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17 results on '"Piyanat, Kittiwisit"'

1. 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

2. 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

3. 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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4. 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

5. 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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6. 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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7. 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

8. Erratum: Sensitivity of the Hydrogen Epoch of Reionization Array and its Build-out Stages to One-point Statistics from Redshifted 21 cm Observations

Author

Judd D. Bowman, Nithyanandan Thyagarajan, Daniel C. Jacobs, Piyanat Kittiwisit, and Adam P. Beardsley

Subjects
Physics, Hydrogen, 010308 nuclear & particles physics, chemistry.chemical_element, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Redshift, Methods statistical, chemistry, Space and Planetary Science, 0103 physical sciences, Dark Ages, Point (geometry), Sensitivity (control systems), 010303 astronomy & astrophysics, Reionization
Published
2018

9. 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

10. 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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11. 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

12. Sensitivity of the Hydrogen Epoch of Reionization Array and its Build-out Stages to One-point Statistics from Redshifted 21 cm Observations

Author

Piyanat Kittiwisit, Daniel C. Jacobs, Judd D. Bowman, Adam P. Beardsley, and Nithyanandan Thyagarajan

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, media_common.quotation_subject, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, HERA, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Redshift, Space and Planetary Science, Skewness, Sky, 0103 physical sciences, Statistics, Kurtosis, Sample variance, Sensitivity (control systems), 010303 astronomy & astrophysics, Reionization, media_common, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present a baseline sensitivity analysis of the Hydrogen Epoch of Reionization Array (HERA) and its build-out stages to one-point statistics (variance, skewness, and kurtosis) of redshifted 21 cm intensity fluctuation from the Epoch of Reionization (EoR) based on realistic mock observations. By developing a full-sky 21 cm lightcone model, taking into account the proper field of view and frequency bandwidth, utilising a realistic measurement scheme, and assuming perfect foreground removal, we show that HERA will be able to recover statistics of the sky model with high sensitivity by averaging over measurements from multiple fields. All build-out stages will be able to detect variance, while skewness and kurtosis should be detectable for HERA128 and larger. We identify sample variance as the limiting constraint of the variance measurement while skewness and kurtosis measurements will be primarily limited by thermal noise. The sensitivity can be improved by performing frequency binning and windowing. In addition, we find that strong sample variance fluctuation in the kurtosis measured from an individual field of observation indicates the present of outlying cold or hot regions in the underlying fluctuations, a feature that can potentially be used as an EoR bubble indicator. This manuscript is altered from the originally published paper to reflect corrections in the erratum., Comment: 14 pages, 10 figures, 2 tables, altered from the originally published paper to reflect corrections in the erratum

Published
2017
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13. Delay Spectrum with Phase-Tracking Arrays: Extracting the HI power spectrum from the Epoch of Reionization

Author

C. J. Lonsdale, Steven Tingay, Piyanat Kittiwisit, Rachel L. Webster, L. J. Greenhill, K. S. Srivani, David L. Kaplan, Nithyanandan Thyagarajan, Bryna J. Hazelton, Lu Feng, R. B. Wayth, Bryan Gaensler, Judd D. Bowman, Stephen R. McWhirter, Aaron Ewall-Wice, Natasha Hurley-Walker, B. McKinley, Emil Lenc, Pietro Procopio, J. S. B. Wyithe, A. de Oliveira-Costa, Shiv K. Sethi, Donald J. Jacobs, J. L. B. Line, K. S. Dwarkanath, Jacqueline N. Hewitt, Jonathan C. Pober, N. Udaya Shankar, Nichole Barry, Stephen M. Ord, Han-Seek Kim, Abraham R. Neben, C. L. Williams, Roger J. Cappallo, Thiagaraj Prabu, J. Riding, A. P. Beardsley, Andrew R. Williams, B. Pindor, P. Carroll, F. Briggs, Daniel A. Mitchell, Avi Loeb, Cathryn M. Trott, Miguel F. Morales, A. R. Offringa, Ian Sullivan, Eric R. Morgan, Joshua S. Dillon, Max Tegmark, Melanie Johnston-Hollitt, S. Paul, Ravi Subrahmanyan, and Divya Oberoi

