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27 results on '"B. Pindor"'

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

Author

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

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

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

Published
2021

2. Optimising MWA EoR data processing for improved 21-cm power spectrum measurements—fine-tuning ionospheric corrections

Author

J. Kariuki Chege, C. H. Jordan, C. Lynch, C. M. Trott, J. L. B. Line, B. Pindor, and S. Yoshiura

Subjects
Space and Planetary Science, Astronomy and Astrophysics
Abstract

The redshifted cosmological 21-cm signal emitted by neutral hydrogen during the first billion years of the universe is much fainter relative to other galactic and extragalactic radio emissions, posing a great challenge towards detection of the signal. Therefore, precise instrumental calibration is a vital prerequisite for the success of radio interferometers such as the Murchison Widefield Array (MWA), which aim for a 21-cm detection. Over the previous years, novel calibration techniques targeting the power spectrum paradigm of EoR science have been actively researched and where possible implemented. Some of these improvements, for the MWA, include the accuracy of sky models used in calibration and the treatment of ionospheric effects, both of which introduce unwanted contamination to the EoR window. Despite sophisticated non-traditional calibration algorithms being continuously developed over the years to incorporate these methods, the large datasets needed for EoR measurements require high computational costs, leading to trade-offs that impede making use of these new tools to maximum benefit. Using recently acquired computation resources for the MWA, we test the full capabilities of the state-of-the-art calibration techniques available for the MWA EoR project, with a focus on both direction-dependent and direction-independent calibration. Specifically, we investigate improvements that can be made in the vital calibration stages of sky modelling, ionospheric correction, and compact source foreground subtraction as applied in the hybrid foreground mitigation approach (one that combines both foreground subtraction and avoidance). Additionally, we investigate a method of ionospheric correction using interpolated ionospheric phase screens and assess its performance in the power spectrum space. Overall, we identify a refined RTS calibration configuration that leads to an at least 2 factor reduction of the EoR window power contamination at the$0.1 \; \textrm{hMpc}^{-1}$scale. The improvement marks a step further towards detecting the 21-cm signal using the MWA and the forthcoming SKA low telescope.

Published
2022

3. Study of systematics effects on the cross power spectrum of 21 cm line and cosmic microwave background using Murchison Widefield Array data

Author

Keitaro Takahashi, B. Pindor, Shintaro Yoshiura, Hiroyuki Tashiro, Kiyotomo Ichiki, and Cathryn M. Trott

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), media_common.quotation_subject, Cosmic microwave background, Cosmic background radiation, FOS: Physical sciences, Murchison Widefield Array, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, symbols.namesake, 0103 physical sciences, Planck, 010303 astronomy & astrophysics, Reionization, Astrophysics::Galaxy Astrophysics, media_common, Physics, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, 13. Climate action, Space and Planetary Science, Sky, Dark Ages, symbols, Hydrogen line, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Observation of the 21cm line signal from neutral hydrogen during the Epoch of Reionization is challenging due to extremely bright Galactic and extragalactic foregrounds and complicated instrumental calibration. A reasonable approach for mitigating these problems is the cross correlation with other observables. In this work, we present the first results of the cross power spectrum (CPS) between radio images observed by the Murchison Widefield Array and the cosmic microwave background (CMB), measured by the Planck experiment. We study the systematics due to the ionospheric activity, the dependence of CPS on group of pointings, and frequency. The resulting CPS is consistent with zero because the error is dominated by the foregrounds in the 21cm observation. Additionally, the variance of the signal indicates the presence of unexpected systematics error at small scales. Furthermore, we reduce the error by one order of magnitude with application of a foreground removal using a polynomial fitting method. Based on the results, we find that the detection of the 21cm-CMB CPS with the MWA Phase I requires more than 99.95% of the foreground signal removed, 2000 hours of deep observation and 50% of the sky fraction coverage., Comment: 15 pages, 16 figures, accepted to MNRAS

Published
2018

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

Author

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

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

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

Published
2021
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5. Searching for stochastic gravitational waves using data from the two colocated LIGO Hanford detectors

