ON THE POSSIBLE MECHANISMS OF TWO GROUND-LEVEL ENHANCEMENT EVENTS

Journal Article · Tue Dec 20 04:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/743/2/190· OSTI ID:22004379

Firoz, Kazi A; Islam, Jamal N ^[1]; Moon, Y -J ^[2]; Park, S -H ^[3]; Kudela, K ^[4]; Dorman, Lev I ^[5]

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1. Research Centre for Mathematical and Physical Sciences, University of Chittagong, 4331 Chittagong (Bangladesh)
2. School of Space Research, Kyung Hee University, 446-701 yongin-si Gyeonggi-do (Korea, Republic of)
3. Solar and Space Weather Research Group, Korea Astronomy and Space Science Institute, 305-348 Daejeon (Korea, Republic of)
4. Institute of Experimental Physics, Slovak Academy of Sciences, 04001 Kosice (Slovakia)
5. Cosmic Ray Department, Russian Academy of Sciences, N. V. Pushkov IZMIRAN, Troitsk 142190, Moscow (Russian Federation)

We have carried out a case study on the possible mechanism of ground-level enhancement (GLE) occurrence. For this, we have considered two GLE events (GLE69 and GLE70) and scrutinized their relationships with simultaneous soft/hard X-rays as well as solar energetic particle (SEP) fluxes of different energy bands. Although most of the energy bands of the flares maintain strong correlations (r {>=} 0.8) with the GLEs, depending only on this evidence we could not precisely imply that GLEs can be caused by solar flares. So, we have attempted to understand possible relativistic energies of the GLEs, which have been determined by availing the relativistic traversing time and velocities of the particles along the nominal path of Archimedean spiral magnetic field lines. Results suggest that the energy released from accelerated particles in high-energy ({gamma}-ray) solar flares might sometimes cause the GLE. We found that during hard X-ray flares {<=}7 MeV, the relativistic energy ({<=}0.23 GeV) of GLE69 was much less than 1 GeV whereas during SEP flares >30 MeV the possible relativistic energy of GLE69 amounts to {approx}2.78 GeV, and this makes us believe that GLE69 might be caused by the energy released from particle accelerations in high-energy solar flares. On the contrary, during hard X-ray ({<=}7 MeV) as well as {gamma}-ray solar flares (>30 MeV) the relativistic energy of GLE70 amounts to {<=}{approx}0.35 GeV, indicating that the GLE70 was presumably not caused by the released energy from accelerated particles in the solar flare. Alternatively, the released energy from particle accelerations in solar radio emission type II burst concomitant coronal-mass-ejection-driven shocks seems to have been responsible for causing the GLE70.

• OSTI ID: 22004379
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 743; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
GAMMA RADIATION
HARD X RADIATION
MAGNETIC FIELDS
RELATIVISTIC RANGE
SOLAR FLARES
SUN