Author: "Mosiane, T" - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Mosiane, T"' showing total 28 results

Start Over Author "Mosiane, T"

28 results on '"Mosiane, T"'

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

Author: Fagnoni, N, De Lera Acedo, E, Deboer, DR, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carilli, CL, Cheng, C, Dexter, M, Dillon, JS, Ewall-Wice, A, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Josaitis, A, Julius, A, Kern, NS, Kerrigan, J, Kim, H, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, Plante, PL, Lekalake, T, Liu, A, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mena Parra, J, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Neben, AR, Nikolic, B, Parsons, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Thyagarajan, N, Williams, PKG, and Zheng, H
Subjects: instrumentation: interferometers, methods: numerical, techniques: interferometric, telescopes, dark ages, reionization, first stars, astro-ph.IM, dark ages, reionization, Astronomy & Astrophysics, Astronomical and Space Sciences
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 backend. 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 104 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 105 after 1400 ns because of the reflections in the cable, which corresponds to characterizable ka-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.
Published: 2021

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

Author: Thyagarajan, N, Carilli, CL, Nikolic, B, Kent, J, Mesinger, A, Kern, NS, Bernardi, G, Matika, S, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Billings, TS, Bowman, JD, Bradley, RF, Burba, J, Carey, S, Cheng, C, Deboer, DR, Dexter, M, Acedo, EDL, Dillon, JS, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, La Plante, P, Lekalake, T, Lewis, D, Liu, A, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Molewa, M, Morales, MF, Mosiane, T, Neben, AR, Parsons, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Williams, PKG, and Zheng, H
Subjects: astro-ph.CO, astro-ph.IM
Abstract: Characterizing the epoch of reionization (EoR) at z 6 via the redshifted 21 cm line of neutral Hydrogen (H i) 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 H i 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 "1σ"upper limits on the IGM brightness temperature to be ≤ 316 "pseudo"mK at κ =0.33 "pseudo"h Mpc-1 (data-limited) and ≤ 1000 "pseudo"mK at κ =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 H i signal from the foregrounds is similar to that in standard approaches, and the power spectrum of the bispectrum phase is still data-limited (at 106 dynamic range) indicating scope for further improvement in sensitivity as the array build-out continues.
Published: 2020

3. Redundant-baseline calibration of the hydrogen epoch of reionization array

Author: Dillon, JS, Lee, M, Ali, ZS, Parsons, AR, Orosz, N, Nunhokee, CD, La Plante, P, Beardsley, AP, Kern, NS, Abdurashidova, Z, Aguirre, JE, Alexander, P, Balfour, Y, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, de Lera Acedo, E, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, Lekalake, T, Lewis, D, Liu, A, Ma, YZ, MacMahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Murray, S, Neben, AR, Nikolic, B, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Santos, MG, Sims, P, Smith, C, Syce, A, Tegmark, M, Thyagarajan, N, Williams, PKG, and Zheng, H
Subjects: instrumentation: interferometers, dark ages, reionization, first stars, astro-ph.IM, astro-ph.CO, dark ages, reionization, first stars, Astronomy & Astrophysics, Astronomical and Space Sciences
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.
Published: 2020

4. Optimizing sparse RFI prediction using deep learning

Author: Kerrigan, J, la Plante, P, Kohn, S, Pober, JC, Aguirre, J, Abdurashidova, Z, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Bowman, JD, Bradley, RF, Burba, J, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, de Lera Acedo, E, Dillon, JS, Estrada, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Glendenning, B, Greig, B, Grobbelaar, J, Gorthi, D, Halday, Z, Hazelton, BJ, Hickish, J, Jacobs, DC, Julius, A, Kern, NS, Kittiwisit, P, Kolopanis, M, Lanman, A, Lekalake, T, Liu, A, MacMahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Neben, AR, Parsons, AR, Patra, N, Pieterse, S, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Thyagarajan, N, Williams, PKG, and Zheng, H
Subjects: methods: data analysis, techniques: interferometric, astro-ph.IM, astro-ph.CO, Astronomy & Astrophysics, Astronomical and Space Sciences
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 (HERA) 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’ data set 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 × 105 HERA time-ordered 1024 channelled 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 F2 score of 0.75 as applied to our HERA-67 observations.
Published: 2019

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

Author: 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., and Zheng, H.
Published: 2021
Full Text: View/download PDF

