[
{
"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
As wireless technology advances towards the sixth generation (6G), new and emerging applications require everincreasing data rates and capacity to match the demand. Generally, wireless receivers are developed with the theoretical background of an unbiased estimator that can maximize the posterior likelihood of the transmitted message (modulated symbols) based on the received signal impaired by the wireless channel. This method however is limited by theoretical channel capacity. In this work, we propose XPRT that can efficiently extract spatiotemporally invariant priors of the waveform that can be made available as common knowledge to all the receivers at the design stage without increasing any overhead during communication. This prior increases the probability of correct detection of transmit symbols -in a simpler term, it increases effective SNR. Consequently, higher modulation orders can be used without compromising the receiver accuracy, hence increasing throughput. We analyzed the equivalence of XPRT to an ideal receiver along with defining theoretical boundaries. Finally, we implemented XPRT for different waveforms over simulation with AWGN and multipath faded channel where we observed up to 2.2 dB improvement in received SNR at a reference BER of 10\u207b².
",
"doi": "10.1109/lwc.2025.3637081",
"issn": "2162-2337",
"publisher": "IEEE",
"publication": "IEEE Wireless Communications Letters",
"publication_date": "2025-12-18",
"volume": "15",
"pages": "690-694"
},
{
"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: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
\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
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: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
Approximately half of the Universe’s dark matter resides in collapsed halos; significantly less than half of the baryonic matter (protons and neutrons) remains confined to halos. A small fraction of baryons are in stars and the interstellar medium within galaxies. The majority are diffuse (<10−3 cm−3) and ionized (neutral fraction <10−4), located in the intergalactic medium (IGM) and in the halos of galaxy clusters, groups and galaxies. This diffuse ionized gas is notoriously difficult to measure, but has wide implications for galaxy formation, astrophysical feedback and precision cosmology. Recently, the dispersion of extragalactic fast radio bursts (FRBs) has been used to measure the total content of cosmic baryons. Here we present a large cosmological sample of FRB sources localized to their host galaxies. We have robustly partitioned the missing baryons into the IGM, galaxy clusters and galaxies, providing a late-Universe measurement of the cosmic baryon abundance, x03A9bh70 = 0.051^(+0.006)_(-0.006) where Ωb is the baryon density parameter and h70 is the scaled Hubble constant. Our results indicate efficient feedback processes that can deplete galaxy halos and enrich the IGM (total baryon fraction in the IGM is f_(IGM) = 0.76^(+0.10_(-0.11)), agreeing with the baryon-rich cosmic web scenario seen in cosmological simulations. Our results may reduce the ‘S8 tension’ in cosmology, as strong feedback leads to suppression of the matter power spectrum.
",
"doi": "10.1038/s41550-025-02566-y",
"issn": "2397-3366",
"publisher": "Nature Publishing Group",
"publication": "Nature Astronomy",
"publication_date": "2025-08",
"series_number": "8",
"volume": "9",
"issue": "8",
"pages": "1226-1239"
},
{
"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
\n
We present the Deep Synoptic Array (DSA-110) discovery and interferometric localization of the so far nonrepeating FRB 20220319D. The FRB originates in a young, rapidly star-forming barred spiral galaxy, IRAS 02044+7048, at just 50 Mpc. Although the NE2001 and YMW16 models for the Galactic interstellar-medium (ISM) contribution to the DM of FRB 20220319D exceed its total observed DM, we show that uncertainties in these models accommodate an extragalactic origin for the burst. We derive a conservative upper limit on the DM contributed by the circumgalactic medium (CGM) of the Milky Way of 47.3 pc cm−3, based on a pulsar nearby on the sky to FRB 20220319D that is used to estimate the ISM DM. This limit implies that the total Galactic CGM mass is <1011M\u2299, and that the baryonic mass of the Milky Way is \u227260% of the cosmological average given the total halo mass. More stringent albeit less conservative constraints are possible when the DMs of pulsars in the distant globular cluster M53 are additionally considered. Although our constraints are sensitive to possible anisotropy in the CGM and to the assumed form of the radial-density profile, they are not subject to uncertainties in the chemical and thermal properties of the CGM. Our results strongly support scenarios commonly predicted by galaxy-formation simulations wherein feedback processes expel baryonic matter from the halos of galaxies such as the Milky Way.
