【讲座题目&摘要】
Particle acceleration by transient structures around Earth’s bow shock
Upstream of Earth’s bow shock, the foreshock is filled with particles that have been reflected at the bow shock and are streaming away from it. Interaction of these particles with solar wind particles and discontinuities within this region can cause foreshock transients to form. Downstream of Earth’s bow shock, localized magnetosheath jets with high dynamic pressure are frequently observed. When such a fast magnetosheath jet compresses the ambient magnetosheath plasma, an earthward compressional bow wave/shock can form. Here I present that foreshock transients and magnetosheath jets can accelerate particles through shock drift acceleration, Fermi acceleration, and the betatron acceleration. Foreshock transients and magnetosheath jets therefore can increase the particle acceleration efficiency of the parent shock by providing additional acceleration. The shock environment relevant for particle acceleration is not just the shock itself, but also the nonlinear transient structures both upstream and downstream of it.
【讲座嘉宾简历】
Terry Z. Liu (Zixu Liu)
tel: (+1) 310 592 9104
Education
Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles
PhD in Geophysics and Space Physics 09/2013-06/2018
School of Earth and Space Sciences, Peking University
B.S in Space Science and Technology 09/2009-07/2013
Employment
Jack Eddy postdoctoral fellow, Cooperative Programs for the Advancement of Earth System Science, University Corporation for Atmospheric Research; Geophysical Institute, University of Alaska, Fairbanks 09/2019-present
Assistant researcher, Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles 06/2018-09/2019
Awards and Honors
Fred L. Scarf Award by American Geophysical Union in 2019
Harold and Mayla Sullwold Scholarship at EPSS, UCLA in 2017
Outstanding Poster Award at the international Geospace Environment Modeling conference in 2017
Outstanding Student Paper Award at American Geophysical Union Fall Meeting in 2016
Eugene B. Waggoner Scholarship at EPSS, UCLA in 2016
Outstanding Poster Award at the international Geospace Environment Modeling conference in 2016
Research Funding
Principal Investigator for NSF GEM award, Particle acceleration by foreshock transients (2020-2023)
Jack Eddy Fellowship (2019-2021)
Co-Investigator for NASA HSR grant, Impact of foreshock transients on the Earth’s nightside magnetosphere (2019-2022)
Professional Activity
Young scientist of the ISSI Team, Resolving the Microphysics of Collisionless Shock Waves, led by Lynn Wilson (2018-2020)
Young scientist of the ISSI Team, Foreshocks Across the Heliosphere: System Specific or Universal Physical Processes?, led by Heli Hietala (2019-2021)
MMS senior review – shock section – foreshock transients (2019)
THEMIS Tohban (2015-present)
Judge of AGU Outstanding Student Paper Award (2018, 2019)
Reviewing Activity
Science Advances
Astrophysics and Space Science
Secretary in NASA Heliophysics Phase I DRIVE Panel (2019)
Invited Presentations
5th Cluster-THEMIS workshop 09/2018
Particle acceleration inside foreshock transients
European Geosciences Union General Assembly 04/2018
Properties and evolution of foreshock bubbles
Fundamental Physical Processes in Solar-Terrestrial Research and Their Relevance to Planetary Physics 01/2018
Fermi acceleration of electrons inside foreshock transient cores
American Geophysical Union Fall Meeting 12/2017
Understanding of Particle Acceleration by Foreshock Transients (eLightning)
Other Presentations
Physics Days 2019 in Helsinki (presentation)
American Geophysical Union Fall Meeting (poster) in 2014, 2015, 2016, 2017, 2018
Geospace Environment Modeling conference (poster & presentation) in 2014, 2015, 2016, 2017, 2018, 2019
Publications
Liu, T. Z., Hietala, H., Angelopoulos, V., Omelchenko, Y., Roytershteyn, V., & Vainio, R. (2019). THEMIS observations of particle acceleration by a magnetosheath jet‐driven bow wave. Geophysical Research Letters, 46. https://doi.org/10.1029/2019GL082614
Liu, T. Z., Angelopoulos, V., and Lu, S. (2019), Relativistic electrons generated at Earth’s quasi-parallel bow shock, Science Advances, 5, 7, doi:10.1126/sciadv.aaw1368
Wang, C.‐P., Liu, T. Z., Xing, X., & Masson, A. (2018). Multispacecraft observations of tailward propagation of transient foreshock perturbations to midtail magnetosheath. Journal of Geophysical Research: Space Physics, 123, 9381–9394. https://doi.org/10.1029/2018JA025921
Gedalin, M., Zhou, X., Russell, C. T., Drozdov, A. Y., & Liu, T. Z. (2018). Ion dynamics and the shock profile of a low‐Mach number shock. Journal of Geophysical Research: Space Physics, 123, 8913–8923. https://doi.org/10.1029/2018JA025945
Turner D. L., L. B. Wilson III, T. Z. Liu, et al. (2018), Autogenous and efficient acceleration of energetic ions upstream of Earth’s bow shock. Nature, 561, 206, doi:10.1038/s41586-018-0472-9
Liu, T. Z., Lu, S., Angelopoulos, V., Lin, Y., & Wang, X. Y. (2018). Ion acceleration inside foreshock transients. Journal of Geophysical Research: Space Physics, 122. https://doi.org/10.1002/2017JA024838
Liu, T. Z., S. Lu, V. Angelopoulos, H. Hietala, and L. B. Wilson III (2017), Fermi acceleration of electrons inside foreshock transient cores, J. Geophys. Res. Space Physics, 122, doi:10.1002/2017JA024480.
Liu, T. Z., V. Angelopoulos, and H. Hietala (2017), Energetic ion leakage from foreshock transient cores, J. Geophys. Res. Space Physics, 122, doi:10.1002/2017JA024257.
Liu, T. Z., V. Angelopoulos, H. Hietala, and L. B. Wilson III (2017), Statistical study of particle acceleration in the core of foreshock transients, J. Geophys. Res. Space Physics, 122, doi:10.1002/2017JA024043. Editor's Highlight
Wang, C.-P., R. Thorne, T. Z. Liu, et al. (2017), A multispacecraft event study of Pc5 ultralow-frequency waves in the magnetosphere and their external drivers, J. Geophys. Res. Space Physics, 122, 5132–5147, doi:10.1002/2016JA023610.
Liu, T. Z., D. L. Turner, V. Angelopoulos, and N. Omidi (2016), Multipoint observations of the structure and evolution of foreshock bubbles and their relation to hot flow anomalies, J. Geophys. Res. Space Physics, 121, doi:10.1002/2016JA022461.
Liu, T. Z., H. Hietala, V. Angelopoulos, and D. L. Turner (2016), Observations of a new foreshock region upstream of a foreshock bubble’s shock, Geophys. Res. Lett., 43, doi:10.1002/2016GL068984. Geophys. Res. Lett. Cover Image
Liu, Z., D. L. Turner, V. Angelopoulos, and N. Omidi (2015), THEMIS observations of tangential discontinuity-driven foreshock bubbles, Geophys. Res. Lett., 42, doi:10.1002/2015GL065842.
Liu, Z.-X., J.-S. He, and L.-M. Yan (2014), Observations of counter-propagating Alfvénic and compressive fluctuations in the chromosphere, Res. Astron. Astrophys. 14, 3, doi: 10.1088/1674-4527/14/3/004