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

Author: Abdurashidova, THCZ, Adams, T, Aguirre, JE, Alexander, P, Ali, ZS, Baartman, R, Balfour, Y, Barkana, R, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Breitman, D, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, Choudhuri, S, DeBoer, DR, De Lera Acedo, E, Dexter, M, Dillon, JS, Ely, J, Ewall-Wice, A, Fagnoni, N, Fialkov, A, Fritz, R, Furlanetto, Gale-Sides, K, Garsden, H, Glendenning, B, Gorce, A, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Heimersheim, S, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kern, NS, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, La Plante, P, Lewis, D, Liu, A, Loots, A, Ma, YZ, MacMahon, DHE, Malan, L, Malgas, K, Malgas, C, Maree, M, Marero, B, Martinot, ZE, McBride, L, Mesinger, A, Mirocha, J, Molewa, M, Morales, MF, Mosiane, T, Muñoz, JB, Murray, SG, Nagpal, V, Neben, AR, Nikolic, B, Nunhokee, CD, Nuwegeld, H, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Qin, Y, Razavi-Ghods, N, Robnett, J, Rosie, K, Santos, MG, Sims, P, Singh, S, Smith, C, Swarts, H, Tan, J, Thyagarajan, N, Wilensky, MJ, Williams, PKG, Van Wyngaarden, P, Zheng, H, 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], Breitman, D [0000-0002-2349-3341], Bull, P [0000-0001-5668-3101], Carilli, CL [0000-0001-6647-3861], Choudhuri, S [0000-0002-2338-935X], DeBoer, DR [0000-0003-3197-2294], de Lera Acedo, E [0000-0001-8530-6989], Dillon, JS [0000-0003-3336-9958], Ewall-Wice, A [0000-0002-0086-7363], Fagnoni, N [0000-0001-5300-3166], Fialkov, A [0000-0002-1369-633X], Furlanetto, SR [0000-0002-0658-1243], Gorce, A [0000-0002-1712-737X], 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], Lanman, A [0000-0003-2116-3573], 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], Muñoz, JB [0000-0002-8984-0465], Murray, SG [0000-0003-3059-3823], Nagpal, V [0000-0001-5909-4433], Neben, AR [0000-0001-7776-7240], Nikolic, B [0000-0001-7168-2705], Nunhokee, CD [0000-0002-5445-6586], Parsons, AR [0000-0002-5400-8097], Pascua, R [0000-0003-0073-5528], Patra, N [0000-0002-9457-1941], Qin, Y [0000-0002-4314-1810], Razavi-Ghods, N [0000-0003-2930-5396], Rosie, K [0000-0003-3611-8804], Santos, MG [0000-0003-3892-3073], Sims, P [0000-0002-2871-0413], Singh, S [0000-0001-7755-902X], Tan, J [0000-0001-6161-7037], Thyagarajan, N [0000-0003-1602-7868], Wilensky, MJ [0000-0001-7716-9312], Williams, PKG [0000-0003-3734-3587], Zheng, H [0000-0001-8267-3425], and Apollo - University of Cambridge Repository
Subjects: Space and Planetary Science, 5101 Astronomical Sciences, Astronomy and Astrophysics, 51 Physical Sciences
Abstract: We report the most sensitive upper limits to date on the 21 cm epoch of reionization power spectrum using 94 nights of observing with Phase I of the Hydrogen Epoch of Reionization Array (HERA). Using similar analysis techniques as in previously reported limits, we find at 95% confidence that Δ2(k = 0.34 h Mpc−1) ≤ 457 mK2 at z = 7.9 and that Δ2(k = 0.36 h Mpc−1) ≤ 3496 mK2 at z = 10.4, an improvement by a factor of 2.1 and 2.6, respectively. These limits are mostly consistent with thermal noise over a wide range of k after our data quality cuts, despite performing a relatively conservative analysis designed to minimize signal loss. Our results are validated with both statistical tests on the data and end-to-end pipeline simulations. We also report updated constraints on the astrophysics of reionization and the cosmic dawn. Using multiple independent modeling and inference techniques previously employed by HERA Collaboration, we find that the intergalactic medium must have been heated above the adiabatic cooling limit at least as early as z = 10.4, ruling out a broad set of so-called “cold reionization” scenarios. If this heating is due to high-mass X-ray binaries during the cosmic dawn, as is generally believed, our result’s 99% credible interval excludes the local relationship between soft X-ray luminosity and star formation and thus requires heating driven by evolved low-metallicity stars.
Published: 2023