\n
\n
\n
Fast radio bursts (FRBs) are millisecond-duration events detected from beyond the Milky Way. FRB emission characteristics favour highly magnetized neutron stars, or magnetars, as the sources1, as evidenced by FRB-like bursts from a galactic magnetar2,3, and the star-forming nature of FRB host galaxies4,5. However, the processes that produce FRB sources remain unknown6. Although galactic magnetars are often linked to core-collapse supernovae (CCSNe)7, it is uncertain what determines which supernovae result in magnetars. The galactic environments of FRB sources can be used to investigate their progenitors. Here, we present the stellar population properties of 30 FRB host galaxies discovered by the Deep Synoptic Array (DSA-110). Our analysis shows a marked deficit of low-mass FRB hosts compared with the occurrence of star formation in the Universe, implying that FRBs are a biased tracer of star formation, preferentially selecting massive star-forming galaxies. This bias may be driven by galaxy metallicity, which is positively correlated with stellar mass8. Metal-rich environments may favour the formation of magnetar progenitors through stellar mergers9,10, as higher-metallicity stars are less compact and more likely to fill their Roche lobes, leading to unstable mass transfer. Although massive stars do not have convective interiors to generate strong magnetic fields by dynamo11, merger remnants are thought to have the requisite internal magnetic-field strengths to result in magnetars11,12. The preferential occurrence of FRBs in massive star-forming galaxies suggests that a core-collapse supernova of merger remnants preferentially forms magnetars.
\n
\n
\n
\n
We present an initial analysis of Radio Frequency Interference (RFI) flagging statistics from archived Australian SKA Pathfinder (ASKAP) observations for the ‘Survey and Monitoring of ASKAP’s RFI environment and Trends’ (SMART) project. SMART is a two-part observatoryled project combining analysis of archived observations with a dedicated, comprehensive RFI survey. The survey component covers ASKAP’s full 700–1 800 MHz frequency range, including bands not typically used due to severe RFI. Observations are underway to capture a detailed snapshot of the ASKAP RFI environment over representative 24 h periods. In addition to this dedicated survey, we routinely archive and analyse flagging statistics for all scientific observations to monitor the observatory’s RFI environment in near real-time. We use the telescope itself as a very sensitive RFI monitor and directly assess the fraction of scientific observations impacted by RFI. To this end, flag tables are now automatically ingested and aggregated as part of routine ASKAP operations for all science observations, as a function of frequency and time. The data presented in this paper come from processing all archived data for several ASKAP Survey Science Projects (SSPs). We found that the average amount of flagging due to RFI across the routinely used ‘clean’ continuum science bands is 3%. The ‘clean’ mid band from 1 293 to 1 437 MHz (excluding the 144 MHz below 1293 MHz impacted by radionavigation-satellites which is discarded before processing) is the least affected by RFI, followed by the ‘clean’ low band from 742 to 1 085 MHz. ASKAP SSPs lose most of their data to the mobile service in the low band, aeronautical service in the mid band and satellite navigation service in the 1 510–1 797 MHz high band. We also show that for some of these services, the percentage of discarded data has been increasing year-on-year. SMART provides a unique opportunity to study ASKAP’s changing RFI environment, including understanding and updating the default flagging behaviour, inferring the suitability of and calibrating RFI monitoring equipment, monitoring spectrum management compliance in the Australian Radio Quiet Zone – Western Australia (ARQZWA), and informing the implementation of a suite of RFI mitigation techniques.