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Phase (waves), Astrophysics::Instrumentation and Methods for Astrophysics, Spectral density, FOS: Physical sciences, Astronomy and Astrophysics, LOFAR, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Tracking (particle physics), 01 natural sciences, Signal, Redshift, Computational physics, Space and Planetary Science, 0103 physical sciences, Phase center, 010303 astronomy & astrophysics, Reionization, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The Detection of redshifted 21 cm emission from the epoch of reionization (EoR) is a challenging task owing to strong foregrounds that dominate the signal. In this paper, we propose a general method, based on the delay spectrum approach, to extract HI power spectra that is applicable to tracking observations using an imaging radio interferometer (Delay Spectrum with Imaging Arrays (DSIA)). Our method is based on modelling the HI signal taking into account the impact of wide field effects such as the $w$-term which are then used as appropriate weights in cross-correlating the measured visibilities. Our method is applicable to any radio interferometer that tracks a phase center and could be utilized for arrays such as MWA, LOFAR, GMRT, PAPER and HERA. In the literature the delay spectrum approach has been implemented for near-redundant baselines using drift scan observations. In this paper we explore the scheme for non-redundant tracking arrays, and this is the first application of delay spectrum methodology to such data to extract the HI signal. We analyze 3 hours of MWA tracking data on the EoR1 field. We present both 2-dimensional ($k_\parallel,k_\perp$) and 1-dimensional (k) power spectra from the analysis. Our results are in agreement with the findings of other pipelines developed to analyse the MWA EoR data., Comment: 17 pages, 10 figures, accepted for publication in The Astrophysical Journal

Published
2016
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14. The low-frequency environment of the Murchison Widefield Array: radio-frequency interference analysis and mitigation

Author

Anna D. Kapińska, Nichole Barry, Ian Sullivan, Han-Seek Kim, Joshua S. Dillon, Lincoln J. Greenhill, Ravi Subrahmanyan, Jonathan C. Pober, Joseph R. Callingham, Edward H. Morgan, Natasha Hurley-Walker, Lister Staveley-Smith, Emil Lenc, D. L. Kaplan, Daniel C. Jacobs, Paul Hancock, Bartosz Pindor, Steven Tingay, Qinghua Zheng, J. L. B. Line, Cathryn M. Trott, S. Paul, Divya Oberoi, Miguel F. Morales, Bryan Gaensler, N. Udaya Shankar, Luke Hindson, J. Riding, Abraham R. Neben, Christopher L. Williams, Bryna J. Hazelton, Nithyanandan Thyagarajan, K. S. Dwarakanath, Aaron Ewall-Wice, Stephen M. Ord, Chen Wu, Abraham Loeb, Colin J. Lonsdale, Gianni Bernardi, T. Prabu, P. Carroll, Martin Bell, Daniel A. Mitchell, Roger J. Cappallo, Rachel L. Webster, Shiv K. Sethi, Jacqueline N. Hewitt, Benjamin McKinley, Piyanat Kittiwisit, Judd D. Bowman, Avinash A. Deshpande, J. S. B. Wyithe, John Morgan, Adam P. Beardsley, Bi-Qing For, Frank H. Briggs, S. R. McWhirter, K. S. Srivani, Randall B. Wayth, Pietro Procopio, Anne M. Williams, Max Tegmark, Melanie Johnston-Hollitt, A. R. Offringa, Lu Feng, Haystack Observatory, MIT Kavli Institute for Astrophysics and Space Research, Cappallo, Roger J., Lonsdale, Colin John, McWhirter, Stephen R., Dillon, Joshua Shane, Ewall-Wice, Aaron Michael, Feng, Lu, Hewitt, Jacqueline N., Morgan, Edward H., Neben, Abraham Richard, Tegmark, Max Erik, Williams, Christopher Leigh, ITA, USA, and AUS

Subjects
010504 meteorology & atmospheric sciences, Computer science, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Murchison Widefield Array, LOFAR, Astrophysics::Cosmology and Extragalactic Astrophysics, Interference (wave propagation), 01 natural sciences, Electromagnetic interference, Radio telescope, Interferometry, Space and Planetary Science, 0103 physical sciences, Ionosphere, Astrophysics - Instrumentation and Methods for Astrophysics, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 0105 earth and related environmental sciences, Remote sensing, Computer Science::Information Theory
Abstract