Author

J. Aasi, J. Abadie, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, T. Accadia, F. Acernese, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, C. Affeldt, M. Agathos, N. Aggarwal, O. D. Aguiar, P. Ajith, B. Allen, A. Allocca, E. Amador Ceron, D. Amariutei, R. A. Anderson, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. Areeda, S. Ast, S. M. Aston, P. Astone, P. Aufmuth, C. Aulbert, L. Austin, B. E. Aylott, S. Babak, P. T. Baker, G. Ballardin, S. W. Ballmer, J. C. Barayoga, D. Barker, S. H. Barnum, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, M. A. Barton, I. Bartos, R. Bassiri, A. Basti, J. Batch, J. Bauchrowitz, Th. S. Bauer, M. Bebronne, B. Behnke, M. Bejger, M. G. Beker, A. S. Bell, C. Bell, I. Belopolski, G. Bergmann, J. M. Berliner, D. Bersanetti, A. Bertolini, D. Bessis, J. Betzwieser, P. T. Beyersdorf, T. Bhadbhade, I. A. Bilenko, G. Billingsley, J. Birch, S. Biscans, M. Bitossi, M. A. Bizouard, E. Black, J. K. Blackburn, L. Blackburn, D. Blair, M. Blom, O. Bock, T. P. Bodiya, M. Boer, C. Bogan, C. Bond, F. Bondu, L. Bonelli, R. Bonnand, R. Bork, M. Born, V. Boschi, S. Bose, L. Bosi, J. Bowers, C. Bradaschia, P. R. Brady, V. B. Braginsky, M. Branchesi, C. A. Brannen, J. E. Brau, J. Breyer, T. Briant, D. O. Bridges, A. Brillet, M. Brinkmann, V. Brisson, M. Britzger, A. F. Brooks, D. A. Brown, D. D. Brown, F. Brückner, T. Bulik, H. J. Bulten, A. Buonanno, D. Buskulic, C. Buy, R. L. Byer, L. Cadonati, G. Cagnoli, J. Calderón Bustillo, E. Calloni, J. B. Camp, P. Campsie, K. C. Cannon, B. Canuel, J. Cao, C. D. Capano, F. Carbognani, L. Carbone, S. Caride, A. Castiglia, S. Caudill, M. Cavaglià, F. Cavalier, R. Cavalieri, G. Cella, C. Cepeda, E. Cesarini, R. Chakraborty, T. Chalermsongsak, S. Chao, P. Charlton, E. Chassande-Mottin, X. Chen, Y. Chen, A. Chincarini, A. Chiummo, H. S. Cho, J. Chow, N. Christensen, Q. Chu, S. S. Y. Chua, S. Chung, G. Ciani, F. Clara, D. E. Clark, J. A. Clark, F. Cleva, E. Coccia, P.-F. Cohadon, A. Colla, M. Colombini, M. Constancio, A. Conte, D. Cook, T. R. Corbitt, M. Cordier, N. Cornish, A. Corsi, C. A. Costa, M. W. Coughlin, J.-P. Coulon, S. Countryman, P. Couvares, D. M. Coward, M. Cowart, D. C. Coyne, K. Craig, J. D. E. Creighton, T. D. Creighton, S. G. Crowder, A. Cumming, L. Cunningham, E. Cuoco, K. Dahl, T. Dal Canton, M. Damjanic, S. L. Danilishin, S. D’Antonio, K. Danzmann, V. Dattilo, B. Daudert, H. Daveloza, M. Davier, G. S. Davies, E. J. Daw, R. Day, T. Dayanga, G. Debreczeni, J. Degallaix, E. Deleeuw, S. Deléglise, W. Del Pozzo, T. Denker, T. Dent, H. Dereli, V. Dergachev, R. T. DeRosa, R. De Rosa, R. DeSalvo, S. Dhurandhar, M. Díaz, A. Dietz, L. Di Fiore, A. Di Lieto, I. Di Palma, A. Di Virgilio, K. Dmitry, F. Donovan, K. L. Dooley, S. Doravari, M. Drago, R. W. P. Drever, J. C. Driggers, Z. Du, J.-C. Dumas, S. Dwyer, T. Eberle, M. Edwards, A. Effler, P. Ehrens, J. Eichholz, S. S. Eikenberry, G. Endrőczi, R. Essick, T. Etzel, K. Evans, M. Evans, T. Evans, M. Factourovich, V. Fafone, S. Fairhurst, Q. Fang, B. Farr, W. Farr, M. Favata, D. Fazi, H. Fehrmann, D. Feldbaum, I. Ferrante, F. Ferrini, F. Fidecaro, L. S. Finn, I. Fiori, R. Fisher, R. Flaminio, E. Foley, S. Foley, E. Forsi, N. Fotopoulos, J.-D. Fournier, S. Franco, S. Frasca, F. Frasconi, M. Frede, M. Frei, Z. Frei, A. Freise, R. Frey, T. T. Fricke, P. Fritschel, V. V. Frolov, M.-K. Fujimoto, P. Fulda, M. Fyffe, J. Gair, L. Gammaitoni, J. Garcia, F. Garufi, N. Gehrels, G. Gemme, E. Genin, A. Gennai, L. Gergely, S. Ghosh, J. A. Giaime, S. Giampanis, K. D. Giardina, A. Giazotto, S. Gil-Casanova, C. Gill, J. Gleason, E. Goetz, R. Goetz, L. Gondan, G. González, N. Gordon, M. L. Gorodetsky, S. Gossan, S. Goßler, R. Gouaty, C. Graef, P. B. Graff, M. Granata, A. Grant, S. Gras, C. Gray, R. J. S. Greenhalgh, A. M. Gretarsson, C. Griffo, H. Grote, K. Grover, S. Grunewald, G. M. Guidi, C. Guido, K. E. Gushwa, E. K. Gustafson, R. Gustafson, B. Hall, E. Hall, D. Hammer, G. Hammond, M. Hanke, J. Hanks, C. Hanna, J. Hanson, J. Harms, G. M. Harry, I. W. Harry, E. D. Harstad, M. T. Hartman, K. Haughian, K. Hayama, J. Heefner, A. Heidmann, M. Heintze, H. Heitmann, P. Hello, G. Hemming, M. Hendry, I. S. Heng, A. W. Heptonstall, M. Heurs, S. Hild, D. Hoak, K. A. Hodge, K. Holt, T. Hong, S. Hooper, T. Horrom, D. J. Hosken, J. Hough, E. J. Howell, Y. Hu, Z. Hua, V. Huang, E. A. Huerta, B. Hughey, S. Husa, S. H. Huttner, M. Huynh, T. Huynh-Dinh, J. Iafrate, D. R. Ingram, R. Inta, T. Isogai, A. Ivanov, B. R. Iyer, K. Izumi, M. Jacobson, E. James, H. Jang, Y. J. Jang, P. Jaranowski, F. Jiménez-Forteza, W. W. Johnson, D. I. Jones, D. Jones, R. Jones, R. J. G. Jonker, L. Ju, Haris K, P. Kalmus, V. Kalogera, S. Kandhasamy, G. Kang, J. B. Kanner, M. Kasprzack, R. Kasturi, E. Katsavounidis, W. Katzman, H. Kaufer, K. Kaufman, K. Kawabe, S. Kawamura, F. Kawazoe, F. Kéfélian, D. Keitel, D. B. Kelley, W. Kells, D. G. Keppel, A. Khalaidovski, F. Y. Khalili, E. A. Khazanov, B. K. Kim, C. Kim, K. Kim, N. Kim, W. Kim, Y.-M. Kim, E. King, P. J. King, D. L. Kinzel, J. S. Kissel, S. Klimenko, J. Kline, S. Koehlenbeck, K. Kokeyama, V. Kondrashov, S. Koranda, W. Z. Korth, I. Kowalska, D. Kozak, A. Kremin, V. Kringel, B. Krishnan, A. Królak, C. Kucharczyk, S. Kudla, G. Kuehn, A. Kumar, D. Nanda Kumar, P. Kumar, R. Kumar, R. Kurdyumov, P. Kwee, M. Landry, B. Lantz, S. Larson, P. D. Lasky, C. Lawrie, A. Lazzarini, P. Leaci, E. O. Lebigot, C.-H. Lee, H. K. Lee, H. M. Lee, J. J. Lee, J. Lee, M. Leonardi, J. R. Leong, A. Le Roux, N. Leroy, N. Letendre, B. Levine, J. B. Lewis, V. Lhuillier, T. G. F. Li, A. C. Lin, T. B. Littenberg, V. Litvine, F. Liu, H. Liu, Y. Liu, Z. Liu, D. Lloyd, N. A. Lockerbie, V. Lockett, D. Lodhia, K. Loew, J. Logue, A. L. Lombardi, M. Lorenzini, V. Loriette, M. Lormand, G. Losurdo, J. Lough, J. Luan, M. J. Lubinski, H. Lück, A. P. Lundgren, J. Macarthur, E. Macdonald, B. Machenschalk, M. MacInnis, D. M. Macleod, F. Magana-Sandoval, M. Mageswaran, K. Mailand, E. Majorana, I. Maksimovic, V. Malvezzi, N. Man, G. M. Manca, I. Mandel, V. Mandic, V. Mangano, M. Mantovani, F. Marchesoni, F. Marion, S. Márka, Z. Márka, A. Markosyan, E. Maros, J. Marque, F. Martelli, L. Martellini, I. W. Martin, R. M. Martin, G. Martini, D. Martynov, J. N. Marx, K. Mason, A. Masserot, T. J. Massinger, F. Matichard, L. Matone, R. A. Matzner, N. Mavalvala, G. May, N. Mazumder, G. Mazzolo, R. McCarthy, D. E. McClelland, S. C. McGuire, G. McIntyre, J. McIver, D. Meacher, G. D. Meadors, M. Mehmet, J. Meidam, T. Meier, A. Melatos, G. Mendell, R. A. Mercer, S. Meshkov, C. Messenger, M. S. Meyer, H. Miao, C. Michel, E. Mikhailov, L. Milano, J. Miller, Y. Minenkov, C. M. F. Mingarelli, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, B. Moe, M. Mohan, S. R. P. Mohapatra, F. Mokler, D. Moraru, G. Moreno, N. Morgado, T. Mori, S. R. Morriss, K. Mossavi, B. Mours, C. M. Mow-Lowry, C. L. Mueller, G. Mueller, S. Mukherjee, A. Mullavey, J. Munch, D. Murphy, P. G. Murray, A. Mytidis, M. F. Nagy, I. Nardecchia, T. Nash, L. Naticchioni, R. Nayak, V. Necula, I. Neri, M. Neri, G. Newton, T. Nguyen, E. Nishida, A. Nishizawa, A. Nitz, F. Nocera, D. Nolting, M. E. Normandin, L. K. Nuttall, E. Ochsner, J. O’Dell, E. Oelker, G. H. Ogin, J. J. Oh, S. H. Oh, F. Ohme, P. Oppermann, B. O’Reilly, W. Ortega Larcher, R. O’Shaughnessy, C. Osthelder, D. J. Ottaway, R. S. Ottens, J. Ou, H. Overmier, B. J. Owen, C. Padilla, A. Pai, C. Palomba, Y. Pan, C. Pankow, F. Paoletti, R. Paoletti, H. Paris, A. Pasqualetti, R. Passaquieti, D. Passuello, M. Pedraza, P. Peiris, S. Penn, A. Perreca, M. Phelps, M. Pichot, M. Pickenpack, F. Piergiovanni, V. Pierro, L. Pinard, B. Pindor, I. M. Pinto, M. Pitkin, J. Poeld, R. Poggiani, V. Poole, F. Postiglione, C. Poux, V. Predoi, T. Prestegard, L. R. Price, M. Prijatelj, S. Privitera, G. A. Prodi, L. Prokhorov, O. Puncken, M. Punturo, P. Puppo, V. Quetschke, E. Quintero, R. Quitzow-James, F. J. Raab, D. S. Rabeling, I. Rácz, H. Radkins, P. Raffai, S. Raja, G. Rajalakshmi, M. Rakhmanov, C. Ramet, P. Rapagnani, V. Raymond, V. Re, C. M. Reed, T. Reed, T. Regimbau, S. Reid, D. H. Reitze, F. Ricci, R. Riesen, K. Riles, N. A. Robertson, F. Robinet, A. Rocchi, S. Roddy, C. Rodriguez, M. Rodruck, C. Roever, L. Rolland, J. G. Rollins, J. D. Romano, R. Romano, G. Romanov, J. H. Romie, D. Rosińska, S. Rowan, A. Rüdiger, P. Ruggi, K. Ryan, F. Salemi, L. Sammut, V. Sandberg, J. Sanders, V. Sannibale, I. Santiago-Prieto, E. Saracco, B. Sassolas, B. S. Sathyaprakash, P. R. Saulson, R. Savage, R. Schilling, R. Schnabel, R. M. S. Schofield, E. Schreiber, D. Schuette, B. Schulz, B. F. Schutz, P. Schwinberg, J. Scott, S. M. Scott, F. Seifert, D. Sellers, A. S. Sengupta, D. Sentenac, V. Sequino, A. Sergeev, D. Shaddock, S. Shah, M. S. Shahriar, M. Shaltev, B. Shapiro, P. Shawhan, D. H. Shoemaker, T. L. Sidery, K. Siellez, X. Siemens, D. Sigg, D. Simakov, A. Singer, L. Singer, A. M. Sintes, G. R. Skelton, B. J. J. Slagmolen, J. Slutsky, J. R. Smith, M. R. Smith, R. J. E. Smith, N. D. Smith-Lefebvre, K. Soden, E. J. Son, B. Sorazu, T. Souradeep, L. Sperandio, A. Staley, E. Steinert, J. Steinlechner, S. Steinlechner, S. Steplewski, D. Stevens, A. Stochino, R. Stone, K. A. Strain, N. Straniero, S. Strigin, A. S. Stroeer, R. Sturani, A. L. Stuver, T. Z. Summerscales, S. Susmithan, P. J. Sutton, B. Swinkels, G. Szeifert, M. Tacca, D. Talukder, L. Tang, D. B. Tanner, S. P. Tarabrin, R. Taylor, A. P. M. ter Braack, M. P. Thirugnanasambandam, M. Thomas, P. Thomas, K. A. Thorne, K. S. Thorne, E. Thrane, V. Tiwari, K. V. Tokmakov, C. Tomlinson, A. Toncelli, M. Tonelli, O. Torre, C. V. Torres, C. I. Torrie, F. Travasso, G. Traylor, M. Tse, D. Ugolini, C. S. Unnikrishnan, H. Vahlbruch, G. Vajente, M. Vallisneri, J. F. J. van den Brand, C. Van Den Broeck, S. van der Putten, M. V. van der Sluys, J. van Heijningen, A. A. van Veggel, S. Vass, M. Vasúth, R. Vaulin, A. Vecchio, G. Vedovato, P. J. Veitch, J. Veitch, K. Venkateswara, D. Verkindt, S. Verma, F. Vetrano, A. Viceré, R. Vincent-Finley, J.-Y. Vinet, S. Vitale, B. Vlcek, T. Vo, H. Vocca, C. Vorvick, W. D. Vousden, D. Vrinceanu, S. P. Vyachanin, A. Wade, L. Wade, M. Wade, S. J. Waldman, M. Walker, L. Wallace, Y. Wan, J. Wang, M. Wang, X. Wang, A. Wanner, R. L. Ward, M. Was, B. Weaver, L.-W. Wei, M. Weinert, A. J. Weinstein, R. Weiss, T. Welborn, L. Wen, P. Wessels, M. West, T. Westphal, K. Wette, J. T. Whelan, D. J. White, B. F. Whiting, S. Wibowo, K. Wiesner, C. Wilkinson, L. Williams, R. Williams, T. Williams, J. L. Willis, B. Willke, M. Wimmer, L. Winkelmann, W. Winkler, C. C. Wipf, H. Wittel, G. Woan, J. Worden, J. Yablon, I. Yakushin, H. Yamamoto, C. C. Yancey, H. Yang, D. Yeaton-Massey, S. Yoshida, H. Yum, M. Yvert, A. Zadrożny, M. Zanolin, J.-P. Zendri, F. Zhang, L. Zhang, C. Zhao, H. Zhu, X. J. Zhu, N. Zotov, M. E. Zucker, and J. Zweizig

Published
2015
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6. The impact of tandem redundant/sky-based calibration in MWA Phase II data analysis

Author

Nichole Barry, Adam Lanman, Wenyang Li, Q. Zheng, M. Wilensky, Randall B. Wayth, Kenji Hasegawa, Daniel A. Mitchell, Christopher H. Jordan, Rachel L. Webster, Jonathan C. Pober, R. Byrne, Cathryn M. Trott, Steven Tingay, Miguel F. Morales, M. Rahimi, Bryna J. Hazelton, J. L. B. Line, Daniel C. Jacobs, Zheng Zhang, A. Chokshi, Steven G. Murray, Keitaro Takahashi, Shintaro Yoshiura, Christene Lynch, R. C. Joseph, B. Pindor, Benjamin McKinley, and Adam P. Beardsley

Subjects
Physics, 010308 nuclear & particles physics, Radio galaxy, Calibration (statistics), media_common.quotation_subject, Instrumentation, FOS: Physical sciences, Spectral density, Astronomy and Astrophysics, Murchison Widefield Array, 01 natural sciences, Space and Planetary Science, Sky, 0103 physical sciences, Astronomical interferometer, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Reionization, Remote sensing, media_common
Abstract

Precise instrumental calibration is of crucial importance to 21-cm cosmology experiments. The Murchison Widefield Array's (MWA) Phase II compact configuration offers us opportunities for both redundant calibration and sky-based calibration algorithms; using the two in tandem is a potential approach to mitigate calibration errors caused by inaccurate sky models. The MWA Epoch of Reionization (EoR) experiment targets three patches of the sky (dubbed EoR0, EoR1, and EoR2) with deep observations. Previous work in \cite{Li_2018} and \cite{Wenyang_2019} studied the effect of tandem calibration on the EoR0 field and found that it yielded no significant improvement in the power spectrum over sky-based calibration alone. In this work, we apply similar techniques to the EoR1 field and find a distinct result: the improvements in the power spectrum from tandem calibration are significant. To understand this result, we analyze both the calibration solutions themselves and the effects on the power spectrum over three nights of EoR1 observations. We conclude that the presence of the bright radio galaxy Fornax A in EoR1 degrades the performance of sky-based calibration, which in turn enables redundant calibration to have a larger impact. These results suggest that redundant calibration can indeed mitigate some level of model-incompleteness error., Comment: 20 pages, 11 figures, accepted for publication in PASA

Published
2020

7. Exploring reionisation and high-z galaxy observables with recent multi-redshift MWA upper limits on the 21-cm signal

Author

Nichole Barry, Cathryn M. Trott, B. Pindor, Bradley Greig, Rachel L. Webster, Simon J. Mutch, and J. Stuart B. Wyithe

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, Context (language use), Murchison Widefield Array, Astrophysics, 01 natural sciences, Galaxy, Redshift, Luminosity, Space and Planetary Science, 0103 physical sciences, Dark Ages, 010303 astronomy & astrophysics, Reionization, Luminosity function (astronomy), Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We use the latest multi-redshift ($z=6.5-8.7$) upper limits on the 21-cm signal from the Murchison Widefield Array (MWA) to explore astrophysical models which are inconsistent with the data. These upper limits are achieved using 298 h of carefully excised data over four observing seasons. To explore these upper limits in the context of reionisation astrophysics, we use 21CMMC. We then connect the disfavoured regions of parameter space to existing observational constraints on reionisation such as high-$z$ galaxy ultra-violet (UV) luminosity functions, background UV photoionisation rate, intergalactic medium (IGM) neutral fraction, the electron scattering optical depth and the soft-band X-ray emissivity. We find the vast majority of models disfavoured by the MWA limits are already inconsistent with existing observational constraints. These inconsistent models arise from two classes of models: (i) `cold' reionisation and (ii) pure matter density fluctuations (i.e. no reionisation). However, a small subsample of models are consistent implying the existing MWA limits provide unique information in disfavouring models of reionisation, albeit extremely weakly. We also provide the first limits on the soft-band X-ray emissivity from galaxies at high redshifts, finding $1\sigma$ lower limits of $\epsilon_{{\rm X},0.5-2~{\rm keV}}\gtrsim10^{34.5}$ erg s$^{-1}$ Mpc$^{-3}$. Finally, we recover 95 per cent disfavoured limits on the IGM spin temperature of $\bar{T}_{\rm S}\lesssim$ 1.3, 1.4, 1.5, 1.8, 2.1, 2.4 K at $z=6.5, 6.8, 7.1, 7.8, 8.2, 8.7$. With this we infer the IGM must have undergone, at the very least, a small amount of X-ray heating. Note, the limits on $\epsilon_{{\rm X},0.5-2~{\rm keV}}$ and $\bar{T}_{\rm S}$ are conditional on the IGM neutral fraction., Comment: 14 pages, 7 figures, 1 table. Submitted to MNRAS, comments welcome. arXiv admin note: text overlap with arXiv:2006.03203