\n
\n
Faraday rotation measures (RMs) of fast radio bursts (FRBs) offer the prospect of directly measuring extragalactic magnetic fields. We present an analysis of the RMs of 10 as yet nonrepeating FRBs detected and localized to host galaxies with robust redshift measurements by the 63-antenna prototype of the Deep Synoptic Array (DSA-110). We combine this sample with published RMs of 15 localized FRBs, nine of which are repeating sources. For each FRB in the combined sample, we estimate the host-galaxy dispersion measure (DM) contributions and extragalactic RM. We find compelling evidence that the extragalactic components of FRB RMs are often dominated by contributions from the host-galaxy interstellar medium (ISM). Specifically, we find that both repeating and as yet nonrepeating FRBs show a correlation between the host DM and host RM in the rest frame, and we find an anticorrelation between extragalactic RM (in the observer frame) and redshift for nonrepeaters, as expected if the magnetized plasma is in the host galaxy. Important exceptions to the ISM origin include a dense, magnetized circumburst medium in some repeating FRBs, and the intracluster medium of host or intervening galaxy clusters. We find that the estimated ISM magnetic-field strengths, B¯||, are characteristically ∼1–2 μG larger than those inferred from Galactic radio pulsars. This suggests either increased ISM magnetization in FRB hosts in comparison with the Milky Way, or that FRBs preferentially reside in regions of increased magnetic-field strength within their hosts.
",
"doi": "10.3847/2041-8213/ad0380",
"issn": "2041-8205",
"publisher": "American Astronomical Society",
"publication": "Astrophysical Journal Letters",
"publication_date": "2023-11-01",
"series_number": "1",
"volume": "957",
"issue": "1",
"pages": "L8"
},
{
"id": "authors:58npv-2p066",
"collection": "authors",
"collection_id": "58npv-2p066",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230705-704041500.10",
"type": "article",
"title": "Deep Synoptic Array Science: A Massive Elliptical Host Among Two Galaxy-cluster Fast Radio Bursts",
"author": [
{
"family_name": "Sharma",
"given_name": "Kritti",
"orcid": "0000-0002-4477-3625",
"clpid": "Sharma-Kritti"
},
{
"family_name": "Somalwar",
"given_name": "Jean",
"orcid": "0000-0001-8426-5732",
"clpid": "Somalwar-Jean-J"
},
{
"family_name": "Law",
"given_name": "Casey",
"orcid": "0000-0002-4119-9963",
"clpid": "Law-Casey-J"
},
{
"family_name": "Ravi",
"given_name": "Vikram",
"orcid": "0000-0002-7252-5485",
"clpid": "Ravi-Vikram"
},
{
"family_name": "Catha",
"given_name": "Morgan",
"clpid": "Catha-Morgan"
},
{
"family_name": "Chen",
"given_name": "Ge",
"orcid": "0000-0003-2867-4544",
"clpid": "Chen-Ge"
},
{
"family_name": "Connor",
"given_name": "Liam",
"orcid": "0000-0002-7587-6352",
"clpid": "Connor-Liam-D"
},
{
"family_name": "Faber",
"given_name": "Jakob T.",
"orcid": "0000-0001-9855-5781",
"clpid": "Faber-Jakob-T"
},
{
"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": "Hobbs",
"given_name": "Rick",
"clpid": "Hobbs-Rick"
},
{
"family_name": "Hodge",
"given_name": "David",
"clpid": "Hodge-David-C"
},
{
"family_name": "Hodges",
"given_name": "Mark",
"clpid": "Hodges-Mark-W"
},
{
"family_name": "Lamb",
"given_name": "James W.",
"orcid": "0000-0002-5959-1285",
"clpid": "Lamb-James-W"
},
{
"family_name": "Rasmussen",
"given_name": "Paul",
"clpid": "Rasmussen-Paul"
},
{
"family_name": "Sherman",
"given_name": "Myles B.",
"orcid": "0000-0002-6573-7316",
"clpid": "Sherman-Myles-B"
},
{
"family_name": "Shi",
"given_name": "Jun",
"orcid": "0000-0003-1647-7762",
"clpid": "Shi-Jun"
},
{
"family_name": "Simard",
"given_name": "Dana",
"orcid": "0000-0002-8873-8784",
"clpid": "Simard-Dana"
},
{
"family_name": "Squillace",
"given_name": "Reynier",
"orcid": "0000-0001-6748-5290",
"clpid": "Squillace-Reynier"
},
{
"family_name": "Weinreb",
"given_name": "Sander",
"orcid": "0000-0002-9353-6204",