The Murchison Widefield Array (MWA) is a new low-frequency interferometric radio telescope built in Western Australia at one of the locations of the future Square Kilometre Array (SKA). We describe the automated radio-frequency interference (RFI) detection strategy implemented for the MWA, which is based on the AOFlagger platform, and present 72-231-MHz RFI statistics from 10 observing nights. RFI detection removes 1.1% of the data. RFI from digital TV (DTV) is observed 3% of the time due to occasional ionospheric or atmospheric propagation. After RFI detection and excision, almost all data can be calibrated and imaged without further RFI mitigation efforts, including observations within the FM and DTV bands. The results are compared to a previously published Low-Frequency Array (LOFAR) RFI survey. The remote location of the MWA results in a substantially cleaner RFI environment compared to LOFAR's radio environment, but adequate detection of RFI is still required before data can be analysed. We include specific recommendations designed to make the SKA more robust to RFI, including: the availability of sufficient computing power for RFI detection; accounting for RFI in the receiver design; a smooth band-pass response; and the capability of RFI detection at high time and frequency resolution (second and kHz-scale respectively)., Comment: Accepted for publication in PASA

Published
2015
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15. Spectral Energy Distribution and Radio Halo of NGC 253 at Low Radio Frequencies

Author

Anna D. Kapińska, Ian Sullivan, Joshua S. Dillon, T. Prabu, Chen Wu, J. L. B. Line, Nick Seymour, N. Udaya Shankar, Abraham R. Neben, Bi-Qing For, S. Paul, Nithyanandan Thyagarajan, Bryan Gaensler, Nichole Barry, Cathryn M. Trott, Miguel F. Morales, Andrew Williams, Han-Seek Kim, Steven Tingay, Avinash A. Deshpande, Ronald D. Ekers, John Morgan, Aaron Ewall-Wice, D. J. Hanish, P. Carroll, Abraham Loeb, Ravi Subrahmanyan, Stephen M. Ord, Randall B. Wayth, Judd D. Bowman, Martin Bell, Gerhardt R. Meurer, Bryna J. Hazelton, Rachel L. Webster, Max Tegmark, Lincoln J. Greenhill, Luke Hindson, Benjamin McKinley, Jonathan C. Pober, Roger J. Cappallo, Melanie Johnston-Hollitt, Stuart Wyithe, K. S. Srivani, K. S. Dwarakanath, Lister Staveley-Smith, A. R. Offringa, Joseph R. Callingham, Natasha Hurley-Walker, Daniel A. Mitchell, Emil Lenc, Divya Oberoi, Adam P. Beardsley, Colin J. Lonsdale, D. J. Jacobs, J. Riding, Christopher L. Williams, Pietro Procopio, Roland M. Crocker, David L. Kaplan, Frank H. Briggs, S. R. McWhirter, Shivani Bhandari, Lu Feng, Bartosz Pindor, Qinghua Zheng, Paul Hancock, Shiv K. Sethi, Jacqueline N. Hewitt, Piyanat Kittiwisit, and Edward T. Morgan

Subjects
010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Starburst region, Murchison Widefield Array, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astronomy & Astrophysics, 01 natural sciences, law.invention, law, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Synchrotron, Galaxy, Radio halo, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Spectral energy distribution, Halo, Radio frequency
Abstract

We present new radio continuum observations of NGC253 from the Murchison Widefield Array at frequencies between 76 and 227 MHz. We model the broadband radio spectral energy distribution for the total flux density of NGC253 between 76 MHz and 11 GHz. The spectrum is best described as a sum of central starburst and extended emission. The central component, corresponding to the inner 500pc of the starburst region of the galaxy, is best modelled as an internally free-free absorbed synchrotron plasma, with a turnover frequency around 230 MHz. The extended emission component of the NGC253 spectrum is best described as a synchrotron emission flattening at low radio frequencies. We find that 34% of the extended emission (outside the central starburst region) at 1 GHz becomes partially absorbed at low radio frequencies. Most of this flattening occurs in the western region of the SE halo, and may be indicative of synchrotron self-absorption of shock re-accelerated electrons or an intrinsic low-energy cut off of the electron distribution. Furthermore, we detect the large-scale synchrotron radio halo of NGC253 in our radio images. At 154 - 231 MHz the halo displays the well known X-shaped/horn-like structure, and extends out to ~8kpc in z-direction (from major axis)., Accepted for publication in Astrophysical Journal on 06 February 2017

