TY - JOUR
T1 - Imaging spectroscopy of CME-associated solar radio bursts using OVRO-LWA
AU - Chhabra, Sherry
AU - Gary, Dale E.
AU - Hallinan, Gregg
AU - Anderson, Marin M.
AU - Chen, Bin
AU - Greenhill, Lincoln J.
AU - Price, Danny C.
N1 - Funding Information:
S.C. thanks Robin Colaninno and Angelos Vourlidas for their helpful discussions in understanding the CME morphology. S.C. also thanks Camilia Scolini for sharing her insights on the GCS reconstruction method. This work was supported in part by the NSF grants AST-1615807, AGS-1654382, and AST-19010354 and by NASA grants 80NSSC18K1128 and 80NSSC17K0660 to New Jersey Institute of Technology. G.H. acknowledges support by NSF grants AST-1654815, AST-1828784. L.G. acknowledges support by NSF grants PHY-0835713, OIA-1125087, AST-1106059 and AST-1616709. The CME catalog is generated and maintained at the CDAW Data Center by NASA and The Catholic University of America in cooperation with the Naval Research Laboratory. SOHO is a project of international cooperation between ESA and NASA.
Publisher Copyright:
© 2021. The American Astronomical Society.
PY - 2021/1/10
Y1 - 2021/1/10
N2 - We present the first results of a solar radio event observed with the Owens Valley Radio Observatory Long Wavelength Array at metric wavelengths. We examine a complex event consisting of multiple radio sources/bursts associated with a fast coronal mass ejection (CME) and an M2.1 GOES soft X-ray flare from 2015 September 20. Images of 9 s cadence are used to analyze the event over a 120 minute period, and solar emission is observed out to a distance of ≈3.5 Re, with an instantaneous bandwidth covering 22 MHz within the frequency range of 40-70 MHz. We present our results from the investigation of the radio event, focusing particularly on one burst source that exhibits outward motion, which we classify as a moving type IV burst. We image the event at multiple frequencies and use the source centroids to obtain the velocity for the outward motion. Spatial and temporal comparison with observations of the CME in white light from the C2 coronagraph of the Large Angle and Spectrometric COronagraph, indicates an association of the outward motion with the core of the CME. By performing graduated-cylindrical-shell reconstruction of the CME, we constrain the density in the volume. The electron plasma frequency obtained from the density estimates do not allow us to completely dismiss plasma emission as the underlying mechanism. However, based on source height and smoothness of the emission in frequency and time, we argue that gyrosynchrotron is the more plausible mechanism. We use gyrosynchrotron spectral-fitting techniques to estimate the evolving physical conditions during the outward motion of this burst source.
AB - We present the first results of a solar radio event observed with the Owens Valley Radio Observatory Long Wavelength Array at metric wavelengths. We examine a complex event consisting of multiple radio sources/bursts associated with a fast coronal mass ejection (CME) and an M2.1 GOES soft X-ray flare from 2015 September 20. Images of 9 s cadence are used to analyze the event over a 120 minute period, and solar emission is observed out to a distance of ≈3.5 Re, with an instantaneous bandwidth covering 22 MHz within the frequency range of 40-70 MHz. We present our results from the investigation of the radio event, focusing particularly on one burst source that exhibits outward motion, which we classify as a moving type IV burst. We image the event at multiple frequencies and use the source centroids to obtain the velocity for the outward motion. Spatial and temporal comparison with observations of the CME in white light from the C2 coronagraph of the Large Angle and Spectrometric COronagraph, indicates an association of the outward motion with the core of the CME. By performing graduated-cylindrical-shell reconstruction of the CME, we constrain the density in the volume. The electron plasma frequency obtained from the density estimates do not allow us to completely dismiss plasma emission as the underlying mechanism. However, based on source height and smoothness of the emission in frequency and time, we argue that gyrosynchrotron is the more plausible mechanism. We use gyrosynchrotron spectral-fitting techniques to estimate the evolving physical conditions during the outward motion of this burst source.
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U2 - 10.3847/1538-4357/abc94b
DO - 10.3847/1538-4357/abc94b
M3 - Article
AN - SCOPUS:85100312240
SN - 0004-637X
VL - 906
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - abc94b
ER -