Published
2020
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8. Characterization of the ionosphere above the Murchison Radio Observatory using the Murchison Widefield Array

Author

John Morgan, B. Pindor, Randall B. Wayth, Daniel A. Mitchell, M. Rahimi, Christopher H. Jordan, Cathryn M. Trott, Pietro Procopio, and Steven G. Murray

Subjects
Physics, Total electron content, Epoch (reference date), Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy, Spectral density, 020206 networking & telecommunications, Astronomy and Astrophysics, Murchison Widefield Array, 02 engineering and technology, LOFAR, 01 natural sciences, Physics::Geophysics, Space and Planetary Science, Physics::Space Physics, 0103 physical sciences, Metric (mathematics), 0202 electrical engineering, electronic engineering, information engineering, Calibration, Ionosphere, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Remote sensing
Abstract

We detail new techniques for analysing ionospheric activity, using Epoch of Reionisation (EoR) datasets obtained with the Murchison Widefield Array (MWA), calibrated by the `Real-Time System' (RTS). Using the high spatial- and temporal-resolution information of the ionosphere provided by the RTS calibration solutions over 19 nights of observing, we find four distinct types of ionospheric activity, and have developed a metric to provide an `at a glance' value for data quality under differing ionospheric conditions. For each ionospheric type, we analyse variations of this metric as we reduce the number of pierce points, revealing that a modest number of pierce points is required to identify the intensity of ionospheric activity; it is possible to calibrate in real-time, providing continuous information of the phase screen. We also analyse temporal correlations, determine diffractive scales, examine the relative fractions of time occupied by various types of ionospheric activity, and detail a method to reconstruct the total electron content responsible for the ionospheric data we observe. These techniques have been developed to be instrument agnostic, useful for application on LOFAR and SKA-Low., Accepted by MNRAS on 14 July 2017

Published
2017

9. Robust statistics toward detection of the 21 cm signal from the Epoch of Reionisation

Author

Rachel L. Webster, Keitaro Takahashi, J. L. B. Line, Jonathan C. Pober, R. Byrne, Christene Lynch, R. C. Joseph, Christopher H. Jordan, Steven G. Murray, B. Pindor, M. Wilensky, Bryna J. Hazelton, Nichole Barry, Steven Tingay, B. McKinley, Daniel A. Mitchell, Shintaro Yoshiura, Kenji Kubota, W. Li, M. Walker, J. S. B. Wyithe, Kenji Hasegawa, Shih Ching Fu, Cathryn M. Trott, Miguel F. Morales, Q. Zheng, Randall B. Wayth, T. Kaneuji, and M. Rahimi

Subjects
Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Kernel density estimation, Robust statistics, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Spectral density, Estimator, Astronomy and Astrophysics, Murchison Widefield Array, Probability density function, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Weighting, Space and Planetary Science, 0103 physical sciences, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Reionization, Algorithm, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We explore methods for robust estimation of the 21 cm signal from the Epoch of Reionisation (EoR). A Kernel Density Estimator (KDE) is introduced for measuring the spatial temperature fluctuation power spectrum from the EoR. The KDE estimates the underlying probability distribution function of fluctuations as a function of spatial scale, and contains different systematic biases and errors to the typical approach to estimating the fluctuation power spectrum. Extraction of histograms of visibilities allows moments analysis to be used to discriminate foregrounds from 21 cm signal and thermal noise. We use the information available in the histograms, along with the statistical dis-similarity of foregrounds from two independent observing fields, to robustly separate foregrounds from cosmological signal, while making no assumptions about the Gaussianity of the signal. Using two independent observing fields to robustly discriminate signal from foregrounds is crucial for the analysis presented in this paper. We apply the techniques to 13 hours of Murchison Widefield Array (MWA) EoR data over two observing fields. We compare the output to that obtained with a comparative power spectrum estimation method, and demonstrate the reduced foreground contamination using this approach. Using the second moment obtained directly from the KDE distribution functions yields a factor of 2-3 improvement in power for k < 0.3hMpc^{-1} compared with a matched delay space power estimator, while weighting data by additional statistics does not offer significant improvement beyond that available for thermal noise-only weights., 19 pages, 18 figures, accepted for publication in MNRAS

Published
2019

10. First Season MWA Phase II Epoch of Reionization Power Spectrum Results at Redshift 7

Author

Adam Lanman, J. L. B. Line, Cathryn M. Trott, Miguel F. Morales, Jonathan C. Pober, Christene Lynch, Bryna J. Hazelton, R. C. Joseph, R. Byrne, Judd D. Bowman, Daniel Jacobs, B. Pindor, Christopher H. Jordan, David L. Kaplan, A. P. Beardsley, D. Kenney, Tom Booler, Kenji Kubota, Melanie Johnston-Hollitt, S. S. Murray, Steven Tingay, T. M. O. Franzen, M. Wilensky, Andrew R. Williams, Chen Wu, Rachel L. Webster, S. Yoshiura, M. Walker, D. Pallot, Daniel A. Mitchell, G. Sleap, Qinghua Zheng, Keitaro Takahashi, David Emrich, L. Horsley, Kenji Hasegawa, Brian Crosse, K. Steele, J. Riding, B. McKinley, Ian Sullivan, Nichole Barry, Wenyang Li, R. B. Wayth, J. S. B. Wyithe, T. Kaneuji, and M. Rahimi

Subjects
Physics, 010504 meteorology & atmospheric sciences, Phase (waves), Spectral density, Astronomy and Astrophysics, Murchison Widefield Array, Astrophysics, Space (mathematics), 01 natural sciences, Redshift, Interferometry, Space and Planetary Science, 0103 physical sciences, Calibration, Sensitivity (control systems), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

The compact configuration of Phase II of the Murchison Widefield Array (MWA) consists of both a redundant subarray and pseudo-random baselines, offering unique opportunities to perform sky-model and redundant interferometric calibration. The highly redundant hexagonal cores give improved power spectrum sensitivity. In this paper, we present the analysis of nearly 40 hours of data targeting one of the MWA's EoR fields observed in 2016. We use both improved analysis techniques presented in Barry et al. (2019) as well as several additional techniques developed for this work, including data quality control methods and interferometric calibration approaches. We show the EoR power spectrum limits at redshift 6.5, 6.8 and 7.1 based on our deep analysis on this 40-hour data set. These limits span a range in $k$ space of $0.18$ $h$ $\mathrm{Mpc^{-1}}$ $

Published
2019

11. Assessment of ionospheric activity tolerances for Epoch of Reionisation science with the Murchison Widefield Array

Author

U. Shankar, Daniel C. Jacobs, J. S. B. Wyithe, Steven G. Murray, Bryna J. Hazelton, Steven Tingay, Daniel A. Mitchell, Jonathan C. Pober, Ravi Subrahmanyan, Judd D. Bowman, Cathryn M. Trott, Frank H. Briggs, Christopher H. Jordan, Miguel F. Morales, Benjamin McKinley, B. Pindor, Rachel L. Webster, Randall B. Wayth, Max Tegmark, Jacqueline N. Hewitt, Shiv K. Sethi, Adam P. Beardsley, and J. L. B. Line

Subjects
Physics, Total electron content, Astrophysics::Instrumentation and Methods for Astrophysics, Spectral density, FOS: Physical sciences, 020206 networking & telecommunications, Astronomy and Astrophysics, Murchison Widefield Array, Quasar, 02 engineering and technology, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Spectral line, Computational physics, Space and Planetary Science, 0103 physical sciences, Physics::Space Physics, 0202 electrical engineering, electronic engineering, information engineering, Emission spectrum, Ionosphere, Astrophysics - Instrumentation and Methods for Astrophysics, 010303 astronomy & astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract

Structure imprinted in foreground extragalactic point sources by ionospheric refraction has the potential to contaminate Epoch of Reionisation (EoR) power spectra of the 21~cm emission line of neutral hydrogen. The alteration of the spatial and spectral structure of foreground measurements due to total electron content (TEC) gradients in the ionosphere create a departure from the expected sky signal. We present a general framework for understanding the signatures of ionospheric behaviour in the two-dimensional (2D) neutral hydrogen power spectrum measured by a low-frequency radio interferometer. Two primary classes of ionospheric behaviour are considered, corresponding to dominant modes observed in Murchison Widefield Array (MWA) EoR data; namely, anisotropic structured wave behaviour, and isotropic turbulence. Analytic predictions for power spectrum bias due to this contamination are computed, and compared with simulations. We then apply the ionospheric metric described in Jordan et al. (2017) to study the impact of ionospheric structure on MWA data, by dividing MWA EoR datasets into classes with good and poor ionospheric conditions, using sets of matched 30-minute observations from 2014 September. The results are compared with the analytic and simulated predictions, demonstrating the observed bias in the power spectrum when the ionosphere is active (displays coherent structures or isotropic turbulence). The analysis demonstrates that unless ionospheric activity can be quantified and corrected, active data should not be included in EoR analysis in order to avoid systematic biases in cosmological power spectra. When data are corrected with a model formed from the calibration information, bias reduces below the expected 21~cm signal level. Data are considered `quiet' when the median measured source position offsets are less than 10-15~arcseconds., Comment: 19 pages, 11 figures, Accepted for publication in the Astrophysical Journal

Published
2018
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12. Measuring the global 21-cm signal with the MWA-I: improved measurements of the Galactic synchrotron background using lunar occultation

Author

Rachel L. Webster, Steven Tingay, Marcin Sokolowski, Gianni Bernardi, Benjamin McKinley, Natasha Hurley-Walker, Emil Lenc, J. L. B. Line, Randall B. Wayth, Cathryn M. Trott, A. R. Offringa, B. Pindor, F. Briggs, Judd D. Bowman, Christopher H. Jordan, Astronomy, ITA, USA, and AUS

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010504 meteorology & atmospheric sciences, media_common.quotation_subject, first stars, SPECTRAL INDEX, FOS: Physical sciences, Murchison Widefield Array, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Occultation, 10 MHZ, law.invention, Telescope, SARAS, law, 0103 physical sciences, Astronomical interferometer, dark ages, reionization, first stars, dark ages, Moon, 010303 astronomy & astrophysics, Reionization, Instrumentation and Methods for Astrophysics (astro-ph.IM), 0105 earth and related environmental sciences, media_common, EPOCH, Physics, Spectral index, IONOSPHERE, Astrophysics::Instrumentation and Methods for Astrophysics, CONSTRAINTS, Astronomy, Astronomy and Astrophysics, RADAR DETERMINATION, MODEL, techniques: interferometric, Space and Planetary Science, Sky, Brightness temperature, RADIO-EMISSION, Physics::Space Physics, reionization, RADIATION, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present early results from a project to measure the sky-averaged (global), redshifted $21\,$cm signal from the Epoch of Reionisation (EoR), using the Murchison Widefield Array (MWA) telescope. Because interferometers are not sensitive to a spatially-invariant global average, they cannot be used to detect this signal using standard techniques. However, lunar occultation of the radio sky imprints a spatial structure on the global signal, allowing us to measure the average brightness temperature of the patch of sky immediately surrounding the Moon. In this paper we present one night of Moon observations with the MWA between 72 - 230 MHz and verify our techniques to extract the background sky temperature from measurements of the Moon's flux density. We improve upon previous work using the lunar occultation technique by using a more sophisticated model for reflected `earthshine' and by employing image differencing to remove imaging artefacts. We leave the Moon's (constant) radio brightness temperature as a free parameter in our fit to the data and as a result, measure $T_{\rm{moon}} = 180 \pm 12 $ K and a Galactic synchrotron spectral index of $-2.64\pm0.14$, at the position of the Moon. Finally, we evaluate the prospects of the lunar occultation technique for a global EoR detection and map out a way forward for future work with the MWA., Comment: 13 pages, 7 figures, accepted in MNRAS

