astronomy & astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Observations of the 21cm Epoch of Reionization (EoR) signal are dominated by Galactic and extragalactic foregrounds. The need for foreground removal has led to the development of two main techniques, often referred to as "foreground avoidance" and "foreground subtraction." Avoidance is associated with filtering foregrounds in Fourier space, while subtraction uses an explicit foreground model that is removed. Using 1088 hours of data from the 64-element PAPER array, we demonstrate that subtraction of a foreground model prior to delay-space foreground filtering results in a modest but measurable improvement of the performance of the filter. This proof-of-concept result shows that improvement stems from the reduced dynamic range requirements needed for the foreground filter: subtraction of a foreground model reduces the total foreground power, so for a fixed dynamic range, the filter can push towards fainter limits. We also find that the choice of window function used in the foreground filter can have an appreciable affect on the performance near the edges of the observing band. We demonstrate these effects using a smaller 3 hour sampling of data from the MWA, and find that the hybrid filtering and subtraction removal approach provides similar improvements across the band as seen in the case with PAPER-64., Comment: 20 pages, 12 figures

Published
2018
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31. Characterizing Signal Loss in the 21 cm Reionization Power Spectrum: A Revised Study of PAPER-64

Author

Jonathan C. Pober, Chris Carilli, Joshua S. Dillon, David MacMahon, Daniel C. Jacobs, Adrian Liu, Chuneeta D. Nunhokee, Aaron R. Parsons, Gianni Bernardi, Pat Klima, Richard F. Bradley, Matthew Kolopanis, Matthew R. Dexter, David DeBoer, Zaki S. Ali, Carina Cheng, Saul A. Kohn, James E. Aguirre, David F. Moore, William P. Walbrugh, Andre Walker, and USA

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, media_common.quotation_subject, FOS: Physical sciences, Spectral density, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Galaxy, Universe, Statistical power, Precision Array for Probing the Epoch of Reionization, Stars, Space and Planetary Science, 0103 physical sciences, Dark Ages, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Reionization, Astrophysics - Cosmology and Nongalactic Astrophysics, media_common
Abstract

The Epoch of Reionization (EoR) is an uncharted era in our Universe's history during which the birth of the first stars and galaxies led to the ionization of neutral hydrogen in the intergalactic medium. There are many experiments investigating the EoR by tracing the 21cm line of neutral hydrogen. Because this signal is very faint and difficult to isolate, it is crucial to develop analysis techniques that maximize sensitivity and suppress contaminants in data. It is also imperative to understand the trade-offs between different analysis methods and their effects on power spectrum estimates. Specifically, with a statistical power spectrum detection in HERA's foreseeable future, it has become increasingly important to understand how certain analysis choices can lead to the loss of the EoR signal. In this paper, we focus on signal loss associated with power spectrum estimation. We describe the origin of this loss using both toy models and data taken by the 64-element configuration of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER). In particular, we highlight how detailed investigations of signal loss have led to a revised, higher 21cm power spectrum upper limit from PAPER-64. Additionally, we summarize errors associated with power spectrum error estimation that were previously unaccounted for. We focus on a subset of PAPER-64 data in this paper; revised power spectrum limits from the PAPER experiment are presented in a forthcoming paper by Kolopanis et al. (in prep.) and supersede results from previously published PAPER analyses., 25 pages, 18 figures, Accepted by ApJ

Published
2018

32. Quantum excitations in time-dependent backgrounds

Author

Matthew Kolopanis and Tanmay Vachaspati

Subjects
High Energy Physics - Theory, Physics, Nuclear and High Energy Physics, Spectrum (functional analysis), FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Mathematical Physics (math-ph), General Relativity and Quantum Cosmology, Condensed Matter - Other Condensed Matter, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Classical mechanics, High Energy Physics - Theory (hep-th), Quantum mechanics, Gravitational collapse, Quantum, Mathematical Physics, Other Condensed Matter (cond-mat.other)
Abstract

We give a technique for calculating the occupation number of quantum fields in time-dependent backgrounds by using the relation between one-dimensional {\em quantum} oscillators and two-dimensional {\em classical} oscillators. We illustrate our method by giving closed analytical results for the time-dependent spectrum of occupation numbers during gravitational collapse in 3+1 dimensions., Comment: 5 pages; 3 figures. Clarifying remarks added. Version published in PRD

Published
2013

33. A Simplified, Lossless Reanalysis of PAPER-64.

Author

Matthew Kolopanis, Daniel C. Jacobs, Carina Cheng, Aaron R. Parsons, Saul A. Kohn, Jonathan C. Pober, James E. Aguirre, Zaki S. Ali, Gianni Bernardi, Richard F. Bradley, Chris L. Carilli, David R. DeBoer, Matthew R. Dexter, Joshua S. Dillon, Joshua Kerrigan, Pat Klima, Adrian Liu, David H. E. MacMahon, David F. Moore, and Nithyanandan Thyagarajan

Subjects
*POWER spectra, *REDSHIFT, *FOURIER analysis, *FOURIER transforms, *PHYSICAL cosmology, *POCKETKNIVES
Abstract

