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106 results on '"Bradley, R. F."'

1. Beamforming Errors in Murchison Widefield Array Phased Array Antennas and their effects on Epoch of Reionization Science

Author

Neben, A. R., Hewitt, J. N., Bradley, R. F., Dillon, J. S., Bernardi, G., Bowman, J. D., Briggs, F., Cappallo, R. J., Corey, B. E., Deshpande, A. A., Goeke, R., Greenhill, L. J., Hazelton, B. J., Johnston-Hollitt, M., Kaplan, D. L., Lonsdale, C. J., McWhirter, S. R., Mitchell, D. A., Morales, M. F., Morgan, E., Oberoi, D., Ord, S. M., Prabu, T., Shankar, N. Udaya, Srivani, K. S., Subrahmanyan, R., Tingay, S. J., Wayth, R. B., Webster, R. L., Williams, A., and Williams, C. L.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Accurate antenna beam models are critical for radio observations aiming to isolate the redshifted 21cm spectral line emission from the Dark Ages and the Epoch of Reionization and unlock the scientific potential of 21cm cosmology. Past work has focused on characterizing mean antenna beam models using either satellite signals or astronomical sources as calibrators, but antenna-to-antenna variation due to imperfect instrumentation has remained unexplored. We characterize this variation for the Murchison Widefield Array (MWA) through laboratory measurements and simulations, finding typical deviations of order +/- 10-20% near the edges of the main lobe and in the sidelobes. We consider the ramifications of these results for image- and power spectrum-based science. In particular, we simulate visibilities measured by a 100m baseline and find that using an otherwise perfect foreground model, unmodeled beamforming errors severely limit foreground subtraction accuracy within the region of Fourier space contaminated by foreground emission (the "wedge"). This region likely contains much of the cosmological signal, and accessing it will require measurement of per-antenna beam patterns. However, unmodeled beamforming errors do not contaminate the Fourier space region expected to be free of foreground contamination (the "EOR window"), showing that foreground avoidance remains a viable strategy., Comment: Accepted to ApJ

Published
2016
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2. Measuring Phased-Array Antenna Beampatterns with High Dynamic Range for the Murchison Widefield Array using 137 MHz ORBCOMM Satellites

Author

Neben, A. R., Bradley, R. F., Hewitt, J. N., Bernardi, G., Bowman, J. D., Briggs, F., Cappallo, R. J., Deshpande, A. A., Goeke, R., Greenhill, L. J., Hazelton, B. J., Johnston-Hollitt, M., Kaplan, D. L., Lonsdale, C. J., McWhirter, S. R., Mitchell, D. A., Morales, M. F., Morgan, E., Oberoi, D., Ord, S. M., Prabu, T., Shankar, N. Udaya, Srivani, K. S., Subrahmanyan, R., Tingay, S. J., Wayth, R. B., Webster, R. L., Williams, A., and Williams, C. L.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Detection of the fluctuations in 21 cm line emission from neutral hydrogen during the Epoch of Reionization in thousand hour integrations poses stringent requirements on calibration and image quality, both of which necessitate accurate primary beam models. The Murchison Widefield Array (MWA) uses phased array antenna elements which maximize collecting area at the cost of complexity. To quantify their performance, we have developed a novel beam measurement system using the 137 MHz ORBCOMM satellite constellation and a reference dipole antenna. Using power ratio measurements, we measure the {\it in situ} beampattern of the MWA antenna tile relative to that of the reference antenna, canceling the variation of satellite flux or polarization with time. We employ angular averaging to mitigate multipath effects (ground scattering), and assess environmental systematics with a null experiment in which the MWA tile is replaced with a second reference dipole. We achieve beam measurements over 30 dB dynamic range in beam sensitivity over a large field of view (65\% of the visible sky), far wider and deeper than drift scans through astronomical sources allow. We verify an analytic model of the MWA tile at this frequency within a few percent statistical scatter within the full width at half maximum. Towards the edges of the main lobe and in the sidelobes, we measure tens of percent systematic deviations. We compare these errors with those expected from known beamforming errors., Comment: 22 pages, 8 figures. Accepted for publication in Radio Science

Published
2015
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3. Single electron detection and spectroscopy via relativistic cyclotron radiation

Author

Asner, D. M., Bradley, R. F., de Viveiros, L., Doe, P. J., Fernandes, J. L., Fertl, M., Finn, E. C., Formaggio, J. A., Furse, D., Jones, A. M., Kofron, J. N., LaRoque, B. H., Leber, M., McBride, E. L., Miller, M. L., Mohanmurthy, P., Monreal, B., Oblath, N. S., Robertson, R. G. H., Rosenberg, L. J, Rybka, G., Rysewyk, D., Sternberg, M. G., Tedeschi, J. R., Thummler, T., VanDevender, B. A., and Woods, N. L.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment, Nuclear Experiment
Abstract

It has been understood since 1897 that accelerating charges must emit electromagnetic radiation. Cyclotron radiation, the particular form of radiation emitted by an electron orbiting in a magnetic field, was first derived in 1904. Despite the simplicity of this concept, and the enormous utility of electron spectroscopy in nuclear and particle physics, single-electron cyclotron radiation has never been observed directly. Here we demonstrate single-electron detection in a novel radiofrequency spec- trometer. We observe the cyclotron radiation emitted by individual magnetically-trapped electrons that are produced with mildly-relativistic energies by a gaseous radioactive source. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta elec- tron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay endpoint, and this work demonstrates a fundamentally new approach to precision beta spectroscopy for future neutrino mass experiments., Comment: 6 pages, 3 figures

Published
2014
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4. Probing the First Stars and Black Holes in the Early Universe with the Dark Ages Radio Explorer (DARE)