"clpid": "Weinreb-Sander"
},
{
"family_name": "Woody",
"given_name": "David P.",
"clpid": "Woody-David-P"
},
{
"family_name": "Yadlapalli",
"given_name": "Nitika",
"orcid": "0000-0003-3255-4617",
"clpid": "Yadlapalli-Nitika"
},
{
"literal": "Deep Synoptic Array team"
}
],
"abstract": "The stellar population environments that are associated with fast radio burst (FRB) sources provide important insights for developing their progenitor theories. We expand the diversity of known FRB host environments by reporting two FRBs in massive galaxy clusters that were discovered by the Deep Synoptic Array (DSA-110) during its commissioning observations. FRB 20220914A has been localized to a star-forming, late-type galaxy at a redshift of 0.1139 with multiple starbursts at lookback times less than \u223c3.5 Gyr in the A2310 galaxy cluster. Although the host galaxy of FRB 20220914A is similar to typical FRB hosts, the FRB 20220509G host stands out as a quiescent, early-type galaxy at a redshift of 0.0894 in the A2311 galaxy cluster. The discovery of FRBs in both late- and early-type galaxies adds to the body of evidence that the FRB sources have multiple formation channels. Therefore, even though FRB hosts are typically star-forming, there must exist formation channels that are consistent with old stellar population in galaxies. The varied star formation histories of the two FRB hosts that we report here indicate a wide delay-time distribution of FRB progenitors. Future work in constraining the FRB delay-time distribution, using the methods that we develop herein, will prove crucial in determining the evolutionary histories of FRB sources.",
"doi": "10.3847/1538-4357/accf1d",
"issn": "0004-637X",
"publisher": "American Astronomical Society",
"publication": "Astrophysical Journal",
"publication_date": "2023-06-20",
"series_number": "2",
"volume": "950",
"issue": "2",
"pages": "Art. No. 175"
},
{
"id": "authors:y5as0-3fq51",
"collection": "authors",
"collection_id": "y5as0-3fq51",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230615-812788000.9",
"type": "article",
"title": "Deep Synoptic Array Science: Two Fast Radio Burst Sources in Massive Galaxy Clusters",
"author": [
{
"family_name": "Connor",
"given_name": "Liam",
"orcid": "0000-0002-7587-6352",
"clpid": "Connor-Liam-D"
},
{
"family_name": "Ravi",
"given_name": "Vikram",
"orcid": "0000-0002-7252-5485",
"clpid": "Ravi-Vikram"
},
{
"family_name": "Catha",
"given_name": "Morgan",
"clpid": "Catha-Morgan"
},
{
"family_name": "Chen",
"given_name": "Ge",
"orcid": "0000-0003-2867-4544",
"clpid": "Chen-Ge"
},
{
"family_name": "Faber",
"given_name": "Jakob T.",
"orcid": "0000-0001-9855-5781",
"clpid": "Faber-Jakob-T"
},
{
"family_name": "Lamb",
"given_name": "James W.",
"orcid": "0000-0002-5959-1285",
"clpid": "Lamb-James-W"
},
{
"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": "Hobbs",
"given_name": "Rick",
"clpid": "Hobbs-Rick"
},
{
"family_name": "Hodge",
"given_name": "David",
"clpid": "Hodge-David-C"
},
{
"family_name": "Hodges",
"given_name": "Mark",
"clpid": "Hodges-Mark-W"
},
{
"family_name": "Law",
"given_name": "Casey J.",
"orcid": "0000-0002-4119-9963",
"clpid": "Law-Casey-J"
},
{
"family_name": "Rasmussen",
"given_name": "Paul",
"clpid": "Rasmussen-Paul"
},
{
"family_name": "Sayers",
"given_name": "Jack",
"orcid": "0000-0002-8213-3784",
"clpid": "Sayers-Jack"
},
{
"family_name": "Sharma",
"given_name": "Kritti",
"orcid": "0000-0002-4477-3625",
"clpid": "Sharma-Kritti"
},
{
"family_name": "Sherman",
"given_name": "Myles B.",
"orcid": "0000-0002-6573-7316",
"clpid": "Sherman-Myles-B"
},
{
"family_name": "Shi",
"given_name": "Jun",
"orcid": "0000-0003-1647-7762",
"clpid": "Shi-Jun"
},
{
"family_name": "Simard",
"given_name": "Dana",
"orcid": "0000-0002-8873-8784",
"clpid": "Simard-Dana"
},
{
"family_name": "Somalwar",
"given_name": "Jean J.",
"orcid": "0000-0001-8426-5732",
"clpid": "Somalwar-Jean-J"