7. Direct Optimal Mapping for 21cm Cosmology: A Demonstration with the Hydrogen Epoch of Reionization Array

Author: Xu, Z, Hewitt, JN, Chen, KF, Kim, H, Dillon, JS, Kern, NS, Morales, MF, Hazelton, BJ, Byrne, R, Fagnoni, N, Acedo, EDL, Abdurashidova, Z, Adams, T, Aguirre, JE, Alexander, P, Ali, ZS, Baartman, R, Balfour, Y, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, Eksteen, N, Ely, J, Ewall-Wice, A, Fritz, R, Furlanetto, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hickish, J, Jacobs, DC, Julius, A, Kariseb, M, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, Plante, PL, Liu, A, Loots, A, Ma, YZ, Edward MacMahon, DH, Malan, L, Malgas, C, Malgas, K, Marero, B, Martinot, ZE, Mesinger, A, Molewa, M, Mosiane, T, Murray, SG, Neben, AR, Nikolic, B, Nuwegeld, H, Parsons, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Robnett, J, Rosie, K, Sims, P, Smith, C, Swarts, H, Thyagarajan, N, Wyngaarden, PVV, Williams, PKG, Zheng, H, Xu, Z [0000-0001-5112-2567], Hewitt, JN [0000-0002-4117-570X], Chen, KF [0000-0002-3839-0230], Dillon, JS [0000-0003-3336-9958], Kern, NS [0000-0002-8211-1892], Morales, MF [0000-0001-7694-4030], Hazelton, BJ [0000-0001-7532-645X], Byrne, R [0000-0003-4980-2736], Aguirre, JE [0000-0002-4810-666X], 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], Jacobs, DC [0000-0002-0917-2269], Kerrigan, J [0000-0002-1876-272X], Kittiwisit, P [0000-0003-0953-313X], Kohn, SA [0000-0001-6744-5328], Kolopanis, M [0000-0002-2950-2974], Lanman, A [0000-0003-2116-3573], Plante, PL [0000-0002-4693-0102], Liu, A [0000-0001-6876-0928], Ma, YZ [0000-0001-8108-0986], Mesinger, A [0000-0003-3374-1772], Murray, SG [0000-0003-3059-3823], Neben, AR [0000-0001-7776-7240], Parsons, AR [0000-0002-5400-8097], Patra, N [0000-0002-9457-1941], Pober, JC [0000-0002-3492-0433], Sims, P [0000-0002-2871-0413], Thyagarajan, N [0000-0003-1602-7868], Williams, PKG [0000-0003-3734-3587], Apollo - University of Cambridge Repository, Xu, Zhilei, Hewitt, Jacqueline N., Chen, Kai-Feng, Kim, Honggeun, Dillon, Joshua S., Kern, Nicholas S., Morales, Miguel F., Hazelton, Bryna J., Byrne, Ruby, Fagnoni, Nicola, de Lera Acedo, Eloy, Abdurashidova, Zara, Adams, Tyrone, Aguirre, James E., Alexander, Paul, Ali, Zaki S., Baartman, Rushelle, Balfour, Yanga, Beardsley, Adam P., Bernardi, Gianni, Billings, Tashalee S., Bowman, Judd D., Bradley, Richard F., Bull, Philip, Burba, Jacob, Carey, Steven, Carilli, Chris L., Cheng, Carina, Deboer, David R., Dexter, Matt, Eksteen, Nico, Ely, John, Ewall-Wice, Aaron, Fritz, Randall, Furlanetto, Steven R., Gale-Sides, Kingsley, Glendenning, Brian, Gorthi, Deepthi, Greig, Bradley, Grobbelaar, Jasper, Halday, Ziyaad, Hickish, Jack, Jacobs, Daniel C., Julius, Austin, Kariseb, Maccalvin, Kerrigan, Joshua, Kittiwisit, Piyanat, Kohn, Saul A., Kolopanis, Matthew, Lanman, Adam, La Plante, Paul, Liu, Adrian, Loots, Anita, Ma, Yin-Zhe, Harold Edward MacMahon, David, Malan, Lourence, Malgas, Cresshim, Malgas, Keith, Marero, Bradley, Martinot, Zachary E., Mesinger, ANDREI ALBERT, Molewa, Mathakane, Mosiane, Tshegofalang, Murray, Steven G., Neben, Abraham R., Nikolic, Bojan, Nuwegeld, Han, Parsons, Aaron R., Patra, Nipanjana, Pieterse, Samantha, Pober, Jonathan C., Razavi-Ghods, Nima, Robnett, Jame, Rosie, Kathryn, Sims, Peter, Smith, Craig, Swarts, Hilton, Thyagarajan, Nithyanandan, Van Van Wyngaarden, Pieter, Williams, Peter K. G., and Zheng, Haoxuan
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), model, maps, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galactic radio-emission, 5109 Space Sciences, power spectrum, calibration, 10 mhz, Settore FIS/05 - Astronomia e Astrofisica, 5101 Astronomical Sciences, Space and Planetary Science, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), upper limit, 51 Physical Sciences, 5107 Particle and High Energy Physics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Motivated by the desire for wide-field images with well-defined statistical properties for 21cm cosmology, we implement an optimal mapping pipeline that computes a maximum likelihood estimator for the sky using the interferometric measurement equation. We demonstrate this direct optimal mapping with data from the Hydrogen Epoch of Reionization (HERA) Phase I observations. After validating the pipeline with simulated data, we develop a maximum likelihood figure-of-merit for comparing four sky models at 166MHz with a bandwidth of 100kHz. The HERA data agree with the GLEAM catalogs to, 16 pages, 10 figures, 2 tables, published on ApJ
Published: 2022

8. Automated Detection of Antenna Malfunctions in Large-N Interferometers: A case study With the Hydrogen Epoch of Reionization Array

Author: Storer, D, Dillon, JS, Jacobs, DC, Morales, MF, Hazelton, BJ, Ewall-Wice, A, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Acedo, EL, Dexter, M, Dynes, S, Ely, J, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hewitt, JN, Hickish, J, Huang, T, Josaitis, A, Julius, A, Kariseb, M, Kern, NS, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, La Plante, P, Liu, A, Loots, A, MacMahon, D, Malan, L, Malgas, C, Martinot, ZE, Mesinger, A, Molewa, M, Mosiane, T, Murray, SG, Neben, AR, Nikolic, B, Nunhokee, CD, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Riley, D, Robnett, J, Rosie, K, Santos, MG, Sims, P, Singh, S, Smith, C, Tan, J, Thyagarajan, N, Williams, PKG, Zheng, H, Storer, D, Dillon, JS, Jacobs, DC, Morales, MF, Hazelton, BJ, Ewall-Wice, A, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Acedo, EL, Dexter, M, Dynes, S, Ely, J, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hewitt, JN, Hickish, J, Huang, T, Josaitis, A, Julius, A, Kariseb, M, Kern, NS, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, La Plante, P, Liu, A, Loots, A, MacMahon, D, Malan, L, Malgas, C, Martinot, ZE, Mesinger, A, Molewa, M, Mosiane, T, Murray, SG, Neben, AR, Nikolic, B, Nunhokee, CD, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Riley, D, Robnett, J, Rosie, K, Santos, MG, Sims, P, Singh, S, Smith, C, Tan, J, Thyagarajan, N, Williams, PKG, and Zheng, H
Published: 2022

