Comparing long-duration gamma-ray flares and high-energy solar energetic particles

G. A. De Nolfo, A. Bruno, J. M. Ryan, S. Dalla, J. Giacalone, I. G. Richardson, E. R. Christian, S. J. Stochaj, G. A. Bazilevskaya, M. Boezio, M. Martucci, V. V. Mikhailov, R. Munini

Research output: Contribution to journalArticle

Abstract

Little is known about the origin of the high-energy and sustained emission from solar long-duration gamma-ray flares (LDGRFs) identified with the Compton Gamma Ray Observatory, the Solar Maximum Mission, and now Fermi. Though the Fermi Large Area Telescope (LAT) has identified dozens of flares with LDGRF signatures, the nature of this phenomenon has been a challenge to explain due to both extreme energies and long durations. The highest-energy emission has generally been attributed to pion production from the interaction of ⪆300 MeV protons with the ambient matter. The extended duration suggests that particle acceleration occurs over large volumes extending high in the corona, either from stochastic acceleration within large coronal loops or from back precipitation from coronal mass ejection-driven shocks. It is possible to test these models by making a direct comparison between the properties of the accelerated ion population producing the γ-ray emission derived from the Fermi/LAT observations and the characteristics of solar energetic particles (SEPs) measured by the Payload for Matter-Antimatter Exploration and Light Nuclei Astrophysics spacecraft in the energy range corresponding to the pion-related emission detected with Fermi. For 14 of these events, we compare the two populations - SEPs in space and the interacting particles at the Sun - and discuss the implications in terms of potential sources. Our analysis shows that the two proton numbers are poorly correlated, with their ratio spanning more than 5 orders of magnitude, suggesting that the back precipitation of shock-acceleration particles is unlikely to be the source of the LDGRF emission.

Original languageEnglish (US)
Article number90
JournalAstrophysical Journal
Volume879
Issue number2
DOIs
StatePublished - Jul 10 2019

Fingerprint

solar energy
energetic particles
flares
energetics
gamma rays
particle acceleration
energy
pions
shock
Solar Maximum Mission
telescopes
Gamma Ray Observatory
antimatter
coronal loops
protons
astrophysics
coronal mass ejection
payloads
model test
coronas

Keywords

  • Earth
  • Sun: coronal mass ejections (CMEs)
  • Sun: flares
  • Sun: heliosphere
  • Sun: particle emission
  • Sun: X-rays, gamma-rays

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

De Nolfo, G. A., Bruno, A., Ryan, J. M., Dalla, S., Giacalone, J., Richardson, I. G., ... Munini, R. (2019). Comparing long-duration gamma-ray flares and high-energy solar energetic particles. Astrophysical Journal, 879(2), [90]. https://doi.org/10.3847/1538-4357/ab258f

Comparing long-duration gamma-ray flares and high-energy solar energetic particles. / De Nolfo, G. A.; Bruno, A.; Ryan, J. M.; Dalla, S.; Giacalone, J.; Richardson, I. G.; Christian, E. R.; Stochaj, S. J.; Bazilevskaya, G. A.; Boezio, M.; Martucci, M.; Mikhailov, V. V.; Munini, R.

In: Astrophysical Journal, Vol. 879, No. 2, 90, 10.07.2019.

Research output: Contribution to journalArticle

De Nolfo, GA, Bruno, A, Ryan, JM, Dalla, S, Giacalone, J, Richardson, IG, Christian, ER, Stochaj, SJ, Bazilevskaya, GA, Boezio, M, Martucci, M, Mikhailov, VV & Munini, R 2019, 'Comparing long-duration gamma-ray flares and high-energy solar energetic particles', Astrophysical Journal, vol. 879, no. 2, 90. https://doi.org/10.3847/1538-4357/ab258f
De Nolfo, G. A. ; Bruno, A. ; Ryan, J. M. ; Dalla, S. ; Giacalone, J. ; Richardson, I. G. ; Christian, E. R. ; Stochaj, S. J. ; Bazilevskaya, G. A. ; Boezio, M. ; Martucci, M. ; Mikhailov, V. V. ; Munini, R. / Comparing long-duration gamma-ray flares and high-energy solar energetic particles. In: Astrophysical Journal. 2019 ; Vol. 879, No. 2.
@article{9c6af93b8c7a43f6b26d379a939b9c1e,
title = "Comparing long-duration gamma-ray flares and high-energy solar energetic particles",
abstract = "Little is known about the origin of the high-energy and sustained emission from solar long-duration gamma-ray flares (LDGRFs) identified with the Compton Gamma Ray Observatory, the Solar Maximum Mission, and now Fermi. Though the Fermi Large Area Telescope (LAT) has identified dozens of flares with LDGRF signatures, the nature of this phenomenon has been a challenge to explain due to both extreme energies and long durations. The highest-energy emission has generally been attributed to pion production from the interaction of ⪆300 MeV protons with the ambient matter. The extended duration suggests that particle acceleration occurs over large volumes extending high in the corona, either from stochastic acceleration within large coronal loops or from back precipitation from coronal mass ejection-driven shocks. It is possible to test these models by making a direct comparison between the properties of the accelerated ion population producing the γ-ray emission derived from the Fermi/LAT observations and the characteristics of solar energetic particles (SEPs) measured by the Payload for Matter-Antimatter Exploration and Light Nuclei Astrophysics spacecraft in the energy range corresponding to the pion-related emission detected with Fermi. For 14 of these events, we compare the two populations - SEPs in space and the interacting particles at the Sun - and discuss the implications in terms of potential sources. Our analysis shows that the two proton numbers are poorly correlated, with their ratio spanning more than 5 orders of magnitude, suggesting that the back precipitation of shock-acceleration particles is unlikely to be the source of the LDGRF emission.",
keywords = "Earth, Sun: coronal mass ejections (CMEs), Sun: flares, Sun: heliosphere, Sun: particle emission, Sun: X-rays, gamma-rays",
author = "{De Nolfo}, {G. A.} and A. Bruno and Ryan, {J. M.} and S. Dalla and J. Giacalone and Richardson, {I. G.} and Christian, {E. R.} and Stochaj, {S. J.} and Bazilevskaya, {G. A.} and M. Boezio and M. Martucci and Mikhailov, {V. V.} and R. Munini",
year = "2019",
month = "7",
day = "10",
doi = "10.3847/1538-4357/ab258f",
language = "English (US)",
volume = "879",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2",