Author

Burns, Jack O., Lazio, T. J. W., Bale, S. D., Bowman, J. D., Bradley, R. F., Carilli, C. L., Furlanetto, S. R., Harker, G. J. A., Loeb, A., and Pritchard, J. R.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

A concept for a new space-based cosmology mission called the Dark Ages Radio Explore (DARE) is presented in this paper. DARE's science objectives include (1) When did the first stars form? (2) When did the first accreting black holes form? (3) When did Reionization begin? (4) What surprises does the end of the Dark Ages hold (e.g., Dark Matter decay)? DARE will use the highly-redshifted hyperfine 21-cm transition from neutral hydrogen to track the formation of the first luminous objects by their impact on the intergalactic medium during the end of the Dark Ages and during Cosmic Dawn (redshifts z=11-35). It will measure the sky-averaged spin temperature of neutral hydrogen at the unexplored epoch 80-420 million years after the Big Bang, providing the first evidence of the earliest stars and galaxies to illuminate the cosmos and testing our models of galaxy formation. DARE's approach is to measure the expected spectral features in the sky-averaged, redshifted 21-cm signal over a radio bandpass of 40-120 MHz. DARE orbits the Moon for a mission lifetime of 3 years and takes data above the lunar farside, the only location in the inner solar system proven to be free of human-generated radio frequency interference and any significant ionosphere. The science instrument is composed of a three-element radiometer, including electrically-short, tapered, bi-conical dipole antennas, a receiver, and a digital spectrometer. The smooth frequency response of the antennas and the differential spectral calibration approach using a Markov Chain Monte Carlo technique will be applied to detect the weak cosmic 21-cm signal in the presence of the intense solar system and Galactic foreground emissions., Comment: 33 pages, 12 figures; submitted to Advances in Space Research

Published
2011
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5. Large Instrument Development for Radio Astronomy

Author

Fisher, J. R., Bradley, R. F., Brisken, W. F., Cotton, W. D., Emerson, D. T., Kerr, A. R., Lacasse, R. J., Morgan, M. A., Napier, P. J., Norrod, R. D., Payne, J. M., Pospieszalski, M. W., Symmes, A., Thompson, A. R., and Webber, J. C.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

This white paper offers cautionary observations about the planning and development of new, large radio astronomy instruments. Complexity is a strong cost driver so every effort should be made to assign differing science requirements to different instruments and probably different sites. The appeal of shared resources is generally not realized in practice and can often be counterproductive. Instrument optimization is much more difficult with longer lists of requirements, and the development process is longer and less efficient. More complex instruments are necessarily further behind the technology state of the art because of longer development times. Including technology R&D in the construction phase of projects is a growing trend that leads to higher risks, cost overruns, schedule delays, and project de-scoping. There are no technology breakthroughs just over the horizon that will suddenly bring down the cost of collecting area. Advances come largely through careful attention to detail in the adoption of new technology provided by industry and the commercial market. Radio astronomy instrumentation has a very bright future, but a vigorous long-term R&D program not tied directly to specific projects needs to be restored, fostered, and preserved.

Published
2009

6. A High Resolution Search for Dark-Matter Axions

Author

Duffy, L. D., Sikivie, P., Tanner, D. B., Asztalos, S. J., Hagmann, C., Kinion, D., Rosenberg, L. J, van Bibber, K., Yu, D. B., and Bradley, R. F.

Subjects
Astrophysics, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

We have performed a high resolution search for galactic halo axions in cold flows using a microwave cavity detector. The analysis procedure and other details of this search are described. No axion signal was found in the mass range 1.98-2.17 micro-eV. We place upper limits on the density of axions in local discrete flows based on this result., Comment: 11 pages, 10 figures, 2 tables

Published
2006
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7. Results of a Search for Cold Flows of Dark Matter Axions

Author

Duffy, L., Sikivie, P., Tanner, D. B., Asztalos, S., Hagmann, C., Kinion, D., Rosenberg, L. J, van Bibber, K., Yu, D., and Bradley, R. F.

Subjects
Astrophysics, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

Theoretical arguments predict that the distribution of cold dark matter in spiral galaxies has peaks in velocity space associated with non-thermalized flows of dark matter particles. We searched for the corresponding peaks in the spectrum of microwave photons from axion to photon conversion in the cavity detector of dark matter axions. We found none and place limits on the density of any local flow of axions as a function of the flow velocity dispersion over the axion mass range 1.98 to 2.17 $\mu$eV., Comment: 5 pages, 3 figures

Published
2005
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8. Mitigation of Pulsed Interference to Redshifted HI and OH Observations between 960 and 1215 MHz

Author

Fisher, J. R., Zhang, Q., Zheng, Y., Wilson, S. G., and Bradley, R. F.

Subjects
Astrophysics
Abstract

The neutral hydrogen 21-cm spectral line (1420.4 MHz) and the four 18-cm lines of the hydroxyl molecule (1612-1720 MHz) are observable at redshifts which put their measured line frequencies well below their protected frequency bands. Part of the redshift ranges (z = 0.171-0.477 for HI and z = 0.37-0.73 for OH) fall in the 960 to 1215 MHz band that is allocated to aircraft navigation. Most of the signals in this band are pulsed emissions of low duty cycle so much of the time between pulses is interference free. This paper outlines the structure and measured properties of signals in this band and demonstrates a signal processing strategy that is effective at removing the pulsed signals from spectra at sensitivities produced by several hours of integration., Comment: Astronomical Journal, May 2005, in press

Published
2005
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9. An Improved RF Cavity Search for Halo Axions

Author

Asztalos, S. J., Bradley, R. F., Duffy, L., Hagmann, C., Kinion, D., Moltz, D. M., Rosenberg, L. J, Sikivie, P., Stoeffl, W., Sullivan, N. S., Tanner, D. B., van Bibber, K., and Yu, D. B.