},
{
"family_name": "Squillace",
"given_name": "Reynier",
"orcid": "0000-0001-6748-5290",
"clpid": "Squillace-Reynier"
},
{
"family_name": "Weinreb",
"given_name": "Sander",
"orcid": "0000-0002-9353-6204",
"clpid": "Weinreb-Sander"
},
{
"family_name": "Woody",
"given_name": "David P.",
"clpid": "Woody-David-P"
},
{
"family_name": "Yadlapalli",
"given_name": "Nitika",
"orcid": "0000-0003-3255-4617",
"clpid": "Yadlapalli-Nitika"
}
],
"abstract": "The hot gas that constitutes the intracluster medium (ICM) has been studied at X-ray and millimeter/submillimeter wavelengths (Sunyaev\u2013Zel'dovich effect) for decades. Fast radio bursts (FRBs) offer an additional method of directly measuring the ICM and gas surrounding clusters via observables such as dispersion measure (DM) and Faraday rotation measure. We report the discovery of two FRB sources detected with the Deep Synoptic Array whose host galaxies belong to massive galaxy clusters. In both cases, the FRBs exhibit excess extragalactic DM, some of which likely originate in the ICM of their respective clusters. FRB 20220914A resides in the galaxy cluster A2310 at z = 0.1125 with a projected offset from the cluster center of 520 \u00b1 50 kpc. The host of a second source, FRB 20220509G, is an elliptical galaxy at z = 0.0894 that belongs to the galaxy cluster A2311 at the projected offset of 870 \u00b1 50 kpc. These sources represent the first time an FRB has been localized to a galaxy cluster. We combine our FRB data with archival X-ray, Sunyaev\u2013Zel'dovich (SZ), and optical observations of these clusters in order to infer properties of the ICM, including a measurement of gas temperature from DM and ySZ of 0.8\u20133.9 keV. We then compare our results to massive cluster halos from the IllustrisTNG simulation. Finally, we describe how large samples of localized FRBs from future surveys will constrain the ICM, particularly beyond the virial radius of clusters.",
"doi": "10.3847/2041-8213/acd3ea",
"issn": "2041-8205",
"publisher": "American Astronomical Society",
"publication": "Astrophysical Journal Letters",
"publication_date": "2023-06-01",
"series_number": "2",
"volume": "949",
"issue": "2",
"pages": "Art. No. L26"
},
{
"id": "authors:fcc49-b8736",
"collection": "authors",
"collection_id": "fcc49-b8736",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230628-332770500.8",
"type": "article",
"title": "Collaboration With Cellular Networks for RFI Cancellation at Radio Telescope",
"author": [
{
"family_name": "Chakraborty",
"given_name": "Shuvam",
"orcid": "0000-0003-2135-9277",
"clpid": "Chakraborty-Shuvam"
},
{
"family_name": "Hellbourg",
"given_name": "Gregory",
"orcid": "0000-0002-8191-3885",
"clpid": "Hellbourg-Gregory"
},
{
"family_name": "Careem",
"given_name": "Maqsood",
"orcid": "0000-0001-5586-9748",
"clpid": "Careem-Maqsood-A-A"
},
{
"family_name": "Saha",
"given_name": "Dola",
"orcid": "0000-0003-1219-575X",
"clpid": "Saha-Dola"
},
{
"family_name": "Dutta",
"given_name": "Aveek",
"orcid": "0000-0001-9364-0565",
"clpid": "Dutta-Aveek"
}
],
"abstract": "The growing need for electromagnetic spectrum to support the next generation (xG) communication networks increasingly generate unwanted radio frequency interference (RFI) in protected bands for radio astronomy. RFI is commonly mitigated at the Radio Telescope without any active collaboration with the interfering sources. In this work, we provide a method of signal characterization and its use in subsequent cancellation, that uses Eigenspaces derived from the telescope and the transmitter signals. This is different from conventional time-frequency domain analysis, which is limited to fixed characterizations (e.g., complex exponential in Fourier methods) that cannot adapt to the changing statistics (e.g., autocorrelation) of the RFI, typically observed in communication systems. We have presented effectiveness of this collaborative method using real-world astronomical signals and practical simulated LTE signals (downlink and uplink) as source of RFI along with propagation conditions based on preset benchmarks and standards. Through our analysis and simulation using these signals, we are able to remove 89.04% of the RFI from cellular networks, which reduces excision at the Telescope and is capable of significantly improving throughput as corrupted time-frequency bins of data become usable.",
