Deciphering Faint Gyrosynchrotron Emission from Coronal Mass Ejection using Spectro-polarimetric Radio Imaging

Abstract

Measurements of the plasma parameters of coronal mass ejections (CMEs), particularly the magnetic field and nonthermal electron population entrained in the CME plasma, are crucial to understand their propagation, evolution, and geo-effectiveness. Spectral modeling of gyrosynchrotron (GS) emission from CME plasma has been regarded as one of the most promising remote-sensing techniques for estimating spatially resolved CME plasma parameters. Imaging the very low flux density CME GS emission in close proximity to the Sun with orders of magnitude higher flux density has, however, proven to be rather challenging. This challenge has only recently been met using the high dynamic range imaging capability of the Murchison Widefield Array (MWA). Although routine detection of GS is now within reach, the challenge has shifted to constraining the large number of free parameters in GS models, a few of which are degenerate, using the limited number of spectral points at which the observations are typically available. These degeneracies can be broken using polarimetric imaging. For the first time, we demonstrate this using our recently developed capability of high-fidelity polarimetric imaging on the data from the MWA. We show that spectropolarimetric imaging, even when only sensitive upper limits on circularly polarization flux density are available, is not only able to break the degeneracies but also yields tighter constraints on the plasma parameters of key interest than possible with total intensity spectroscopic imaging alone.

arXiv commentPublished at the Astrophysical Journal (23 pages, 15 figures, 3 tables)

References in corpus (39)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• emcee: The MCMC Hammer
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The Murchison Widefield Array: the Square Kilometre Array Precursor at low radio frequencies
• CASA, the Common Astronomy Software Applications for Radio Astronomy
• The Murchison Widefield Array: Design Overview
• The Phase II Murchison Widefield Array: Design Overview
• Solar-MACH: An open-source tool to analyze solar magnetic connection configurations
• The Strength and Radial Profile of Coronal Magnetic Field from the Standoff Distance of a CME-driven Shock
• Constraining the intergalactic medium at $z\approx$ 9.1 using LOFAR Epoch of Reionization observations
• Quantifying errors in 3D CME parameters derived from synthetic data using white-light reconstruction techniques
• Interpreting LOFAR 21-cm signal upper limits at z~9.1 in the context of high-z galaxy and reionisation observations
• An all-sky survey of circular polarisation at 200 MHz
• Exploring reionisation and high-z galaxy observables with recent multi-redshift MWA upper limits on the 21-cm signal
• Estimation of a Coronal Mass Ejection Magnetic Field Strength using Radio Observations of Gyrosynchrotron Radiation
• Radio Spectral Evolution of an X-ray Poor Impulsive Solar Flare: Implications for Plasma Heating and Electron Acceleration
• Astrophysical Constraints from the SARAS3 non-detection of the Cosmic Dawn Sky-Averaged 21-cm Signal
• The gas mass of star-forming galaxies at $z\approx 1.3$
• An estimate of the magnetic field strength associated with a solar coronal mass ejection from low frequency radio observations
• Strength of the Solar Coronal Magnetic field - A Comparison of Independent Estimates Using Contemporaneous Radio and White-light Observations
• Astrophysical constraints on massive black hole binary evolution from Pulsar Timing Arrays
• Estimation of the physical parameters of a CME at high coronal heights using low frequency radio observations
• A Giant Metrewave Radio Telescope search for associated HI 21cm absorption in high-redshift flat-spectrum sources
• A search for circularly polarised emission from young exoplanets
• Constraints on Stellar Flare Energy Ratios in the NUV and Optical From a Multiwavelength Study of GALEX and Kepler Flare Stars
• Unsupervised generation of high dynamic range solar images: A novel algorithm for self-calibration of interferometry data
• Ultimate Fast Gyrosynchrotron Codes
• Probing the thermal history during reionization using a semi-numerical photon-conserving code SCRIPT
• Constraining the reionization and thermal history of the Universe using a semi-numerical photon-conserving code SCRIPT
• Tackling the Unique Challenges of Low-frequency Solar Polarimetry with the Square Kilometre Array Low Precursor: The Algorithm
• Imaging Spectroscopy of CME-Associated Solar Radio Bursts
• A Pilot Radio Search for Magnetic Activity in Directly Imaged Exoplanets
• Gyrosynchrotron emission generated by nonthermal electrons with energy spectra of a broken power law
• Working Principle of the Calibration Algorithm for High Dynamic Range Solar Imaging with Square Kilometre Array Precursor
• Robust absolute solar flux density calibration for the Murchison Widefield Array
• Tackling the Unique Challenges of Low-frequency Solar Polarimetry with the Square Kilometre Array Low Precursor: Pipeline Implementation
• New results on the direct observations of thermal radio emission from a solar coronal mass ejection
• A new constraint on the molecular oxygen abundance at $z\sim 0.886$

Cited by in corpus (3)

• Spectropolarimetric Radio Imaging of Faint Gyrosynchrotron Emission from a CME : A Possible Indication of the Insufficiency of Homogeneous Models
• Solar Observation with MeerKAT: Demonstration of Technical Readiness and Initial Science Highlight
• Possible First Detection of Gyroresonance Emission from a Coronal Mass Ejection in the Middle Corona