Subjects
Astrophysics
Abstract

The axion is a hypothetical elementary particle and cold dark matter candidate. In this RF cavity experiment, halo axions entering a resonant cavity immersed in a static magnetic field convert into microwave photons, with the resulting photons detected by a low-noise receiver. The ADMX Collaboration presents new limits on the axion-to-photon coupling and local axion dark matter halo mass density from a RF cavity axion search in the axion mass range 1.9-2.3 microeV, broadening the search range to 1.9-3.3 microeV. In addition, we report first results from an improved analysis technique., Comment: 5 pages, submitted to Physical Review D rapid communications

Published
2003
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10. Brute-force mapmaking with compact interferometers: a MITEoR northern sky map from 128 to 175 MHz

Author

Zheng, H., primary, Tegmark, M., additional, Dillon, J. S., additional, Liu, A., additional, Neben, A. R., additional, Tribiano, S. M., additional, Bradley, R. F., additional, Buza, V., additional, Ewall-Wice, A., additional, Gharibyan, H., additional, Hickish, J., additional, Kunz, E., additional, Losh, J., additional, Lutomirski, A., additional, Morgan, E., additional, Narayanan, S., additional, Perko, A., additional, Rosner, D., additional, Sanchez, N., additional, Schutz, K., additional, Valdez, M., additional, Villasenor, J., additional, Yang, H., additional, Zarb Adami, K., additional, Zelko, I., additional, and Zheng, K., additional

Published
2016
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11. Measuring phased-array antenna beampatterns with high dynamic range for the Murchison Widefield Array using 137 MHz ORBCOMM satellites

Author

Bradley, R. F., Bernardi, G., Bowman, J. D., Briggs, F., Cappallo, R. J., Deshpande, A. A., Greenhill, L. J., Hazelton, B. J., Johnston-Hollitt, M., Kaplan, D. L., Mitchell, D. A., Morales, M. F., Morgan, E., Oberoi, D., Ord, S. M., Prabu, T., Shankar, N. Udaya, Srivani, K. S., Subrahmanyan, R., Tingay, S. J., Wayth, R. B., Webster, R. L., Williams, A., Neben, Abraham Richard, Hewitt, Jacqueline N, Goeke, Robert F, Lonsdale, Colin John, McWhirter, Stephen R., Williams, Christopher Leigh, Haystack Observatory, MIT Kavli Institute for Astrophysics and Space Research, Neben, Abraham Richard, Hewitt, Jacqueline N, Goeke, Robert F, Lonsdale, Colin John, McWhirter, Stephen R., and Williams, Christopher Leigh

Subjects
Astrophysics::Instrumentation and Methods for Astrophysics
Abstract

Detection of the fluctuations in a 21 cm line emission from neutral hydrogen during the Epoch of Reionization in thousand hour integrations poses stringent requirements on calibration and image quality, both of which necessitate accurate primary beam models. The Murchison Widefield Array (MWA) uses phased-array antenna elements which maximize collecting area at the cost of complexity. To quantify their performance, we have developed a novel beam measurement system using the 137 MHz ORBCOMM satellite constellation and a reference dipole antenna. Using power ratio measurements, we measure the in situ beampattern of the MWA antenna tile relative to that of the reference antenna, canceling the variation of satellite flux or polarization with time. We employ angular averaging to mitigate multipath effects (ground scattering) and assess environmental systematics with a null experiment in which the MWA tile is replaced with a second-reference dipole. We achieve beam measurements over 30 dB dynamic range in beam sensitivity over a large field of view (65% of the visible sky), far wider and deeper than drift scans through astronomical sources allow. We verify an analytic model of the MWA tile at this frequency within a few percent statistical scatter within the full width at half maximum. Toward the edges of the main lobe and in the sidelobes, we measure tens of percent systematic deviations. We compare these errors with those expected from known beamforming errors., National Science Foundation (U.S.) (AST-0821321), National Science Foundation (U.S.) (AST-0457585), National Science Foundation (U.S.) (PHY-0835713), National Science Foundation (U.S.) (CAREER-0847753), National Science Foundation (U.S.) (AST-0908884), United States. Air Force Office of Scientific Research (FA9550-0510247)

Published
2015

12. CONSTRAINING POLARIZED FOREGROUNDS FOR EoR EXPERIMENTS. I. 2D POWER SPECTRA FROM THE PAPER-32 IMAGING ARRAY

Author

Kohn, S. A., primary, Aguirre, J. E., additional, Nunhokee, C. D., additional, Bernardi, G., additional, Pober, J. C., additional, Ali, Z. S., additional, Bradley, R. F., additional, Carilli, C. L., additional, DeBoer, D. R., additional, Gugliucci, N. E., additional, Jacobs, D. C., additional, Klima, P., additional, MacMahon, D. H. E., additional, Manley, J. R., additional, Moore, D. F., additional, Parsons, A. R., additional, Stefan, I. I., additional, and Walbrugh, W. P., additional

Published
2016
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14. Measuring phased-array antenna beampatterns with high dynamic range for the Murchison Widefield Array using 137 MHz ORBCOMM satellites

