STIX workshop

Session

Session 4

22 Jul 2026, 16:00

DIAS Burlington Road

7. From C-class to X-class: investigating efficient particle acceleration in Fermi/LAT gamma-ray solar flares

Andrea F. Battaglia (IRSOL)

22/07/2026, 16:00

Particle acceleration and nonthermal diagnostics

Talk

We present solar flares with gamma-ray emission observed by Fermi/LAT to investigate efficient particle acceleration during magnetic reconnection. We analyze these events using Fermi/LAT data combined with imaging in HXRs (Solar Orbiter/STIX and ASO-S/HXI), EUV (SDO/AIA), and white light (SDO/HMI and ASO-S/WST). First, we report the smallest Fermi/LAT solar flare to date, which is the first...

5. Non-thermal emission in failed filament eruptions

Song Tan (Leibniz Institute for Astrophysics Potsdam (AIP))

22/07/2026, 16:30

Particle acceleration and nonthermal diagnostics

Talk

Solar flare hard X-ray (HXR) emission is conventionally interpreted within a thin-target / thick-target dichotomy, corresponding to coronal looptop and chromospheric footpoint sources respectively. Solar filaments, with characteristic densities of 10e10–10e11cme−3, occupy an intermediate density regime that fits neither limit. Motivated by this gap, we examine two failed filament eruptions in...

14. HXR observations at flux rope anchor points evidenced by magnetic field extrapolations

Muriel Zoë Stiefel (FHNW & ETHZ)

22/07/2026, 17:00

Particle acceleration and nonthermal diagnostics

Talk

We present recent results on the X9-class flare on October 3rd 2024. STIX analysis shows the existence of multiple HXR sources during the impulsive phase of the flare. Combining HXR analysis with other wavelength observations, coronal dimming studies, and magnetic field extrapolations, we provide strong observational evidence that the outer HXR sources originate from the anchor points of an...

8. Search for signatures of nonthermal collisions in optical spectropolarimetry: combined STIX and IRSOL/ZIMPOL flare observations

Andrea F. Battaglia (IRSOL)

22/07/2026, 17:30

Open questions in high-energy solar flare physics

Talk

The existence of linear polarization due to the impact of flare-accelerated particles with the lower atmosphere, known as impact polarization, has been a long-debated question. Although theories predict this phenomenon, convincing observational evidence has remained elusive. In the past, the H-alpha line has been used to search for impact polarization, but no convincing signature has been...