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

Author: Gehlot, BK, Jacobs, DC, Bowman, JD, Mahesh, N, Murray, SG, Kolopanis, M, Beardsley, AP, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Bernardi, G, Billings, TS, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, Acedo, EDL, Dillon, JS, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Julius, A, Kern, NS, Kerrigan, J, Kittiwisit, P, Kohn, SA, Lanman, A, La Plante, P, Lekalake, T, Lewis, D, Liu, A, Ma, Y-Z, MacMahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Monsalve, RA, Morales, MF, Mosiane, T, Neben, AR, Nikolic, B, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Santos, MG, Sims, P, Smith, C, Syce, A, Tegmark, M, Thyagarajan, N, Williams, PKG, Zheng, H, Gehlot, BK, Jacobs, DC, Bowman, JD, Mahesh, N, Murray, SG, Kolopanis, M, Beardsley, AP, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Bernardi, G, Billings, TS, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, Acedo, EDL, Dillon, JS, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Julius, A, Kern, NS, Kerrigan, J, Kittiwisit, P, Kohn, SA, Lanman, A, La Plante, P, Lekalake, T, Lewis, D, Liu, A, Ma, Y-Z, MacMahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Monsalve, RA, Morales, MF, Mosiane, T, Neben, AR, Nikolic, B, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Santos, MG, Sims, P, Smith, C, Syce, A, Tegmark, M, Thyagarajan, N, Williams, PKG, and Zheng, H
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 autocorrelations 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.
Published: 2021

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

Author: La Plante, P, Williams, PKG, Kolopanis, M, Dillon, JS, Beardsley, AP, Kern, NS, Wilensky, M, Ali, ZS, Abdurashidova, Z, Aguirre, JE, Alexander, P, Balfour, Y, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, Acedo, EDL, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kerrigan, J, Kittiwisit, P, Kohn, SA, Lanman, A, Lekalake, T, Lewis, D, Liu, A, MacMahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Murray, S, Neben, AR, Nikolic, B, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Santos, MG, Sims, P, Smith, C, Syce, A, Thyagarajan, N, Zheng, H, La Plante, P, Williams, PKG, Kolopanis, M, Dillon, JS, Beardsley, AP, Kern, NS, Wilensky, M, Ali, ZS, Abdurashidova, Z, Aguirre, JE, Alexander, P, Balfour, Y, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Carilli, CL, Cheng, C, DeBoer, DR, Dexter, M, Acedo, EDL, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kerrigan, J, Kittiwisit, P, Kohn, SA, Lanman, A, Lekalake, T, Lewis, D, Liu, A, MacMahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Murray, S, Neben, AR, Nikolic, B, Parsons, AR, Pascua, R, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Santos, MG, Sims, P, Smith, C, Syce, A, Thyagarajan, N, and Zheng, H
Published: 2021

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

Author: Fagnoni, N, De Lera Acedo, E, Deboer, DR, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carilli, CL, Cheng, C, Dexter, M, Dillon, JS, Ewall-Wice, A, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Josaitis, A, Julius, A, Kern, NS, Kerrigan, J, Kim, H, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, Plante, PL, Lekalake, T, Liu, A, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mena Parra, J, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Neben, AR, Nikolic, B, Parsons, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Thyagarajan, N, Williams, PKG, Zheng, H, De Lera Acedo, Eloy [0000-0001-8530-6989], Alexander, Paul [0000-0002-0292-9513], Nikolic, Bojan [0000-0001-7168-2705], Razavi-Ghods, Nima [0000-0003-2930-5396], and Apollo - University of Cambridge Repository
Subjects: interferometers [instrumentation], first stars, Astrophysics::Instrumentation and Methods for Astrophysics, numerical [methods], telescopes, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, interferometric [techniques], methods: numerical, dark ages, reionization, techniques: interferometric, reionization, dark ages, instrumentation: interferometers, 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.
Published: 2020
Full Text: View/download PDF

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

Author: Carilli, CL, Thyagarajan, N, Kent, J, Nikolic, B, Gale-Sides, K, Kern, NS, Bernardi, G, Mesinger, A, Matika, S, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Cheng, C, Deboer, DR, Dexter, M, Acedo, EDL, Dillon, JS, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Josaitis, A, Julius, A, Kerrigan, J, Kim, H, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, Plante, PL, Lekalake, T, Liu, A, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Molewa, M, Morales, MF, Mosiane, T, Neben, AR, Parra, JM, Parsons, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Robnett, J, Rosie, K, Sims, P, Syce, A, Williams, PKG, Zheng, H, Carilli, CL, Thyagarajan, N, Kent, J, Nikolic, B, Gale-Sides, K, Kern, NS, Bernardi, G, Mesinger, A, Matika, S, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Cheng, C, Deboer, DR, Dexter, M, Acedo, EDL, Dillon, JS, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Josaitis, A, Julius, A, Kerrigan, J, Kim, H, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, Plante, PL, Lekalake, T, Liu, A, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Molewa, M, Morales, MF, Mosiane, T, Neben, AR, Parra, JM, Parsons, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Robnett, J, Rosie, K, Sims, P, Syce, A, Williams, PKG, and Zheng, H
Abstract: We analyze data from the Hydrogen Epoch of Reionization Array (HERA). This is the third in a series of papers on the closure phase delay spectrum technique designed to detect the H i 21 cm emission from cosmic reionization. We present the details of the data and models employed in the power spectral analysis and discuss limitations to the process. We compare images and visibility spectra made with HERA data to parallel quantities generated from sky models based on the Galactic and Extra-Galactic All-Sky MWA (GLEAM) survey, incorporating the HERA telescope model. We find reasonable agreement between images made from HERA data with those generated from the models, down to the confusion level. For the visibility spectra, there is broad agreement between model and data across the full band of ∼80 MHz. However, models with only GLEAM sources do not reproduce a roughly sinusoidal spectral structure at the tens of percent level seen in the observed visibility spectra on scales of ∼10 MHz on 29 m baselines. We find that this structure is likely due to diffuse Galactic emission, predominantly the Galactic plane, filling the far sidelobes of the antenna primary beam. We show that our current knowledge of the frequency dependence of the diffuse sky radio emission, and the primary beam at large zenith angles, is inadequate to provide an accurate reproduction of the diffuse structure in the models. We discuss some implications arising due to this missing structure in the models, in terms of calibration, and in the search for the H i 21 cm signal, as well as possible mitigation techniques.
Published: 2020