}

TY - JOUR

T1 - Comparing long-duration gamma-ray flares and high-energy solar energetic particles

AU - De Nolfo, G. A.

AU - Bruno, A.

AU - Ryan, J. M.

AU - Dalla, S.

AU - Giacalone, J.

AU - Richardson, I. G.

AU - Christian, E. R.

AU - Stochaj, S. J.

AU - Bazilevskaya, G. A.

AU - Boezio, M.

AU - Martucci, M.

AU - Mikhailov, V. V.

AU - Munini, R.

PY - 2019/7/10

Y1 - 2019/7/10

N2 - Little is known about the origin of the high-energy and sustained emission from solar long-duration gamma-ray flares (LDGRFs) identified with the Compton Gamma Ray Observatory, the Solar Maximum Mission, and now Fermi. Though the Fermi Large Area Telescope (LAT) has identified dozens of flares with LDGRF signatures, the nature of this phenomenon has been a challenge to explain due to both extreme energies and long durations. The highest-energy emission has generally been attributed to pion production from the interaction of ⪆300 MeV protons with the ambient matter. The extended duration suggests that particle acceleration occurs over large volumes extending high in the corona, either from stochastic acceleration within large coronal loops or from back precipitation from coronal mass ejection-driven shocks. It is possible to test these models by making a direct comparison between the properties of the accelerated ion population producing the γ-ray emission derived from the Fermi/LAT observations and the characteristics of solar energetic particles (SEPs) measured by the Payload for Matter-Antimatter Exploration and Light Nuclei Astrophysics spacecraft in the energy range corresponding to the pion-related emission detected with Fermi. For 14 of these events, we compare the two populations - SEPs in space and the interacting particles at the Sun - and discuss the implications in terms of potential sources. Our analysis shows that the two proton numbers are poorly correlated, with their ratio spanning more than 5 orders of magnitude, suggesting that the back precipitation of shock-acceleration particles is unlikely to be the source of the LDGRF emission.

AB - Little is known about the origin of the high-energy and sustained emission from solar long-duration gamma-ray flares (LDGRFs) identified with the Compton Gamma Ray Observatory, the Solar Maximum Mission, and now Fermi. Though the Fermi Large Area Telescope (LAT) has identified dozens of flares with LDGRF signatures, the nature of this phenomenon has been a challenge to explain due to both extreme energies and long durations. The highest-energy emission has generally been attributed to pion production from the interaction of ⪆300 MeV protons with the ambient matter. The extended duration suggests that particle acceleration occurs over large volumes extending high in the corona, either from stochastic acceleration within large coronal loops or from back precipitation from coronal mass ejection-driven shocks. It is possible to test these models by making a direct comparison between the properties of the accelerated ion population producing the γ-ray emission derived from the Fermi/LAT observations and the characteristics of solar energetic particles (SEPs) measured by the Payload for Matter-Antimatter Exploration and Light Nuclei Astrophysics spacecraft in the energy range corresponding to the pion-related emission detected with Fermi. For 14 of these events, we compare the two populations - SEPs in space and the interacting particles at the Sun - and discuss the implications in terms of potential sources. Our analysis shows that the two proton numbers are poorly correlated, with their ratio spanning more than 5 orders of magnitude, suggesting that the back precipitation of shock-acceleration particles is unlikely to be the source of the LDGRF emission.

KW - Earth

KW - Sun: coronal mass ejections (CMEs)

KW - Sun: flares

KW - Sun: heliosphere

KW - Sun: particle emission

KW - Sun: X-rays, gamma-rays

UR - http://www.scopus.com/inward/record.url?scp=85071934818&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85071934818&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/ab258f

DO - 10.3847/1538-4357/ab258f

M3 - Article

AN - SCOPUS:85071934818

VL - 879

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 90

ER -