Author

Neben, A. R., primary, Bradley, R. F., additional, Hewitt, J. N., additional, Bernardi, G., additional, Bowman, J. D., additional, Briggs, F., additional, Cappallo, R. J., additional, Deshpande, A. A., additional, Goeke, R., additional, Greenhill, L. J., additional, Hazelton, B. J., additional, Johnston-Hollitt, M., additional, Kaplan, D. L., additional, Lonsdale, C. J., additional, McWhirter, S. R., additional, Mitchell, D. A., additional, Morales, M. F., additional, Morgan, E., additional, Oberoi, D., additional, Ord, S. M., additional, Prabu, T., additional, Shankar, N. Udaya, additional, Srivani, K. S., additional, Subrahmanyan, R., additional, Tingay, S. J., additional, Wayth, R. B., additional, Webster, R. L., additional, Williams, A., additional, and Williams, C. L., additional

Published
2015
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15. MITEoR: a scalable interferometer for precision 21 cm cosmology

Author

Zheng, H., primary, Tegmark, M., additional, Buza, V., additional, Dillon, J. S., additional, Gharibyan, H., additional, Hickish, J., additional, Kunz, E., additional, Liu, A., additional, Losh, J., additional, Lutomirski, A., additional, Morrison, S., additional, Narayanan, S., additional, Perko, A., additional, Rosner, D., additional, Sanchez, N., additional, Schutz, K., additional, Tribiano, S. M., additional, Valdez, M., additional, Yang, H., additional, Adami, K. Zarb, additional, Zelko, I., additional, Zheng, K., additional, Armstrong, R. P., additional, Bradley, R. F., additional, Dexter, M. R., additional, Ewall-Wice, A., additional, Magro, A., additional, Matejek, M., additional, Morgan, E., additional, Neben, A. R., additional, Pan, Q., additional, Penna, R. F., additional, Peterson, C. M., additional, Su, M., additional, Villasenor, J., additional, Williams, C. L., additional, and Zhu, Y., additional

Published
2014
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17. Brute-force mapmaking with compact interferometers: a MITEoR northern sky map from 128 to 175 MHz.

Author

Zheng, H., Tegmark, M., Dillon, J. S., Liu, A., Neben, A. R., Tribiano, S. M., Bradley, R. F., Buza, V., Ewall-Wice, A., Gharibyan, H., Hickish, J., Kunz, E., Losh, J., Lutomirski, A., Morgan, E., Narayanan, S., Perko, A., Rosner, D., Sanchez, N., and Schutz, K.

Subjects
COMPACT objects (Astronomy), INTERFEROMETERS, ASTRONOMY experiments, HYDROGEN, IONIZATION (Atomic physics)
Abstract

We present a new method for interferometric imaging that is ideal for the large fields of view and compact arrays common in 21 cm cosmology. We first demonstrate the method with the simulations for two very different low-frequency interferometers, the Murchison Widefield Array and the MIT Epoch of Reionization (MITEoR) experiment. We then apply the method to the MITEoR data set collected in 2013 July to obtain the first northern sky map from 128 to 175 MHz at ~2° resolution and find an overall spectral index of -2.73 ± 0.11. The success of this imaging method bodes well for upcoming compact redundant low-frequency arrays such as Hydrogen Epoch of Reionization Array. Both the MITEoR interferometric data and the 150 MHz sky map are available at http://space.mit.edu/home/tegmark/omniscope.html. [ABSTRACT FROM AUTHOR]

Published
2017
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18. Project 8: Precision electron specroscopy to measure the mass of the neutrino

Author

VanDevender, B. A., primary, Asner, D. M., additional, Bahr, M., additional, Bradley, R. F., additional, Doelman, S., additional, Jones, A. M., additional, Fernandes, J., additional, Formaggio, J. A., additional, Furse, D., additional, Kelly, J. F., additional, Kofron, J., additional, LaRoque, B. H., additional, Leber, M. L., additional, McBride, L., additional, Monreal, B., additional, Oblath, N., additional, Patterson, R., additional, Rogers, A., additional, Robertson, R. G. H., additional, Rosenberg, L., additional, Rybka, G., additional, and Thümmler, T., additional

Published
2013
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20. Single-Electron Detection and Spectroscopy via Relativistic Cyclotron Radiation.

Author

Asner, D. M., Bradley, R. F., de Viveiros, L., Doe, P. J., Fernandes, J. L., Fertl, M., Finn, E. C., Formaggio, J. A., Furse, D., Jones, A. M., Kofron, J. N., LaRoque, B. H., Leber, M., McBride, E. L., Miller, M. L., Mohanmurthy, P., Monreal, B., Oblath, N. S., Robertson, R. G. H., and Rosenberg, L. J

Subjects
*ELECTRON detection, *SPECTROMETRY, *CYCLOTRON radiation, *RADIOFREQUENCY spectroscopy, *NEUTRINO interactions
Abstract

It has been understood since 1897 that accelerating charges must emit electromagnetic radiation. Although first derived in 1904, cyclotron radiation from a single electron orbiting in a magnetic field has never been observed directly. We demonstrate single-electron detection in a novel radio-frequency spectrometer. The relativistic shift in the cyclotron frequency permits a precise electron energy measurement. Precise beta electron spectroscopy from gaseous radiation sources is a key technique in modern efforts to measure the neutrino mass via the tritium decay end point, and this work demonstrates a fundamentally new approach to precision beta spectroscopy for future neutrino mass experiments. [ABSTRACT FROM AUTHOR]

Published
2015
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21. High resolution search for dark-matter axions

Author

Duffy, L. D., primary, Sikivie, P., additional, Tanner, D. B., additional, Asztalos, S. J., additional, Hagmann, C., additional, Kinion, D., additional, Rosenberg, L. J, additional, van Bibber, K., additional, Yu, D. B., additional, and Bradley, R. F., additional

Published
2006
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22. Results of a Search for Cold Flows of Dark Matter Axions