Published
2018
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13. Delay Spectrum with Phase-Tracking Arrays: Extracting the HI power spectrum from the Epoch of Reionization

Author

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

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

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

Published
2016
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14. CHIPS: The Cosmological HI Power Spectrum Estimator

Author

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

Subjects
Cosmology and Nongalactic Astrophysics (astro-ph.CO), 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Estimator, Spectral density, FOS: Physical sciences, Astronomy and Astrophysics, Murchison Widefield Array, Astrophysics::Cosmology and Extragalactic Astrophysics, Parameter space, 01 natural sciences, Redshift, Weighting, Radio telescope, Space and Planetary Science, 0103 physical sciences, Astrophysics - Instrumentation and Methods for Astrophysics, 010303 astronomy & astrophysics, Reionization, Algorithm, Instrumentation and Methods for Astrophysics (astro-ph.IM), Mathematics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Detection of the cosmological neutral hydrogen signal from the Epoch of Reionization, and estimation of its basic physical parameters, is the principal scientific aim of many current low-frequency radio telescopes. Here we describe the Cosmological HI Power Spectrum Estimator (CHIPS), an algorithm developed and implemented with data from the Murchison Widefield Array (MWA), to compute the two-dimensional and spherically-averaged power spectrum of brightness temperature fluctuations. The principal motivations for CHIPS are the application of realistic instrumental and foreground models to form the optimal estimator, thereby maximising the likelihood of unbiased signal estimation, and allowing a full covariant understanding of the outputs. CHIPS employs an inverse-covariance weighting of the data through the maximum likelihood estimator, thereby allowing use of the full parameter space for signal estimation ("foreground suppression"). We describe the motivation for the algorithm, implementation, application to real and simulated data, and early outputs. Upon application to a set of 3 hours of data, we set a 2$\sigma$ upper limit on the EoR dimensionless power at $k=0.05$~h.Mpc$^{-1}$ of $\Delta_k^2, Comment: 34 pages, accepted for publication in ApJ

Published
2016
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15. Subtraction of point sources from interferometric radio images through an algebraic forward modelling scheme

Author

Stephen M. Ord, Daniel A. Mitchell, Gianni Bernardi, B. Pindor, L. J. Greenhill, J. S. B. Wyithe, and Randall B. Wayth

Subjects
Physics, Observational error, 010308 nuclear & particles physics, Dynamic range, Astrophysics::Instrumentation and Methods for Astrophysics, Subtraction, Astronomy and Astrophysics, Astrophysics, Residual, 01 natural sciences, Interferometry, Orders of magnitude (time), Space and Planetary Science, 0103 physical sciences, Deconvolution, 010303 astronomy & astrophysics, Reionization, Algorithm
Abstract

We present a method for subtracting point sources from interferometric radio images via forward modeling of the instrument response and involving an algebraic nonlinear minimization. The method is applied to simulated maps of the Murchison Wide-field Array but is generally useful in cases where only image data are available. After source subtraction, the residual maps have no statistical difference to the expected thermal noise distribution at all angular scales, indicating high effectiveness in the subtraction. Simulations indicate that the errors in recovering the source parameters decrease with increasing signal-to-noise ratio, which is consistent with the theoretical measurement errors. In applying the technique to simulated snapshot observations with the Murchison Wide-field Array, we found that all 101 sources present in the simulation were recovered with an average position error of 10 arcsec and an average flux density error of 0.15%. This led to a dynamic range increase of approximately 3 orders of magnitude. Since all the sources were deconvolved jointly, the subtraction was not limited by source sidelobes but by thermal noise. This technique is a promising deconvolution method for upcoming radio arrays with a huge number of elements, and a candidate for the difficult task of subtracting foreground sources from observations of the 21 cm neutral Hydrogen signal from the epoch of reionization.

Published
2011

16. Ionospheric Modelling using GPS to Calibrate the MWA. I: Comparison of First Order Ionospheric Effects between GPS Models and MWA Observations

Author

R. B. Wayth, Stephen M. Ord, K. S. Srivani, Bryna J. Hazelton, Judd D. Bowman, Pietro Procopio, Rachel L. Webster, Andrew Williams, Qinghua Zheng, Christopher L. Williams, Lincoln J. Greenhill, Miguel F. Morales, Anna D. Kapińska, Donald J. Jacobs, Paul Hancock, Avinash A. Deshpande, David Emrich, Roger J. Cappallo, Luke Hindson, Eric Kratzenberg, N. Udaya Shankar, Eric R. Morgan, Lister Staveley-Smith, J. C. Kasper, M. J. Lynch, Alan R. Whitney, Stephen R. McWhirter, Bi-Qing For, A. R. Offringa, Ravi Subrahmanyan, Lu Feng, John Morgan, K. S. Dwarakanath, A. Roshi, B. McKinley, David L. Kaplan, Martin Bell, B. S. Arora, Divya Oberoi, Daniel A. Mitchell, Robert F. Goeke, Nadia Kudryavtseva, Gianni Bernardi, M. Waterson, Steven Tingay, Alan E. E. Rogers, Thiagaraj Prabu, Joseph R. Callingham, B. Pindor, Natasha Hurley-Walker, F. Briggs, Emil Lenc, Melanie Johnston-Hollitt, Brian E. Corey, J. Riding, Chen Wu, R. Bhat, Aaron Ewall-Wice, Colin J. Lonsdale, ITA, USA, and AUS

Subjects
010504 meteorology & atmospheric sciences, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Field of view, Murchison Widefield Array, Geodesy, First order, 01 natural sciences, Physics::Geophysics, 13. Climate action, Space and Planetary Science, 0103 physical sciences, Physics::Space Physics, Calibration, Global Positioning System, Ionosphere, business, Orbit determination, 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences, Radio astronomy
Abstract

We compare first order (refractive) ionospheric effects seen by the Murchison Widefield Array (MWA) with the ionosphere as inferred from Global Positioning System (GPS) data. The first order ionosphere manifests itself as a bulk position shift of the observed sources across an MWA field of view. These effects can be computed from global ionosphere maps provided by GPS analysis centres, namely the Center for Orbit Determination in Europe (CODE), using data from globally distributed GPS receivers. However, for the more accurate local ionosphere estimates required for precision radio astronomy applications, data from local GPS networks needs to be incorporated into ionospheric modelling. For GPS observations, the ionospheric parameters are biased by GPS receiver instrument delays, among other effects, also known as receiver Differential Code Biases (DCBs). The receiver DCBs need to be estimated for any non-CODE GPS station used for ionosphere modelling, a requirement for establishing dense GPS networks in arbitrary locations in the vicinity of the MWA. In this work, single GPS station-based ionospheric modelling is performed at a time resolution of 10 minutes. Also the receiver DCBs are estimated for selected Geoscience Australia (GA) GPS receivers, located at Murchison Radio Observatory (MRO1), Yarragadee (YAR3), Mount Magnet (MTMA) and Wiluna (WILU). The ionospheric gradients estimated from GPS are compared with the ionospheric gradients inferred from radio source position shifts observed with the MWA. The ionospheric gradients at all the GPS stations show a correlation with the gradients observed with the MWA. The ionosphere estimates obtained using GPS measurements show promise in terms of providing calibration information for the MWA.