Published
2017

16. THE IMPORTANCE OF WIDE-FIELD FOREGROUND REMOVAL FOR 21 cm COSMOLOGY: A DEMONSTRATION WITH EARLY MWA EPOCH OF REIONIZATION OBSERVATIONS

Author

Nichole Barry, Edward T. Morgan, Han-Seek Kim, Mervyn J. Lynch, Luke Hindson, Nithyanandan Thyagarajan, B. E. Corey, Piyanat Kittiwisit, Gianni Bernardi, T. Prabu, D. L. Kaplan, E. Kratzenberg, J. L. B. Line, N. D. R. Bhat, Andrew Williams, Randall B. Wayth, N. Udaya Shankar, Lu Feng, A. R. Whitney, Avinash A. Deshpande, Max Tegmark, Bartosz Pindor, Natasha Hurley-Walker, Daniel A. Mitchell, Stephen M. Ord, Emil Lenc, Melanie Johnston-Hollitt, K. S. Srivani, R. Goeke, Ian Sullivan, Joshua S. Dillon, Mark Waterson, Judd D. Bowman, Lincoln J. Greenhill, Pietro Procopio, Bryna J. Hazelton, A. de Oliveira-Costa, Jonathan C. Pober, Benjamin McKinley, David Emrich, Daniel C. Jacobs, Z. E. Martinot, J. S. B. Wyithe, P. Carroll, A. R. Offringa, A. Roshi, Justin C. Kasper, Cathryn M. Trott, Abraham R. Neben, Miguel F. Morales, Ravi Subrahmanyan, Frank H. Briggs, S. R. McWhirter, Adam P. Beardsley, Aaron Ewall-Wice, Colin J. Lonsdale, Divya Oberoi, S. Paul, Nadia Kudryavtseva, Rachel L. Webster, J. Riding, Steven Tingay, Alan E. E. Rogers, Christopher L. Williams, Abraham Loeb, Martin Bell, Roger J. Cappallo, Shiv K. Sethi, Jacqueline N. Hewitt, ITA, USA, and AUS

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Murchison Widefield Array, Astrophysics::Cosmology and Extragalactic Astrophysics, LOFAR, 01 natural sciences, Wide field, Cosmology, 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
Abstract

In this paper we present observations, simulations, and analysis demonstrating the direct connection between the location of foreground emission on the sky and its location in cosmological power spectra from interferometric redshifted 21 cm experiments. We begin with a heuristic formalism for understanding the mapping of sky coordinates into the cylindrically averaged power spectra measurements used by 21 cm experiments, with a focus on the effects of the instrument beam response and the associated sidelobes. We then demonstrate this mapping by analyzing power spectra with both simulated and observed data from the Murchison Widefield Array. We find that removing a foreground model which includes sources in both the main field-of-view and the first sidelobes reduces the contamination in high k_parallel modes by several percent relative to a model which only includes sources in the main field-of-view, with the completeness of the foreground model setting the principal limitation on the amount of power removed. While small, a percent-level amount of foreground power is in itself more than enough to prevent recovery of any EoR signal from these modes. This result demonstrates that foreground subtraction for redshifted 21 cm experiments is truly a wide-field problem, and algorithms and simulations must extend beyond the main instrument field-of-view to potentially recover the full 21 cm power spectrum., 13 pages, 9 figures, matches version accepted to ApJ

