Source of Energetic Protons in the 2014 September 1 Sustained Gamma-ray Emission Event

Abstract

We report on the source of greater than 300 MeV protons during the SOL2014-09-01 sustained gamma-ray emission (SGRE) event based on multi-wavelength data from a wide array of space- and ground-based instruments. Based on the eruption geometry we provide concrete explanation for the spatially and temporally extended γ-ray emission from the eruption. We show that the associated flux rope is of low inclination (roughly oriented in the east-west direction), which enables the associated shock to extend to the frontside. We compare the centroid of the SGRE source with the location of the flux rope leg to infer that the high-energy protons must be precipitating between the flux rope leg and the shock front. The durations of the SOL2014-09-01 SGRE event and the type II radio burst agree with the linear relationship between these parameters obtained for other SGRE events with duration exceeding 3 hrs. The fluence spectrum of the SEP event is very hard, indicating the presence of high-energy (GeV) particles in this event. This is further confirmed by the presence of an energetic coronal mass ejection (CME) with a speed more than 2000 km/s, similar to those in ground level enhancement (GLE) events. The type II radio burst had emission components from metric to kilometric wavelengths as in events associated with GLE events. All these factors indicate that the high-energy particles from the shock were in sufficient numbers needed for the production of γ-rays via neutral pion decay.

arXiv comment39 pages, 14 figures, to appear in Solar Physics

References in corpus (27)

• The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission
• Properties and Geoeffectiveness of Magnetic Clouds during Solar Cycles 23 and 24
• High-Energy Gamma-Ray Emission From Solar Flares: Summary of Fermi LAT Detections and Analysis of Two M-Class Flares
• The First Ground Level Enhancement Event of Solar Cycle 24: Direct Observation of Shock Formation and Particle Release Heights
• Height of Shock Formation in the Solar Corona Inferred from Observations of Type II Radio Bursts and Coronal Mass Ejections
• The Strength and Radial Profile of Coronal Magnetic Field from the Standoff Distance of a CME-driven Shock
• Solar energetic particle events observed by the PAMELA mission
• Characteristics of Sustained >100 MeV Gamma-ray Emission Associated with Solar Flares
• Extreme Kinematics of the 2017 September 10 Solar Eruption and the Spectral Characteristics of the Associated Energetic Particles
• Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares
• First detection of >100 MeV gamma rays associated with a behind-the-limb solar flare
• On the detection of coronal dimmings and the extraction of their characteristic properties
• Coronal Flux Ropes and their Interplanetary Counterparts
• The 2012 July 23 Backside Eruption: An Extreme Energetic Particle Event?
• Estimation of a Coronal Mass Ejection Magnetic Field Strength using Radio Observations of Gyrosynchrotron Radiation
• Testing the Empirical Shock Arrival Model using Quadrature Observations
• The magnetic connectivity of coronal shocks from behind-the-limb flares to the visible solar surface during $\gamma$-ray events
• Soft X-ray Fluxes of Major Flares Far Behind the Limb as Estimated Using STEREO EUV Images
• Probing the Puzzle of Behind-the-Limb $\gamma$-ray Flares: Data-driven Simulations of Magnetic Connectivity and CME-driven Shock Evolution
• Comparing Long-Duration Gamma-Ray Flares and High-Energy Solar Energetic Particles
• Sun-to-Earth Propagation of the 2015 June 21 Coronal Mass Ejection Revealed by Optical, EUV, and Radio Observations
• Radio, Hard X-Ray, and Gamma-Ray Emissions Associated with a Far-Side Solar Event
• High-energy solar particle events in cycle 24
• A Statistical Study to Determine the Origin of Long-Duration Gamma-ray Flares
• On the Shock Source of Sustained Gamma-Ray Emission from the Sun
• A Simple Way to Estimate the Soft X-ray Class of Far-Side Solar Flares Observed with STEREO/EUVI
• The Relationship between Long-Duration Gamma-Ray Flares and Solar Cosmic Rays

Cited by in corpus (7)

• The coupling of an EUV coronal wave and ion acceleration in a Fermi-LAT behind-the-limb solar flare
• The Common Origin of High-energy Protons in Solar Energetic Particle Events and Sustained Gamma-ray Emission from the Sun
• Evidence for flare-accelerated particles in large scale loops in the behind-the-limb gamma-ray solar flare of September 29, 2022
• On the origin of hard X-ray emissions from the behind-the-limb flare on 2014 September 1
• The 2024 July 16 Solar Event: A Challenge To The Coronal Mass Ejection Origin Of Long-Duration Gamma-Ray Flares
• Relationship between solar energetic particle intensities and coronal mass ejection kinematics using STEREO/SECCHI field of view
• Role of CME clusters and CME-CME interactions in producing sustained $\gamma$-ray emission