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

Author: Kern, NS, Parsons, AR, Dillon, JS, Lanman, AE, Liu, A, Bull, P, Ewall-Wice, A, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Bowman, JD, Bradley, RF, Burba, J, Carilli, CL, Cheng, C, Deboer, DR, Dexter, M, De Lera Acedo, E, Fagnoni, N, Fritz, R, Furlanetto, SR, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, La Plante, P, Lekalake, T, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Murray, SG, Neben, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Thyagarajan, N, Williams, PKG, Zheng, H, Kern, NS, Parsons, AR, Dillon, JS, Lanman, AE, Liu, A, Bull, P, Ewall-Wice, A, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Bernardi, G, Bowman, JD, Bradley, RF, Burba, J, Carilli, CL, Cheng, C, Deboer, DR, Dexter, M, De Lera Acedo, E, Fagnoni, N, Fritz, R, Furlanetto, SR, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, La Plante, P, Lekalake, T, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Murray, SG, Neben, AR, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Thyagarajan, N, Williams, PKG, and Zheng, H
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 Mpc < $" SRC="apjab5e8aieqn1.gif"/ < 0.5 h Mpc . 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 10 in power (mK 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. -1 -1 -1 -1 6 2
Published: 2020

14. Absolute Calibration Strategies for the Hydrogen Epoch of Reionization Array and Their Impact on the 21 cm Power Spectrum

Author: Kern, NS, Dillon, JS, Parsons, AR, Carilli, CL, Bernardi, G, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Cheng, C, Deboer, DR, Dexter, M, De Lera Acedo, E, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, La Plante, P, Lekalake, T, Liu, A, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Murray, SG, Neben, AR, Nikolic, B, Nunhokee, CD, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Thyagarajan, N, Williams, PKG, Zheng, H, Kern, NS, Dillon, JS, Parsons, AR, Carilli, CL, Bernardi, G, Abdurashidova, Z, Aguirre, JE, Alexander, P, Ali, ZS, Balfour, Y, Beardsley, AP, Billings, TS, Bowman, JD, Bradley, RF, Bull, P, Burba, J, Carey, S, Cheng, C, Deboer, DR, Dexter, M, De Lera Acedo, E, Ely, J, Ewall-Wice, A, Fagnoni, N, Fritz, R, Furlanetto, SR, Gale-Sides, K, Glendenning, B, Gorthi, D, Greig, B, Grobbelaar, J, Halday, Z, Hazelton, BJ, Hewitt, JN, Hickish, J, Jacobs, DC, Julius, A, Kerrigan, J, Kittiwisit, P, Kohn, SA, Kolopanis, M, Lanman, A, La Plante, P, Lekalake, T, Liu, A, Macmahon, D, Malan, L, Malgas, C, Maree, M, Martinot, ZE, Matsetela, E, Mesinger, A, Molewa, M, Morales, MF, Mosiane, T, Murray, SG, Neben, AR, Nikolic, B, Nunhokee, CD, Patra, N, Pieterse, S, Pober, JC, Razavi-Ghods, N, Ringuette, J, Robnett, J, Rosie, K, Sims, P, Smith, C, Syce, A, Thyagarajan, N, Williams, PKG, and Zheng, H
Abstract: We discuss absolute calibration strategies for Phase I of the Hydrogen Epoch of Reionization Array (HERA), which aims to measure the cosmological 21 cm signal from the Epoch of Reionization. HERA is a drift-scan array with a 10° wide field of view, meaning bright, well-characterized point-source transits are scarce. This, combined with HERA's redundant sampling of the uv plane and the modest angular resolution of the Phase I instrument, make traditional sky-based and self-calibration techniques difficult to implement with high dynamic range. Nonetheless, in this work, we demonstrate calibration for HERA using point-source catalogs and electromagnetic simulations of its primary beam. We show that unmodeled diffuse flux and instrumental contaminants can corrupt the gain solutions and present a gain-smoothing approach for mitigating their impact on the 21 cm power spectrum. We also demonstrate a hybrid sky and redundant calibration scheme and compare it to pure sky-based calibration, showing only a marginal improvement to the gain solutions at intermediate delay scales. Our work suggests that the HERA Phase I system can be well calibrated for a foreground avoidance power spectrum estimator by applying direction-independent gains with a small set of degrees of freedom across the frequency and time axes.
Published: 2020

15. 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

16. 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

17. 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

18. 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

19. 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
Full Text: View/download PDF

20. 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
Full Text: View/download PDF