Author

Duffy, L., primary, Sikivie, P., additional, Tanner, D. B., additional, Asztalos, S., additional, Hagmann, C., additional, Kinion, D., additional, Rosenberg, L. J, additional, van Bibber, K., additional, Yu, D., additional, and Bradley, R. F., additional

Published
2005
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24. Improved rf cavity search for halo axions

Author

Asztalos, S. J., primary, Bradley, R. F., additional, Duffy, L., additional, Hagmann, C., additional, Kinion, D., additional, Moltz, D. M., additional, Rosenberg, L. J., additional, Sikivie, P., additional, Stoeffl, W., additional, Sullivan, N. S., additional, Tanner, D. B., additional, van Bibber, K., additional, and Yu, D. B., additional

Published
2004
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26. 6-Nitrophthalide

Author

Bradley, R. F., primary, Schwalbe, C. H., additional, Ross, K. C., additional, Fraser, W., additional, and Freeman, S., additional

Published
1997
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28. Project 8: Precision electron specroscopy to measure the mass of the neutrino.

Author

VanDevender, B. A., Asner, D. M., Bahr, M., Bradley, R. F., Doelman, S., Jones, A. M., Fernandes, J., Formaggio, J. A., Furse, D., Kelly, J. F., Kofron, J., LaRoque, B. H., Leber, M. L., McBride, L., Monreal, B., Oblath, N., Patterson, R., Rogers, A., Robertson, R. G. H., and Rosenberg, L.

Subjects
NEUTRINOS, LEPTONS (Nuclear physics), NEUTRONS, ELECTRON spectroscopy, CYCLOTRONS
Abstract

The Project 8 Collaboration is exploring a new technique for the spectroscopy of medium-energy electrons (∼ 1 - 100 keV) with the ultimate goal of measuring the effective mass of the electron antineutrino by the tritium endpoint method. Our method is based on the detection of microwave-frequency cyclotron radiation emitted by magnetically trapped electrons. The immediate goal of Project 8 is to demonstrate the utility of this technique for a tritium endpoint experiment through a high-precision measurement of the conversion electron spectrum of 83mKr. We present concepts for detecting this cyclotron radiation, focusing on a guided wave design currently being implemented in a prototype apparatus at the University of Washington. [ABSTRACT FROM AUTHOR]

Published
2013
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31. Prevalence of diabetic retinopathy. Age, sex, and duration of diabetes.

Author

Kahn, H. A. and Bradley, R. F.

Abstract

From a list of all patients seen at the Joslin Clinic in a recent 6-month period, a random sample of 965 was selected for record review by a clinic assistant. A house physician specializing in diabetes then verified and adjusted the assistant's work as necessary. The data were analyzed both by simple cross-classification and by fitting a multiple logistic risk function. As often reported previously, we found a strong positive association between retinopathy and duration of diabetes. One of our findings which has not been so clearly reported in earlier papers is that the positive association between retinopathy and age is limited to the group with diabetes of less than 10 years' duration. We also found sex differences in retinopathy prevalence which were not large enough to rule out attributing them to chance. [ABSTRACT FROM PUBLISHER]

Published
1975

37. Authors

Author

Okamoto, Martha S., primary, Thompson, Major C., additional, DePoorter, G. L., additional, Rofer-DePoorter, C. K., additional, Hayter, S. W., additional, Navratil, James D., additional, Thompson, Gary H., additional, Grimm, E. A., additional, Richards, L. M., additional, Szulinski, M. J., additional, Johnson, A. B., additional, Schenk, H. J., additional, Huppert, K. L., additional, Stoll, W., additional, Mishima, Tsuyoshi, additional, Aoki, Minoru, additional, Muto, Tadashi, additional, Amanuma, Tsuyoshi, additional, Ritter, G. L., additional, Birchler, J. E., additional, Caudill, H. L., additional, Lakey, L. T., additional, Dayem, H. A., additional, Cobb, D. D., additional, Dietz, R. J., additional, Hakkila, E. A., additional, Shipley, J. P., additional, Smith, D. B., additional, Witt, D. C., additional, Bradley, R. F, additional, Goodlett, C B., additional, Wilev, Jolw R., additional, Jardine, L. J., additional, and Steindler, M. J., additional

Published
1979
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39. 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

40. HERA Phase I Limits on the Cosmic 21 cm Signal: Constraints on Astrophysics and Cosmology during the Epoch of Reionization