Published
2016

17. Hydrogen Intensity and Real-Time Analysis Experiment: 256-element array status and overview

Author

Devin Crichton, Moumita Aich, Adam Amara, Kevin Bandura, Bruce A. Bassett, Carlos Bengaly, Pascale Berner, Shruti Bhatporia, Martin Bucher, Tzu-Ching Chang, H. Cynthia Chiang, Jean-Francois Cliche, Carolyn Crichton, Romeel Dave, Dirk I. L. De Villiers, Matt Dobbs, Aaron M. Ewall-Wice, Scott Eyono, Christopher Finlay, Sindhu Gaddam, Ken Ganga, Kevin G. Gayley, Kit Gerodias, Tim B. Gibbon, Austine Gumba, Neeraj Gupta, Maile Harris, Heiko Heilgendorff, Matt Hilton, Adam D. Hincks, Pascal Hitz, Mona Jalilvand, Roufurd P. M. Julie, Zahra Kader, Joseph Kania, Dionysios Karagiannis, Aris Karastergiou, Kabelo Kesebonye, Piyanat Kittiwisit, Jean-Paul Kneib, Kenda Knowles, Emily R. Kuhn, Martin Kunz, Roy Maartens, Vincent MacKay, Stuart MacPherson, Christian Monstein, Kavilan Moodley, V. Mugundhan, Warren Naidoo, Arun Naidu, Laura B. Newburgh, Viraj Nistane, Amanda Di Nitto, Deniz Ölçek, Xinyu Pan, Sourabh Paul, Jeffrey B. Peterson, Elizabeth Pieters, Carla Pieterse, Aritha Pillay, Anna R. Polish, Liantsoa Randrianjanahary, Alexandre Refregier, Andre Renard, Edwin Retana-Montenegro, Ian H. Rout, Cyndie Russeeawon, Alireza Vafaei Sadr, Benjamin R. B. Saliwanchik, Ajith Sampath, Pranav Sanghavi, Mario G. Santos, Onkabetse Sengate, J. Richard Shaw, Jonathan L. Sievers, Oleg M. Smirnov, Kendrick M. Smith, Ulrich Armel Mbou Sob, Raghunathan Srianand, Pieter Stronkhorst, Dhaneshwar D. Sunder, Simon Tartakovsky, Russ Taylor, Peter Timbie, Emma E. Tolley, Junaid Townsend, Will Tyndall, Cornelius Ungerer, Jacques van Dyk, Gary van Vuuren, Keith Vanderlinde, Thierry Viant, Anthony Walters, Jingying Wang, Amanda Weltman, Patrick Woudt, Dallas Wulf, Anatoly Zavyalov, Zheng Zhang, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de physique de l'ENS - ENS Paris (LPENS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Astrophysique, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Sorbonne Université (SU)-École normale supérieure - Paris (ENS Paris)

Subjects
Signal processing, Cosmology and Nongalactic Astrophysics (astro-ph.CO), anisotropic power spectrum, bao, Observatories, spectroscopic survey measurement, 21 cm, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Receivers, redshift 0.6, 010309 optics, scale, project, interferometers, 0103 physical sciences, radio transients, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Radio astronomy, dark energy, 010303 astronomy & astrophysics, Instrumentation, Instrumentation and Methods for Astrophysics (astro-ph.IM), Pulsars, Baryon acoustic oscillations, Mechanical Engineering, Physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Electronic, Optical and Magnetic Materials, Space and Planetary Science, Control and Systems Engineering, intensity mapping, galaxy sample, Visibility, astropy, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], cosmology, growth-rate, Astrophysics - Cosmology and Nongalactic Astrophysics, Hydrogen, Telescopes
Abstract

The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is a radio interferometer array currently in development, with an initial 256-element array to be deployed at the South African Radio Astronomy Observatory (SARAO) Square Kilometer Array (SKA) site in South Africa. Each of the 6m, $f/0.23$ dishes will be instrumented with dual-polarisation feeds operating over a frequency range of 400-800 MHz. Through intensity mapping of the 21 cm emission line of neutral hydrogen, HIRAX will provide a cosmological survey of the distribution of large-scale structure over the redshift range of $0.775 < z < 2.55$ over $\sim$15,000 square degrees of the southern sky. The statistical power of such a survey is sufficient to produce $\sim$7 percent constraints on the dark energy equation of state parameter when combined with measurements from the Planck satellite. Additionally, HIRAX will provide a highly competitive platform for radio transient and HI absorber science while enabling a multitude of cross-correlation studies. In this paper, we describe the science goals of the experiment, overview of the design and status of the sub-components of the telescope system, and describe the expected performance of the initial 256-element array as well as the planned future expansion to the final, 1024-element array., 24 pages, 6 figures. Updated to match published version

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