A rogue solar energetic particle event at 0.33 AU: Importance of interplanetary structures in SEP events

Lario, D.; Ho, G. C.; Roelof, E. C.; Decker, R. B.; Anderson, B. J.

doi:10.1063/1.4811026

Cited by 3 publications

(5 citation statements)

References 9 publications

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“…Finally, column (13) lists, for those shocks displaying an ESP intensity increase in the S6 energy channel, the time when the peak intensity I pk in this energy channel was observed, obtained using the 5-minute averages of the SEPEM/RDS data set. In general, peak intensities during ESP events tend to occur close to passage of the shock (see, e.g., Figure 3 in Lario et al 2003). However, I pk does not necessarily coincide with passage of the shock.…”

Section: Energetic Storm Particle Event Sizementioning

confidence: 97%

“…The effects of a shock passage on the heliospheric energetic particle population are energy dependent. In general, the higher the particle energy, the less prominent the ESP enhancement is (e.g., Lario et al 2003). But occasionally, ESP events observed at 1 au may reach proton energies of >100 MeV versus the more usual maximum energies of 10 MeV.…”

Section: Introductionmentioning

confidence: 99%

“…We then analyze the factors that could determine whether a high-energy ESP event is observed, including the properties of the parent solar eruption associated with the origin of the IP shock, the parameters of the IP shock, and the presence of other IP structures that may have influenced the intensity of the ESP event. Our study falls within the framework of prior statistical analyses of ESP events including those providing phenomenological classifications of ESP particle signatures such as intensity-time profiles, energy spectra, and particle anisotropies (e.g., van Nes et al 1984;Tsurutani & Lin 1985;Wenzel et al 1985;Kallenrode 1995;Lario et al 2003Lario et al , 2005bCohen et al 2005;Huttunen-Heikinmaa & Valtonen 2005;Ho et al 2008;Richardson & Cane 2010a;Mäkelä et al 2011;Giacalone 2012;Reames 2012;Dresing et al 2016;Dayeh et al 2018;Ameri et al 2023, and references therein), and those relating ESP signatures with the properties of the solar eruptions that generate the IP shocks (e.g., Mäkelä et al 2011;Santa Fe Dueñas et al 2022;Ameri et al 2023, and references therein). Most of these studies focus on low-energy (20 MeV nucleon −1 ) ESP particle signatures, whereas the extension to higher energies entails the study of the temporal and, when possible, spatial evolution of the associated SEP events and thus the isolation of the ESP components (e.g., Luhmann & Mann 2007;Chiappetta et al 2021;Reames 2023, and references therein).…”

Section: Introductionmentioning

confidence: 99%

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High-energy (>40 MeV) Proton Intensity Enhancements Associated with the Passage of Interplanetary Shocks at 1 au

Lario

Richardson

Aran

et al. 2023

ApJ

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We analyze periods with elevated >40 MeV proton intensities observed near Earth over a time span of 43 yr (1973–2016) that coincide with the passage of interplanetary (IP) shocks. Typically, elevated proton intensities result from large solar energetic particle (SEP) events. The IP shocks observed during these elevated-intensity periods may or may not be related to the origin of the SEP events. By choosing those cases when the shocks can be confidently associated with the solar eruption that generated the SEP event, we analyze the components of these SEP events that are localized in the vicinity of the shock (so-called “energetic storm particles”, ESPs), focusing on those events where the ESP component exceeds 40 MeV. We examine the interdependence of these high-energy ESPs with (i) the properties of the solar eruptions that generated the shocks and the SEP events, and (ii) the parameters of the shocks at their arrival at 1 au. The solar eruptions at the origin of the shocks producing >40 MeV proton ESP intensity enhancements are within ±50° longitude of central meridian and are associated with fast coronal mass ejections (plane-of-sky speeds ≳1000 km s−1). The ESP events with the largest >40 MeV proton intensity increases tend to occur when there are structures such as intervening IP coronal mass ejections and other unrelated shocks present in the solar wind through which the shock is propagating. Among the various local shock parameters considered, only the shock speed shows a certain degree of correlation with the observed ESP intensity increase.

