Simulation of Quiet-Sun Hard X-Rays Related to Solar Wind Superhalo Electrons

Wang, Wen; Wang, Linghua; Krucker, S.; Hannah, I. G.

doi:10.1007/s11207-016-0916-z

Cited by 9 publications

(7 citation statements)

References 39 publications

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“…Our observations of numerous microjets in quiet-Sun regions might be consistent with the results of Wang et al (2016), who suggested interchange reconnection as the coronal source of superhalo electrons (Wang et al 2012). Specifically, they proposed that small-scale interchange reconnections in quiet-Sun regions produce an upward-traveling population of accelerated electrons, which could escape into the interplanetary space and form the superhalo electrons measured in the solar wind.…”

Section: Chen Et Al 2020)supporting

confidence: 91%

Coronal microjets in quiet-Sun regions observed with the Extreme Ultraviolet Imager onboard Solar Orbiter

Hou,

Tian,

Berghmans

et al. 2021

Preprint

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We report the smallest coronal jets ever observed in the quiet Sun with recent highresolution observations from the High Resolution Telescopes (HRI EUV and HRI Lyα ) of the Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter. In the HRI EUV (174 Å) images, these microjets usually appear as nearly collimated structures with brightenings at their footpoints. Their average lifetime, projected speed, width, and maximum length are 4.6 min, 62 km s −1 , 1.0 Mm, and 7.7 Mm, respectively. Inverted-Y shaped structures and moving blobs can be identified in some events. A subset of these events also reveal signatures in the HRI Lyα (H i Lyα at 1216 Å) images and the extreme ultraviolet images taken by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. Our differential emission measure analysis suggests a multi-thermal nature and an average density of ∼1.4×10 9 cm −3 for these microjets. Their thermal and kinetic energies were estimated to be ∼3.9×10 24 erg and ∼2.9×10 23 erg, respectively, which are of the same order of the released energy predicted by the nanoflare theory. Most events appear to be located at the edges of network lanes and magnetic flux concentrations, suggesting that these coronal microjets are likely generated by magnetic reconnection between small-scale magnetic loops and the adjacent network field.

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Section: Chen Et Al 2020)supporting

confidence: 91%

Coronal microjets in quiet-Sun regions observed with the Extreme Ultraviolet Imager onboard Solar Orbiter

Hou,

Tian,

Berghmans

et al. 2021

Preprint

Self Cite

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“…By comparison, Krucker et al (2007), who analyzed much larger (typically M class) flares, found a ratio of ≈ 0.2%. On the other hand, based on simulations, Wang et al (2016) estimate that, in the quiet Sun, the ratio of electrons propagating outwards to form the solar wind superhalo to those that could potentially propagate downwards and produce HXR emission can be as high as 30 %.…”

Section: Discussionmentioning

confidence: 99%

Small electron acceleration episodes in the solar corona

James

Subramanian

Kontar

2017

Monthly Notices of the Royal Astronomical Society

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We study the energetics of nonthermal electrons produced in small acceleration episodes in the solar corona. We carried out an extensive survey spanning 2004-2015 and shortlisted 6 impulsive electron events detected at 1 AU that were not associated with large solar flares(GOES soft x-ray class > C1) or with coronal mass ejections. Each of these events had weak, but detectable hard Xray (HXR) emission near the west limb, and were associated with interplanetary type III bursts. In some respects, these events seem like weak counterparts of "cold/tenuous" flares. The energy carried by the HXR producing electron population was ≈ 10 23 -10 25 erg, while that in the corresponding population detected at 1 AU was ≈ 10 24 -10 25 erg. The number of electrons that escape the coronal acceleration site and reach 1 AU constitute 6 % to 148 % of those that precipitate downwards to produce thick target HXR emission.

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“…Previous studies provide conflicting evidence regarding where in situ electrons are energized compared to their HXRemitting counterparts. In certain flares, for example, emerging flux or interchange reconnection (e.g., Heyvaerts et al 1977;Wang et al 2016;Battaglia et al 2023) 2011; Musset et al 2020) may ultimately allow loop-top electrons to escape, while having access to hot, over-dense material usually related to HXR-emitting electrons. Alternatively, or in conjunction, the presence of a turbulent acceleration mechanism (e.g., Kontar et al 2017a;Stores et al 2021) may both heat the surrounding plasma and energize electrons simultaneously.…”

Section: Summary and Discussionmentioning

confidence: 99%

Exploring the Origin of Solar Energetic Electrons. I. Constraining the Properties of the Acceleration Region Plasma Environment

Pallister,

Jeffrey

2023

ApJ

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Solar flare electron acceleration is an efficient process, but its properties (mechanism, location) are not well constrained. Via hard X-ray (HXR) emission, we routinely observe energetic electrons at the Sun, and sometimes we detect energetic electrons in interplanetary space. We examine if the plasma properties of an acceleration region (size, temperature, density) can be constrained from in situ observations, helping to locate the acceleration region in the corona, and infer the relationship between electrons observed in situ and at the Sun. We model the transport of energetic electrons, accounting for collisional and non-collisional effects, from the corona into the heliosphere (to 1.0 au). In the corona, electrons are transported through a hot, over-dense region. We test if the properties of this region can be extracted from electron spectra (fluence and peak flux) at different heliospheric locations. We find that cold, dense coronal regions significantly reduce the energy at which we see the peak flux and fluence for distributions measured out to 1.0 au, the degree of which correlates with the temperature and density of plasma in the region. Where instrument energy resolution is insufficient to differentiate the corresponding peak values, the spectral ratio of [7–10) to [4–7) keV can be more readily identified and demonstrates the same relationship. If flare electrons detected in situ are produced in, and/or transported through, hot, over-dense regions close to HXR-emitting electrons, then this plasma signature should be present in their lower-energy spectra (1–20 keV), observable at varying heliospheric distances with missions such as Solar Orbiter.

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Simulation of Quiet-Sun Hard X-Rays Related to Solar Wind Superhalo Electrons

Cited by 9 publications

References 39 publications

Coronal microjets in quiet-Sun regions observed with the Extreme Ultraviolet Imager onboard Solar Orbiter

Coronal microjets in quiet-Sun regions observed with the Extreme Ultraviolet Imager onboard Solar Orbiter

Small electron acceleration episodes in the solar corona

Exploring the Origin of Solar Energetic Electrons. I. Constraining the Properties of the Acceleration Region Plasma Environment

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