"doi": "10.1109/tccn.2023.3242360",
"issn": "2332-7731",
"publisher": "IEEE",
"publication": "IEEE Transactions on Cognitive Communications and Networking",
"publication_date": "2023-06",
"series_number": "3",
"volume": "9",
"issue": "3",
"pages": "765-778"
},
{
"id": "authors:007av-e5z32",
"collection": "authors",
"collection_id": "007av-e5z32",
"cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230607-125641600.2",
"type": "article",
"title": "Deep Synoptic Array Science: Discovery of the Host Galaxy of FRB 20220912A",
"author": [
{
"family_name": "Ravi",
"given_name": "Vikram",
"orcid": "0000-0002-7252-5485",
"clpid": "Ravi-Vikram"
},
{
"family_name": "Catha",
"given_name": "Morgan",
"clpid": "Catha-Morgan"
},
{
"family_name": "Chen",
"given_name": "Ge",
"orcid": "0000-0003-2867-4544",
"clpid": "Chen-Ge"
},
{
"family_name": "Connor",
"given_name": "Liam",
"orcid": "0000-0002-7587-6352",
"clpid": "Connor-Liam-D"
},
{
"family_name": "Faber",
"given_name": "Jakob T.",
"orcid": "0000-0001-9855-5781",
"clpid": "Faber-Jakob-T"
},
{
"family_name": "Lamb",
"given_name": "James W.",
"orcid": "0000-0002-5959-1285",
"clpid": "Lamb-James-W"
},
{
"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": "Hobbs",
"given_name": "Rick",
"clpid": "Hobbs-Rick"
},
{
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{
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{
"family_name": "Woody",
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{
"family_name": "Yadlapalli",
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{
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{
"family_name": "Dong",
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{
"family_name": "Fremling",
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{
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{
"family_name": "Karambelkar",
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{
"family_name": "Miller",
"given_name": "Jessie M.",
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{
"literal": "Deep Synoptic Array team"
}
],
"abstract": "We report the detection and interferometric localization of the repeating fast radio burst (FRB) source FRB 20220912A during commissioning observations with the Deep Synoptic Array (DSA-110). Two bursts were detected from FRB 20220912A, one each on 2022 October 18 and 2022 October 25. The best-fit position is (R.A. J2000, decl. J2000) = (23:09:04.9, +48:42:25.4), with a 90% confidence error ellipse with radii \u00b12\u2033 and \u00b11\u2033 in R.A. and decl., respectively. The two bursts are polarized, and we find a Faraday rotation measure that is consistent with the low value of +0.6 rad m\u207b\u00b2 reported by CHIME/FRB. The DSA-110 localization overlaps with the galaxy PSO J347.2702+48.7066 at a redshift z = 0.0771, which we identify as the likely host. PSO J347.2702+48.7066 has a stellar mass of approximately 10\u00b9\u2070 M_\u2299, modest internal dust extinction, and a star formation rate likely in excess of 0.1 M_\u2299 yr\u207b\u00b9. The host-galaxy contribution to the dispersion measure is likely \u227250 pc cm\u207b\u00b3. The FRB 20220912A source is therefore likely viewed along a tenuous plasma column through the host galaxy.",
"doi": "10.3847/2041-8213/acc4b6",
"issn": "2041-8205",
"publisher": "American Astronomical Society",
"publication": "Astrophysical Journal Letters",
"publication_date": "2023-05-20",
"series_number": "1",
"volume": "949",
"issue": "1",
"pages": "Art. No. L3"
}
]