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Section: Energetic Storm Particle Event Sizementioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High-energy (>40 MeV) Proton Intensity Enhancements Associated with the Passage of Interplanetary Shocks at 1 au

Lario

Richardson

Aran

et al. 2023

ApJ

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“…15a in Papaioannou et al 2016). Singular intense events, particularly at low (<30 MeV) energies, termed "rogue" SEP events by Kallenrode & Cliver (2001), occurred on 14 July 1959 (Bazilevskaya et al 2010), 4 August 1972 (Lario et al 2013;Knipp et al 2018), 19 October 1989(Vainio 2003Lario et al 2013), and 14 July 2000 (Belov et al 2001;Lario et al 2013;Mishev & Usoskin 2016). Such events are associated with multiple CMEs and converging shocks.…”

Section: Introductionmentioning

confidence: 99%

Revisiting empirical solar energetic particle scaling relations

Papaioannou

Herbst

Ramm

et al. 2023

A&A

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Aims. The possible influence of solar superflares on the near-Earth space radiation environment are assessed through the investigation of scaling laws between the peak proton flux and fluence of solar energetic particle (SEP) events with the solar flare soft X-ray peak photon flux. Methods. We compiled a catalog of 65 well-connected (W20-90) SEP events during the last three solar cycles covering a period of ∼34 yr (1984–2020) that were associated with flares of class ≥C6.0, and investigated the statistical relations between the recorded peak proton fluxes (IP) and the fluences (FP) at a set of integral energies from E > 10, > 30, and > 60 to > 100 MeV versus the associated solar flare peak soft X-ray flux in the 1–8 Å band (FSXR). Based on the inferred relations, we calculated the integrated energy dependence of the peak proton flux (IP) and fluence (FP) of the SEP events, assuming that they follow an inverse power law with respect to energy. Finally, we made use of simple physical assumptions, combining our derived scaling laws, and estimated the upper limits for IP and FP focusing on the flare associated with the strongest ground level enhancement (GLE) directly observed to date (GLE 05 on 23 February 1956), and that inferred for the cosmogenic radionuclide-based SEP event of AD774/775. Results. A scaling law relating IP and FP to the solar soft X-ray peak intensity (FSXR) as ∝ $ {F}_{\mathrm{SXR}}^{5/6} $ for a flare with a FSXR = X600 (in the revised scale) is consistent with values of FP inferred for the cosmogenic nuclide event of AD774/775.

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“…Understanding how particles are accelerated at shock waves remains a fundamental challenge for astrophysics and space physics. The description provided by the basic process, diffusive shock acceleration (DSA; e.g., Bell 1978;Blandford & Ostriker 1978;Drury 1983;Blandford & Eichler 1987) is not complete and does not always describe the behavior at interplanetary shocks (see, e.g., Lario et al 2003). The influence of preexisting turbulence upstream of a shock is an important question in the acceleration theory, yet is still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Simulations of Nonrelativistic High-mach-number Perpendicular Shocks Propagating in a Turbulent Medium

Fulat,

Bohdan,

Torralba Paz

et al. 2023

ApJ

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Strong nonrelativistic shocks are known to accelerate particles up to relativistic energies. However, for diffusive shock acceleration, electrons must have a highly suprathermal energy, implying the need for very efficient preacceleration. Most published studies consider shocks propagating through homogeneous plasma, which is an unrealistic assumption for astrophysical environments. Using 2D3V particle-in-cell simulations, we investigate electron acceleration and heating processes at nonrelativistic high-Mach-number shocks in electron-ion plasma with a turbulent upstream medium. For this purpose, slabs of plasma with compressive turbulence are simulated separately and then inserted into shock simulations, which require matching of the plasma slabs at the interface. Using a novel procedure of matching electromagnetic fields and currents, we perform simulations of perpendicular shocks setting different intensities of density fluctuations (≲10%) in the upstream region. The new simulation technique provides a framework for studying shocks propagating in turbulent media. We explore the impact of the fluctuations on electron heating, the dynamics of upstream electrons, and the driving of plasma instabilities. Our results indicate that while the presence of turbulence enhances variations in the upstream magnetic field, their levels remain too low to significantly influence the behavior of electrons at perpendicular shocks.

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A rogue solar energetic particle event at 0.33 AU: Importance of interplanetary structures in SEP events

Cited by 3 publications

References 9 publications

High-energy (>40 MeV) Proton Intensity Enhancements Associated with the Passage of Interplanetary Shocks at 1 au

High-energy (>40 MeV) Proton Intensity Enhancements Associated with the Passage of Interplanetary Shocks at 1 au

Revisiting empirical solar energetic particle scaling relations

Kinetic Simulations of Nonrelativistic High-mach-number Perpendicular Shocks Propagating in a Turbulent Medium

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