21. 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

22. 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

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

Author: Nipanjana Patra, Ziyaad Halday, Adrian Liu, Matt Dexter, Joshua Kerrigan, Judd D. Bowman, Samantha Pieterse, Chris Carilli, David DeBoer, Eloy de Lera Acedo, Peter K. G. Williams, Zara Abdurashidova, Haoxuan Zheng, Piyanat Kittiwisit, Nithyanandan Thyagarajan, Kathryn Rosie, Austin Julius, Adam P. Beardsley, Philip Bull, David MacMahon, Adam Lanman, Jack Hickish, Gianni Bernardi, James Robnett, Angelo Syce, Jacob Burba, Bryna J. Hazelton, Deepthi Gorthi, Joshua S. Dillon, Richard F. Bradley, Matthew Kolopanis, Brian Glendenning, Matthys Maree, Paul Alexander, Carina Cheng, Miguel F. Morales, Mathakane Molewa, Zaki S. Ali, Bradley Greig, Craig Smith, Aaron Ewall-Wice, Saul A. Kohn, Telalo Lekalake, Nima Razavi-Ghods, Tshegofalang Mosiane, Jon Ringuette, Steve R. Furlanetto, Lourence Malan, Jacqueline N. Hewitt, Aaron R. Parsons, Jonathan C. Pober, Andrei Mesinger, Jasper Grobbelaar, Nicholas S. Kern, Zachary E. Martinot, Paul La Plante, Steven G. Murray, Daniel C. Jacobs, Cresshim Malgas, Abraham R. Neben, Nicolas Fagnoni, Randall Fritz, Yanga Balfour, Eunice Matsetela, Peter Sims, James E. Aguirre, ITA, USA, ZAF, Kern, N. S., Parsons, A. R., Dillon, J. S., Lanman, A. E., Liu, A., Bull, P., Ewall-Wice, A., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Bernardi, G., Bowman, J. D., Bradley, R. F., Burba, J., Carilli, C. L., Chen, Cheng, Deboer, D. R., Dexter, M., De Lera Acedo, E., Fagnoni, N., Fritz, R., Furlanetto, S. R., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Jacobs, D. C., Julius, A., Kerrigan, J., Kittiwisit, P., Kohn, S. A., Kolopanis, M., La Plante, P., Lekalake, T., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mesinger, A., Molewa, M., Morales, M. F., Mosiane, T., Murray, S. G., Neben, A. R., Patra, N., Pieterse, S., Pober, J. C., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Sims, P., Smith, C., Syce, A., Thyagarajan, N., Williams, P. K. G., and Zheng, H.
Subjects: Coupling, Physics, 010504 meteorology & atmospheric sciences, Dynamic range, Spectral density, Astronomy and Astrophysics, Astrophysics, HERA, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Signal, Noise floor, Cosmology, Settore FIS/05 - Astronomia e Astrofisica, Space and Planetary Science, 0103 physical sciences, 010303 astronomy & astrophysics, Reionization, 0105 earth and related environmental sciences
Abstract: We present a study of internal reflection and cross-coupling systematics in Phase I of the Hydrogen Epoch of Reionization Array (HERA). In a companion paper, we outlined the mathematical formalism for such systematics and presented algorithms for modeling and removing them from the data. In this work, we apply these techniques to data from HERA’s first observing season as a method demonstration. The data show evidence for systematics that, without removal, would hinder a detection of the 21 cm power spectrum for the targeted Epoch of Reionization (EoR) line-of-sight modes in the range 0.2 h -1 Mpc-1 < {k}\parallel < 0.5 h -1 Mpc-1. In particular, we find evidence for nonnegligible amounts of spectral structure in the raw autocorrelations that overlaps with the EoR window and is suggestive of complex instrumental effects. Through systematic modeling on a single night of data, we find we can recover these modes in the power spectrum down to the integrated noise floor, achieving a dynamic range in the EoR window of 106 in power (mK2 units) with respect to the bright galactic foreground signal. Future work with deeper integrations will help determine whether these systematics can continue to be mitigated down to EoR levels. For future observing seasons, HERA will have upgraded analog and digital hardware to better control these systematics in the field.
Published: 2020