Author

The HERA Collaboration, Abdurashidova, Zara, Aguirre, James E., Alexander, Paul, Ali, Zaki, Balfour, Yanga, Barkana, Rennan, Beardsley, Adam, Bernardi, Gianni, Billings, Tashalee, Bowman, Judd, Bradley, Richard, Bull, Phillip, Burba, Jacob, Carey, Steven, Carilli, Christopher, Cheng, Carina, DeBoer, David, Dexter, Matthew, Acedo, Eloy de Lera, Dillon, Joshua, Ely, John, Ewall-Wice, Aaron, Fagnoni, Nicolas, Fialkov, Anastasia, Fritz, Randall, Furlanetto, Steven, Gale-Sides, Kingsley, Glendenning, Brian, Gorthi, Deepthi, Greig, Bradley, Grobbelaar, Jasper, Halday, Ziyaad, Hazelton, Bryna, Heimersheim, Stefan, Hewitt, Jacqueline, Hickish, Jack, Jacobs, Daniel, Julius, Austin, Kern, Nicholas, Kerrigan, Joshua, Kittiwisit, Piyanat, Kohn, Saul, Kolopanis, Matthew, Lanman, Adam, La Plante, Paul, Lekalake, Telalo, Lewis, David, Liu, Adrian, Ma, Yin-Zhe, MacMahon, David, Malan, Lourence, Malgas, Cresshim, Maree, Matthys, Martinot, Zachary, Matsetela, Eunice, Mesinger, Andrei, Mirocha, Jordan, Molewa, Mathakane, Morales, Miguel, Mosiane, Tshegofalang, Munoz, Julian, Murray, Steven, Neben, Abraham, Nikolic, Bojan, Nunhokee, Chuneeta Devi, Parsons, Aaron, Patra, Nipanjana, Pieterse, Samantha, Pober, Jonathan, Qin, Yuxiang, Razavi-Ghods, N., Reis, Itamar, Ringuette, Jon, Robnett, James, Rosie, Kathryn, Santos, Mario, Sikder, Sudipta, Sims, Peter, Smith, Craig, Syce, Angelo, Thyagarajan, Nithyanandan, Williams, Peter, Zheng, Haoxuan, Abdurashidova, Z., Aguirre, J. E., Alexander, P., Ali, Z. S., Balfour, Y., Barkana, R., 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., Fialkov, A., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Heimersheim, S., Hewitt, J. N., Hickish, J., Jacobs, D. C., Julius, A., Kern, N. S., Kerrigan, J., Kittiwisit, P., Kohn, S. A., Kolopanis, M., 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., Mirocha, J., Molewa, M., Morales, M. F., Mosiane, T., Munoz, J. B., Murray, S. G., Neben, A. R., Nikolic, B., Nunhokee, C. D., Parsons, A. R., Patra, N., Pieterse, S., Pober, J. C., Qin, Y., Razavi-Ghods, N., Reis, I., Ringuette, J., Robnett, J., Rosie, K., Santos, M. G., Sikder, S., Sims, P., Smith, C., Syce, A., Thyagarajan, N., Williams, P. K. G., Zheng, H., USA, GBR, ZAF, Aguirre, JE [0000-0002-4810-666X], Barkana, R [0000-0002-1557-693X], Beardsley, AP [0000-0001-9428-8233], Bernardi, G [0000-0002-0916-7443], Bowman, JD [0000-0002-8475-2036], Bradley, RF [0000-0003-1172-8331], Bull, P [0000-0001-5668-3101], Carilli, CL [0000-0001-6647-3861], Deboer, DR [0000-0003-3197-2294], Dillon, JS [0000-0003-3336-9958], Ewall-Wice, A [0000-0002-0086-7363], Fialkov, A [0000-0002-1369-633X], Furlanetto, SR [0000-0002-0658-1243], Gorthi, D [0000-0002-0829-167X], Greig, B [0000-0002-4085-2094], Hazelton, BJ [0000-0001-7532-645X], Heimersheim, S [0000-0001-9631-4212], Hewitt, JN [0000-0002-4117-570X], Jacobs, DC [0000-0002-0917-2269], Kern, NS [0000-0002-8211-1892], Kerrigan, J [0000-0002-1876-272X], Kittiwisit, P [0000-0003-0953-313X], Kohn, SA [0000-0001-6744-5328], Kolopanis, M [0000-0002-2950-2974], La Plante, P [0000-0002-4693-0102], Liu, A [0000-0001-6876-0928], Ma, YZ [0000-0001-8108-0986], Mesinger, A [0000-0003-3374-1772], Mirocha, J [0000-0002-8802-5581], Morales, MF [0000-0001-7694-4030], Munoz, JB [0000-0002-8984-0465], Neben, AR [0000-0001-7776-7240], Nunhokee, CD [0000-0002-5445-6586], Patra, N [0000-0002-9457-1941], Pober, JC [0000-0002-3492-0433], Qin, Y [0000-0002-4314-1810], Reis, I [0000-0002-6203-7496], Santos, MG [0000-0003-3892-3073], Sims, P [0000-0002-2871-0413], Thyagarajan, N [0000-0003-1602-7868], and Apollo - University of Cambridge Repository

Subjects
High Energy Physics - Theory, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, astro-ph.GA, hep-th, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, High Energy Physics - Theory (hep-th), Settore FIS/05 - Astronomia e Astrofisica, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, astro-ph.CO, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Recently, the Hydrogen Epoch of Reionization Array (HERA) collaboration has produced the experiment's first upper limits on the power spectrum of 21-cm fluctuations at z~8 and 10. Here, we use several independent theoretical models to infer constraints on the intergalactic medium (IGM) and galaxies during the epoch of reionization (EoR) from these limits. We find that the IGM must have been heated above the adiabatic cooling threshold by z~8, independent of uncertainties about the IGM ionization state and the nature of the radio background. Combining HERA limits with galaxy and EoR observations constrains the spin temperature of the z~8 neutral IGM to 27 K < T_S < 630 K (2.3 K < T_S < 640 K) at 68% (95%) confidence. They therefore also place a lower bound on X-ray heating, a previously unconstrained aspects of early galaxies. For example, if the CMB dominates the z~8 radio background, the new HERA limits imply that the first galaxies produced X-rays more efficiently than local ones (with soft band X-ray luminosities per star formation rate constrained to L_X/SFR = { 10^40.2, 10^41.9 } erg/s/(M_sun/yr) at 68% confidence), consistent with expectations of X-ray binaries in low-metallicity environments. The z~10 limits require even earlier heating if dark-matter interactions (e.g., through millicharges) cool down the hydrogen gas. Using a model in which an extra radio background is produced by galaxies, we rule out (at 95% confidence) the combination of high radio and low X-ray luminosities of L_{r,ν}/SFR > 3.9 x 10^24 W/Hz/(M_sun/yr) and L_X/SFR, 40 pages, 19 figures, accepted to ApJ

