English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The sustained gamma-ray emission (SGRE) events from the Sun are associatedwith an ultrafast (2000 km/s or greater) halo coronal mass ejection (CME) and atype II radio burst in the decameter-hectometric (DH) wavelengths. The SGREduration is linearly related to the type II burst duration indicating that >300MeV protons required for SGREs are accelerated by the same shock thataccelerates tens of keV electrons that produce type II bursts. Whenmagnetically well connected, the associated solar energetic particle (SEP)event has a hard spectrum, indicating copious acceleration of high-energyprotons. In one of the SGRE events observed on 2014 January 7 by Fermi/LAT, theSEP event detected by GOES has a very soft spectrum with not many particlesbeyond 100 MeV. This contradicts the presence of the SGRE, implying thepresence of significant number of >300 MeV protons. Furthermore, the durationsof the type II burst and the SGRE agree with the known linear relationshipbetween them (Gopalswamy et al. 2018, ApJ 868, L19). We show that the softspectrum is due to poor magnetic connectivity of the shock nose to an Earthobserver. Even though the location of the eruption (S15W11) is close to thedisk center, the CME propagated non-radially making the CME flank crossing theecliptic rather than the nose. High-energy particles are accelerated near thenose, so they do not reach GOES but they do precipitate to the vicinity of theeruption region to produce SGRE. This study provides further evidence that SGREis caused by protons accelerated in shocks and propagating sunward to interactwith the atmospheric ions.

Particle Acceleration and Transport at the Sun Inferred from Fermi/LAT Observations of >100 MeV Gamma-rays