We present limits on the 21 cm power spectrum from the Epoch of Reionization using data from the 64 antenna configuration of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) analyzed through a power spectrum pipeline independent from previous PAPER analyses. Previously reported results from PAPER have been found to contain significant signal loss. Several lossy steps from previous PAPER pipelines have not been included in this analysis, namely delay-based foreground filtering, optimal fringe-rate filtering, and empirical covariance-based estimators. Steps that remain in common with previous analyses include redundant calibration and local sidereal time (LST) binning. The power spectra reported here are effectively the result of applying a linear Fourier transform analysis to the calibrated, LST-binned data. This analysis also uses more data than previous publications, including the complete available redshift range of z ∼ 7.5 to 11. In previous PAPER analyses, many power spectrum measurements were found to be detections of noncosmological power at levels of significance ranging from two to hundreds of times the theoretical noise. Here, excess power is examined using redundancy between baselines and power spectrum jackknives. The upper limits we find on the 21 cm power spectrum from reionization are , , , , , and at redshifts z = 10.87, 9.93, 8.68, 8.37, 8.13, and 7.48, respectively. For reasons described in Cheng et al., these limits supersede all previous PAPER results. [ABSTRACT FROM AUTHOR]

Published
2019
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34. Characterizing Signal Loss in the 21 cm Reionization Power Spectrum: A Revised Study of PAPER-64.

Author

Carina Cheng, Aaron R. Parsons, Matthew Kolopanis, Daniel C. Jacobs, Adrian Liu, Saul A. Kohn, James E. Aguirre, Jonathan C. Pober, Zaki S. Ali, Gianni Bernardi, Richard F. Bradley, Chris L. Carilli, David R. DeBoer, Matthew R. Dexter, Joshua S. Dillon, Pat Klima, David H. E. MacMahon, David F. Moore, Chuneeta D. Nunhokee, and William P. Walbrugh

Subjects
GALAXIES, ATMOSPHERIC ionization, HYDROGEN, INTERSTELLAR medium, COSMIC background radiation
Abstract

The Epoch of Reionization (EoR) is an uncharted era in our universe’s history during which the birth of the first stars and galaxies led to the ionization of neutral hydrogen in the intergalactic medium. There are many experiments investigating the EoR by tracing the 21 cm line of neutral hydrogen. Because this signal is very faint and difficult to isolate, it is crucial to develop analysis techniques that maximize sensitivity and suppress contaminants in data. It is also imperative to understand the trade-offs between different analysis methods and their effects on power spectrum estimates. Specifically, with a statistical power spectrum detection in HERA’s foreseeable future, it has become increasingly important to understand how certain analysis choices can lead to the loss of the EoR signal. In this paper, we focus on signal loss associated with power spectrum estimation. We describe the origin of this loss using both toy models and data taken by the 64-element configuration of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER). In particular, we highlight how detailed investigations of signal loss have led to a revised, higher 21 cm power spectrum upper limit from PAPER-64. Additionally, we summarize errors associated with power spectrum error estimation that were previously unaccounted for. We focus on a subset of PAPER-64 data in this paper; revised power spectrum limits from the PAPER experiment are presented in a forthcoming paper by Kolopanis et al. and supersede results from previously published PAPER analyses. [ABSTRACT FROM AUTHOR]

Published
2018
Full Text
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35. Improved 21 cm Epoch of Reionization Power Spectrum Measurements with a Hybrid Foreground Subtraction and Avoidance Technique.

Author

Joshua R. Kerrigan, Jonathan C. Pober, Zaki S. Ali, Carina Cheng, Adam P. Beardsley, Aaron R. Parsons, James E. Aguirre, Nichole Barry, Richard F. Bradley, Gianni Bernardi, Chris L. Carilli, David R. DeBoer, Joshua S. Dillon, Daniel C. Jacobs, Saul A. Kohn, Matthew Kolopanis, Adam Lanman, Wenyang Li, Adrian Liu, and Ian Sullivan

Subjects
IONIZATION (Atomic physics), GALACTIC coordinates, SAMPLING (Process), FOURIER analysis
Abstract

Observations of the 21 cm Epoch of Reionization signal are dominated by Galactic and extragalactic foregrounds. The need for foreground removal has led to the development of two main techniques, often referred to as “foreground avoidance” and “foreground subtraction.” Avoidance is associated with filtering foregrounds in Fourier space, while subtraction uses an explicit foreground model that is removed. Using 1088 hr of data from the 64-element PAPER array, we demonstrate that subtraction of a foreground model prior to delay-space foreground filtering results in a modest but measurable improvement of the performance of the filter. This proof-of-concept result shows that improvement stems from the reduced dynamic range requirements needed for the foreground filter: subtraction of a foreground model reduces the total foreground power, so for a fixed dynamic range, the filter can push toward fainter limits. We also find that the choice of window function used in the foreground filter can have an appreciable affect on the performance near the edges of the observing band. We demonstrate these effects using a smaller 3 hr sampling of data from the MWA, and find that the hybrid filtering and subtraction removal approach provides similar improvements across the band as seen in the case with PAPER-64. [ABSTRACT FROM AUTHOR]

Published
2018
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