Time-dependent Acceleration and Escape of Charged Particles at Traveling Shocks in the Near-Sun Environment
Current multi-spacecraft in situ measurements allow for the investigation of the time evolution of energetic particles at interplanetary shocks (IPs) at small (≲0.1 au) heliocentric distances. The energy spectrum of accelerated particles at IPs was shown by a previous 1D transport model that include...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad93b2 |
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| author | Thomas M. Do Federico Fraschetti Jozsef Kota Joe Giacalone Christina M. S. Cohen David J. McComas |
| author_facet | Thomas M. Do Federico Fraschetti Jozsef Kota Joe Giacalone Christina M. S. Cohen David J. McComas |
| author_sort | Thomas M. Do |
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| description | Current multi-spacecraft in situ measurements allow for the investigation of the time evolution of energetic particles at interplanetary shocks (IPs) at small (≲0.1 au) heliocentric distances. The energy spectrum of accelerated particles at IPs was shown by a previous 1D transport model that includes both self-excited plus preexisting turbulence and a term representing the escape of particles from the system to gradually steepen as a result of a finite acceleration-to-escape timescales ratio; such a model was found in excellent agreement with the entire sample of the ground-level enhancement spectra of solar cycle 23. We solve the time-dependent case of such a model in the case of diffusion dominated by preexisting turbulence. The average timescale for particle acceleration at various heliocentric distances, from 1 au down to the inner heliosphere (<0.1 au), is shorter than in the no-escape case, as higher energy particles have a shorter time to accelerate before completely leaving the system into the upstream medium. A simple scaling with time of the time-dependent spectrum is provided. We compare the “nose” structure at a few ∼100s keV protons first measured in situ by Parker Solar Probe in crossing the very fast 2022 September 5 shock at 0.07 au; we find that the nose is reasonably well explained by a lack of the highest energy particles not yet produced by the young shock by both our model and the no-escape version. |
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| institution | Kabale University |
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| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-eb05642718e7434e85e252056fc81b2c2025-01-17T09:39:52ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0197915010.3847/1538-4357/ad93b2Time-dependent Acceleration and Escape of Charged Particles at Traveling Shocks in the Near-Sun EnvironmentThomas M. Do0https://orcid.org/0000-0001-6105-7308Federico Fraschetti1https://orcid.org/0000-0002-5456-4771Jozsef Kota2Joe Giacalone3https://orcid.org/0000-0002-0850-4233Christina M. S. Cohen4https://orcid.org/0000-0002-0978-8127David J. McComas5https://orcid.org/0000-0001-6160-1158Center for Astrophysics | Harvard & Smithsonian , Cambridge, MA, 02138, USA; Department of Astronomy, University of Washington , Seattle, WA, 98195, USA; Department of Physics and Astronomy, Michigan State University , East Lansing, MI, 48824, USACenter for Astrophysics | Harvard & Smithsonian , Cambridge, MA, 02138, USA; Department of Planetary Sciences—Lunar and Planetary Laboratory, University of Arizona , Tucson, AZ, 85721, USADepartment of Planetary Sciences—Lunar and Planetary Laboratory, University of Arizona , Tucson, AZ, 85721, USADepartment of Planetary Sciences—Lunar and Planetary Laboratory, University of Arizona , Tucson, AZ, 85721, USASpace Radiation Lab, California Institute of Technology , Pasadena, CA, 91125, USADepartment of Astrophysical Sciences, Princeton University , Princeton, NJ, 08544, USACurrent multi-spacecraft in situ measurements allow for the investigation of the time evolution of energetic particles at interplanetary shocks (IPs) at small (≲0.1 au) heliocentric distances. The energy spectrum of accelerated particles at IPs was shown by a previous 1D transport model that includes both self-excited plus preexisting turbulence and a term representing the escape of particles from the system to gradually steepen as a result of a finite acceleration-to-escape timescales ratio; such a model was found in excellent agreement with the entire sample of the ground-level enhancement spectra of solar cycle 23. We solve the time-dependent case of such a model in the case of diffusion dominated by preexisting turbulence. The average timescale for particle acceleration at various heliocentric distances, from 1 au down to the inner heliosphere (<0.1 au), is shorter than in the no-escape case, as higher energy particles have a shorter time to accelerate before completely leaving the system into the upstream medium. A simple scaling with time of the time-dependent spectrum is provided. We compare the “nose” structure at a few ∼100s keV protons first measured in situ by Parker Solar Probe in crossing the very fast 2022 September 5 shock at 0.07 au; we find that the nose is reasonably well explained by a lack of the highest energy particles not yet produced by the young shock by both our model and the no-escape version.https://doi.org/10.3847/1538-4357/ad93b2Interplanetary shocksSolar windSolar energetic particles |
| spellingShingle | Thomas M. Do Federico Fraschetti Jozsef Kota Joe Giacalone Christina M. S. Cohen David J. McComas Time-dependent Acceleration and Escape of Charged Particles at Traveling Shocks in the Near-Sun Environment The Astrophysical Journal Interplanetary shocks Solar wind Solar energetic particles |
| title | Time-dependent Acceleration and Escape of Charged Particles at Traveling Shocks in the Near-Sun Environment |
| title_full | Time-dependent Acceleration and Escape of Charged Particles at Traveling Shocks in the Near-Sun Environment |
| title_fullStr | Time-dependent Acceleration and Escape of Charged Particles at Traveling Shocks in the Near-Sun Environment |
| title_full_unstemmed | Time-dependent Acceleration and Escape of Charged Particles at Traveling Shocks in the Near-Sun Environment |
| title_short | Time-dependent Acceleration and Escape of Charged Particles at Traveling Shocks in the Near-Sun Environment |
| title_sort | time dependent acceleration and escape of charged particles at traveling shocks in the near sun environment |
| topic | Interplanetary shocks Solar wind Solar energetic particles |
| url | https://doi.org/10.3847/1538-4357/ad93b2 |
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