Published
2015

17. Application of a Hough search for continuous gravitational waves on data from the fifth LIGO science run

Author

J. Aasi, J. Abadie, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, T. Accadia, F. Acernese, C. Adams, T. Adams, R. X. Adhikari, C. Affeldt, M. Agathos, N. Aggarwal, O. D. Aguiar, P. Ajith, B. Allen, A. Allocca, E. Amador Ceron, D. Amariutei, R. A. Anderson, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. Areeda, S. Ast, S. M. Aston, P. Astone, P. Aufmuth, C. Aulbert, L. Austin, B. E. Aylott, S. Babak, P. T. Baker, G. Ballardin, S. W. Ballmer, J. C. Barayoga, D. Barker, S. H. Barnum, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, M. A. Barton, I. Bartos, R. Bassiri, A. Basti, J. Batch, J. Bauchrowitz, Th S. Bauer, M. Bebronne, B. Behnke, M. Bejger, M. G. Beker, A. S. Bell, C. Bell, I. Belopolski, G. Bergmann, J. M. Berliner, D. Bersanetti, A. Bertolini, D. Bessis, J. Betzwieser, P. T. Beyersdorf, T. Bhadbhade, I. A. Bilenko, G. Billingsley, J. Birch, M. Bitossi, M. A. Bizouard, E. Black, J. K. Blackburn, L. Blackburn, D. Blair, M. Blom, O. Bock, T. P. Bodiya, M. Boer, C. Bogan, C. Bond, F. Bondu, L. Bonelli, R. Bonnand, R. Bork, M. Born, V. Boschi, S. Bose, L. Bosi, J. Bowers, C. Bradaschia, P. R. Brady, V. B. Braginsky, M. Branchesi, C. A. Brannen, J. E. Brau, J. Breyer, T. Briant, D. O. Bridges, A. Brillet, M. Brinkmann, V. Brisson, M. Britzger, A. F. Brooks, D. A. Brown, D. D. Brown, F. Br?ckner, T. Bulik, H. J. Bulten, A. Buonanno, D. Buskulic, C. Buy, R. L. Byer, L. Cadonati, G. Cagnoli, J. Calder?n Bustillo, J. B. Camp, P. Campsie, K. C. Cannon, B. Canuel, J. Cao, C. D. Capano, F. Carbognani, L. Carbone, S. Caride, A. Castiglia, S. Caudill, M. Cavagli?, F. Cavalier, R. Cavalieri, G. Cella, C. Cepeda, E. Cesarini, R. Chakraborty, T. Chalermsongsak, S. Chao, P. Charlton, E. Chassande Mottin, X. Chen, Y. Chen, A. Chincarini, A. Chiummo, H. S. Cho, J. Chow, N. Christensen, Q. Chu, S. S. Y. Chua, S. Chung, G. Ciani, F. Clara, D. E. Clark, J. A. Clark, F. Cleva, E. Coccia, P. F. Cohadon, A. Colla, M. Colombini, M. Constancio, A. Conte, R. Conte, D. Cook, T. R. Corbitt, M. Cordier, N. Cornish, A. Corsi, C. A. Costa, M. W. Coughlin, J. P. Coulon, S. Countryman, P. Couvares, D. M. Coward, M. Cowart, D. C. Coyne, K. Craig, J. D. E. Creighton, T. D. Creighton, S. G. Crowder, A. Cumming, L. Cunningham, E. Cuoco, K. Dahl, T. Dal Canton, M. Damjanic, S. L. Danilishin, S. D?Antonio, K. Danzmann, V. Dattilo, B. Daudert, H. Daveloza, M. Davier, G. S. Davies, E. J. Daw, R. Day, T. Dayanga, G. Debreczeni, J. Degallaix, E. Deleeuw, S. Del?glise, W. Del Pozzo, T. Denker, T. Dent, H. Dereli, V. Dergachev, R. T. DeRosa, R. DeSalvo, S. Dhurandhar, M. D?az, A. Dietz, L. Di Fiore, A. Di Lieto, I. Di Palma, A. Di Virgilio, K. Dmitry, F. Donovan, K. L. Dooley, S. Doravari, M. Drago, R. W. P. Drever, J. C. Driggers, Z. Du, J. C. Dumas, S. Dwyer, T. Eberle, M. Edwards, A. Effler, P. Ehrens, J. Eichholz, S. S. Eikenberry, G. EndrHoczi, R. Essick, T. Etzel, K. Evans, M. Evans, T. Evans, M. Factourovich, V. Fafone, S. Fairhurst, Q. Fang, S. Farinon, B. Farr, W. Farr, M. Favata, D. Fazi, H. Fehrmann, D. Feldbaum, I. Ferrante, F. Ferrini, F. Fidecaro, L. S. Finn, I. Fiori, R. Fisher, R. Flaminio, E. Foley, S. Foley, E. Forsi, N. Fotopoulos, J. D. Fournier, S. Franco, S. Frasca, F. Frasconi, M. Frede, M. Frei, Z. Frei, A. Freise, R. Frey, T. T. Fricke, P. Fritschel, V. V. Frolov, M. K. Fujimoto, P. Fulda, M. Fyffe, J. Gair, L. Gammaitoni, J. Garcia, N. Gehrels, G. Gemme, E. Genin, A. Gennai, L. Gergely, S. Ghosh, J. A. Giaime, S. Giampanis, K. D. Giardina, A. Giazotto, S. Gil Casanova, C. Gill, J. Gleason, E. Goetz, R. Goetz, L. Gondan, G. Gonz?lez, N. Gordon, M. L. Gorodetsky, S. Gossan, S. Go?ler, R. Gouaty, C. Graef, P. B. Graff, M. Granata, A. Grant, S. Gras, C. Gray, R. J. S. Greenhalgh, A. M. Gretarsson, C. Griffo, P. Groot, H. Grote, K. Grover, S. Grunewald, G. M. Guidi, C. Guido, K. E. Gushwa, E. K. Gustafson, R. Gustafson, B. Hall, E. Hall, D. Hammer, G. Hammond, M. Hanke, J. Hanks, C. Hanna, J. Hanson, J. Harms, G. M. Harry, I. W. Harry, E. D. Harstad, M. T. Hartman, K. Haughian, K. Hayama, J. Heefner, A. Heidmann, M. Heintze, H. Heitmann, P. Hello, G. Hemming, M. Hendry, I. S. Heng, A. W. Heptonstall, M. Heurs, S. Hild, D. Hoak, K. A. Hodge, K. Holt, T. Hong, S. Hooper, T. Horrom, D. J. Hosken, J. Hough, E. J. Howell, Y. Hu, Z. Hua, V. Huang, E. A. Huerta, B. Hughey, S. Husa, S. H. Huttner, M. Huynh, T. Huynh Dinh, J. Iafrate, D. R. Ingram, R. Inta, T. Isogai, A. Ivanov, B. R. Iyer, K. Izumi, M. Jacobson, E. James, H. Jang, Y. J. Jang, P. Jaranowski, F. Jim?nez Forteza, W. W. Johnson, D. Jones, D. I. Jones, R. Jones, R. J. G. Jonker, L. Ju, Haris K, P. Kalmus, V. Kalogera, S. Kandhasamy, G. Kang, J. B. Kanner, M. Kasprzack, R. Kasturi, E. Katsavounidis, W. Katzman, H. Kaufer, K. Kaufman, K. Kawabe, S. Kawamura, F. Kawazoe, F. K?f?lian, D. Keitel, D. B. Kelley, W. Kells, D. G. Keppel, A. Khalaidovski, F. Y. Khalili, E. A. Khazanov, B. K. Kim, C. Kim, K. Kim, N. Kim, W. Kim, Y. M. Kim, E. J. King, P. J. King, D. L. Kinzel, J. S. Kissel, S. Klimenko, J. Kline, S. Koehlenbeck, K. Kokeyama, V. Kondrashov, S. Koranda, W. Z. Korth, I. Kowalska, D. Kozak, A. Kremin, V. Kringel, B. Krishnan, A. Kr?lak, C. Kucharczyk, S. Kudla, G. Kuehn, A. Kumar, P. Kumar, R. Kumar, R. Kurdyumov, P. Kwee, M. Landry, B. Lantz, S. Larson, P. D. Lasky, C. Lawrie, P. Leaci, E. O. Lebigot, C. H. Lee, H. K. Lee, H. M. Lee, J. Lee, M. Leonardi, J. R. Leong, A. Le Roux, N. Leroy, N. Letendre, B. Levine, J. B. Lewis, V. Lhuillier, T. G. F. Li, A. C. Lin, T. B. Littenberg, V. Litvine, F. Liu, H. Liu, Y. Liu, Z. Liu, D. Lloyd, N. A. Lockerbie, V. Lockett, D. Lodhia, K. Loew, J. Logue, A. L. Lombardi, M. Lorenzini, V. Loriette, M. Lormand, G. Losurdo, J. Lough, J. Luan, M. J. Lubinski, H. L?ck, A. P. Lundgren, J. Macarthur, E. Macdonald, B. Machenschalk, M. MacInnis, D. M. Macleod, F. Magana Sandoval, M. Mageswaran, K. Mailand, E. Majorana, I. Maksimovic, V. Malvezzi, N. Man, G. M. Manca, I. Mandel, V. Mandic, V. Mangano, M. Mantovani, F. Marchesoni, F. Marion, S. M?rka, Z. M?rka, A. Markosyan, E. Maros, J. Marque, F. Martelli, I. W. Martin, R. M. Martin, L. Martinelli, D. Martynov, J. N. Marx, K. Mason, A. Masserot, T. J. Massinger, F. Matichard, L. Matone, R. A. Matzner, N. Mavalvala, G. May, N. Mazumder, G. Mazzolo, R. McCarthy, D. E. McClelland, S. C. McGuire, G. McIntyre, J. McIver, D. Meacher, G. D. Meadors, M. Mehmet, J. Meidam, T. Meier, A. Melatos, G. Mendell, R. A. Mercer, S. Meshkov, C. Messenger, M. S. Meyer, H. Miao, C. Michel, E. E. Mikhailov, J. Miller, Y. Minenkov, C. M. F. Mingarelli, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, B. Moe, M. Mohan, S. R. P. Mohapatra, F. Mokler, D. Moraru, G. Moreno, N. Morgado, T. Mori, S. R. Morriss, K. Mossavi, B. Mours, C. M. Mow Lowry, C. L. Mueller, G. Mueller, S. Mukherjee, A. Mullavey, J. Munch, D. Murphy, P. G. Murray, A. Mytidis, M. F. Nagy, D. Nanda Kumar, I. Nardecchia, T. Nash, L. Naticchioni, R. Nayak, V. Necula, G. Nelemans, I. Neri, M. Neri, G. Newton, T. Nguyen, E. Nishida, A. Nishizawa, A. Nitz, F. Nocera, D. Nolting, M. E. Normandin, L. K. Nuttall, E. Ochsner, J. O?Dell, E. Oelker, G. H. Ogin, J. J. Oh, S. H. Oh, F. Ohme, P. Oppermann, B. O?Reilly, W. Ortega Larcher, R. O?Shaughnessy, C. Osthelder, C. D. Ott, D. J. Ottaway, R. S. Ottens, J. Ou, H. Overmier, B. J. Owen, C. Padilla, A. Pai, C. Palomba, Y. Pan, C. Pankow, F. Paoletti, R. Paoletti, M. A. Papa, H. Paris, A. Pasqualetti, R. Passaquieti, D. Passuello, M. Pedraza, P. Peiris, S. Penn, A. Perreca, M. Phelps, M. Pichot, M. Pickenpack, F. Piergiovanni, V. Pierro, L. Pinard, B. Pindor, I. M. Pinto, M. Pitkin, J. Poeld, R. Poggiani, V. Poole, C. Poux, V. Predoi, T. Prestegard, L. R. Price, M. Prijatelj, M. Principe, S. Privitera, R. Prix, G. A. Prodi, L. Prokhorov, O. Puncken, M. Punturo, P. Puppo, V. Quetschke, E. Quintero, R. Quitzow James, F. J. Raab, D. S. Rabeling, I. R?cz, H. Radkins, P. Raffai, S. Raja, G. Rajalakshmi, M. Rakhmanov, C. Ramet, P. Rapagnani, V. Raymond, V. Re, C. M. Reed, T. Reed, T. Regimbau, S. Reid, D. H. Reitze, F. Ricci, R. Riesen, K. Riles, N. A. Robertson, F. Robinet, A. Rocchi, S. Roddy, C. Rodriguez, M. Rodruck, C. Roever, L. Rolland, J. G. Rollins, R. Romano, G. Romanov, J. H. Romie, D. Rosi?ska, S. Rowan, A. R?diger, P. Ruggi, K. Ryan, F. Salemi, L. Sammut, L. Sancho de la Jordana, V. Sandberg, J. Sanders, V. Sannibale, I. Santiago Prieto, E. Saracco, B. Sassolas, B. S. Sathyaprakash, P. R. Saulson, R. Savage, R. Schilling, R. Schnabel, R. M. S. Schofield, E. Schreiber, D. Schuette, B. Schulz, B. F. Schutz, P. Schwinberg, J. Scott, S. M. Scott, F. Seifert, D. Sellers, A. S. Sengupta, D. Sentenac, V. Sequino, A. Sergeev, D. Shaddock, S. Shah, M. S. Shahriar, M. Shaltev, B. Shapiro, P. Shawhan, D. H. Shoemaker, T. L. Sidery, K. Siellez, X. Siemens, D. Sigg, D. Simakov, A. Singer, L. Singer, A. M. Sintes, G. R. Skelton, B. J. J. Slagmolen, J. Slutsky, J. R. Smith, M. R. Smith, R. J. E. Smith, N. D. Smith Lefebvre, K. Soden, E. J. Son, B. Sorazu, T. Souradeep, L. Sperandio, A. Staley, E. Steinert, J. Steinlechner, S. Steinlechner, S. Steplewski, D. Stevens, A. Stochino, R. Stone, K. A. Strain, N. Straniero, S. Strigin, A. S. Stroeer, R. Sturani, A. L. Stuver, T. Z. Summerscales, S. Susmithan, P. J. Sutton, B. Swinkels, G. Szeifert, M. Tacca, D. Talukder, L. Tang, D. B. Tanner, S. P. Tarabrin, R. Taylor, A. P. M. ter Braack, M. P. Thirugnanasambandam, M. Thomas, P. Thomas, K. A. Thorne, K. S. Thorne, E. Thrane, V. Tiwari, K. V. Tokmakov, C. Tomlinson, A. Toncelli, M. Tonelli, O. Torre, C. V. Torres, C. I. Torrie, F. Travasso, G. Traylor, M. Tse, D. Ugolini, C. S. Unnikrishnan, H. Vahlbruch, G. Vajente, M. Vallisneri, J. F. J. van den Brand, C. Van Den Broeck, S. van der Putten, M. V. van der Sluys, J. van Heijningen, A. A. van Veggel, S. Vass, M. Vas?th, R. Vaulin, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, K. Venkateswara, D. Verkindt, S. Verma, F. Vetrano, A. Vicer?, R. Vincent Finley, J. Y. Vinet, S. Vitale, B. Vlcek, T. Vo, H. Vocca, C. Vorvick, W. D. Vousden, D. Vrinceanu, S. P. Vyachanin, A. Wade, L. Wade, M. Wade, S. J. Waldman, M. Walker, L. Wallace, Y. Wan, J. Wang, M. Wang, X. Wang, A. Wanner, R. L. Ward, M. Was, B. Weaver, L. W. Wei, M. Weinert, A. J. Weinstein, R. Weiss, T. Welborn, L. Wen, P. Wessels, M. West, T. Westphal, K. Wette, J. T. Whelan, S. E. Whitcomb, D. J. White, B. F. Whiting, S. Wibowo, K. Wiesner, C. Wilkinson, L. Williams, R. Williams, T. Williams, J. L. Willis, B. Willke, M. Wimmer, L. Winkelmann, W. Winkler, C. C. Wipf, H. Wittel, G. Woan, J. Worden, J. Yablon, I. Yakushin, H. Yamamoto, C. C. Yancey, H. Yang, D. Yeaton Massey, S. Yoshida, H. Yum, M. Yvert, A. Zadro?ny, M. Zanolin, J. P. Zendri, F. Zhang, L. Zhang, C. Zhao, H. Zhu, X. J. Zhu, N. Zotov, M. E. Zucker, J. Zweizig, PINTO, INNOCENZO, CALLONI, ENRICO, DE ROSA, ROSARIO, GARUFI, FABIO, MILANO, LEOPOLDO, Massachusetts Institute of Technology. Department of Physics, Lincoln Laboratory, LIGO (Observatory : Massachusetts Institute of Technology), MIT Kavli Institute for Astrophysics and Space Research, (Astro)-Particles Physics, Aasi, J., Abadie, J., Abbott, B. P., Abbott, R., Abbott, T., Abernathy, M. R., Accadia, T., Acernese, F., Adams, C., Adams, T., Adhikari, R. X., Affeldt, C., Agathos, M., Aggarwal, N., Aguiar, O. D., Ajith, P., Allen, B., Allocca, A., Amador