| Author(s) and Co-Author(s) with Affiliation: Surajit Mondal(National Centre for Radio Astrophysics, Tata Institute of Fundamental Research), Shaheda Begum Shaik(George Mason University), Russell Alfred Howard(Johns Hopkins University Applied Physics Laboratory), Peijin Zhang(New Jersey Institute of Technology), Bin Chen(New Jersey Institute of Technology), Xingyao Chen(New Jersey Institute of Technology), Sijie Yu(New Jersey Institute of Technology), Dale Gary(New Jersey Institute of Technology), Marin Anderson(Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91011, USA), Judd Bowman(Arizona State University), Ruby Byrne(California Institute of Technology), Morgan Catha(California Institute of Technology), Sherry Chhabra(George Mason University), Larry R D addario(California Institute of Technology), Ivey Davis(California Institute of Technology), Jayce D Dowell(University of New Mexico), Gregg Hallinan(California Institute of Technology), Charlie Harnach(California Institute of Technology), Gregory Hellbourg(California Institute of Technology), Jack Hickish(University of California, Berkeley), Rick Hobbs(California Institute of Technology), David Hodge(California Institute of Technology), Mark Hodges(California Institute of Technology), Andrea Isella(Rice University), Daniel C Jacobs(Arizona State University), Ghislain Kemby(California Institute of Technology), John Klinefelter(California Institute of Technology), Matthew Kolopanis(School of Earth and Space Exploration, Arizona State University, Tempe, AZ), Nikita Kosogorov(California Institute of Technology), James Lamb(California Institute of Technology), Casey J. Law(California Institute of Technology), Nivedita Mahesh(California Institute of Technology), Brian E O Donnell(New Jersey Institute of Technology), Yuping Huang(California Institute of Technology), Kathryn Plant(Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91011, USA), Corey Posner(California Institute of Technology), Travis Powell(California Institute of Technology), Vinand Prayag(California Institute of Technology), Andres Rizo(California Institute of Technology), OVRO LWA team(OVRO-LWA team) |
| Abstract: Decades of solar observations have provided significant evidence for the presence nonthermal particles in the corona. In most cases, the site of particle acceleration can be approximately identified by combining high spatial and temporal resolution data from multiple instruments across a broad frequency range. Practically in all cases, these nonthermal particles are associated with quiescent active regions, flares, and coronal mass ejections (CMEs). Only recently, there has been some reports on the detection of nonthermal emission at locations outside these well-accepted regions. These emissions, now known as Weak Impulsive Narrowband Quiet Sun Emissions, were detected at heliocentric distances of approximately 1.2-1.5 solar radii. Here, we report for the first time multiple cases of transient nonthermal emissions, at much higher coronal heights, in the heliocentric range of ∼3–7 solar radii. These emissions 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.
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