Conveners
Working Group 3: Ion studies and Fermi/LAT
- Alexandra Lysenko (Ioffe Institute, St. Petersburg, Russian Federation)
- Melissa Pesce-Rollins (PI)
Description
Over the past 12 years, Fermi-LAT observations of high-energy solar flares have revealed an extremely rich and diverse sample of events with a wide variety of characteristics providing valuable information on accelerated ions. In order to fully understand the acceleration mechanisms at work during these flares it is imperative to combine gamma-ray observations with the observations of the UV/optical/IR/radio counterparts as well as the frequently accompanying CMEs and SEPs. Although there are space-based observatories in high energy range operating at present, every instrument has its own limitations, thus it is also important to understand what new observations are needed and to develop requirements for potential future instrumental capabilities. This working group invites contributions relating to solar flares observed in gamma-ray range by Fermi-LAT and other instruments and their connection with multiwavelength counterparts, theory/modeling of the acceleration processes associated with these flares. Also contributions on new instrumentation requirements in gamma-ray range are welcomed.
NOTE: The times and duration of each talk are the true times and duration of the talks for this session.
As well as their gamma-ray signatures, energetic flare ions at the Sun also produce hard X-rays (HXRs) by various mechanisms. Compton scattering of gamma-ray photons was recently studied by Murphy and Share and proton bremsstrahlung by Heristchi and others. Further bremsstrahlung contributions come from secondary electrons (and positrons) produced via pion decay and also as knock-on products...
We have updated the nuclear templates used in our fits to gamma-ray spectra and have corrected a systematic that we found in SMM/GRS data. We have now fit spectra from 19 SMM flare and 1 RHESSI flare clearly separating nuclear lines and continua from electron continua. We discuss these fits and information derived on the ambient composition of the solar atmosphere where the flare-accelerated...
We discuss RHESSI observations of the 2005 January 20 flare that revealed Late Phase Gamma-Ray Emission extending for several hours after the impulsive flare.
Hanna et al. (2010) show the 3-200 keV spectrum of the total Sun observed by RHESSI during the
quiet phase of the Sun from 2005 to 2009. A possible source of this radiation could be synchrotron
emission by Cosmic Ray Electrons (CRes). I will present results from a preliminary exploration of
this model. Several near Earth instruments have observed CRe spectra at 1 AU during quiet and...
We use background-subtracted spectra from Fermi GBM to separate electron and ion components of the impulsive phase of the 2017 September 10 solar flare. This phase is distinct from the Late Phase Gamma Ray Emission (LPGRE) that peaks at 16:00 UT that is explained by CME shock acceleration of protons onto field lines returning to the Sun (Kouloumvakos,et al. 2020). We show evidence for...
Monte Carlo codes are used in many fields to study energetic particle propagation, secondary production and radiation. They can thus be useful tools for interpreting flare gamma-rays and drawing conclusions about energetic ions at the Sun. In magnetised plasmas such as those found in solar active regions. The enormous disparity between particle gyroradii and system scales proves to be a major...
The modelling of gamma-ray emission spectra observed in solar flares is
generally carried out via the best-fit of data using a set of independent
templates and functions for the several spectral components produced by the
relevant physical processes (bremsstrahlung of electrons and positrons, nuclear
de-excitation, neutron capture, positron annihilation and decay of pions). In
recent works...
It is commonly accepted that impulsive solar eruptions (flares/CMEs) and more gradually-evolving energetic processes (coronal heating, solar wind outflows) are powered by the Sun's complex coronal magnetic field. However, despite many decades of research, it is still poorly understood exactly how magnetic energy is stored and impulsively released to power plasma heating, particle acceleration,...