Ceron, E., Amariutei, D., Anderson, R. A., Anderson, S. B., Anderson, W. G., Arai, K., Araya, M. C., Arceneaux, C., Areeda, J., Ast, S., Aston, S. M., Astone, P., Aufmuth, P., Aulbert, C., Austin, L., Aylott, B. E., Babak, S., Baker, P. T., Ballardin, G., Ballmer, S. W., Barayoga, J. C., Barker, D., Barnum, S. H., Barone, F., Barr, B., Barsotti, L., Barsuglia, M., Barton, M. A., Bartos, I., Bassiri, R., Basti, A., Batch, J., Bauchrowitz, J., Bauer, Th S., Bebronne, M., Behnke, B., Bejger, M., Beker, M. G., Bell, A. S., Bell, C., Belopolski, I., Bergmann, G., Berliner, J. M., Bersanetti, D., Bertolini, A., Bessis, D., Betzwieser, J., Beyersdorf, P. T., Bhadbhade, T., Bilenko, I. A., Billingsley, G., Birch, J., Bitossi, M., Bizouard, M. A., Black, E., Blackburn, J. K., Blackburn, L., Blair, D., Blom, M., Bock, O., Bodiya, T. P., Boer, M., Bogan, C., Bond, C., Bondu, F., Bonelli, L., Bonnand, R., Bork, R., Born, M., Boschi, V., Bose, S., Bosi, L., Bowers, J., Bradaschia, C., Brady, P. R., Braginsky, V. B., Branchesi, M., Brannen, C. A., Brau, J. E., Breyer, J., Briant, T., Bridges, D. O., Brillet, A., Brinkmann, M., Brisson, V., Britzger, M., Brooks, A. F., Brown, D. A., Brown, D. D., Br?ckner, F., Bulik, T., Bulten, H. J., Buonanno, A., Buskulic, D., Buy, C., Byer, R. L., Cadonati, L., Cagnoli, G., Bustillo, J. Calder?n., Calloni, Enrico, Camp, J. B., Campsie, P., Cannon, K. C., Canuel, B., Cao, J., Capano, C. D., Carbognani, F., Carbone, L., Caride, S., Castiglia, A., Caudill, S., Cavagli?, M., Cavalier, F., Cavalieri, R., Cella, G., Cepeda, C., Cesarini, E., Chakraborty, R., Chalermsongsak, T., Chao, S., Charlton, P., Chassande Mottin, E., Chen, X., Chen, Y., Chincarini, A., Chiummo, A., Cho, H. S., Chow, J., Christensen, N., Chu, Q., Chua, S. S. Y., Chung, S., Ciani, G., Clara, F., Clark, D. E., Clark, J. A., Cleva, F., Coccia, E., Cohadon, P. F., Colla, A., Colombini, M., Constancio, M., Conte, A., Conte, R., Cook, D., Corbitt, T. R., Cordier, M., Cornish, N., Corsi, A., Costa, C. A., Coughlin, M. W., Coulon, J. P., Countryman, S., Couvares, P., Coward, D. M., Cowart, M., Coyne, D. C., Craig, K., Creighton, J. D. E., Creighton, T. D., Crowder, S. G., Cumming, A., Cunningham, L., Cuoco, E., Dahl, K., Dal Canton, T., Damjanic, M., Danilishin, S. L., D?antonio, S., Danzmann, K., Dattilo, V., Daudert, B., Daveloza, H., Davier, M., Davies, G. S., Daw, E. J., Day, R., Dayanga, T., Debreczeni, G., Degallaix, J., Deleeuw, E., Del?glise, S., Del Pozzo, W., Denker, T., Dent, T., Dereli, H., Dergachev, V., Derosa, R. T., DE ROSA, Rosario, Desalvo, R., Dhurandhar, S., D?az, M., Dietz, A., Di Fiore, L., Di Lieto, A., Di Palma, I., Di Virgilio, A., Dmitry, K., Donovan, F., Dooley, K. L., Doravari, S., Drago, M., Drever, R. W. P., Driggers, J. C., Du, Z., Dumas, J. C., Dwyer, S., Eberle, T., Edwards, M., Effler, A., Ehrens, P., Eichholz, J., Eikenberry, S. S., Endrhoczi, G., Essick, R., Etzel, T., Evans, K., Evans, M., Evans, T., Factourovich, M., Fafone, V., Fairhurst, S., Fang, Q., Farinon, S., Farr, B., Farr, W., Favata, M., Fazi, D., Fehrmann, H., Feldbaum, D., Ferrante, I., Ferrini, F., Fidecaro, F., Finn, L. S., Fiori, I., Fisher, R., Flaminio, R., Foley, E., Foley, S., Forsi, E., Fotopoulos, N., Fournier, J. D., Franco, S., Frasca, S., Frasconi, F., Frede, M., Frei, M., Frei, Z., Freise, A., Frey, R., Fricke, T. T., Fritschel, P., Frolov, V. V., Fujimoto, M. K., Fulda, P., Fyffe, M., Gair, J., Gammaitoni, L., Garcia, J., Garufi, Fabio, Gehrels, N., Gemme, G., Genin, E., Gennai, A., Gergely, L., Ghosh, S., Giaime, J. A., Giampanis, S., Giardina, K. D., Giazotto, A., Gil Casanova, S., Gill, C., Gleason, J., Goetz, E., Goetz, R., Gondan, L., Gonz?lez, G., Gordon, N., Gorodetsky, M. L., Gossan, S., Go?ler, S., Gouaty, R., Graef, C., Graff, P. B., Granata, M., Grant, A., Gras, S., Gray, C., Greenhalgh, R. J. S., Gretarsson, A. M., Griffo, C., Groot, P., Grote, H., Grover, K., Grunewald, S., Guidi, G. M., Guido, C., Gushwa, K. E., Gustafson, E. K., Gustafson, R., Hall, B., Hall, E., Hammer, D., Hammond, G., Hanke, M., Hanks, J., Hanna, C., Hanson, J., Harms, J., Harry, G. M., Harry, I. W., Harstad, E. D., Hartman, M. T., Haughian, K., Hayama, K., Heefner, J., Heidmann, A., Heintze, M., Heitmann, H., Hello, P., Hemming, G., Hendry, M., Heng, I. S., Heptonstall, A. W., Heurs, M., Hild, S., Hoak, D., Hodge, K. A., Holt, K., Hong, T., Hooper, S., Horrom, T., Hosken, D. J., Hough, J., Howell, E. J., Hu, Y., Hua, Z., Huang, V., Huerta, E. A., Hughey, B., Husa, S., Huttner, S. H., Huynh, M., Huynh Dinh, T., Iafrate, J., Ingram, D. R., Inta, R., Isogai, T., Ivanov, A., Iyer, B. R., Izumi, K., Jacobson, M., James, E., Jang, H., Jang, Y. J., Jaranowski, P., Jim?nez Forteza, F., Johnson, W. W., Jones, D., Jones, D. I., Jones, R., Jonker, R. J. G., Ju, L., Haris, K, Kalmus, P., Kalogera, V., Kandhasamy, S., Kang, G., Kanner, J. B., Kasprzack, M., Kasturi, R., Katsavounidis, E., Katzman, W., Kaufer, H., Kaufman, K., Kawabe, K., Kawamura, S., Kawazoe, F., K?f?lian, F., Keitel, D., Kelley, D. B., Kells, W., Keppel, D. G., Khalaidovski, A., Khalili, F. Y., Khazanov, E. A., Kim, B. K., Kim, C., Kim, K., Kim, N., Kim, W., Kim, Y. M., King, E. J., King, P. J., Kinzel, D. L., Kissel, J. S., Klimenko, S., Kline, J., Koehlenbeck, S., Kokeyama, K., Kondrashov, V., Koranda, S., Korth, W. Z., Kowalska, I., Kozak, D., Kremin, A., Kringel, V., Krishnan, B., Kr?lak, A., Kucharczyk, C., Kudla, S., Kuehn, G., Kumar, A., Kumar, P., Kumar, R., Kurdyumov, R., Kwee, P., Landry, M., Lantz, B., Larson, S., Lasky, P. D., Lawrie, C., Leaci, P., Lebigot, E. O., Lee, C. H., Lee, H. K., Lee, H. M., Lee, J., Leonardi, M., Leong, J. R., Le Roux, A., Leroy, N., Letendre, N., Levine, B., Lewis, J. B., Lhuillier, V., T. G. F., Li, Lin, A. C., Littenberg, T. B., Litvine, V., Liu, F., Liu, H., Liu, Y., Liu, Z., Lloyd, D., Lockerbie, N. A., Lockett, V., Lodhia, D., Loew, K., Logue, J., Lombardi, A. L., Lorenzini, M., Loriette, V., Lormand, M., Losurdo, G., Lough, J., Luan, J., Lubinski, M. J., L?ck, H., Lundgren, A. P., Macarthur, J., Macdonald, E., Machenschalk, B., Macinnis, M., Macleod, D. M., Magana Sandoval, F., Mageswaran, M., Mailand, K., Majorana, E., Maksimovic, I., Malvezzi, V., Man, N., Manca, G. M., Mandel, I., Mandic, V., Mangano, V., Mantovani, M., Marchesoni, F., Marion, F., M?rka, S., M?rka, Z., Markosyan, A., Maros, E., Marque, J., Martelli, F., Martin, I. W., Martin, R. M., Martinelli, L., Martynov, D., Marx, J. N., Mason, K., Masserot, A., Massinger, T. J., Matichard, F., Matone, L., Matzner, R. A., Mavalvala, N., May, G., Mazumder, N., Mazzolo, G., Mccarthy, R., Mcclelland, D. E., Mcguire, S. C., Mcintyre, G., Mciver, J., Meacher, D., Meadors, G. D., Mehmet, M., Meidam, J., Meier, T., Melatos, A., Mendell, G., Mercer, R. A., Meshkov, S., Messenger, C., Meyer, M. S., Miao, H., Michel, C., Mikhailov, E. E., Milano, Leopoldo, Miller, J., Minenkov, Y., Mingarelli, C. M. F., Mitra, S., Mitrofanov, V. P., Mitselmakher, G., Mittleman, R., Moe, B., Mohan, M., Mohapatra, S. R. P., Mokler, F., Moraru, D., Moreno, G., Morgado, N., Mori, T., Morriss, S. R., Mossavi, K., Mours, B., Mow Lowry, C. M., Mueller, C. L., Mueller, G., Mukherjee, S., Mullavey, A., Munch, J., Murphy, D., Murray, P. G., Mytidis, A., Nagy, M. F., Nanda Kumar, D., Nardecchia, I., Nash, T., Naticchioni, L., Nayak, R., Necula, V., Nelemans, G., Neri, I., Neri, M., Newton, G., Nguyen, T., Nishida, E., Nishizawa, A., Nitz, A., Nocera, F., Nolting, D., Normandin, M. E., Nuttall, L. K., Ochsner, E., O?dell, J., Oelker, E., Ogin, G. H., J. J., Oh, S. H., Oh, Ohme, F., Oppermann, P., O?reilly, B., Ortega Larcher, W., O?shaughnessy, R., Osthelder, C., Ott, C. D., Ottaway, D. J., Ottens, R. S., Ou, J., Overmier, H., Owen, B. J., Padilla, C., Pai, A., Palomba, C., Pan, Y., Pankow, C., Paoletti, F., Paoletti, R., Papa, M. A., Paris, H., Pasqualetti, A., Passaquieti, R., Passuello, D., Pedraza, M., Peiris, P., Penn, S., Perreca, A., Phelps, M., Pichot, M., Pickenpack, M., Piergiovanni, F., Pierro, V., Pinard, L., Pindor, B., Pinto, I. M., Pitkin, M., Poeld, J., Poggiani, R., Poole, V., Poux, C., Predoi, V., Prestegard, T., Price, L. R., Prijatelj, M., Principe, M., Privitera, S., Prix, R., Prodi, G. A., Prokhorov, L., Puncken, O., Punturo, M., Puppo, P., Quetschke, V., Quintero, E., Quitzow James, R., Raab, F. J., Rabeling, D. S., R?cz, I., Radkins, H., Raffai, P., Raja, S., Rajalakshmi, G., Rakhmanov, M., Ramet, C., Rapagnani, P., Raymond, V., Re, V., Reed, C. M., Reed, T., Regimbau, T., Reid, S., Reitze, D. H., Ricci, F., Riesen, R., Riles, K., Robertson, N. A., Robinet, F., Rocchi, A., Roddy, S., Rodriguez, C., Rodruck, M., Roever, C., Rolland, L., Rollins, J. G., Romano, R., Romanov, G., Romie, J. H., Rosi?ska, D., Rowan, S., R?diger, A., Ruggi, P., Ryan, K., Salemi, F., Sammut, L., Sancho de la Jordana, L., Sandberg, V., Sanders, J., Sannibale, V., Santiago Prieto, I., Saracco, E., Sassolas, B., Sathyaprakash, B. S., Saulson, P. R., Savage, R., Schilling, R., Schnabel, R., Schofield, R. M. S., Schreiber, E., Schuette, D., Schulz, B., Schutz, B. F., Schwinberg, P., Scott, J., Scott, S. M., Seifert, F., Sellers, D., Sengupta, A. S., Sentenac, D., Sequino, V., Sergeev, A., Shaddock, D., Shah, S., Shahriar, M. S., Shaltev, M., Shapiro, B., Shawhan, P., Shoemaker, D. H., Sidery, T. L., Siellez, K., Siemens, X., Sigg, D., Simakov, D., Singer, A., Singer, L., Sintes, A. M., Skelton, G. R., Slagmolen, B. J. J., Slutsky, J., Smith, J. R., Smith, M. R., Smith, R. J. E., Smith Lefebvre, N. D., Soden, K., Son, E. J., Sorazu, B., Souradeep, T., Sperandio, L., Staley, A., Steinert, E., Steinlechner, J., Steinlechner, S., Steplewski, S., Stevens, D., Stochino, A., Stone, R., Strain, K. A., Straniero, N., Strigin, S., Stroeer, A. S., Sturani, R., Stuver, A. L., Summerscales, T. Z., Susmithan, S., Sutton, P. J., Swinkels, B., Szeifert, G., Tacca, M., Talukder, D., Tang, L., Tanner, D. B., Tarabrin, S. P., Taylor, R., ter Braack, A. P. M., Thirugnanasambandam, M. P., Thomas, M., Thomas, P., Thorne, K. A., Thorne, K. S., Thrane, E., Tiwari, V., Tokmakov, K. V., Tomlinson, C., Toncelli, A., Tonelli, M., Torre, O., Torres, C. V., Torrie, C. I., Travasso, F., Traylor, G., Tse, M., Ugolini, D., Unnikrishnan, C. S., Vahlbruch, H., Vajente, G., Vallisneri, M., van den Brand, J. F. J., Van Den Broeck, C., van der Putten, S., van der Sluys, M. V., van Heijningen, J., van Veggel, A. A., Vass, S., Vas?th, M., Vaulin, R., Vecchio, A., Vedovato, G., Veitch, J., Veitch, P. J., Venkateswara, K., Verkindt, D., Verma, S., Vetrano, F., Vicer?, A., Vincent Finley, R., Vinet, J. Y., Vitale, S., Vlcek, B., Vo, T., Vocca, H., Vorvick, C., Vousden, W. D., Vrinceanu, D., Vyachanin, S. P., Wade, A., Wade, L., Wade, M., Waldman, S. J., Walker, M., Wallace, L., Wan, Y., Wang, J., Wang, M., Wang, X., Wanner, A., Ward, R. L., Was, M., Weaver, B., Wei, L. W., Weinert, M., Weinstein, A. J., Weiss, R., Welborn, T., Wen, L., Wessels, P., West, M., Westphal, T., Wette, K., Whelan, J. T., Whitcomb, S. E., White, D. J., Whiting, B. F., Wibowo, S., Wiesner, K., Wilkinson, C., Williams, L., Williams, R., Williams, T., Willis, J. L., Willke, B., Wimmer, M., Winkelmann, L., Winkler, W., Wipf, C. C., Wittel, H., Woan, G., Worden, J., Yablon, J., Yakushin, I., Yamamoto, H., Yancey, C. C., Yang, H., Yeaton Massey, D., Yoshida, S., Yum, H., Yvert, M., Zadro?ny, A., Zanolin, M., Zendri, J. P., Zhang, F., Zhang, L., Zhao, C., Zhu, H., Zhu, X. J., Zotov, N., Zucker, M. E., Zweizig, J., and Pinto, Innocenzo