24. 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

25. Optimizing sparse RFI prediction using deep learning

Author: Nithyanandan Thyagarajan, Adam Lanman, Kathryn Rosie, Angelo Syce, Gianni Bernardi, Deepthi Gorthi, Joshua S. Dillon, Peter Sims, Judd D. Bowman, Brian Glendenning, Carina Cheng, Samantha Pieterse, Craig Smith, Nicholas S. Kern, Eunice Matsetela, Joshua Kerrigan, Miguel F. Morales, Piyanat Kittiwisit, Mathakane Molewa, Zaki S. Ali, Paul Alexander, Tshegofalang Mosiane, Aaron Ewall-Wice, Daniel C. Jacobs, Jack Hickish, Haoxuan Zheng, David MacMahon, Telalo Lekalake, Matt Dexter, Cresshim Malgas, Nicolas Fagnoni, Jacob Burba, Yanga Balfour, Adam P. Beardsley, Bradley Greig, Abraham R. Neben, Steve R. Furlanetto, Matthys Maree, Julia Estrada, David DeBoer, Randall Fritz, James E. Aguirre, Nipanjana Patra, Peter K. G. Williams, Nima Razavi-Ghods, Ziyaad Halday, Richard F. Bradley, Matthew Kolopanis, Paul La Plante, Aaron R. Parsons, Lourence Malan, Adrian Liu, Zara Abdurashidova, Austin Julius, Eloy de Lera Acedo, Jon Ringuette, James Robnett, Jonathan C. Pober, Andrei Mesinger, Jasper Grobbelaar, Saul A. Kohn, Chris Carilli, Zachary E. Martinot, Bryna J. Hazelton, USA, Kerrigan, J., la Plante, P., Kohn, S., Pober, J. C., Aguirre, J., Abdurashidova, Z., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Bernardi, G., Bowman, J. D., Bradley, R. F., Burba, J., Carilli, C. L., Cheng, C., Deboer, D. R., Dexter, M., de Lera Acedo, E., Dillon, J. S., Estrada, J., Ewall-Wice, A., Fagnoni, N., Fritz, R., Furlanetto, S. R., Glendenning, B., Greig, B., Grobbelaar, J., Gorthi, D., Halday, Z., Hazelton, B. J., Hickish, J., Jacobs, D. C., Julius, A., Kern, N. S., Kittiwisit, P., Kolopanis, M., Lanman, A., Lekalake, T., Liu, A., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mesinger, A., Molewa, M., Morales, M. F., Mosiane, T., Neben, A. R., Parsons, A. R., Patra, N., Pieterse, S., Razavi-Ghods, N., Ringuette, J., Robnett, J., Rosie, K., Sims, P., Smith, C., Syce, A., Thyagarajan, N., Williams, P. K. G., and Zheng, H.
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), FOS: Physical sciences, Context (language use), 02 engineering and technology, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, 01 natural sciences, Radio telescope, Settore FIS/05 - Astronomia e Astrofisica, 020204 information systems, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, data analysis [methods], 010303 astronomy & astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), Discrete mathematics, Physics, business.industry, Deep learning, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, HERA, interferometric [techniques], Amplitude, Space and Planetary Science, data analysis – Techniques: interferometric [Methods], astro-ph.CO, Artificial intelligence, Radio interferometer, Astrophysics - Instrumentation and Methods for Astrophysics, business, Astronomical and Space Sciences, Astrophysics - Cosmology and Nongalactic Astrophysics, astro-ph.IM
Abstract: Radio Frequency Interference (RFI) is an ever-present limiting factor among radio telescopes even in the most remote observing locations. When looking to retain the maximum amount of sensitivity and reduce contamination for Epoch of Reionization studies, the identification and removal of RFI is especially important. In addition to improved RFI identification, we must also take into account computational efficiency of the RFI-Identification algorithm as radio interferometer arrays such as the Hydrogen Epoch of Reionization Array grow larger in number of receivers. To address this, we present a Deep Fully Convolutional Neural Network (DFCN) that is comprehensive in its use of interferometric data, where both amplitude and phase information are used jointly for identifying RFI. We train the network using simulated HERA visibilities containing mock RFI, yielding a known "ground truth" dataset for evaluating the accuracy of various RFI algorithms. Evaluation of the DFCN model is performed on observations from the 67 dish build-out, HERA-67, and achieves a data throughput of 1.6$\times 10^{5}$ HERA time-ordered 1024 channeled visibilities per hour per GPU. We determine that relative to an amplitude only network including visibility phase adds important adjacent time-frequency context which increases discrimination between RFI and Non-RFI. The inclusion of phase when predicting achieves a Recall of 0.81, Precision of 0.58, and $F_{2}$ score of 0.75 as applied to our HERA-67 observations., Comment: 11 pages, 7 figures
Published: 2019