Published
2022

41. 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

42. 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

43. First Results from HERA Phase I: Upper Limits on the Epoch of Reionization 21 cm Power Spectrum

Author

The HERA Collaboration, Abdurashidova, Zara, Aguirre, James E., Alexander, Paul, Ali, Zaki S., Balfour, Yanga, Beardsley, Adam P., Bernardi, Gianni, Billings, Tashalee S., Bowman, Judd D., Bradley, Richard F., Bull, Philip, Burba, Jacob, Carey, Steve, Carilli, Chris L., Cheng, Carina, DeBoer, David R., Dexter, Matt, Acedo, Eloy de Lera, Dibblee-Barkman, Taylor, Dillon, Joshua S., Ely, John, Ewall-Wice, Aaron, Fagnoni, Nicolas, Fritz, Randall, Furlanetto, Steven 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., Julius, Austin, Kern, Nicholas S., Kerrigan, Joshua, Kittiwisit, Piyanat, Kohn, Saul A., Kolopanis, Matthew, Lanman, Adam, La Plante, Paul, Lekalake, Telalo, Lewis, David, Liu, Adrian, MacMahon, David, Malan, Lourence, Malgas, Cresshim, Maree, Matthys, Martinot, Zachary E., Matsetela, Eunice, Mesinger, Andrei, Molewa, Mathakane, Morales, Miguel F., Mosiane, Tshegofalang, Murray, Steven G., Neben, Abraham R., Nikolic, Bojan, Nunhokee, Chuneeta D., Parsons, Aaron R., Patra, Nipanjana, Pascua, Robert, Pieterse, Samantha, Pober, Jonathan C., Razavi-Ghods, Nima, Ringuette, Jon, Robnett, James, Rosie, Kathryn, Sims, Peter, Singh, Saurabh, Smith, Craig, Syce, Angelo, Thyagarajan, Nithyanandan, Williams, Peter K. G., Zheng, Haoxuan, USA, GBR, ZAF, 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., Dibblee-Barkman, T., 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., Kern, N. S., 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., 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., Pascua, R., 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., Zheng, H., Aguirre, JE [0000-0002-4810-666X], Beardsley, AP [0000-0001-9428-8233], Bernardi, G [0000-0002-0916-7443], Bowman, JD [0000-0002-8475-2036], Bull, P [0000-0001-5668-3101], Carilli, CL [0000-0001-6647-3861], Deboer, DR [0000-0003-3197-2294], Dillon, JS [0000-0003-3336-9958], Ewall-Wice, A [0000-0002-0086-7363], Furlanetto, SR [0000-0002-0658-1243], Gorthi, D [0000-0002-0829-167X], Greig, B [0000-0002-4085-2094], Hazelton, BJ [0000-0001-7532-645X], Jacobs, DC [0000-0002-0917-2269], Kern, NS [0000-0002-8211-1892], 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], Mesinger, A [0000-0003-3374-1772], Morales, MF [0000-0001-7694-4030], Murray, SG [0000-0003-3059-3823], Neben, AR [0000-0001-7776-7240], Nunhokee, CD [0000-0002-5445-6586], Patra, N [0000-0002-9457-1941], Pober, JC [0000-0002-3492-0433], Sims, P [0000-0002-2871-0413], Singh, S [0000-0001-7755-902X], Thyagarajan, N [0000-0003-1602-7868], Williams, PKG [0000-0003-3734-3587], and Apollo - University of Cambridge Repository

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

We report upper-limits on the Epoch of Reionization (EoR) 21 cm power spectrum at redshifts 7.9 and 10.4 with 18 nights of data ($\sim36$ hours of integration) from Phase I of the Hydrogen Epoch of Reionization Array (HERA). The Phase I data show evidence for systematics that can be largely suppressed with systematic models down to a dynamic range of $\sim10^9$ with respect to the peak foreground power. This yields a 95% confidence upper limit on the 21 cm power spectrum of $\Delta^2_{21} \le (30.76)^2\ {\rm mK}^2$ at $k=0.192\ h\ {\rm Mpc}^{-1}$ at $z=7.9$, and also $\Delta^2_{21} \le (95.74)^2\ {\rm mK}^2$ at $k=0.256\ h\ {\rm Mpc}^{-1}$ at $z=10.4$. At $z=7.9$, these limits are the most sensitive to-date by over an order of magnitude. While we find evidence for residual systematics at low line-of-sight Fourier $k_\parallel$ modes, at high $k_\parallel$ modes we find our data to be largely consistent with thermal noise, an indicator that the system could benefit from deeper integrations. The observed systematics could be due to radio frequency interference, cable sub-reflections, or residual instrumental cross-coupling, and warrant further study. This analysis emphasizes algorithms that have minimal inherent signal loss, although we do perform a careful accounting in a companion paper of the small forms of loss or bias associated with the pipeline. Overall, these results are a promising first step in the development of a tuned, instrument-specific analysis pipeline for HERA, particularly as Phase II construction is completed en route to reaching the full sensitivity of the experiment., Comment: Accepted to ApJ. https://reionization.org/science/public-data-release-1/

Published
2021

44. 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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45. 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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46. 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