Subjects
Particle physics, Gravitational Waves, LIGO, Neutron Stars, Physics and Astronomy (miscellaneous), Astronomy, neutron stars, Hough transform, law.invention, Settore FIS/05 - Astronomia e Astrofisica, SPIN-DOWN LIMIT, law, Range (statistics), SDG 7 - Affordable and Clean Energy, Limit (mathematics), Sensitivity (control systems), gravitational wave, QC, gravitational waves, LIGO/neutron stars, Physics, Gravitational wave, Settore FIS/01 - Fisica Sperimentale, Pulsara, PULSARS, Gravitation, Gravitational waves, Amplitude, Product (mathematics), ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, RADIATION, EMISSION
Abstract

We report on an all-sky search for periodic gravitational waves in the frequency range $\mathrm{50-1000 Hz}$ with the first derivative of frequency in the range $-8.9 \times 10^{-10}$ Hz/s to zero in two years of data collected during LIGO's fifth science run. Our results employ a Hough transform technique, introducing a $\chi^2$ test and analysis of coincidences between the signal levels in years 1 and 2 of observations that offers a significant improvement in the product of strain sensitivity with compute cycles per data sample compared to previously published searches. Since our search yields no surviving candidates, we present results taking the form of frequency dependent, 95$%$ confidence upper limits on the strain amplitude $h_0$. The most stringent upper limit from year 1 is $1.0\times 10^{-24}$ in the $\mathrm{158.00-158.25 Hz}$ band. In year 2, the most stringent upper limit is $\mathrm{8.9\times10^{-25}}$ in the $\mathrm{146.50-146.75 Hz}$ band. This improved detection pipeline, which is computationally efficient by at least two orders of magnitude better than our flagship Einstein$@$Home search, will be important for "quick-look" searches in the Advanced LIGO and Virgo detector era.

Published
2014

18. Subtraction of Bright Point Sources from Synthesis Images of the Epoch of Reionization.

Author

B. Pindor, J. S. B. Wyithe, D. A. Mitchell, S. M. Ord, R. B. Wayth, and L. J. Greenhill

Subjects
*GALACTIC nuclei, *RADIO galaxies, *REDSHIFT, *HYDROGEN, *IONIZATION (Atomic physics), *SIMULATION methods & models
Abstract

Bright point sources associated with extragalactic active galactic nuclei and radio galaxies are an important foreground for low-frequency radio experiments aimed at detecting the redshifted 21-cm emission from neutral hydrogen during the epoch of reionization. The frequency dependence of the synthesized beam implies that the sidelobes of these sources will move across the field of view as a function of observing frequency, hence frustrating line-of-sight foreground subtraction techniques. We describe a method for subtracting these point sources from dirty maps produced by an instrument such as the MWA. This technique combines matched filters with an iterative centroiding scheme to locate and characterize point sources in the presence of a diffuse background. Simulations show that this technique can improve the dynamic range of epoch-of-reionization maps by 2–3 orders of magnitude. [ABSTRACT FROM AUTHOR]

Published
2011
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19. Improving the Epoch of Reionization Power Spectrum Results from Murchison Widefield Array Season 1 Observations.

Author

N. Barry, M. Wilensky, C. M. Trott, B. Pindor, A. P. Beardsley, B. J. Hazelton, I. S. Sullivan, M. F. Morales, J. C. Pober, J. Line, B. Greig, R. Byrne, A. Lanman, W. Li, C. H. Jordan, R. C. Joseph, B. McKinley, M. Rahimi, S. Yoshiura, and J. D. Bowman

Subjects
POWER spectra, FACTOR analysis, MAGNITUDE (Mathematics), SEASONS
Abstract

Measurements of 21 cm Epoch of Reionization (EoR) structure are subject to systematics originating from both the analysis and the observation conditions. Using 2013 data from the Murchison Widefield Array (MWA), we show the importance of mitigating both sources of contamination. A direct comparison between results from Beardsley et al. and our updated analysis demonstrates new precision techniques, lowering analysis systematics by a factor of 2.8 in power. We then further lower systematics by excising observations contaminated by ultra-faint RFI, reducing by an additional factor of 3.8 in power for the zenith pointing. With this enhanced analysis precision and newly developed RFI mitigation, we calculate a noise-dominated upper limit on the EoR structure of Δ2 ≤ 3.9 × 103 mK2 at k = 0.20 h Mpc−1 and z = 7 using 21 hr of data, improving previous MWA limits by almost an order of magnitude. [ABSTRACT FROM AUTHOR]

Published
2019
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20. Assessment of Ionospheric Activity Tolerances for Epoch of Reionization Science with the Murchison Widefield Array.

Author

Cathryn M. Trott, C. H. Jordan, S. G. Murray, B. Pindor, D. A. Mitchell, R. B. Wayth, J. Line, B. McKinley, A. Beardsley, J. Bowman, F. Briggs, B. J. Hazelton, J. Hewitt, D. Jacobs, M. F. Morales, J. C. Pober, S. Sethi, U. Shankar, R. Subrahmanyan, and M. Tegmark

Subjects
IONOSPHERIC currents, IONIZATION (Atomic physics), HYDROGEN, IONOSPHERE, TURBULENCE
Abstract

Structure imprinted in foreground extragalactic point sources by ionospheric refraction has the potential to contaminate Epoch of Reionization (EoR) power spectra of the 21 cm emission line of neutral hydrogen. The alteration of the spatial and spectral structure of foreground measurements due to total electron content gradients in the ionosphere creates a departure from the expected sky signal. We present a general framework for understanding the signatures of ionospheric behavior in the 2D neutral hydrogen power spectrum measured by a low-frequency radio interferometer. Two primary classes of ionospheric behavior are considered, corresponding to dominant modes observed in Murchison Widefield Array (MWA) EoR data, namely, anisotropic structured wave behavior and isotropic turbulence. Analytic predictions for power spectrum bias due to this contamination are computed and compared with simulations. We then apply the ionospheric metric described in Jordan et al. to study the impact of ionospheric structure on MWA data, by dividing MWA EoR data sets into classes with good and poor ionospheric conditions, using sets of matched 30-minute observations from 2014 September. The results are compared with the analytic and simulated predictions, demonstrating the observed bias in the power spectrum when the ionosphere is active (displays coherent structures or isotropic turbulence). The analysis demonstrates that unless ionospheric activity can be quantified and corrected, active data should not be included in EoR analysis in order to avoid systematic biases in cosmological power spectra. When data are corrected with a model formed from the calibration information, bias reduces below the expected 21 cm signal level. Data are considered “quiet” when the median measured source position offsets are less than 10.″–15.″. [ABSTRACT FROM AUTHOR]

Published
2018
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21. Photometry and Spectroscopy of GRB 030329 and its Associated Supernova 2003dh: The First Two Months

Author

T. Matheson, P. M. Garnavich, K. Z. Stanek, D. Bersier, S. T. Holland, K. Krisciunas, N. Caldwell, P. Berlind, J. S. Bloom, M. Bolte, A. Z. Bonanos, M. J. I. Brown, W. R. Brown, M. L. Calkins, P. Challis, R. Chornock, L. Echevarria, D. J. Eisenstein, M. E. Everett, A. V. Filippenko, K. Flint, R. J. Foley, D. L. Freedman, Mario Hamuy, P. Harding, N. P. Hathi, M. Hicken, C. Hoopes, C. Impey, B. T. Jannuzi, R. A. Jansen, S. Jha, J. Kaluzny, S. Kannappan, R. P. Kirshner, D. W. Latham, J. C. Lee, D. C. Leonard, W. Li, K. L. Luhman, P. Martini, H. Mathis, J. Maza, S. T. Megeath, L. R. Miller, D. Minniti, E. W. Olszewski, M. Papenkova, M. M. Phillips, B. Pindor, D. D. Sasselov, R. Schild, H. Schweiker, T. Spahr, J. Thomas‐Osip, I. Thompson, D. Weisz, R. Windhorst, and D. Zaritsky

Subjects
Physics, GRB 980425, Infrared, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Light curve, Afterglow, Supernova, Space and Planetary Science, GRB 030329, Astrophysics::Solar and Stellar Astrophysics, Spectroscopy, Gamma-ray burst, Astrophysics::Galaxy Astrophysics
Abstract

We present extensive optical and infrared photometry of the afterglow of gamma-ray burst (GRB) 030329 and its associated supernova (SN) 2003dh over the first two months after detection (2003 March 30-May 29 UT). Optical spectroscopy from a variety of telescopes is shown and, when combined with the photometry, allows an unambiguous separation between the afterglow and supernova contributions. The optical afterglow of the GRB is initially a power-law continuum but shows significant color variations during the first week that are unrelated to the presence of a supernova. The early afterglow light curve also shows deviations from the typical power-law decay. A supernova spectrum is first detectable ~7 days after the burst and dominates the light after ~11 days. The spectral evolution and the light curve are shown to closely resemble those of SN 1998bw, a peculiar Type Ic SN associated with GRB 980425, and the time of the supernova explosion is close to the observed time of the GRB. It is now clear that at least some GRBs arise from core-collapse SNe., Comment: 57 pages, 13 figures, accepted by ApJ, revised per referee's comments, includes full photometry table. Data available at ftp://cfa-ftp.harvard.edu/pub/kstanek/GRB030329 or through WWW at http://cfa-www.harvard.edu/cfa/oir/Research/GRB/

22. FIRST SEASON MWA EOR POWER SPECTRUM RESULTS AT REDSHIFT 7.

Author

A. P. Beardsley, B. J. Hazelton, I. S. Sullivan, P. Carroll, N. Barry, M. Rahimi, B. Pindor, C. M. Trott, J. Line, Daniel C. Jacobs, M. F. Morales, J. C. Pober, G. Bernardi, Judd D. Bowman, M. P. Busch, F. Briggs, R. J. Cappallo, B. E. Corey, A. de Oliveira-Costa, and Joshua S. Dillon

Subjects
IONS spectra, METAPHYSICAL cosmology, COSMOLOGICAL distances, CALIBRATION, DATA analysis
Abstract

The Murchison Widefield Array (MWA) has collected hundreds of hours of Epoch of Reionization (EoR) data and now faces the challenge of overcoming foreground and systematic contamination to reduce the data to a cosmological measurement. We introduce several novel analysis techniques, such as cable reflection calibration, hyper-resolution gridding kernels, diffuse foreground model subtraction, and quality control methods. Each change to the analysis pipeline is tested against a two-dimensional power spectrum figure of merit to demonstrate improvement. We incorporate the new techniques into a deep integration of 32 hours of MWA data. This data set is used to place a systematic-limited upper limit on the cosmological power spectrum of mK2 at k = 0.27 h Mpc−1 and z = 7.1, consistent with other published limits, and a modest improvement (factor of 1.4) over previous MWA results. From this deep analysis, we have identified a list of improvements to be made to our EoR data analysis strategies. These improvements will be implemented in the future and detailed in upcoming publications. [ABSTRACT FROM AUTHOR]

Published
2016
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23. THE MURCHISON WIDEFIELD ARRAY 21 cm POWER SPECTRUM ANALYSIS METHODOLOGY.

Author

Daniel C. Jacobs, B. J. Hazelton, C. M. Trott, Joshua S. Dillon, B. Pindor, I. S. Sullivan, J. C. Pober, N. Barry, A. P. Beardsley, G. Bernardi, Judd D. Bowman, F. Briggs, R. J. Cappallo, P. Carroll, B. E. Corey, A. de Oliveira-Costa, D. Emrich, A. Ewall-Wice, L. Feng, and B. M. Gaensler

Subjects
GALACTIC redshift, HYDROGEN, BIG bang theory, SPACE interferometry, POWER spectra
Abstract

We present the 21 cm power spectrum analysis approach of the Murchison Widefield Array Epoch of Reionization project. In this paper, we compare the outputs of multiple pipelines for the purpose of validating statistical limits cosmological hydrogen at redshifts between 6 and 12. Multiple independent data calibration and reduction pipelines are used to make power spectrum limits on a fiducial night of data. Comparing the outputs of imaging and power spectrum stages highlights differences in calibration, foreground subtraction, and power spectrum calculation. The power spectra found using these different methods span a space defined by the various tradeoffs between speed, accuracy, and systematic control. Lessons learned from comparing the pipelines range from the algorithmic to the prosaically mundane; all demonstrate the many pitfalls of neglecting reproducibility. We briefly discuss the way these different methods attempt to handle the question of evaluating a significant detection in the presence of foregrounds. [ABSTRACT FROM AUTHOR]

Published
2016
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24. CHIPS: THE COSMOLOGICAL H i POWER SPECTRUM ESTIMATOR.

Author

C. M. Trott, B. Pindor, P. Procopio, R. B. Wayth, D. A. Mitchell, B. McKinley, S. J. Tingay, N. Barry, A. P. Beardsley, G. Bernardi, Judd D. Bowman, F. Briggs, R. J. Cappallo, P. Carroll, A. de Oliveira-Costa, Joshua S. Dillon, A. Ewall-Wice, L. Feng, L. J. Greenhill, and B. J. Hazelton

Subjects
*RADIO telescopes, *HYDROGEN-deuterium exchange, *TELESCOPE mounts, *LUMINESCENCE, *THERMOMETERS
Abstract

Detection of the cosmological neutral hydrogen signal from the Epoch of Reionization (EoR) and estimation of its basic physical parameters are principal scientific aims of many current low-frequency radio telescopes. Here we describe the Cosmological H i Power Spectrum Estimator (CHIPS), an algorithm developed and implemented with data from the Murchison Widefield Array, to compute the two-dimensional and spherically-averaged power spectrum of brightness temperature fluctuations. The principal motivations for CHIPS are the application of realistic instrumental and foreground models to form the optimal estimator, thereby maximizing the likelihood of unbiased signal estimation, and allowing a full covariant understanding of the outputs. CHIPS employs an inverse-covariance weighting of the data through the maximum likelihood estimator, thereby allowing use of the full parameter space for signal estimation (“foreground suppression”). We describe the motivation for the algorithm, implementation, application to real and simulated data, and early outputs. Upon application to a set of 3 hr of data, we set a 2σ upper limit on the EoR dimensionless power at Mpc−1 of mK2 in the redshift range z = [6.2–6.6], consistent with previous estimates. [ABSTRACT FROM AUTHOR]

Published
2016
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25. Constraints on cosmic strings from the LIGO-Virgo gravitational-wave detectors.

Author

Aasi J, Abadie J, Abbott BP, Abbott R, Abbott T, Abernathy MR, Accadia T, Acernese F, Adams C, Adams T, Adhikari RX, Affeldt C, Agathos M, Aggarwal N, Aguiar OD, Ajith P, Allen B, Allocca A, Amador Ceron E, Amariutei D, Anderson RA, Anderson SB, Anderson WG, Arai K, Araya MC, Arceneaux C, Areeda J, Ast S, Aston SM, Astone P, Aufmuth P, Aulbert C, Austin L, Aylott BE, Babak S, Baker PT, Ballardin G, Ballmer SW, Barayoga JC, Barker D, Barnum SH, Barone F, Barr B, Barsotti L, Barsuglia M, Barton MA, Bartos I, Bassiri R, Basti A, Batch J, Bauchrowitz J, Bauer TS, Bebronne M, Behnke B, Bejger M, Beker MG, Bell AS, Bell C, Belopolski I, Bergmann G, Berliner JM, Bersanetti D, Bertolini A, Bessis D, Betzwieser J, Beyersdorf PT, Bhadbhade T, Bilenko IA, Billingsley G, Birch J, Bitossi M, Bizouard MA, Black E, Blackburn JK, Blackburn L, Blair D, Blom M, Bock O, Bodiya TP, Boer M, Bogan C, Bond C, Bondu F, Bonelli L, Bonnand R, Bork R, Born M, Boschi V, Bose S, Bosi L, Bowers J, Bradaschia C, Brady PR, Braginsky VB, Branchesi M, Brannen CA, Brau JE, Breyer J, Briant T, Bridges DO, Brillet A, Brinkmann M, Brisson V, Britzger M, Brooks AF, Brown DA, Brown DD, Brückner F, Bulik T, Bulten HJ, Buonanno A, Buskulic D, Buy C, Byer RL, Cadonati L, Cagnoli G, Calderón Bustillo J, Calloni E, Camp JB, Campsie P, Cannon KC, Canuel B, Cao J, Capano CD, Carbognani F, Carbone L, Caride S, Castiglia A, Caudill S, Cavaglià M, Cavalier F, Cavalieri R, Cella G, Cepeda C, Cesarini E, Chakraborty R, Chalermsongsak T, Chao S, Charlton P, Chassande-Mottin E, Chen X, Chen Y, Chincarini A, Chiummo A, Cho HS, Chow J, Christensen N, Chu Q, Chua SS, Chung S, Ciani G, Clara F, Clark DE, Clark JA, Cleva F, Coccia E, Cohadon PF, Colla A, Colombini M, Constancio M Jr, Conte A, Conte R, Cook D, Corbitt TR, Cordier M, Cornish N, Corsi A, Costa CA, Coughlin MW, Coulon JP, Countryman S, Couvares P, Coward DM, Cowart M, Coyne DC, Craig K, Creighton JD, Creighton TD, Crowder SG, Cumming A, Cunningham L, Cuoco 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Abstract

Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time. We find no evidence of GW signals from cosmic strings. From this result, we derive new constraints on cosmic string parameters, which complement and improve existing limits from previous searches for a stochastic background of GWs from cosmic microwave background measurements and pulsar timing data. In particular, if the size of loops is given by the gravitational backreaction scale, we place upper limits on the string tension Gμ below 10(-8) in some regions of the cosmic string parameter space.

Published
2014
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26. A gravitationally lensed quasar with quadruple images separated by 14.62 arcseconds.

Author

Inada N, Oguri M, Pindor B, Hennawi JF, Chiu K, Zheng W, Ichikawa S, Gregg MD, Becker RH, Suto Y, Strauss MA, Turner EL, Keeton CR, Annis J, Castander FJ, Eisenstein DJ, Frieman JA, Fukugita M, Gunn JE, Johnston DE, Kent SM, Nichol RC, Richards GT, Rix HW, Sheldon ES, Bahcall NA, Brinkmann J, Ivezić Z, Lamb DQ, McKay TA, Schneider DP, and York DG

Abstract

Gravitational lensing is a powerful tool for the study of the distribution of dark matter in the Universe. The cold-dark-matter model of the formation of large-scale structures (that is, clusters of galaxies and even larger assemblies) predicts the existence of quasars gravitationally lensed by concentrations of dark matter so massive that the quasar images would be split by over 7 arcsec. Numerous searches for large-separation lensed quasars have, however, been unsuccessful. All of the roughly 70 lensed quasars known, including the first lensed quasar discovered, have smaller separations that can be explained in terms of galaxy-scale concentrations of baryonic matter. Although gravitationally lensed galaxies with large separations are known, quasars are more useful cosmological probes because of the simplicity of the resulting lens systems. Here we report the discovery of a lensed quasar, SDSS J1004 + 4112, which has a maximum separation between the components of 14.62 arcsec. Such a large separation means that the lensing object must be dominated by dark matter. Our results are fully consistent with theoretical expectations based on the cold-dark-matter model.

Published
2003
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