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

Author: Richard F. Bradley, Matthew Kolopanis, Nithyanandan Thyagarajan, Adam Lanman, Lourence Malan, Saul A. Kohn, Alec Josaitis, Adrian Liu, Bryna J. Hazelton, Matt Dexter, Haoxuan Zheng, Piyanat Kittiwisit, Nicholas S. Kern, Kingsley Gale-Sides, Deepthi Gorthi, Joshua S. Dillon, Paul Alexander, Honggeun Kim, Craig Smith, Miguel F. Morales, Steve R. Furlanetto, Adam P. Beardsley, Mathakane Molewa, Zaki S. Ali, Bojan Nikolic, Aaron Ewall-Wice, Tshegofalang Mosiane, Phil Bull, Nipanjana Patra, Jacqueline N. Hewitt, Ziyaad Halday, Angelo Syce, Abraham R. Neben, Randall Fritz, Juan Mena Parra, Jack Hickish, Aaron R. Parsons, Joshua Kerrigan, Brian Glendenning, Carina Cheng, Paul La Plante, James Robnett, Jacob Burba, Chris Carilli, Eloy de Lera Acedo, Telalo Lekalake, Zara Abdurashidova, Kathryn Rosie, Gianni Bernardi, David MacMahon, Austin Julius, Daniel C. Jacobs, Nima Razavi-Ghods, Cresshim Malgas, Nicolas Fagnoni, Yanga Balfour, Matthys Maree, Peter Sims, Jonathan C. Pober, Andrei Mesinger, Jasper Grobbelaar, Tashalee S. Billings, Zachary E. Martinot, Bradley Greig, James E. Aguirre, Peter K. G. Williams, Eunice Matsetela, Judd D. Bowman, Samantha Pieterse, David DeBoer, ITA, USA, GBR, Fagnoni, N., De Lera Acedo, E., Deboer, D. R., Abdurashidova, Z., Aguirre, J. E., Alexander, P., Ali, Z. S., Balfour, Y., Beardsley, A. P., Bernardi, G., Billings, T. S., Bowman, J. D., Bradley, R. F., Bull, P., Burba, J., Carilli, C. L., Cheng, C., Dexter, M., Dillon, J. S., Ewall-Wice, A., Fritz, R., Furlanetto, S. R., Gale-Sides, K., Glendenning, B., Gorthi, D., Greig, B., Grobbelaar, J., Halday, Z., Hazelton, B. J., Hewitt, J. N., Hickish, J., Jacobs, D. C., Josaitis, A., Julius, A., Kern, N. S., Kerrigan, J., Kim, H., Kittiwisit, P., Kohn, S. A., Kolopanis, M., Lanman, A., Plante, P. L., Lekalake, T., Liu, A., Macmahon, D., Malan, L., Malgas, C., Maree, M., Martinot, Z. E., Matsetela, E., Mena Parra, J., Mesinger, A., Molewa, M., Morales, M. F., Mosiane, T., Neben, A. R., Nikolic, B., Parsons, A. R., Patra, N., Pieterse, S., Pober, J. C., Razavi-Ghods, N., Robnett, J., Rosie, K., Sims, P., Smith, C., Syce, A., Thyagarajan, N., Williams, P. K. G., and Zheng, H.
Subjects: interferometers [instrumentation], first stars, Phase (waves), FOS: Physical sciences, 02 engineering and technology, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, 01 natural sciences, law.invention, Radio telescope, Telescope, Optics, Settore FIS/05 - Astronomia e Astrofisica, law, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, dark ages, 010303 astronomy & astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Spectral density, 020206 networking & telecommunications, Astronomy and Astrophysics, numerical [methods], telescopes, HERA, interferometric [techniques], interferometer [instrumentation], Transmission (telecommunications), Space and Planetary Science, reionization, dark ages, reionization, first star, Antenna (radio), Astrophysics - Instrumentation and Methods for Astrophysics, business, Astronomical and Space Sciences, astro-ph.IM
Abstract: The detection of the Epoch of Reionization (EoR) delay power spectrum using a "foreground avoidance method" highly depends on the instrument chromaticity. The systematic effects induced by the radio-telescope spread the foreground signal in the delay domain, which contaminates the EoR window theoretically observable. Applied to the Hydrogen Epoch of Reionization Array (HERA), this paper combines detailed electromagnetic and electrical simulations in order to model the chromatic effects of the instrument, and quantify its frequency and time responses. In particular, the effects of the analogue receiver, transmission cables, and mutual coupling are included. These simulations are able to accurately predict the intensity of the reflections occurring in the 150-m cable which links the antenna to the back-end. They also show that electromagnetic waves can propagate from one dish to another one through large sections of the array due to mutual coupling. The simulated system time response is attenuated by a factor $10^{4}$ after a characteristic delay which depends on the size of the array and on the antenna position. Ultimately, the system response is attenuated by a factor $10^{5}$ after 1400 ns because of the reflections in the cable, which corresponds to characterizable ${k_\parallel}$-modes above 0.7 $h\;\rm{Mpc}^{-1}$ at 150 MHz. Thus, this new study shows that the detection of the EoR signal with HERA Phase I will be more challenging than expected. On the other hand, it improves our understanding of the telescope, which is essential to mitigate the instrument chromaticity., Comment: 13 pages, 17 figures - Submitted to MNRAS - 2nd revision
Published: 2019
Full Text: View/download PDF

27. 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

28. A Review on Pharmacy Practice in South Africa-A Higher Education Perspective.

Author: Mosiane T, Nkonde K, Mahlatsi G, and Mncwangi NP
Abstract: In April 1994, South Africa underwent the most significant change in its recent history with the disbandment of the policy of apartheid and the attendant race-based politics, which affected most aspects of the country and, of relevance to this review, the education, health delivery, and career choices that race groups could pursue. In the past 28 years, the South African government has tried to implement policies in order to advance political and socioeconomic shifts toward a more equitable society. The healthcare sector was an early target for transformation that was aimed at increasing access to services and the expansion of primary healthcare and hospital facilities to previously underserved areas. This paper seeks to discuss these changes in broad terms, but with specific reference to general health care and pharmacy practice in particular. It will look at the changes in the legislative framework and pharmacy education and factors impacting the pharmacy practices in South Africa over the past 28 years. A discussion of the critical issues that have affected the profession in the last three decades will also be delineated, and future prospects for the profession as a whole, in terms of pharmacy practice and perspectives, will be discussed. We review the current aspects of the pharmacy profession in South Africa today and how the education of those future professionals is a major contribution to the pharmaceutical climate.
Published: 2022
Full Text: View/download PDF

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources

Refine your results

28 results on '"Mosiane, T"'

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

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

3. Redundant-baseline calibration of the hydrogen epoch of reionization array

4. Optimizing sparse RFI prediction using deep learning

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

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

7. Direct Optimal Mapping for 21cm Cosmology: A Demonstration with the Hydrogen Epoch of Reionization Array

8. Automated Detection of Antenna Malfunctions in Large-N Interferometers: A case study With the Hydrogen Epoch of Reionization Array

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

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

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

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

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

14. Absolute Calibration Strategies for the Hydrogen Epoch of Reionization Array and Their Impact on the 21 cm Power Spectrum

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

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

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

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

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

20. A Real Time Processing System for Big Data in Astronomy: Applications to HERA

21. Redundant-baseline calibration of the hydrogen epoch of reionization array

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

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

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

25. Optimizing sparse RFI prediction using deep learning

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

27. Measuring HERA's Primary Beam in Situ: Methodology and First Results

28. A Review on Pharmacy Practice in South Africa-A Higher Education Perspective.

Catalog

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Language

Publication Type

Journal

Database

Publisher

28 results on '"Mosiane, T"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources