[ { "id": "authors:fgt3e-35h14", "collection": "authors", "collection_id": "fgt3e-35h14", "cite_using_url": "https://authors.library.caltech.edu/records/fgt3e-35h14", "type": "article", "title": "Implementation of a Near-real-time Recording and Reporting System of Solar Radio Bursts", "author": [ { "family_name": "Zhang \u5f20", "given_name": "Peijin \u6c9b\u9526", "orcid": "0000-0001-6855-5799" }, { "family_name": "Kuske", "given_name": "Anastasia", "orcid": "0009-0001-6649-5195" }, { "family_name": "Chen", "given_name": "Bin", "orcid": "0000-0002-0660-3350" }, { "family_name": "Xu", "given_name": "Mengjia", "orcid": "0000-0002-3627-8261" }, { "family_name": "Nita", "given_name": "Gelu", "orcid": "0000-0003-2846-2453" }, { "family_name": "Anderson", "given_name": "Marin M.", "orcid": "0000-0003-2238-2698", "clpid": "Anderson-Marin-M" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036" }, { "family_name": "Byrne", "given_name": "Ruby", "orcid": "0000-0003-4980-2736", "clpid": "Byrne-Ruby" }, { "family_name": "Catha", "given_name": "Morgan", "clpid": "Catha-Morgan" }, { "family_name": "Chen", "given_name": "Xingyao", "orcid": "0000-0002-1810-6706" }, { "family_name": "Chhabra", "given_name": "Sherry", "orcid": "0000-0001-7754-0804" }, { "family_name": "D'Addario", "given_name": "Larry", "clpid": "D'Addario-Larry" }, { "family_name": "Davis", "given_name": "Ivey", "orcid": "0000-0001-5397-5969", "clpid": "Davis-Ivey" }, { "family_name": "Dowell", "given_name": "Jayce", "orcid": "0000-0003-1407-0141" }, { "family_name": "Elder", "given_name": "Katherine" }, { "family_name": "Gary", "given_name": "Dale", "orcid": "0000-0003-2520-8396" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Harnach", "given_name": "Charlie", "clpid": "Harnach-Charlie" }, { "family_name": "Hellbourg", "given_name": "Greg", "orcid": "0000-0002-8191-3885", "clpid": "Hellbourg-Gregory" }, { "family_name": "Hickish", "given_name": "Jack", "orcid": "0000-0003-0216-1417" }, { "family_name": "Hobbs", "given_name": "Rick", "clpid": "Hobbs-Rick" }, { "family_name": "Hodge", "given_name": "David", "clpid": "Hodge-David" }, { "family_name": "Hodges", "given_name": "Mark", "clpid": "Hodges-Mark" }, { "family_name": "Huang", "given_name": "Yuping", "orcid": "0000-0003-4267-6108", "clpid": "Huang-Yuping" }, { "family_name": "Isella", "given_name": "Andrea", "orcid": "0000-0001-8061-2207" }, { "family_name": "Jacobs", "given_name": "Daniel C." }, { "family_name": "Kemby", "given_name": "Ghislain", "clpid": "Kemby-Ghislain" }, { "family_name": "Klinefelter", "given_name": "John T.", "clpid": "Klinefelter-John-T" }, { "family_name": "Kolopanis", "given_name": "Matthew", "orcid": "0000-0002-2950-2974" }, { "family_name": "Kosogorov", "given_name": "Nikita", "orcid": "0000-0003-1226-118X", "clpid": "Kosogorov-Nikita" }, { "family_name": "Lamb", "given_name": "James", "orcid": "0000-0002-5959-1285", "clpid": "Lamb-J-W" }, { "family_name": "Law", "given_name": "Casey", "orcid": "0000-0002-4119-9963", "clpid": "Law-Casey-J" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Mondal", "given_name": "Surajit", "orcid": "0000-0002-2325-5298" }, { "family_name": "O'Donnell", "given_name": "Brian" }, { "family_name": "Plant", "given_name": "Kathryn A.", "orcid": "0000-0001-6360-6972", "clpid": "Plant-Kathryn-A" }, { "family_name": "Posner", "given_name": "Corey", "clpid": "Posner-Corey" }, { "family_name": "Powell", "given_name": "Travis", "clpid": "Powell-Travis" }, { "family_name": "Prayag", "given_name": "Vinand", "clpid": "Prayag-Vinand" }, { "family_name": "Rizo", "given_name": "Andres", "clpid": "Rizo-Andres" }, { "family_name": "Romero-Wolf", "given_name": "Andrew", "clpid": "Romero-Wolf-Andrew" }, { "family_name": "Shi", "given_name": "Jun", "orcid": "0000-0003-1647-7762", "clpid": "Shi-Jun" }, { "family_name": "Taylor", "given_name": "Greg", "orcid": "0000-0001-6495-7731" }, { "family_name": "Trim", "given_name": "Jordan", "clpid": "Trim-Jordan" }, { "family_name": "Virgin", "given_name": "Mike", "clpid": "Virgin-Mike" }, { "family_name": "Vydula", "given_name": "Akshatha", "orcid": "0000-0002-6611-2668" }, { "family_name": "Weinreb", "given_name": "Sandy", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "White", "given_name": "Scott", "clpid": "White-Scott" }, { "family_name": "Woody", "given_name": "David", "orcid": "0000-0003-1734-2472" }, { "family_name": "Yu", "given_name": "Sijie", "orcid": "0000-0003-2872-2614" }, { "family_name": "Zentmeyer", "given_name": "Thomas", "clpid": "Zentmeyer-Thomas" } ], "abstract": "

Strong solar activities are often accompanied by a variety of radio bursts. These radio bursts not only serve as valuable diagnostics of coronal and heliospheric processes but also as potential tools in space weather monitoring and forecasting. However, space weather applications call for the capability for low-latency and high-sensitivity radio burst recording and reporting, which has remained lacking. In this work, we present the development of a near-real-time radio burst recording and reporting system with the Owens Valley Radio Observatory's Long Wavelength Array. The system directly clips data from the real-time buffer and streams it as a live real-time radio dynamic spectrogram. The spectrograms are then fed to a deep learning–based burst identification module for type III radio bursts. The identifier is built on a You Only Look Once architecture, trained by synthetic type III radio bursts generated by using a physics-based model to achieve accurate and robust detection. This system enables continuous real-time radio spectrum streaming and the automatic reporting of type III radio bursts within ∼10 s of their occurrence.

", "doi": "10.3847/1538-4357/ae6250", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2026-05-20", "series_number": "1", "volume": "1003", "issue": "1", "pages": "57" }, { "id": "authors:q5xb7-adz83", "collection": "authors", "collection_id": "q5xb7-adz83", "cite_using_url": "https://authors.library.caltech.edu/records/q5xb7-adz83", "type": "article", "title": "Estimating Electron Densities in the Middle Solar Corona Using White-light and Radio Observations", "author": [ { "family_name": "Mondal", "given_name": "Surajit", "orcid": "0000-0002-2325-5298" }, { "family_name": "Shaik", "given_name": "Shaheda Begum", "orcid": "0000-0002-3089-3431" }, { "family_name": "Howard", "given_name": "Russell A.", "orcid": "0000-0001-9027-8249" }, { "family_name": "Zhang \u5f20", "given_name": "Peijin \u6c9b\u9526", "orcid": "0000-0001-6855-5799" }, { "family_name": "Chen", "given_name": "Bin", "orcid": "0000-0002-0660-3350" }, { "family_name": "Chen", "given_name": "Xingyao", "orcid": "0000-0002-1810-6706" }, { "family_name": "Yu", "given_name": "Sijie", "orcid": "0000-0003-2872-2614" }, { "family_name": "Gary", "given_name": "Dale", "orcid": "0000-0003-2520-8396" }, { "family_name": "Anderson", "given_name": "Marin M.", "orcid": "0000-0003-2238-2698", "clpid": "Anderson-Marin-M" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036" }, { "family_name": "Byrne", "given_name": "Ruby", "orcid": "0000-0003-4980-2736", "clpid": "Byrne-Ruby" }, { "family_name": "Catha", "given_name": "Morgan", "clpid": "Catha-Morgan" }, { "family_name": "Chhabra", "given_name": "Sherry", "orcid": "0000-0001-7754-0804" }, { "family_name": "D'Addario", "given_name": "Larry", "clpid": "D'Addario-Larry" }, { "family_name": "Davis", "given_name": "Ivey", "orcid": "0000-0001-5397-5969", "clpid": "Davis-Ivey" }, { "family_name": "Dowell", "given_name": "Jayce", "orcid": "0000-0003-1407-0141" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Harnach", "given_name": "Charlie", "clpid": "Harnach-Charlie" }, { "family_name": "Hellbourg", "given_name": "Greg", "orcid": "0000-0002-8191-3885", "clpid": "Hellbourg-Gregory" }, { "family_name": "Hickish", "given_name": "Jack", "orcid": "0000-0003-0216-1417" }, { "family_name": "Hobbs", "given_name": "Rick", "clpid": "Hobbs-Rick" }, { "family_name": "Hodge", "given_name": "David", "clpid": "Hodge-David" }, { "family_name": "Hodges", "given_name": "Mark", "clpid": "Hodges-Mark" }, { "family_name": "Huang", "given_name": "Yuping", "orcid": "0000-0003-4267-6108", "clpid": "Huang-Yuping" }, { "family_name": "Isella", "given_name": "Andrea", "orcid": "0000-0001-8061-2207" }, { "family_name": "Jacobs", "given_name": "Daniel C.", "orcid": "0000-0002-0917-2269" }, { "family_name": "Kemby", "given_name": "Ghislain", "clpid": "Kemby-Ghislain" }, { "family_name": "Klinefelter", "given_name": "John T.", "clpid": "Klinefelter-John-T" }, { "family_name": "Kolopanis", "given_name": "Matthew", "orcid": "0000-0002-2950-2974" }, { "family_name": "Kosogorov", "given_name": "Nikita", "orcid": "0000-0003-1226-118X", "clpid": "Kosogorov-Nikita" }, { "family_name": "Lamb", "given_name": "James", "orcid": "0000-0002-5959-1285", "clpid": "Lamb-J-W" }, { "family_name": "Law", "given_name": "Casey", "orcid": "0000-0002-4119-9963", "clpid": "Law-Casey-J" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "O'Donnell", "given_name": "Brian" }, { "family_name": "Plant", "given_name": "Kathryn", "orcid": "0000-0001-6360-6972", "clpid": "Plant-Kathryn" }, { "family_name": "Posner", "given_name": "Corey", "clpid": "Posner-Corey" }, { "family_name": "Powell", "given_name": "Travis", "clpid": "Powell-Travis" }, { "family_name": "Prayag", "given_name": "Vinand", "clpid": "Prayag-Vinand" }, { "family_name": "Rizo", "given_name": "Andres", "clpid": "Rizo-Andres" }, { "family_name": "Romero-Wolf", "given_name": "Andrew", "orcid": "0000-0002-4992-4162", "clpid": "Romero-Wolf-Andrew" }, { "family_name": "Shi", "given_name": "Jun", "orcid": "0000-0003-1647-7762", "clpid": "Shi-Jun" }, { "family_name": "Taylor", "given_name": "Greg", "orcid": "0000-0001-6495-7731" }, { "family_name": "Trim", "given_name": "Jordan", "clpid": "Trim-Jordan" }, { "family_name": "Virgin", "given_name": "Mike", "clpid": "Virgin-Mike" }, { "family_name": "Vydula", "given_name": "Akshatha", "orcid": "0000-0002-6611-2668" }, { "family_name": "Weinreb", "given_name": "Sandy", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-Sander" }, { "family_name": "White", "given_name": "Scott", "clpid": "White-Scott" }, { "family_name": "Woody", "given_name": "David", "orcid": "0000-0003-1734-2472", "clpid": "Woody-David" }, { "family_name": "Zentmeyer", "given_name": "Thomas", "clpid": "Zentmeyer-Thomas" } ], "abstract": "

The electron density of the solar corona is a fundamental parameter in many areas of solar physics. Traditionally, routine estimates of coronal density have relied exclusively on white-light observations. However, these density estimates, obtained by inverting the white-light data, require simplifying assumptions, which may affect the robustness of the measurements. Hence, to improve the reliability of coronal density measurements, it is highly desirable to explore other complementary methods. In this study, we estimate the coronal electron densities in the middle corona, between approximately 1.7 and 3.5 R\u2299, using low-frequency radio observations from the recently commissioned Long Wavelength Array at the Owens Valley Radio Observatory (OVRO-LWA). The results demonstrate consistency with those derived from white-light coronagraph data and predictions from theoretical models. We also derive a density model valid between 1.7 and 3.5 r\u2299, given by ρ(r′) = 1.27 r′\u207b² + 29.02 r′\u207b\u2074 + 71.18 r′\u207b\u2076, where r′ = r/R\u2299, with r the heliocentric distance. OVRO-LWA is a solar-dedicated radio interferometer that provides science-ready images with low latency, making it well suited for generating regular and independent estimates of coronal densities to complement existing white-light techniques.

", "doi": "10.3847/1538-4357/ae4353", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2026-03-10", "series_number": "2", "volume": "999", "issue": "2", "pages": "237" }, { "id": "authors:ahk4j-k6h31", "collection": "authors", "collection_id": "ahk4j-k6h31", "cite_using_url": "https://authors.library.caltech.edu/records/ahk4j-k6h31", "type": "article", "title": "Searches for Prompt Low-frequency Radio Counterparts to Gravitational-wave Event S250206dm with the OVRO-LWA Time Machine", "author": [ { "family_name": "Kosogorov", "given_name": "Nikita", "orcid": "0000-0003-1226-118X", "clpid": "Kosogorov-Nikita" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Law", "given_name": "Casey", "orcid": "0000-0002-4119-9963", "clpid": "Law-Casey" }, { "family_name": "Hickish", "given_name": "Jack", "orcid": "0000-0003-0216-1417" }, { "family_name": "Dowell", "given_name": "Jayce", "orcid": "0000-0003-1407-0141" }, { "family_name": "Mooley", "given_name": "Kunal P.", "orcid": "0000-0002-2557-5180", "clpid": "Mooley-Kunal-P" }, { "family_name": "Anderson", "given_name": "Marin M.", "orcid": "0000-0003-2238-2698", "clpid": "Anderson-Marin-M" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036" }, { "family_name": "Byrne", "given_name": "Ruby", "orcid": "0000-0003-4980-2736", "clpid": "Byrne-Ruby" }, { "family_name": "Catha", "given_name": "Morgan", "clpid": "Catha-Morgan" }, { "family_name": "Chen", "given_name": "Bin", "orcid": "0000-0002-0660-3350" }, { "family_name": "Chen", "given_name": "Xingyao", "orcid": "0000-0002-1810-6706" }, { "family_name": "Chhabra", "given_name": "Sherry", "orcid": "0000-0001-7754-0804" }, { "family_name": "D'Addario", "given_name": "Larry", "clpid": "D'Addario-Larry" }, { "family_name": "Davis", "given_name": "Ivey", "clpid": "Davis-Ivey" }, { "family_name": "Elder", "given_name": "Katherine" }, { "family_name": "Gary", "given_name": "Dale", "orcid": "0000-0003-2520-8396" }, { "family_name": "Harnach", "given_name": "Charlie", "clpid": "Harnach-Charlie" }, { "family_name": "Hellbourg", "given_name": "Greg", "orcid": "0000-0002-8191-3885", "clpid": "Hellbourg-Gregory" }, { "family_name": "Hobbs", "given_name": "Rick", "clpid": "Hobbs-Rick" }, { "family_name": "Hodge", "given_name": "David", "clpid": "Hodge-David" }, { "family_name": "Hodges", "given_name": "Mark", "clpid": "Hodges-Mark" }, { "family_name": "Huang", "given_name": "Yuping", "clpid": "Huang-Yuping" }, { "family_name": "Isella", "given_name": "Andrea", "orcid": "0000-0001-8061-2207" }, { "family_name": "Jacobs", "given_name": "Daniel C." }, { "family_name": "Kemby", "given_name": "Ghislain", "clpid": "Kemby-Ghislain" }, { "family_name": "Klinefelter", "given_name": "John T.", "clpid": "Klinefelter-John-T" }, { "family_name": "Kolopanis", "given_name": "Matthew", "orcid": "0000-0002-2950-2974" }, { "family_name": "Lamb", "given_name": "James", "orcid": "0000-0002-5959-1285", "clpid": "Lamb-J-W" }, { "family_name": "Mahesh", "given_name": "Nivedita", "clpid": "Mahesh-Nivedita" }, { "family_name": "Mondal", "given_name": "Surajit", "orcid": "0000-0002-2325-5298" }, { "family_name": "O'Donnell", "given_name": "Brian", "orcid": "0000-0003-2802-850X" }, { "family_name": "Plant", "given_name": "Kathryn", "clpid": "Plant-Kathryn" }, { "family_name": "Posner", "given_name": "Corey", "clpid": "Posner-Corey" }, { "family_name": "Powell", "given_name": "Travis", "clpid": "Powell-Travis" }, { "family_name": "Prayag", "given_name": "Vinand", "clpid": "Prayag-Vinand" }, { "family_name": "Rizo", "given_name": "Andres", "clpid": "Rizo-Andres" }, { "family_name": "Romero-Wolf", "given_name": "Andrew", "orcid": "0000-0002-4992-4162", "clpid": "Romero-Wolf-Andrew" }, { "family_name": "Shi", "given_name": "Jun", "orcid": "0000-0003-1647-7762", "clpid": "Shi-Jun" }, { "family_name": "Taylor", "given_name": "Greg", "orcid": "0000-0001-6495-7731" }, { "family_name": "Trim", "given_name": "Jordan", "clpid": "Trim-Jordan" }, { "family_name": "Virgin", "given_name": "Mike", "clpid": "Virgin-Mike" }, { "family_name": "Vydula", "given_name": "Akshatha", "orcid": "0000-0002-6611-2668" }, { "family_name": "Weinreb", "given_name": "Sandy", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-Sander" }, { "family_name": "White", "given_name": "Scott", "clpid": "White-Scott" }, { "family_name": "Woody", "given_name": "David", "orcid": "0000-0003-1734-2472", "clpid": "Woody-David" }, { "family_name": "Yu", "given_name": "Sijie", "orcid": "0000-0003-2872-2614" }, { "family_name": "Zentmeyer", "given_name": "Thomas", "clpid": "Zentmeyer-Thomas" }, { "family_name": "Zhang (\u5f20\u6c9b\u9526)", "given_name": "Peijin", "orcid": "0000-0001-6855-5799" } ], "abstract": "
\n

We report on a search for prompt, low-frequency radio emission from the gravitational-wave (GW) merger S250206dm using the Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA). Early alerts favored a neutron-star-containing merger, making this a compelling target. Motivated by theoretical predictions of coherent radio bursts from mergers involving a neutron star, we utilized the OVRO-LWA Time Machine system to analyze voltage data recorded around the time of the event. Time Machine is a two-stage voltage buffer and processing pipeline that continuously buffers raw data from all antennas across the array’s nearly full-hemisphere instantaneous field of view, enabling retrospective beamforming, dedispersion, and fast-transient candidate identification. For this event, we analyzed a 30 minute interval beginning 3.5 minutes after the merger, which included 2 minutes of pre-alert data recovered by the ring buffer. We searched the 50% localization probability region with millisecond time resolution in the 69–86 MHz frequency band. No radio counterpart was detected above a 7σ fluence detection threshold of ∼150 Jy ms. Using Bayesian analysis, we place a 95% confidence upper limit on the source luminosity of L95 = 4 × 1041 erg s−1. These constraints start to probe the bright end of the coherent-emission parameter space predicted by jet–interstellar medium shock processes, magnetar and blitzar-like mechanisms, and recent simulation-based scenarios for neutron-star-containing mergers. This study presents the first sensitive, large-area, millisecond-timescale search for prompt low-frequency radio emission from a GW merger with the OVRO-LWA, establishing a framework in which about 10 additional events will yield stringent population-level constraints.

\n
", "doi": "10.3847/1538-4357/ae2ea3", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2026-02-01", "series_number": "2", "volume": "997", "issue": "2", "pages": "311" }, { "id": "authors:p49vn-ppr38", "collection": "authors", "collection_id": "p49vn-ppr38", "cite_using_url": "https://authors.library.caltech.edu/records/p49vn-ppr38", "type": "article", "title": "Enigmatic Centi-SFU and mSFU Nonthermal Radio Transients Detected in the Middle Corona", "author": [ { "family_name": "Mondal", "given_name": "Surajit", "orcid": "0000-0002-2325-5298" }, { "family_name": "Chen", "given_name": "Bin", "orcid": "0000-0002-0660-3350" }, { "family_name": "Yu", "given_name": "Sijie", "orcid": "0000-0003-2872-2614" }, { "family_name": "Chen", "given_name": "Xingyao", "orcid": "0000-0002-1810-6706" }, { "family_name": "Zhang", "given_name": "Peijin", "orcid": "0000-0001-6855-5799" }, { "family_name": "Gary", "given_name": "Dale", "orcid": "0000-0003-2520-8396" }, { "family_name": "Anderson", "given_name": "Marin M.", "orcid": "0000-0003-2238-2698" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036" }, { "family_name": "Byrne", "given_name": "Ruby", "orcid": "0000-0003-4980-2736" }, { "family_name": "Catha", "given_name": "Morgan" }, { "family_name": "Chhabra", "given_name": "Sherry", "orcid": "0000-0001-7754-0804" }, { "family_name": "D'Addario", "given_name": "Larry", "clpid": "D'Addario-Larry-R" }, { "family_name": "Davis", "given_name": "Ivey", "orcid": "0000-0001-5397-5969", "clpid": "Davis-Ivey" }, { "family_name": "Dowell", "given_name": "Jayce", "orcid": "0000-0003-1407-0141" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Harnach", "given_name": "Charlie" }, { "family_name": "Hellbourg", "given_name": "Greg", "orcid": "0000-0002-8191-3885", "clpid": "Hellbourg-Gregory" }, { "family_name": "Hickish", "given_name": "Jack", "orcid": "0000-0003-0216-1417" }, { "family_name": "Hobbs", "given_name": "Rick", "clpid": "Hobbs-Rick" }, { "family_name": "Hodge", "given_name": "David", "clpid": "Hodge-David" }, { "family_name": "Hodges", "given_name": "Mark", "clpid": "Hodges-Mark" }, { "family_name": "Huang", "given_name": "Yuping", "orcid": "0000-0003-4267-6108", "clpid": "Huang-Yuping" }, { "family_name": "Isella", "given_name": "Andrea", "orcid": "0000-0001-8061-2207" }, { "family_name": "Jacobs", "given_name": "Daniel C.", "orcid": "0000-0002-0917-2269" }, { "family_name": "Kemby", "given_name": "Ghislain", "clpid": "Kemby-Ghislain" }, { "family_name": "Klinefelter", "given_name": "John T.", "clpid": "Klinefelter-John-T" }, { "family_name": "Kolopanis", "given_name": "Matthew", "orcid": "0000-0002-2950-2974" }, { "family_name": "Kosogorov", "given_name": "Nikita", "orcid": "0000-0003-1226-118X", "clpid": "Kosogorov-Nikita" }, { "family_name": "Lamb", "given_name": "James", "orcid": "0000-0002-5959-1285", "clpid": "Lamb-J-W" }, { "family_name": "Law", "given_name": "Casey", "orcid": "0000-0002-4119-9963", "clpid": "Law-Casey" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "O'Donnell", "given_name": "Brian", "orcid": "0000-0003-2802-850X" }, { "family_name": "Plant", "given_name": "Kathryn", "orcid": "0000-0001-6360-6972", "clpid": "Plant-Kathryn" }, { "family_name": "Posner", "given_name": "Corey", "clpid": "Posner-Corey" }, { "family_name": "Powell", "given_name": "Travis", "clpid": "Powell-Travis" }, { "family_name": "Prayag", "given_name": "Vinand", "clpid": "Prayag-Vinand" }, { "family_name": "Rizo", "given_name": "Andres", "clpid": "Rizo-Andres" }, { "family_name": "Romero-Wolf", "given_name": "Andrew", "orcid": "0000-0002-4992-4162" }, { "family_name": "Shi", "given_name": "Jun", "orcid": "0000-0003-1647-7762", "clpid": "Shi-Jun" }, { "family_name": "Taylor", "given_name": "Greg", "orcid": "0000-0001-6495-7731" }, { "family_name": "Trim", "given_name": "Jordan", "clpid": "Trim-Jordan" }, { "family_name": "Virgin", "given_name": "Mike", "clpid": "Virgin-Mike" }, { "family_name": "Vydula", "given_name": "Akshatha", "orcid": "0000-0002-6611-2668" }, { "family_name": "Weinreb", "given_name": "Sandy", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "White", "given_name": "Scott", "clpid": "White-Scott" }, { "family_name": "Woody", "given_name": "David", "clpid": "Woody-D-P" }, { "family_name": "Zentmeyer", "given_name": "Thomas", "clpid": "Zentmeyer-Thomas" } ], "abstract": "

Decades of solar coronal observations have provided substantial evidence for accelerated particles in the corona. In most cases, the location of particle acceleration can be roughly identified by combining high spatial and temporal resolution data from multiple instruments across a broad frequency range. In almost all cases, these nonthermal particles are associated with quiescent active regions, flares, and coronal mass ejections (CMEs). Only recently, some evidence of the existence of nonthermal electrons at locations outside these well-accepted regions has been found. Here, we report for the first time multiple cases of transient nonthermal emissions, in the heliocentric range of ∼3–7 R \u2299 , which do not have any obvious counterparts in other wave bands, like white-light and extreme ultraviolet. These detections were made possible by the regular availability of high dynamic-range low-frequency radio images from the Owens Valley Radio Observatory's Long Wavelength Array. While earlier detections of nonthermal emissions at these high heliocentric distances often had comparable extensions in the plane of sky, they were primarily associated with radio CMEs, unlike the cases reported here. Thus, these results add on to the evidence that the middle corona is extremely dynamic and contains a population of nonthermal electrons, which is only becoming visible with high dynamic-range low-frequency radio images.

", "doi": "10.3847/1538-4357/ae113b", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2025-12-01", "series_number": "2", "volume": "994", "issue": "2", "pages": "254" }, { "id": "authors:1nxwp-nzs23", "collection": "authors", "collection_id": "1nxwp-nzs23", "cite_using_url": "https://authors.library.caltech.edu/records/1nxwp-nzs23", "type": "article", "title": "EDGES-3: Instrument Design and Commissioning", "author": [ { "family_name": "Cappallo", "given_name": "Rigel C.", "orcid": "0000-0003-0267-8432" }, { "family_name": "Rogers", "given_name": "Alan E. E.", "orcid": "0000-0003-1941-7458" }, { "family_name": "Lonsdale", "given_name": "Colin J.", "orcid": "0000-0003-4062-4654" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036" }, { "family_name": "Barrett", "given_name": "John P.", "orcid": "0000-0002-9290-0764" }, { "family_name": "Murray", "given_name": "Steven G.", "orcid": "0000-0003-3059-3823" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Sims", "given_name": "Peter", "orcid": "0000-0002-2871-0413" }, { "family_name": "Vydula", "given_name": "Akshatha K.", "orcid": "0000-0002-6611-2668" }, { "family_name": "Monsalve", "given_name": "Raul A.", "orcid": "0000-0002-3287-2327" }, { "family_name": "Eckert", "given_name": "Christopher J.", "orcid": "0000-0003-2496-0383" }, { "family_name": "Steen", "given_name": "Parker", "orcid": "0000-0002-8489-0885" }, { "family_name": "Wilson", "given_name": "Kenneth M." } ], "abstract": "

EDGES-3 is the third iteration of the Experiment to Detect the Global EoR Signature (EDGES) experiment, designed to measure the predicted global absorption feature in the radio spectrum produced by neutral hydrogen gas at cosmic dawn, a critical observation determining when and how the first stars populated the universe. The EDGES-3 instrument has been redesigned to include both the analog and digital electronics within the antenna, allowing for in-situ calibration and removal of the lossy balun found in EDGES-2. EDGES-3 has been on multiple deployments in the past 4 yr; to Oregon, Devon Island, Adak Island, and is currently installed and taking data in the outback of Western Australia. This paper provides an accounting of the challenges inherent in the detection of the global, cosmological 21 cm signal, the strategies EDGES employs to mitigate each of these challenges, a description of the instrument, and a report on the Western Australia deployment along with observational data.

", "doi": "10.1088/1538-3873/ae1bd6", "issn": "0004-6280", "publisher": "IOP Publishing", "publication": "Publications of the Astronomical Society of the Pacific", "publication_date": "2025-12", "series_number": "12", "volume": "137", "issue": "12", "pages": "125002" }, { "id": "authors:gmafk-rq641", "collection": "authors", "collection_id": "gmafk-rq641", "cite_using_url": "https://authors.library.caltech.edu/records/gmafk-rq641", "type": "article", "title": "A Bayesian approach to modelling spectrometer data chromaticity corrected using beam factors - II. Model priors and posterior odds", "author": [ { "family_name": "Sims", "given_name": "Peter H", "orcid": "0000-0002-2871-0413" }, { "family_name": "Bowman", "given_name": "Judd D" }, { "family_name": "Murray", "given_name": "Steven G", "orcid": "0000-0003-3059-3823" }, { "family_name": "Barrett", "given_name": "John P" }, { "family_name": "Cappallo", "given_name": "Rigel C" }, { "family_name": "Lonsdale", "given_name": "Colin J" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Monsalve", "given_name": "Raul A", "orcid": "0000-0002-3287-2327" }, { "family_name": "Rogers", "given_name": "Alan E E" }, { "family_name": "Samson", "given_name": "Titu" }, { "family_name": "Vydula", "given_name": "Akshatha K" } ], "abstract": "

The reliable detection of the global 21-cm signal, a key tracer of Cosmic Dawn and the Epoch of Reionization, requires meticulous data modelling and robust statistical frameworks for model validation and comparison. In Paper I of this series, we presented the Beam-Factor-based Chromaticity Correction (BFCC) model for spectrometer data processed using BFCC to suppress instrumentally induced spectral structure. We demonstrated that the BFCC model, with complexity calibrated by Bayes factor-based model comparison (BFBMC), enables unbiased recovery of a 21-cm signal consistent with the one reported by EDGES from simulated data. Here, we extend the evaluation of the BFCC model to lower amplitude 21-cm signal scenarios where deriving reliable conclusions about a model's capacity to recover unbiased 21-cm signal estimates using BFBMC is more challenging. Using realistic simulations of chromaticity-corrected EDGES-low spectrometer data, we evaluate three signal amplitude regimes – null, moderate, and high. We then conduct a Bayesian comparison between the BFCC model and three alternative models previously applied to 21-cm signal estimation from EDGES data. To mitigate biases introduced by systematics in the 21-cm signal model fit, we incorporate the Bayesian Null-Test-Evidence-Ratio (BaNTER) validation framework and implement a Bayesian inference workflow based on posterior odds of the validated models. The BaNTER validated posterior-odds-based methodology presented here is general and transferable to other global 21-cm experiments employing Bayesian signal inference. We demonstrate that, unlike BFBMC alone, this approach consistently recovers 21-cm signal estimates that align with the true signal across all amplitude regimes, advancing robust global 21-cm signal detection methodologies.

", "doi": "10.1093/mnras/staf1767", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2025-12", "series_number": "2", "volume": "544", "issue": "2", "pages": "2340-2364" }, { "id": "authors:6y3h7-m3t18", "collection": "authors", "collection_id": "6y3h7-m3t18", "cite_using_url": "https://authors.library.caltech.edu/records/6y3h7-m3t18", "type": "article", "title": "A Dedicated System for Coordinated Radio and Optical Monitoring of the Space Weather of Young, Solar-type Stars", "author": [ { "family_name": "Davis", "given_name": "Ivey", "orcid": "0000-0001-5397-5969", "clpid": "Davis-Ivey" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Saini", "given_name": "Navtej", "clpid": "Saini-Navtej" }, { "family_name": "Law", "given_name": "Casey", "orcid": "0000-0002-4119-9963", "clpid": "Law-Casey" }, { "family_name": "Huang", "given_name": "Yuping", "orcid": "0000-0003-4267-6108", "clpid": "Huang-Yuping" }, { "family_name": "Burruss", "given_name": "Rick", "clpid": "Burruss-Rick" }, { "family_name": "Zolkower", "given_name": "Jeffry", "clpid": "Zolkower-Jeffry" }, { "family_name": "Baker", "given_name": "John", "clpid": "Baker-John" }, { "family_name": "Corcoran", "given_name": "Curt", "clpid": "Corcoran-Curt" }, { "family_name": "Heffner", "given_name": "Carolyn", "clpid": "Heffner-Carolyn" }, { "family_name": "Plant", "given_name": "Kathryn", "orcid": "0000-0001-6360-6972", "clpid": "Plant-Kathryn" }, { "family_name": "Kosogorov", "given_name": "Nikita", "orcid": "0000-0003-1226-118X", "clpid": "Kosogorov-Nikita" }, { "family_name": "Anderson", "given_name": "Marin", "orcid": "0000-0003-2238-2698", "clpid": "Anderson-Marin" }, { "family_name": "Isella", "given_name": "Andrea" }, { "family_name": "D'Addario", "given_name": "Larry", "clpid": "D'Addario-Larry" }, { "family_name": "Shi", "given_name": "Jun", "orcid": "0000-0003-1647-7762", "clpid": "Shi-Jun" }, { "family_name": "Hellbourg", "given_name": "Greg", "orcid": "0000-0002-8191-3885", "clpid": "Hellbourg-Gregory" }, { "family_name": "Hodge", "given_name": "David", "clpid": "Hodge-David" }, { "family_name": "Weinreb", "given_name": "Sandy", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-Sandy" }, { "family_name": "Mahesh", "given_name": "Nivedita", "clpid": "Mahesh-Nivedita" }, { "family_name": "Byrne", "given_name": "Ruby", "orcid": "0000-0003-4980-2736", "clpid": "Byrne-Ruby" }, { "family_name": "Hickish", "given_name": "Jack", "orcid": "0000-0003-0216-1417" }, { "family_name": "Hobbs", "given_name": "Rick", "clpid": "Hobbs-Rick" }, { "family_name": "Virgin", "given_name": "Mike", "clpid": "Virgin-Mike" }, { "family_name": "Kemby", "given_name": "Ghislain", "clpid": "Kemby-Ghislain" }, { "family_name": "Posner", "given_name": "Corey", "clpid": "Posner-Corey" }, { "family_name": "Klinefelter", "given_name": "John T.", "clpid": "Klinefelter-John-T" }, { "family_name": "Catha", "given_name": "Morgan", "clpid": "Catha-Morgan" }, { "family_name": "Lamb", "given_name": "James", "orcid": "0000-0002-5959-1285", "clpid": "Lamb-J-W" }, { "family_name": "Hodges", "given_name": "Mark", "clpid": "Hodges-Mark" }, { "family_name": "Harnach", "given_name": "Charlie", "clpid": "Harnach-Charlie" }, { "family_name": "Prayag", "given_name": "Vinand", "clpid": "Prayag-Vinand" }, { "family_name": "Woody", "given_name": "David", "orcid": "0000-0003-1734-2472", "clpid": "Woody-David" }, { "family_name": "Rizo", "given_name": "Andres", "clpid": "Rizo-Andres" }, { "family_name": "Romero-Wolf", "given_name": "Andrew", "orcid": "0000-0002-4992-4162", "clpid": "Romero-Wolf-Andrew" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036" }, { "family_name": "Jacobs", "given_name": "Daniel C." }, { "family_name": "Kolopanis", "given_name": "Matthew", "orcid": "0000-0002-2950-2974" }, { "family_name": "Elder", "given_name": "Katherine" }, { "family_name": "Vydula", "given_name": "Akshatha K.", "orcid": "0000-0002-6611-2668" }, { "family_name": "Gary", "given_name": "Dale", "orcid": "0000-0003-2520-8396" }, { "family_name": "Chen", "given_name": "Bin", "orcid": "0000-0002-0660-3350" }, { "family_name": "Mondal", "given_name": "Surajit", "orcid": "0000-0002-2325-5298" }, { "family_name": "Zhang", "given_name": "Peijin", "orcid": "0000-0001-6855-5799" }, { "family_name": "Yu", "given_name": "Sijie", "orcid": "0000-0003-2872-2614" }, { "family_name": "Chhabra", "given_name": "Sherry", "orcid": "0000-0001-7754-0804" }, { "family_name": "O'Donnell", "given_name": "Brian", "orcid": "0000-0003-2802-850X" }, { "family_name": "Dowell", "given_name": "Jayce", "orcid": "0000-0003-1407-0141" }, { "family_name": "Taylor", "given_name": "Greg", "orcid": "0000-0001-6495-7731" } ], "abstract": "
\n

Low-frequency radio emission in the form of type II and III bursts is a direct indicator of plasma motion in the solar corona and interplanetary medium. However, detecting equivalent events on solar analogs requires thousands of observing hours and complementary multiwavelength observations to constrain the origin of the radio emission. To address this, we have begun the Study of Space Weather Around Young Suns (SWAYS), a multiwavelength program for monitoring space weather around young, solar-type stars. This program currently focuses on five solar-type stars spanning 100–800 Myr in age. It includes a dedicated observing scheme from the recently upgraded Owens Valley Radio Observatory (OVRO) Long Wavelength Array (LWA) operating at 13–86 MHz to search for stellar analogs of solar type II and III bursts. We have built the optical photometry instrument Flarescope to operate simultaneously with OVRO-LWA observations to investigate whether radio bursts are accompanied by magnetic reconnection events. We analyze the performance based on a 1 hr observation of π1 UMa, which shows that Flarescope can reach submillimagnitude precision through nondifferential photometry on π1 UMa in 60 s integration times when diffusing the light with engineered diffusers. A small field of OVRO-LWA cross-correlated data centered on π1 UMa reaches a noise level of 740 mJy at 10 s integration time, consistent with confusion noise. With this precision, we should be able to detect large optical flares and related radio bursts that may indicate accompanying coronal mass ejections and energetic particle events. In this paper, we present the design, framework, and performance of the SWAYS program.

\n
", "doi": "10.3847/1538-4357/adfbe9", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2025-11-01", "series_number": "1", "volume": "993", "issue": "1", "pages": "82" }, { "id": "authors:z4xj5-j0x73", "collection": "authors", "collection_id": "z4xj5-j0x73", "cite_using_url": "https://authors.library.caltech.edu/records/z4xj5-j0x73", "type": "article", "title": "Polarisation performance of offset phase antennas: A study for FARSIDE", "author": [ { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Bowman", "given_name": "Judd", "orcid": "0000-0002-8475-2036" }, { "family_name": "Gehlot", "given_name": "Bharat", "orcid": "0000-0002-3240-9228" }, { "family_name": "Jacobs", "given_name": "Daniel", "orcid": "0000-0002-0917-2269" } ], "abstract": "Abstract\n \n Several radio telescopes have been planned or proposed to be deployed on the Lunar farside in the coming years. These will observe the unexplored ultra-long wavelengths of the electromagnetic spectrum from the lunar farside's unique radio-quiet and ionosphere-free environment. One such lunar radio array is the NASA-funded concept \u2013 the Farside Array for Radio Science Investigations of the Dark Ages and Exoplanets (FARSIDE). FARSIDE will operate over 100 kHz to 40 MHz with 128 spatially non-co-located orthogonal pairs of antenna nodes distributed over a\n \n \n \n $12\\times12$\n \n \n km area in a four-arm spiral configuration. Being on the lunar farside, this radio interferometer will be deployed by tele-operated rovers. The rover deployment mode could lead to a phase offset between each of the two orthogonally polarised antenna elements in the array, which are typically co-located. In this paper, we quantify the effects of such antenna phase offsets on the polarisation response and imaging performance of the lunar radio array. Modelling and analysing the FARSIDE dipole beams with and without offset, we find the latter leads to additional leakages into Stokes\n U\n and\n V\n corresponding to Muller matrix terms of\n \n \n \n $M_{2(0,1,2,3)}$\n \n \n and\n \n \n \n $M_{3(0,1,2,3)}$\n \n \n . Using a custom simulation pipeline to incorporate all four Stokes beams of spatially co-located and non-co-located dipoles, we produce visibilities and simulated images for the GLEAM (GaLactic and Extragalactic All-sky MWA) sky model through the FARSIDE array. We find that for a pure Stokes\n I\n input sky, the output image maximum Stokes\n \n \n \n $V/I$\n \n \n flux ratio for the offset case has increased to\n \n \n \n $2.5\\%$\n \n \n versus\n \n \n \n $0.05\\%$\n \n \n for the co-located case. The additional Stokes\n V\n needs to be corrected since the detection of electron cyclotron maser emissions from exoplanets requires high-fidelity Stokes\n V\n measurements.", "doi": "10.1017/pasa.2025.10112", "issn": "1323-3580", "publisher": "Cambridge University Press (CUP)", "publication": "Publications of the Astronomical Society of Australia", "publication_date": "2025-10-27", "volume": "42", "pages": "e156" }, { "id": "authors:h0jxz-rg957", "collection": "authors", "collection_id": "h0jxz-rg957", "cite_using_url": "https://authors.library.caltech.edu/records/h0jxz-rg957", "type": "article", "title": "Probing the Turbulent Corona and Heliosphere Using Radio Spectral Imaging Observation during the Solar Conjunction of the Crab Nebula", "author": [ { "family_name": "Zhang", "given_name": "Peijin", "orcid": "0000-0001-6855-5799" }, { "family_name": "Mondal", "given_name": "Surajit", "orcid": "0000-0002-2325-5298" }, { "family_name": "Chen", "given_name": "Bin", "orcid": "0000-0002-0660-3350" }, { "family_name": "Yu", "given_name": "Sijie", "orcid": "0000-0003-2872-2614" }, { "family_name": "Gary", "given_name": "Dale", "orcid": "0000-0003-2520-8396" }, { "family_name": "Anderson", "given_name": "Marin M.", "orcid": "0000-0003-2238-2698", "clpid": "Anderson-Marin-M" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036" }, { "family_name": "Byrne", "given_name": "Ruby", "orcid": "0000-0003-4980-2736", "clpid": "Byrne-Ruby" }, { "family_name": "Catha", "given_name": "Morgan", "clpid": "Catha-Morgan" }, { "family_name": "Chen", "given_name": "Xingyao", "orcid": "0000-0002-1810-6706" }, { "family_name": "Chhabra", "given_name": "Sherry", "orcid": "0000-0001-7754-0804" }, { "family_name": "D'Addario", "given_name": "Larry", "clpid": "D'Addario-Larry" }, { "family_name": "Davis", "given_name": "Ivey", "orcid": "0000-0001-5397-5969", "clpid": "Davis-Ivey" }, { "family_name": "Dowell", "given_name": "Jayce", "orcid": "0000-0003-1407-0141" }, { "family_name": "Elder", "given_name": "Katherine" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Harnach", "given_name": "Charlie", "clpid": "Harnach-Charlie" }, { "family_name": "Hellbourg", "given_name": "Greg", "orcid": "0000-0002-8191-3885", "clpid": "Hellbourg-Gregory" }, { "family_name": "Hickish", "given_name": "Jack", "orcid": "0000-0003-0216-1417" }, { "family_name": "Hobbs", "given_name": "Rick", "clpid": "Hobbs-Rick" }, { "family_name": "Hodge", "given_name": "David", "clpid": "Hodge-David" }, { "family_name": "Hodges", "given_name": "Mark", "clpid": "Hodges-Mark" }, { "family_name": "Huang", "given_name": "Yuping", "orcid": "0000-0003-4267-6108", "clpid": "Huang-Yuping" }, { "family_name": "Isella", "given_name": "Andrea" }, { "family_name": "Jacobs", "given_name": "Daniel C.", "orcid": "0000-0002-0917-2269" }, { "family_name": "Kemby", "given_name": "Ghislain", "clpid": "Kemby-Ghislain" }, { "family_name": "Klinefelter", "given_name": "John T.", "clpid": "Klinefelter-John-T" }, { "family_name": "Kolopanis", "given_name": "Matthew", "orcid": "0000-0002-2950-2974" }, { "family_name": "Kosogorov", "given_name": "Nikita", "orcid": "0000-0003-1226-118X", "clpid": "Kosogorov-Nikita" }, { "family_name": "Lamb", "given_name": "James", "orcid": "0000-0002-5959-1285", "clpid": "Lamb-J-W" }, { "family_name": "Law", "given_name": "Casey J.", "orcid": "0000-0002-4119-9963", "clpid": "Law-Casey-J" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "O'Donnell", "given_name": "Brian" }, { "family_name": "Plant", "given_name": "Kathryn", "orcid": "0000-0001-6360-6972", "clpid": "Plant-Kathryn" }, { "family_name": "Posner", "given_name": "Corey", "clpid": "Posner-Corey" }, { "family_name": "Powell", "given_name": "Travis", "clpid": "Powell-Travis" }, { "family_name": "Prayag", "given_name": "Vinand", "clpid": "Prayag-Vinand" }, { "family_name": "Rizo", "given_name": "Andres", "clpid": "Rizo-Andres" }, { "family_name": "Romero-Wolf", "given_name": "Andrew", "orcid": "0000-0002-4992-4162", "clpid": "Romero-Wolf-Andrew" }, { "family_name": "Shi", "given_name": "Jun", "orcid": "0000-0003-1647-7762", "clpid": "Shi-Jun" }, { "family_name": "Taylor", "given_name": "Greg", "orcid": "0000-0001-6495-7731" }, { "family_name": "Trim", "given_name": "Jordan", "clpid": "Trim-Jordan" }, { "family_name": "Virgin", "given_name": "Mike", "clpid": "Virgin-Mike" }, { "family_name": "Vydula", "given_name": "Akshatha", "orcid": "0000-0002-6611-2668" }, { "family_name": "Weinreb", "given_name": "Sandy", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-Sandy" }, { "family_name": "Woody", "given_name": "David", "orcid": "0000-0003-1734-2472", "clpid": "Woody-David" } ], "abstract": "

Measuring plasma parameters in the upper solar corona and inner heliosphere is challenging because of the region's weakly emissive nature and inaccessibility for most in situ observations. Radio imaging of broadened and distorted background astronomical radio sources during solar conjunction can provide unique constraints for the coronal material along the line of sight. In this study, we present radio spectral imaging observations of the Crab Nebula (Tau A) from 2024 June 9 to June 22 when it was near the Sun with a projected heliocentric distance of 5–27 solar radii, using the Owens Valley Radio Observatory's Long Wavelength Array at multiple frequencies in the 30–80 MHz range. The imaging data reveal frequency-dependent broadening and distortion effects caused by anisotropic wave propagation through the turbulent solar corona at different distances. We analyze the brightness, size, and anisotropy of the broadened images. Our results provide detailed observations showing that the eccentricity of the unresolved source increases as the line of sight approaches the Sun, suggesting a higher anisotropic ratio of the plasma turbulence closer to the Sun. In addition, the major axis of the elongated source is consistently oriented in the direction perpendicular to the radial direction, suggesting that the turbulence-induced scattering effect is more pronounced in the direction transverse to the coronal magnetic field. Lastly, when the source undergoes large-scale refraction as the line of sight passes through a streamer, the apparent source exhibits substructures at lower frequencies. This study demonstrates that observations of celestial radio sources with lines of sight near the Sun provide a promising method for measuring turbulence parameters in the inner heliosphere.

", "doi": "10.3847/1538-4357/adff56", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2025-10-10", "series_number": "1", "volume": "992", "issue": "1", "pages": "128" }, { "id": "authors:9bjac-7yw52", "collection": "authors", "collection_id": "9bjac-7yw52", "cite_using_url": "https://authors.library.caltech.edu/records/9bjac-7yw52", "type": "article", "title": "Possible First Detection of Gyroresonance Emission from a Coronal Mass Ejection in the Middle Corona", "author": [ { "family_name": "Mondal", "given_name": "Surajit", "orcid": "0000-0002-2325-5298" }, { "family_name": "Chen", "given_name": "Bin", "orcid": "0000-0002-0660-3350" }, { "family_name": "Chen", "given_name": "Xingyao", "orcid": "0000-0002-1810-6706" }, { "family_name": "Yu", "given_name": "Sijie", "orcid": "0000-0003-2872-2614" }, { "family_name": "Gary", "given_name": "Dale", "orcid": "0000-0003-2520-8396" }, { "family_name": "Zhang", "given_name": "Peijin", "orcid": "0000-0001-6855-5799" }, { "family_name": "Anderson", "given_name": "Marin M.", "orcid": "0000-0003-2238-2698", "clpid": "Anderson-Marin-M" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036" }, { "family_name": "Byrne", "given_name": "Ruby", "orcid": "0000-0003-4980-2736", "clpid": "Byrne-Ruby" }, { "family_name": "Catha", "given_name": "Morgan", "clpid": "Catha-Morgan" }, { "family_name": "Chhabra", "given_name": "Sherry", "orcid": "0000-0001-7754-0804" }, { "family_name": "D'Addario", "given_name": "Larry", "clpid": "D'Addario-Larry" }, { "family_name": "Davis", "given_name": "Ivey", "orcid": "0000-0001-5397-5969", "clpid": "Davis-Ivey" }, { "family_name": "Dowell", "given_name": "Jayce", "orcid": "0000-0003-1407-0141" }, { "family_name": "Elder", "given_name": "Katherine" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Harnach", "given_name": "Charlie", "clpid": "Harnach-Charlie" }, { "family_name": "Hellbourg", "given_name": "Greg", "orcid": "0000-0002-8191-3885", "clpid": "Hellbourg-Gregory" }, { "family_name": "Hickish", "given_name": "Jack", "orcid": "0000-0003-0216-1417" }, { "family_name": "Hobbs", "given_name": "Rick", "clpid": "Hobbs-Rick" }, { "family_name": "Hodge", "given_name": "David", "clpid": "Hodge-David" }, { "family_name": "Hodges", "given_name": "Mark", "clpid": "Hodges-Mark" }, { "family_name": "Huang", "given_name": "Yuping", "orcid": "0000-0003-4267-6108", "clpid": "Huang-Yuping" }, { "family_name": "Isella", "given_name": "Andrea" }, { "family_name": "Jacobs", "given_name": "Daniel C.", "orcid": "0000-0002-0917-2269" }, { "family_name": "Kemby", "given_name": "Ghislain", "clpid": "Kemby-Ghislain" }, { "family_name": "Klinefelter", "given_name": "John T.", "clpid": "Klinefelter-John-T" }, { "family_name": "Kolopanis", "given_name": "Matthew", "orcid": "0000-0002-2950-2974" }, { "family_name": "Kosogorov", "given_name": "Nikita", "orcid": "0000-0003-1226-118X", "clpid": "Kosogorov-Nikita" }, { "family_name": "Lamb", "given_name": "James", "orcid": "0000-0002-5959-1285", "clpid": "Lamb-J-W" }, { "family_name": "Law", "given_name": "Casey", "orcid": "0000-0002-4119-9963", "clpid": "Law-Casey" }, { "family_name": "Mahesh", "given_name": "Nivedita", "clpid": "Mahesh-Nivedita" }, { "family_name": "O'Donnell", "given_name": "Brian", "orcid": "0000-0003-2802-850X" }, { "family_name": "Plant", "given_name": "Kathryn", "orcid": "0000-0001-6360-6972", "clpid": "Plant-Kathryn" }, { "family_name": "Posner", "given_name": "Corey", "clpid": "Posner-Corey" }, { "family_name": "Powell", "given_name": "Travis", "clpid": "Powell-Travis" }, { "family_name": "Prayag", "given_name": "Vinand", "clpid": "Prayag-Vinand" }, { "family_name": "Rizo", "given_name": "Andres", "clpid": "Rizo-Andres" }, { "family_name": "Romero-Wolf", "given_name": "Andrew", "orcid": "0000-0002-4992-4162", "clpid": "Romero-Wolf-Andrew" }, { "family_name": "Shi", "given_name": "Jun", "orcid": "0000-0003-1647-7762", "clpid": "Shi-Jun" }, { "family_name": "Taylor", "given_name": "Greg", "orcid": "0000-0001-6495-7731" }, { "family_name": "Trim", "given_name": "Jordan", "clpid": "Trim-Jordan" }, { "family_name": "Virgin", "given_name": "Mike", "clpid": "Virgin-Mike" }, { "family_name": "Vydula", "given_name": "Akshatha", "orcid": "0000-0002-6611-2668" }, { "family_name": "Weinreb", "given_name": "Sandy", "clpid": "Weinreb-Sandy" }, { "family_name": "White", "given_name": "Scott", "clpid": "White-Scott" }, { "family_name": "Woody", "given_name": "David", "orcid": "0000-0003-1734-2472", "clpid": "Woody-David" }, { "family_name": "Zentmeyer", "given_name": "Thomas", "clpid": "Zentmeyer-Thomas" } ], "abstract": "
\n

Routine measurements of the magnetic field of coronal mass ejections (CMEs) have been a key challenge in solar physics. Making such measurements is important both from a space weather perspective and for understanding the detailed evolution of the CME. In spite of significant efforts and multiple proposed methods, achieving this goal has not been possible to date. Here we report the first possible detection of gyroresonance emission from a CME. Assuming that the emission is happening at the third harmonic, we estimate that the magnetic field strength ranges from 7.9 to 5.6 G between 4.9 and 7.5 R\u2299. We also demonstrate that this high magnetic field is not the average magnetic field inside the CME, but most probably is related to small magnetic islands, which are also being observed more frequently with the availability of high-resolution and high-quality white-light images.

\n
", "doi": "10.3847/1538-4357/ae061f", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2025-10-10", "series_number": "1", "volume": "992", "issue": "1", "pages": "143" }, { "id": "authors:dks16-tcm80", "collection": "authors", "collection_id": "dks16-tcm80", "cite_using_url": "https://authors.library.caltech.edu/records/dks16-tcm80", "type": "article", "title": "Measuring the Magnetic Field of a Coronal Mass Ejection from the Low to Middle Corona", "author": [ { "family_name": "Chen", "given_name": "Xingyao", "orcid": "0000-0002-1810-6706" }, { "family_name": "Chen", "given_name": "Bin", "orcid": "0000-0002-0660-3350" }, { "family_name": "Yu", "given_name": "Sijie", "orcid": "0000-0003-2872-2614" }, { "family_name": "Mondal", "given_name": "Surajit", "orcid": "0000-0002-2325-5298" }, { "family_name": "Stiefel", "given_name": "Muriel Zo\u00eb", "orcid": "0000-0002-8538-3455" }, { "family_name": "Zhang", "given_name": "Peijin", "orcid": "0000-0001-6855-5799" }, { "family_name": "Gary", "given_name": "Dale E.", "orcid": "0000-0003-2520-8396" }, { "family_name": "Krucker", "given_name": "S\u00e4m", "orcid": "0000-0002-2002-9180" }, { "family_name": "Anderson", "given_name": "Marin M.", "orcid": "0000-0003-2238-2698", "clpid": "Anderson-Marin-M" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036" }, { "family_name": "Byrne", "given_name": "Ruby", "orcid": "0000-0003-4980-2736", "clpid": "Byrne-Ruby" }, { "family_name": "Catha", "given_name": "Morgan", "clpid": "Catha-Morgan" }, { "family_name": "Chhabra", "given_name": "Sherry", "orcid": "0000-0001-7754-0804" }, { "family_name": "D'Addario", "given_name": "Larry", "clpid": "D'Addario-Larry" }, { "family_name": "Davis", "given_name": "Ivey", "orcid": "0000-0001-5397-5969", "clpid": "Davis-Ivey" }, { "family_name": "Dowell", "given_name": "Jayce", "orcid": "0000-0003-1407-0141" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Harnach", "given_name": "Charlie", "clpid": "Harnach-Charlie" }, { "family_name": "Hellbourg", "given_name": "Greg", "orcid": "0000-0002-8191-3885", "clpid": "Hellbourg-Gregory" }, { "family_name": "Hickish", "given_name": "Jack" }, { "family_name": "Hobbs", "given_name": "Rick", "clpid": "Hobbs-Rick" }, { "family_name": "Hodge", "given_name": "David", "clpid": "Hodge-David" }, { "family_name": "Hodges", "given_name": "Mark", "clpid": "Hodges-Mark" }, { "family_name": "Huang", "given_name": "Yuping", "orcid": "0000-0003-4267-6108", "clpid": "Huang-Yuping" }, { "family_name": "Isella", "given_name": "Andrea", "orcid": "0000-0001-8061-2207" }, { "family_name": "Jacobs", "given_name": "Daniel C." }, { "family_name": "Kemby", "given_name": "Ghislain", "clpid": "Kemby-Ghislain" }, { "family_name": "Klinefelter", "given_name": "John T.", "clpid": "Klinefelter-John-T" }, { "family_name": "Kolopanis", "given_name": "Matthew", "orcid": "0000-0002-2950-2974" }, { "family_name": "Kosogorov", "given_name": "Nikita", "orcid": "0000-0003-1226-118X", "clpid": "Kosogorov-Nikita" }, { "family_name": "Lamb", "given_name": "James", "orcid": "0000-0002-5959-1285", "clpid": "Lamb-J-W" }, { "family_name": "Law", "given_name": "Casey J.", "orcid": "0000-0002-4119-9963", "clpid": "Law-Casey-J" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "O'Donnell", "given_name": "Brian" }, { "family_name": "Plant", "given_name": "Kathryn", "orcid": "0000-0001-6360-6972", "clpid": "Plant-Kathryn" }, { "family_name": "Posner", "given_name": "Corey", "clpid": "Posner-Corey" }, { "family_name": "Powell", "given_name": "Travis", "clpid": "Powell-Travis" }, { "family_name": "Prayag", "given_name": "Vinand", "clpid": "Prayag-Vinand" }, { "family_name": "Rizo", "given_name": "Andres", "clpid": "Rizo-Andres" }, { "family_name": "Romero-Wolf", "given_name": "Andrew", "orcid": "0000-0002-4992-4162", "clpid": "Romero-Wolf-Andrew" }, { "family_name": "Shi", "given_name": "Jun", "orcid": "0000-0003-1647-7762", "clpid": "Shi-Jun" }, { "family_name": "Taylor", "given_name": "Greg" }, { "family_name": "Trim", "given_name": "Jordan", "clpid": "Trim-Jordan" }, { "family_name": "Virgin", "given_name": "Mike", "clpid": "Virgin-Mike" }, { "family_name": "Vydula", "given_name": "Akshatha", "orcid": "0000-0002-6611-2668" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Woody", "given_name": "David", "orcid": "0000-0003-1734-2472", "clpid": "Woody-David" } ], "abstract": "
\n

A major challenge in understanding the initiation and evolution of coronal mass ejections (CMEs) is measuring the magnetic field of the magnetic flux ropes (MFRs) that drive CMEs. Recent developments in radio imaging spectroscopy have paved the way for diagnosing the CMEs’ magnetic field using gyrosynchrotron radiation. We present magnetic field measurements of a CME associated with an X5-class flare by combining radio imaging spectroscopy data in microwaves (1–18 GHz) and meter waves (20–88 MHz), obtained by the Owens Valley Radio Observatory’s Expanded Owens Valley Solar Array (EOVSA) and Long Wavelength Array (OVRO-LWA), respectively. EOVSA observations reveal that the microwave source, observed in the low corona during the initiation phase of the eruption, outlines the bottom of the rising MFR-hosting CME bubble seen in extreme ultraviolet and expands as the bubble evolves. As the MFR erupts into the middle corona and appears as a white-light CME, its meter-wave counterpart, observed by OVRO-LWA, displays a similar morphology. For the first time, using gyrosynchrotron spectral diagnostics, we obtain magnetic field measurements of the erupting MFR in both the low and middle corona, corresponding to coronal heights of 0.02 and 1.83 R\u2299. The magnetic field strength is found to be around 300 G at 0.02 R\u2299 during the CME initiation and about 0.6 G near the leading edge of the CME when it propagates to 1.83 R\u2299. These results provide critical new insights into the magnetic structure of the CME and its evolution during the early stages of its eruption.

\n
", "doi": "10.3847/2041-8213/adfa71", "issn": "2041-8205", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal Letters", "publication_date": "2025-09-10", "series_number": "2", "volume": "990", "issue": "2", "pages": "L50" }, { "id": "authors:y50y0-7zg66", "collection": "authors", "collection_id": "y50y0-7zg66", "cite_using_url": "https://authors.library.caltech.edu/records/y50y0-7zg66", "type": "article", "title": "A general Bayesian model-validation framework based on null-test evidence ratios, with an example application to global 21-cm cosmology", "author": [ { "family_name": "Sims", "given_name": "Peter H", "orcid": "0000-0002-2871-0413" }, { "family_name": "Bowman", "given_name": "Judd D" }, { "family_name": "Murray", "given_name": "Steven G", "orcid": "0000-0003-3059-3823" }, { "family_name": "Barrett", "given_name": "John P" }, { "family_name": "Cappallo", "given_name": "Rigel C" }, { "family_name": "Lonsdale", "given_name": "Colin J" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Monsalve", "given_name": "Raul A", "orcid": "0000-0002-3287-2327" }, { "family_name": "Rogers", "given_name": "Alan E E" }, { "family_name": "Samson", "given_name": "Titu" }, { "family_name": "Vydula", "given_name": "Akshatha K" } ], "abstract": "

Comparing composite models for multi-component observational data is a prevalent scientific challenge. When fitting composite models, there exists the potential for systematics from a poor fit of one model component to be absorbed by another, resulting in the composite model providing an accurate fit to the data in aggregate but yielding biased a posteriori estimates for individual components. We begin by defining a classification scheme for composite model comparison scenarios, identifying two categories: category I, where models with accurate and predictive components are separable through Bayesian comparison of the unvalidated composite models, and category II, where models with accurate and predictive components may not be separable due to interactions between components, leading to spurious detections or biased signal estimation. To address the limitations of category II model comparisons, we introduce the Bayesian Null Test Evidence Ratio-based (BaNTER) validation framework. Applying this classification scheme and BaNTER to a composite model comparison problem in 21-cm cosmology, where minor systematics from imperfect foreground modelling can bias global 21-cm signal recovery, we validate six composite models using mock data. We show that incorporating BaNTER alongside Bayes-factor-based comparison reliably ensures unbiased inferences of the signal of interest across both categories, positioning BaNTER as a valuable addition to Bayesian inference workflows with potential applications across diverse fields.

", "doi": "10.1093/mnras/staf1109", "issn": "0035-8711", "publisher": "Royal Astronomical Society", "publication": "Monthly Notices of the Royal Astronomical Society", "publication_date": "2025-08", "series_number": "3", "volume": "54", "issue": "3", "pages": "staf1109" }, { "id": "authors:yc4ay-k1a03", "collection": "authors", "collection_id": "yc4ay-k1a03", "cite_using_url": "https://authors.library.caltech.edu/records/yc4ay-k1a03", "type": "article", "title": "Implementing Continuous All-sky Monitoring with the OVRO-LWA to Identify Prompt and Precursor Counterparts of Gravitational Wave Events", "author": [ { "family_name": "Kosogorov", "given_name": "Nikita", "orcid": "0000-0003-1226-118X", "clpid": "Kosogorov-Nikita" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Law", "given_name": "Casey", "orcid": "0000-0002-4119-9963", "clpid": "Law-Casey" }, { "family_name": "Hickish", "given_name": "Jack" }, { "family_name": "Dowell", "given_name": "Jayce", "orcid": "0000-0003-1407-0141" }, { "family_name": "Anderson", "given_name": "Marin M.", "orcid": "0000-0003-2238-2698", "clpid": "Anderson-Marin-M" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036" }, { "family_name": "Byrne", "given_name": "Ruby", "orcid": "0000-0003-4980-2736", "clpid": "Byrne-Ruby" }, { "family_name": "Catha", "given_name": "Morgan", "clpid": "Catha-Morgan" }, { "family_name": "Chen", "given_name": "Bin", "orcid": "0000-0002-0660-3350" }, { "family_name": "Chhabra", "given_name": "Sherry", "orcid": "0000-0001-7754-0804" }, { "family_name": "D'Addario", "given_name": "Larry", "clpid": "D'Addario-Larry" }, { "family_name": "Davis", "given_name": "Ivey", "orcid": "0000-0001-5397-5969", "clpid": "Davis-Ivey" }, { "family_name": "Elder", "given_name": "Katherine" }, { "family_name": "Gary", "given_name": "Dale", "orcid": "0000-0003-2520-8396" }, { "family_name": "Harnach", "given_name": "Charlie", "clpid": "Harnach-Charlie" }, { "family_name": "Hellbourg", "given_name": "Greg", "orcid": "0000-0002-8191-3885", "clpid": "Hellbourg-Gregory" }, { "family_name": "Hobbs", "given_name": "Rick", "clpid": "Hobbs-Rick" }, { "family_name": "Hodge", "given_name": "David", "clpid": "Hodge-David" }, { "family_name": "Hodges", "given_name": "Mark", "clpid": "Hodges-Mark" }, { "family_name": "Huang", "given_name": "Yuping", "orcid": "0000-0003-4267-6108", "clpid": "Huang-Yuping" }, { "family_name": "Isella", "given_name": "Andrea" }, { "family_name": "Jacobs", "given_name": "Daniel C.", "orcid": "0000-0002-0917-2269" }, { "family_name": "Kemby", "given_name": "Ghislain", "clpid": "Kemby-Ghislain" }, { "family_name": "Klinefelter", "given_name": "John T.", "clpid": "Klinefelter-John-T" }, { "family_name": "Kolopanis", "given_name": "Matthew", "orcid": "0000-0002-2950-2974" }, { "family_name": "Lamb", "given_name": "James", "orcid": "0000-0002-5959-1285", "clpid": "Lamb-J-W" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Mondal", "given_name": "Surajit", "orcid": "0000-0002-2325-5298" }, { "family_name": "O'Donnell", "given_name": "Brian" }, { "family_name": "Plant", "given_name": "Kathryn", "orcid": "0000-0001-6360-6972", "clpid": "Plant-Kathryn" }, { "family_name": "Posner", "given_name": "Corey", "clpid": "Posner-Corey" }, { "family_name": "Prayag", "given_name": "Vinand", "clpid": "Prayag-Vinand" }, { "family_name": "Rizo", "given_name": "Andres", "clpid": "Rizo-Andres" }, { "family_name": "Romero-Wolf", "given_name": "Andrew", "orcid": "0000-0002-4992-4162", "clpid": "Romero-Wolf-Andrew" }, { "family_name": "Shi", "given_name": "Jun", "orcid": "0000-0003-1647-7762", "clpid": "Shi-Jun" }, { "family_name": "Taylor", "given_name": "Greg", "orcid": "0000-0001-6495-7731" }, { "family_name": "Virgin", "given_name": "Mike", "clpid": "Virgin-Mike" }, { "family_name": "Vydula", "given_name": "Akshatha", "orcid": "0000-0002-6611-2668" }, { "family_name": "Weinreb", "given_name": "Sandy", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-Sandy" }, { "family_name": "Woody", "given_name": "David", "orcid": "0000-0003-1734-2472", "clpid": "Woody-David" }, { "family_name": "Yu", "given_name": "Sijie", "orcid": "0000-0003-2872-2614" }, { "family_name": "Zhang", "given_name": "Peijin", "orcid": "0000-0001-6855-5799" }, { "family_name": "Zhao", "given_name": "Yifan (Amy)" } ], "abstract": "
\n

A number of theoretical studies have proposed a prompt or precursor low-frequency radio counterpart to gravitational wave events detected by LIGO and Virgo. Detection of such events would offer a new window on the immediate environment of the merger and provide an avenue to rapid localization. However, identifying fast transients in real-time in localization regions spanning hundreds to thousands of square degrees presents severe technical challenges. To address these challenges, we present a novel technique embodied in the Time Machine, a system featuring a two-stage voltage buffer and subsequent processing pipeline designed for the Long Wavelength Array at the Owens Valley Radio Observatory. This array is developed to instantaneously image the entire viewable sky. We detail the system's buffer structure that allows data collection from several minutes before a trigger event, up to 30 minutes after an event. The processing of this voltage data involves beamforming and searching the full 90th-percentile localization region above the horizon with ms-time resolution and the ability to detect events with ∼100 Jy ms (7σ) fluence within the 55–85 MHz band. Furthermore, we incorporate an offline cross-correlation pipeline to improve positional accuracy of identified transients to within subarcminute levels. We present a full overview of the system design and initial testing results.

\n
", "doi": "10.3847/1538-4357/add014", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2025-06-01", "series_number": "2", "volume": "985", "issue": "2", "pages": "265" }, { "id": "authors:91kt9-0n449", "collection": "authors", "collection_id": "91kt9-0n449", "cite_using_url": "https://authors.library.caltech.edu/records/91kt9-0n449", "type": "article", "title": "FarView: An in-situ manufactured lunar far side radio array concept for 21-cm Dark Ages cosmology", "author": [ { "family_name": "Polidan", "given_name": "Ronald S.", "orcid": "0000-0002-8474-1935", "clpid": "Polidan-Ronald-S" }, { "family_name": "Burns", "given_name": "Jack O.", "orcid": "0000-0002-4468-2117", "clpid": "Burns-Jack-O" }, { "family_name": "Ignatiev", "given_name": "Alex", "orcid": "0000-0002-8939-7504", "clpid": "Ignatiev-Alex" }, { "family_name": "Hegedus", "given_name": "Alex", "orcid": "0000-0001-6247-6934", "clpid": "Hegedus-Alexander" }, { "family_name": "Pober", "given_name": "Jonathan" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Chang", "given_name": "Tzu-Ching", "orcid": "0000-0001-5929-4187", "clpid": "Chang-Tzu-Ching" }, { "family_name": "Hallinan", "given_name": "Gregg", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Ning", "given_name": "Yuhong", "clpid": "Ning-Yuhong" }, { "family_name": "Bowman", "given_name": "Judd", "orcid": "0000-0002-8475-2036", "clpid": "Bowman-Judd" } ], "abstract": "
\n
\n
\n

FarView is an early-stage concept for a large, low-frequency radio observatory, manufactured in-situ on the lunar far side using metals extracted from the lunar regolith. It consists of 100,000 dipole antennas in compact subarrays distributed over a large area but with empty space between subarrays in a core-halo structure. FarView covers a total area of ∼200 km2, has a dense core within the inner ∼36 km2, and a ∼power-law falloff of antenna density out to ∼14 km from the center. With this design, it is relatively easy to identify multiple viable build sites on the lunar far side. The science case for FarView emphasizes the unique capabilities to probe the unexplored Cosmic Dark Ages – identified by the 2020 Astrophysics Decadal Survey as the discovery area for cosmology. FarView will deliver power spectra and tomographic maps tracing the evolution of the Universe from before the birth of the first stars to the beginning of Cosmic Dawn, and potentially provide unique insights into dark matter, early dark energy, neutrino masses, and the physics of inflation. What makes FarView feasible and affordable in the timeframe of the 2030s is that it is manufactured in-situ, utilizing space industrial technologies. This in-situ manufacturing architecture utilizes Earth-built equipment that is transported to the lunar surface to extract metals from the regolith and will use those metals to manufacture most of the array components: dipole antennas, power lines, and silicon solar cell power systems. This approach also enables a long functional lifetime, by permitting servicing and repair of the observatory. The full 100,000 dipole FarView observatory will take 4–8 years to build, depending on the realized performance of the manufacturing elements and the lunar delivery scenario.

\n
\n
\n
\n", "doi": "10.1016/j.asr.2024.04.008", "issn": "0273-1177", "publisher": "Elsevier", "publication": "Advances in Space Research", "publication_date": "2024-07-01", "series_number": "1", "volume": "74", "issue": "1", "pages": "528-546" }, { "id": "authors:s2tp4-zcn90", "collection": "authors", "collection_id": "s2tp4-zcn90", "cite_using_url": "https://authors.library.caltech.edu/records/s2tp4-zcn90", "type": "article", "title": "21 cm Intensity Mapping with the DSA-2000", "author": [ { "family_name": "Byrne", "given_name": "Ruby", "orcid": "0000-0003-4980-2736", "clpid": "Byrne-Ruby" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Hallinan", "given_name": "Gregg W.", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G" }, { "family_name": "Connor", "given_name": "Liam", "orcid": "0000-0002-7587-6352", "clpid": "Connor-Liam" }, { "family_name": "Ravi", "given_name": "Vikram", "orcid": "0000-0002-7252-5485", "clpid": "Ravi-Vikram" }, { "family_name": "Lazio", "given_name": "T. Joseph W.", "clpid": "Lazio-T-Joseph-W" } ], "abstract": "
\n

Line-intensity mapping is a promising probe of the Universe's large-scale structure. We explore the sensitivity of the DSA-2000, a forthcoming array consisting of over 2000 dishes, to the statistical power spectrum of neutral hydrogen's 21 cm emission line. These measurements would reveal the distribution of neutral hydrogen throughout the near-redshift Universe without necessitating resolving individual sources. The success of these measurements relies on the instrument's sensitivity and resilience to systematics. We show that the DSA-2000 will have the sensitivity needed to detect the 21 cm power spectrum at z ≈ 0.5 and across power spectrum modes of 0.03–35.12 h Mpc−1 with 0.1 h Mpc−1 resolution. We find that supplementing the nominal array design with a dense core of 200 antennas will expand its sensitivity at low power spectrum modes and enable measurement of Baryon Acoustic Oscillations. Finally, we present a qualitative discussion of the DSA-2000's unique resilience to sources of systematic error that can preclude 21 cm intensity mapping.

\n
", "doi": "10.3847/1538-4357/ad3a6a", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2024-05-10", "series_number": "2", "volume": "966", "issue": "2", "pages": "221" }, { "id": "authors:41qvq-17579", "collection": "authors", "collection_id": "41qvq-17579", "cite_using_url": "https://authors.library.caltech.edu/records/41qvq-17579", "type": "article", "title": "Low-frequency Radio Recombination Lines Away from the Inner Galactic Plane", "author": [ { "family_name": "Vydula", "given_name": "Akshatha K.", "orcid": "0000-0002-6611-2668", "clpid": "Vydula-Akshatha-K" }, { "family_name": "Bowman", "given_name": "Judd D.", "orcid": "0000-0002-8475-2036", "clpid": "Bowman-Judd-D" }, { "family_name": "Lewis", "given_name": "David", "clpid": "Lewis-David" }, { "family_name": "Crawford", "given_name": "Kelsie", "clpid": "Crawford-Kelsie" }, { "family_name": "Kolopanis", "given_name": "Matthew", "orcid": "0000-0002-2950-2974", "clpid": "Kolopanis-Matthew" }, { "family_name": "Rogers", "given_name": "Alan E. E.", "orcid": "0000-0003-1941-7458", "clpid": "Rogers-Alan-E-E" }, { "family_name": "Murray", "given_name": "Steven G.", "orcid": "0000-0003-3059-3823", "clpid": "Murray-Steven-G" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Monsalve", "given_name": "Raul A.", "orcid": "0000-0002-3287-2327", "clpid": "Monsalve-Raul-A" }, { "family_name": "Sims", "given_name": "Peter", "orcid": "0000-0002-2871-0413", "clpid": "Sims-Peter" }, { "family_name": "Samson", "given_name": "Titu", "orcid": "0000-0001-5298-1478", "clpid": "Samson-Titu" } ], "abstract": "

Diffuse radio recombination lines (RRLs) in the Galaxy are possible foregrounds for redshifted 21 cm experiments. We use EDGES drift scans centered at \u221226.\u00b07 decl. to characterize diffuse RRLs across the southern sky. We find that RRLs averaged over the large antenna beam (72\u00b0 \u00d7 110\u00b0) reach minimum amplitudes of R.A. = 2\u20136 hr. In this region, the C\u03b1 absorption amplitude is 33 \u00b1 11 mK (1\u03c3) averaged over 50\u201387 MHz (27 \u2273 z \u2273 15 for the 21 cm line) and increases strongly as frequency decreases. C\u03b2 and H\u03b1 lines are consistent with no detection with amplitudes of 13 \u00b1 14 and 12 \u00b1 10 mK (1\u03c3), respectively. At 108\u2013124.5 MHz (z \u2248 11) in the same region, we find no evidence for carbon or hydrogen lines at the noise level of 3.4 mK (1\u03c3). Conservatively assuming that observed lines come broadly from the diffuse interstellar medium, as opposed to a few compact regions, these amplitudes provide upper limits on the intrinsic diffuse lines. The observations support expectations that Galactic RRLs can be neglected as significant foregrounds for a large region of sky until redshifted 21 cm experiments, particularly those targeting cosmic dawn, move beyond the detection phase. We fit models of the spectral dependence of the lines averaged over the large beam of EDGES, which may contain multiple line sources with possible line blending, and find that including degrees of freedom for expected smooth, frequency-dependent deviations from local thermodynamic equilibrium (LTE) is preferred over simple LTE assumptions for C\u03b1 and H\u03b1 lines. For C\u03b1 we estimate departure coefficients 0.79 <  b\u2099\u03b2\u2099 < 4.5 along the inner Galactic plane and 0 < b\u2099\u03b2\u2099 < 2.3 away from the inner Galactic plane.

", "doi": "10.3847/1538-3881/ad08ba", "issn": "0004-6256", "publisher": "American Astronomical Society", "publication": "Astronomical Journal", "publication_date": "2024-01", "series_number": "1", "volume": "167", "issue": "1", "pages": "2" }, { "id": "authors:vmpz9-tf498", "collection": "authors", "collection_id": "vmpz9-tf498", "cite_using_url": "https://authors.library.caltech.edu/records/vmpz9-tf498", "type": "article", "title": "Fitting and Comparing Galactic Foreground Models for Unbiased 21 cm Cosmology", "author": [ { "family_name": "Hibbard", "given_name": "Joshua J.", "orcid": "0000-0002-9377-5133", "clpid": "Hibbard-Joshua-J" }, { "family_name": "Rapetti", "given_name": "David", "orcid": "0000-0003-2196-6675", "clpid": "Rapetti-David" }, { "family_name": "Burns", "given_name": "Jack O.", "orcid": "0000-0002-4468-2117", "clpid": "Burns-Jack-O" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Bassett", "given_name": "Neil", "orcid": "0000-0001-7051-6385", "clpid": "Bassett-Neil" } ], "abstract": "

Accurate detection of the cosmological 21 cm global signal requires galactic foreground models that can remove power over 10\u2076. Although foreground and global signal models unavoidably exhibit overlap in their vector spaces inducing bias error in the extracted signal, a second source of bias and error arises from inadequate foreground models, i.e., models that cannot fit spectra down to the noise level of the signal. We therefore test the level to which seven commonly employed foreground models\u2014including nonlinear and linear forward models, polynomials, and maximally smooth polynomials\u2014fit realistic simulated mock foreground spectra, as well as their dependence upon model inputs. The mock spectra are synthesized for an EDGES-like experiment and we compare all models' goodness of fit and preference using a Kolmogorov\u2013Smirnov (K-S) test of the noise-normalized residuals in order to compare models with differing, and sometimes indeterminable, degrees of freedom. For a single local sidereal time (LST) bin spectrum and p-value threshold of p = 0.05, the nonlinear forward model with four parameters is preferred (p = 0.99), while the linear forward model fits well with six to seven parameters (p = 0.94, 0.97, respectively). The polynomials and maximally smooth polynomials, like those employed by the EDGES and SARAS3 experiments, cannot produce good fits with five parameters for the experimental simulations in this work (p < 10\u207b\u2076). However, we find that polynomials with six parameters pass the K-S test (p = 0.4), although a nine-parameter fit produces the highest p-value (p \u223c 0.67). When fitting multiple LST bins simultaneously, we find that the linear forward model outperforms (a higher p-value) the nonlinear model for 2, 5, and 10 LST bins. Importantly, the K-S test consistently identifies best-fit and preferred models.

", "doi": "10.3847/1538-4357/ad06b3", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2023-12-20", "series_number": "2", "volume": "959", "issue": "2", "pages": "103" }, { "id": "authors:07b4p-3br40", "collection": "authors", "collection_id": "07b4p-3br40", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230117-372591200.34", "type": "article", "title": "The Impact of Beam Variations on Power Spectrum Estimation for 21 cm Cosmology. I. Simulations of Foreground Contamination for HERA", "author": [ { "family_name": "Kim", "given_name": "Honggeun", "orcid": "0000-0001-5421-8927", "clpid": "Kim-Honggeun" }, { "family_name": "Nhan", "given_name": "Bang D.", "orcid": "0000-0001-5122-9997", "clpid": "Nhan-Bang-D" }, { "family_name": "Hewitt", "given_name": "Jacqueline N.", "orcid": "0000-0002-4117-570X", "clpid": "Hewitt-Jacqueline-N" }, { "family_name": "Kern", "given_name": "Nicholas S.", "orcid": "0000-0002-8211-1892", "clpid": "Kern-Nicholas-S" }, { "family_name": "Dillon", "given_name": "Joshua S.", "orcid": "0000-0003-3336-9958", "clpid": "Dillon-Joshua-S" }, { "family_name": "de Lera Acedo", "given_name": "Eloy", "orcid": "0000-0001-8530-6989", "clpid": "de-Lera-Acedo-Eloy" }, { "family_name": "Dynes", "given_name": "Scott B. C.", "orcid": "0000-0001-7010-0937", "clpid": "Dynes-Scott-B-C" }, { "family_name": "Mahesh", "given_name": "Nivedita", "orcid": "0000-0003-2560-8023", "clpid": "Mahesh-Nivedita" }, { "family_name": "Fagnoni", "given_name": "Nicolas", "orcid": "0000-0001-5300-3166", "clpid": "Fagnoni-Nicolas" }, { "family_name": "DeBoer", "given_name": "David R.", "orcid": "0000-0003-3197-2294", "clpid": "DeBoer-David-R" } ], "abstract": "Detecting cosmological signals from the Epoch of Reionization (EoR) requires high-precision calibration to isolate the cosmological signals from foreground emission. In radio interferometry, the perturbed primary beams of antenna elements can disrupt the precise calibration, which results in the contamination of the foreground-free region, or the EoR window, in the cylindrically averaged power spectrum. For the Hydrogen Epoch of Reionization Array (HERA), we simulate and characterize the perturbed primary beams that are induced by feed motions, such as axial, lateral, and tilting motions, above the 14 m dish. To understand the effect of the perturbed beams, visibility measurements are modeled with two different foreground components, point sources and diffuse sources, and we find that different feed motions present a different reaction to each type of sky source. HERA's redundant baseline calibration in the presence of nonredundant antenna beams due to feed motions introduces chromatic errors in the gain solutions, producing foreground power leakage into the EoR window. The observed leakage from the vertical feed motions comes predominantly from point sources around the zenith. Furthermore, the observed leakage from the horizontal and tilting feed motions comes predominantly from the diffuse components near the horizon. Mitigation of the chromatic gain errors will be necessary for robust detections of the EoR signals with minimal foreground bias, and this will be discussed in a subsequent paper.", "doi": "10.3847/1538-4357/ac9eaf", "issn": "0004-637X", "publisher": "American Astronomical Society", "publication": "Astrophysical Journal", "publication_date": "2022-12-20", "series_number": "2", "volume": "941", "issue": "2", "pages": "Art. No. 207" } ]