How do weak shocks accelerate high energy particles?

弱激波如何加速高能粒子？

• 批准号: ST/R003246/2
• 负责人: David Long
• 金额: $ 14.92万
• 依托单位: Queen's University Belfast
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FR003246%2F2
• 关键词: How; do; weak; shocks; accelerate

Shock waves are found everywhere in the Universe and are one of the most efficient ways of accelerating particles like protons and electrons. However, the conditions required to produce those shocks and accelerate particles are so extreme that they're impossible to recreate on Earth. As a result, we still don't know a lot about how these shocks accelerate particles or how they're affected by things like density or magnetic field. Most of the shocks that produce these very high energy particles are also incredibly far away in other galaxies, making them difficult to study properly. For example, while we can see a supernova shock using astronomical telescopes, it's really hard to then identify and study the particles it accelerates.However, the Earth is located close to a natural laboratory with extreme density, temperature and magnetic field variations which regularly produces large-scale shocks that shower us with energetic particles; the Sun. We have a fleet of spacecraft returning constant observations of the Sun, allowing us to see in near-real-time the sudden release of stored magnetic energy in the solar atmosphere (also called the corona). This energy release can produce bursts of radiation that we call solar flares, hurl massive bubbles of plasma called coronal mass ejections into the solar system towards the Earth and launch vast global shock waves that can travel across the Sun in under an hour. Although these shocks are so much weaker than supernovae that they shouldn't be able to accelerate any particles, they regularly produce billions of energetic particles that we can almost immediately detect at Earth. These particles can be fatal for satellites orbiting the Earth, blinding them and causing them to fail, with knock-on effects for GPS and telecommunications. With my research, I'm trying to understand why these really weak shocks occur, how they accelerate particles to incredibly high energies and how those energetic particles affect the Earth and the near-Earth environment.The Sun offers a unique opportunity to study both extreme shocks and the particles that they accelerate at the same time in unprecedented detail; we can see what happens and "touch" the resulting particles, which is something that you can't do in any other field of astrophysics. Everything about this situation is also very counterintuitive; the Sun is a pretty average star producing very weak shocks that shouldn't be able to accelerate any particles yet it manages to accelerate particles to incredibly high energies. How this happens is still an open question, and one that has implications not just for our understanding of the Sun, but also for fundamental plasma physics and space weather. If we know how this process works we might be able to predict it, which will help us to protect vulnerable spacecraft and infrastructure on Earth. On a more personal level though, working on this topic really hammers home the differences between how calm the Sun is when you look at it from the ground versus the violently active Sun producing solar eruptions which we see from space, which I just think is fascinating.

冲击波在宇宙中无处不在，是加速质子和电子等粒子的最有效方法之一。然而，产生这些冲击和加速粒子所需的条件是如此极端，以至于它们不可能在地球上重现。因此，我们仍然不太了解这些冲击如何加速粒子，或者它们如何受到密度或磁场等因素的影响。大多数产生这些非常高能量粒子的冲击也非常遥远地位于其他星系中，这使得它们很难进行适当的研究。例如，虽然我们可以用天文望远镜看到超新星冲击波，但很难识别和研究它加速的粒子。然而，地球靠近一个天然实验室，密度、温度和磁场变化极大，经常产生大规模的冲击波，使我们充满高能粒子：太阳。我们有一队航天器返回太阳的持续观测，使我们能够近实时地看到太阳大气层（也称为日冕）中储存的磁能的突然释放。这种能量释放可以产生我们称之为太阳耀斑的辐射爆发，将称为日冕物质抛射的大量等离子体气泡抛入太阳系，并向地球发射巨大的全球冲击波，这些冲击波可以在一小时内穿越太阳。虽然这些冲击比超新星弱得多，它们不应该能够加速任何粒子，但它们经常产生数十亿的高能粒子，我们几乎可以立即在地球上检测到。这些粒子对绕地球运行的卫星来说可能是致命的，使它们致盲并导致它们失败，对GPS和电信产生连锁反应。通过我的研究，我试图了解为什么这些非常微弱的冲击会发生，它们如何将粒子加速到难以置信的高能量，以及这些高能粒子如何影响地球和近地环境。太阳提供了一个独特的机会，可以以前所未有的细节研究极端冲击和它们同时加速的粒子;我们可以看到发生了什么，并“触摸”产生的粒子，这是你在天体物理学的任何其他领域都无法做到的。关于这种情况的一切也是非常违反直觉的;太阳是一颗相当普通的星星，产生非常微弱的冲击，不应该能够加速任何粒子，但它却设法将粒子加速到令人难以置信的高能量。这是如何发生的仍然是一个悬而未决的问题，它不仅对我们对太阳的理解有影响，而且对基本等离子体物理学和空间天气也有影响。如果我们知道这个过程是如何工作的，我们就可以预测它，这将有助于我们保护地球上脆弱的航天器和基础设施。然而，在更个人的层面上，研究这个话题确实让人想起了当你从地面上看太阳时太阳是多么平静，而我们从太空中看到的太阳剧烈活动产生太阳爆发，我只是觉得这很有趣。

项目成果

Slow solar wind sources High-resolution observations with a quadrature view

慢速太阳风源 具有正交视图的高分辨率观测

• DOI: 10.1051/0004-6361/202345983
• 发表时间: 2023
• 期刊: Astronomy & Astrophysics
• 影响因子: 6.5
• 作者: Barczynski K

The source of unusual coronal upflows with photospheric abundance in a solar active region

太阳活动区域光球丰度异常的日冕上升流的来源

• DOI: 10.1051/0004-6361/202245747
• 发表时间: 2023
• 期刊: Astronomy & Astrophysics
• 影响因子: 6.5
• 作者: Harra L

Extreme-ultraviolet fine structure and variability associated with coronal rain revealed by Solar Orbiter/EUI HRI EUV and SPICE

太阳轨道飞行器/EUI HRI EUV 和 SPICE 揭示了与日冕雨相关的极紫外精细结构和变化

• DOI: 10.1051/0004-6361/202346016
• 发表时间: 2023
• 期刊: Astronomy & Astrophysics
• 影响因子: 6.5
• 作者: Antolin P

Ultra-high-resolution observations of persistent null-point reconnection in the solar corona.

• DOI: 10.1038/s41467-023-37888-w
• 发表时间: 2023-04-13
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Cheng, X.;Priest, E. R.;Li, H. T.;Chen, J.;Aulanier, G.;Chitta, L. P.;Wang, Y. L.;Peter, H.;Zhu, X. S.;Xing, C.;Ding, M. D.;Solanki, S. K.;Berghmans, D.;Teriaca, L.;Cuadrado, R. Aznar;Zhukov, A. N.;Guo, Y.;Long, D.;Harra, L.;Smith, P. J.;Rodriguez, L.;Verbeeck, C.;Barczynski, K.;Parenti, S.
• 通讯作者: Parenti, S.

Shocklets and Short Large Amplitude Magnetic Structures (SLAMS) in the High Mach Foreshock of Venus

• DOI: 10.1029/2023gl104610
• 发表时间: 2023-09
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: G. Collinson;H. Hietala;Ferdinand Plaschke;T. Karlsson;L. B. Wilson;M. Archer;M. Battarbee;X. Blanco‐Cano;C. Bertucci;David Long;M. Opher;N. Sergis;Claire Gasque;T. Liu;S. Raptis;Sofia Burne;R. Frahm;Tielong Zhang;Y. Futaana