Interplanetary Protons versus Interacting Protons in the 2017 September 10 Solar Eruptive Event

Kocharov, L. G.; Pesce-Rollins, M.; Laitinen, Timo; Mishev, Alexander; Kühl, P.; Klassen, A.; Jin, Meng; Omodei, N.; Longo, F.; Webb, D. F.; Cane, H. V.; Heber, B.; Vainio, Rami; Usoskin, Ilya

doi:10.3847/1538-4357/ab684e

Cited by 30 publications

(22 citation statements)

References 88 publications

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“…The injection of relativistic protons has been assumed to be instantaneous and located near the Sun, which is a reasonable approximation at these energies (Gopalswamy et al 2012). In recently published work, Kocharov et al (2020) presented an analysis of the 2017 September 10 GLE event using a 2D model of particle transport that includes perpendicular diffusion due to magnetic field turbulence. We expect that inclusion of such effects within our 3D model would smooth particle intensity profiles, eliminating discontinuities at low energies that are due to loss of connection to the flux tubes within which acceleration took place, while retaining the important effects of IMF polarity and HCS.…”

Section: Discussionmentioning

confidence: 99%

3D propagation of relativistic solar protons through interplanetary space

Dalla

Nolfo

Bruno

et al. 2020

A&A

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Context. Solar energetic particles (SEPs) with energy in the GeV range can propagate to Earth from their acceleration region near the Sun and produce ground level enhancements (GLEs). The traditional approach to interpreting and modelling GLE observations assumes particle propagation which is only parallel to the magnetic field lines of interplanetary space, that is, spatially 1D propagation. Recent measurements by PAMELA have characterised SEP properties at 1 AU for the ∼100 MeV–1 GeV range at high spectral resolution. Aims. We model the transport of GLE-energy solar protons using a 3D approach to assess the effect of the heliospheric current sheet (HCS) and drifts associated to the gradient and curvature of the Parker spiral. We derive 1 AU observables and compare the simulation results with data from PAMELA. Methods. We use a 3D test particle model including a HCS. Monoenergetic populations are studied first to obtain a qualitative picture of propagation patterns and numbers of crossings of the 1 AU sphere. Simulations for power law injection are used to derive intensity profiles and fluence spectra at 1 AU. A simulation for a specific event, GLE 71, is used for comparison purposes with PAMELA data. Results. Spatial patterns of 1 AU crossings and the average number of crossings per particle are strongly influenced by 3D effects, with significant differences between periods of A+ and A− polarities. The decay time constant of 1 AU intensity profiles varies depending on the position of the observer and it is not a simple function of the mean free path as in 1D models. Energy dependent leakage from the injection flux tube is particularly important for GLE energy particles, resulting in a rollover in the spectrum.

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Section: Discussionmentioning

confidence: 99%

3D propagation of relativistic solar protons through interplanetary space

Dalla

Nolfo

Bruno

et al. 2020

A&A

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“…The high-energy γ-ray flare on 2017 September 10 was observed by Fermi/LAT (Omodei et al 2018;Ajello et al 2021), and the high-energy proton event at 1 au was registered by the ground-based neutron monitor network (Mishev et al 2018;Kocharov et al 2020). The flare-CME eruption was well observed in different electromagnetic emissions, including in particular the microwave (MW) observations by the Expanded Owens Valley Solar Array (EOVSA; Gary et al 2018), the EUV images by the Atmospheric Imaging Assembly (AIA; Lemen et al 2012) on the Solar Dynamics Observatory (SDO), and the hard X-ray (HXR) observations by RHESSI (Lin et al 2002).…”

Section: High-energy Event Morphology and Associationsmentioning

confidence: 99%

Multiple Sources of Solar High-energy Protons

Kocharov

Omodei

Mishev

et al. 2021

ApJ

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During the 24th solar cycle, the Fermi Large Area Telescope (LAT) has observed a total of 27 solar flares possessing delayed γ-ray emission, including the exceptionally well-observed flare and coronal mass ejection (CME) on 2017 September 10. Based on the Fermi/LAT data, we plot, for the first time, maps of possible sources of the delayed >100 MeV γ-ray emission of the 2017 September 10 event. The long-lasting γ-ray emission is localized under the CME core. The γ-ray spectrum exhibits intermittent changes in time, implying that more than one source of high-energy protons was formed during the flare-CME eruption. We find a good statistical correlation between the γ-ray fluences of the Fermi/LAT-observed delayed events and the products of corresponding CME speed and the square root of the soft X-ray flare magnitude. Data support the idea that both flares and CMEs jointly contribute to the production of subrelativistic and relativistic protons near the Sun.

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“…A very good agreement of the derived SEP characteristics, specifically fluence and PAD with direct measurements by the PAMELA space-borne detector was achieved. Therefore, this specific method for data analysis of strong SEP events using NM records is verified at least for a single event and gives a good basis for further quantification of solar proton acceleration [32,33].…”

Section: Discussionmentioning

confidence: 82%

Application of the verified neutron monitor yield function for GLE analysis

Mishev¹,

Usoskin²,

Koldobskiy³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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Systematic study of solar energetic particles provides an important basis to understand their acceleration and propagation in the interplanetary space. After solar eruptive processes, such as solar flares and/or coronal mass ejections, solar ions are accelerated to high energy. In the majority of cases, the maximum energy of the accelerated solar ions is several tens of MeV/nucleon, but in some cases, it exceeds 100 MeV/nucleon or even reaches the GeV/nucleon range. In this case, the energy is high enough, so that solar ions generate an atmospheric cascade in the Earth's atmosphere, whose secondary particles reach the ground, being eventually registered by ground-based detectors, specifically neutron monitors. This particular class of events is known as ground-level enhancements (GLEs). Several methods for analysis of GLEs, using neutron monitor data were developed over the years. Here, we present a method for assessment of the spectral and angular characteristics of the GLEs using data from the world-wide NM network, namely by modeling the global neutron monitor network response with a new verified yield function. The method is based on consecutive steps, specifically detailed computation of asymptotic cones and rigidity cut-off of each station used in the analysis and optimization of the global neutron monitor response over experimental and modeled count rate increases. The method is compared with other methods, including in-situ measurements. A very good agreement between our method and space-borne measurements with PAMELA space probe, specifically the derived fluence of solar protons during GLE 71 was achieved, therefore verification of the method is performed.

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Interplanetary Protons versus Interacting Protons in the 2017 September 10 Solar Eruptive Event

Cited by 30 publications

References 88 publications

3D propagation of relativistic solar protons through interplanetary space

3D propagation of relativistic solar protons through interplanetary space

Multiple Sources of Solar High-energy Protons

Application of the verified neutron monitor yield function for GLE analysis

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