47. Validation of the HERA Phase I Epoch of Reionization 21 cm Power Spectrum Software Pipeline

Author

Aguirre, James E., Murray, Steven G., Pascua, Robert, Martinot, Zachary E., Burba, Jacob, Dillon, Joshua S., Jacobs, Daniel C., Kern, Nicholas S., Kittiwisit, Piyanat, Kolopanis, Matthew, Lanman, Adam, Liu, Adrian, Whitler, Lily, Abdurashidova, Zara, Alexander, Paul, Ali, Zaki S., Balfour, Yanga, Beardsley, Adam P., BERNARDI, GIANNI, Billings, Tashalee S., Bowman, Judd D., Bradley, Richard F., BULL, PHILIP, Carey, Steve, Carilli, Chris L., Cheng, Carina, DeBoer, David R., Dexter, Matt, de Lera Acedo, Eloy, Ely, John, Ewall-Wice, Aaron, Fagnoni, Nicolas, Fritz, Randall, Furlanetto, Steven R., Gale-Sides, Kingsley, Glendenning, Brian, Gorthi, Deepthi, Greig, Bradley, Grobbelaar, Jasper, Halday, Ziyaad, Hazelton, Bryna J., Hewitt, Jacqueline N., Hickish, Jack, Julius, Austin, Kerrigan, Joshua, Kohn, Saul A., La Plante, Paul, Lekalake, Telalo, Lewis, David, MacMahon, David, Malan, Lourence, Malgas, Cresshim, Maree, Matthys, Matsetela, Eunice, Mesinger, Andrei, Molewa, Mathakane, Morales, Miguel F., Mosiane, Tshegofalang, Neben, Abraham R., Nikolic, Bojan, Parsons, Aaron R., Patra, Nipanjana, Pieterse, Samantha, Pober, Jonathan C., Razavi-Ghods, Nima, Ringuette, Jon, Robnett, James, Rosie, Kathryn, Santos, Mario G., Sims, Peter, Singh, Saurabh, Smith, Craig, Syce, Angelo, Thyagarajan, Nithyanandan, Williams, Peter K. G., Zheng, Haoxuan, HERA Collaboration, Aguirre, J. E., Murray, S. G., Pascua, R., Martinot, Z. E., Burba, J., Dillon, J. S., Jacobs, D. C., Kern, N. S., Kittiwisit, P., Kolopanis, M., Lanman, A., Liu, A., Whitler, L., Abdurashidova, Z., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Bernardi, G., Billings, T. S., Bowman, J. D., Bradley, R. F., Bull, P., 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., Julius, A., Kerrigan, J., Kohn, S. A., La Plante, P., Lekalake, T., Lewis, D., Macmahon, D., Malan, L., Malgas, C., Maree, M., Matsetela, E., 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., Ringuette, J., Robnett, J., Rosie, K., Santos, M. G., Sims, P., Singh, S., Smith, C., Syce, A., Thyagarajan, N., Williams, P. K. G., Zheng, H., USA, GBR, ZAF, Aguirre, JE [0000-0002-4810-666X], Murray, SG [0000-0003-3059-3823], Dillon, JS [0000-0003-3336-9958], Jacobs, DC [0000-0002-0917-2269], Kern, NS [0000-0002-8211-1892], Kittiwisit, P [0000-0003-0953-313X], Kolopanis, M [0000-0002-2950-2974], Lanman, A [0000-0003-2116-3573], Liu, A [0000-0001-6876-0928], Beardsley, AP [0000-0001-9428-8233], Bernardi, G [0000-0002-0916-7443], Bowman, JD [0000-0002-8475-2036], Bradley, RF [0000-0003-1172-8331], Bull, P [0000-0001-5668-3101], Carilli, CL [0000-0001-6647-3861], Deboer, DR [0000-0003-3197-2294], Ewall-Wice, A [0000-0002-0086-7363], Furlanetto, SR [0000-0002-0658-1243], Gorthi, D [0000-0002-0829-167X], Greig, B [0000-0002-4085-2094], Hazelton, BJ [0000-0001-7532-645X], Hewitt, JN [0000-0002-4117-570X], Kerrigan, J [0000-0002-1876-272X], Kohn, SA [0000-0001-6744-5328], Mesinger, A [0000-0003-3374-1772], Morales, MF [0000-0001-7694-4030], Neben, AR [0000-0001-7776-7240], Patra, N [0000-0002-9457-1941], Pober, JC [0000-0002-3492-0433], Santos, MG [0000-0003-3892-3073], Sims, P [0000-0002-2871-0413], Singh, S [0000-0001-7755-902X], and Apollo - University of Cambridge Repository

Subjects
Settore FIS/05 - Astronomia e Astrofisica, 010308 nuclear & particles physics, Space and Planetary Science, 0103 physical sciences, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, 01 natural sciences, astro-ph.IM
Abstract

We describe the validation of the HERA Phase I software pipeline by a series of modular tests, building up to an end-to-end simulation. The philosophy of this approach is to validate the software and algorithms used in the Phase I upper limit analysis on wholly synthetic data satisfying the assumptions of that analysis, not addressing whether the actual data meet these assumptions. We discuss the organization of this validation approach, the specific modular tests performed, and the construction of the end-to-end simulations. We explicitly discuss the limitations in scope of the current simulation effort. With mock visibility data generated from a known analytic power spectrum and a wide range of realistic instrumental effects and foregrounds, we demonstrate that the current pipeline produces power spectrum estimates that are consistent with known analytic inputs to within thermal noise levels (at the 2 sigma level) for k > 0.2 h/Mpc for both bands and fields considered. Our input spectrum is intentionally amplified to enable a strong `detection' at k ~0.2 h/Mpc -- at the level of ~25 sigma -- with foregrounds dominating on larger scales, and thermal noise dominating at smaller scales. Our pipeline is able to detect this amplified input signal after suppressing foregrounds with a dynamic range (foreground to noise ratio) of > 10^7. Our validation test suite uncovered several sources of scale-independent signal loss throughout the pipeline, whose amplitude is well-characterized and accounted for in the final estimates. We conclude with a discussion of the steps required for the next round of data analysis., 32 pages, 20 figures. Submitted to the Astrophysical Journal

Published
2022

48. 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

49. 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

50. 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

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