Shock Source Description: Large-Scale Hybrid Simulations Dietmar Krauss-Varban Janet Luhmann Ilan Roth Yan Li Steve Ledvina Space Sciences Laboratory, UC Berkeley CISM All-Hands Meeting, Boston, 9/2004

Overview Black-box Model and Source Description Observations Theory and Transport Models Role of Simulations in CISM SEP model Reames, 1999

Hybrid Simulations Overview and Goals/Deliverables Scales and Extrapolation Early Results Limitations and Outlook

Hybrid Simulations Overview and Goals: Kinetic ions, electron fluid Spatial scale: c/  p ; time scale  p -1 Initially focus on protons; later: arbitrary masses and charge states Primary shock parameters: , M A,  Bn Secondary parameters: absolute n, absolute T

Hybrid Simulations SEP Shock Sources:

Hybrid Simulations Scales and Extrapolation (conservative estimate) : Assume target energy of 1MeV. Convected gyro radius in 6nT B-field 10 5 km ~ 10 3 c/  p Need several resonant in system in 1 direction  e.g., 10,000 x 500 c/  p (assuming 2-D). Typical time step 0.01  p -1, 2.5·10 6 pp/s / CPU 1 hour of real time (~transit time at M A = 5)  5 days on 40 CPUs Power-law  extrapolation

Hybrid Simulations Early Results - Overview B z and T || ; M A = 6.0,  Bn = 30 o

Hybrid Simulations Ion Distributions: quasi-parallel case

Hybrid Simulations Ion Distributions: oblique case

Hybrid Simulations Ion Distributions: upstream vs. downstream

Hybrid Simulations Fluctuations and Anisotropy

Hybrid Simulations Velocity Distributions: quasi-parallel case

Hybrid Simulations Velocity Distributions: oblique case

Hybrid Simulations Limitations: Computational requirements/ infrastructure 3-D necessary for nearly-perpendicular case because of cross-field diffusion

Hybrid Simulations Parameter Space:

Hybrid Simulations Outlook/ Tentative Deliverables 3-D Parameter space: result grid ~ O (100) points Deliver: peak flux, power law index, and pitch-angle distribution both upstream and downstream

Contributions from Test Particle Studies Generic results Shock surfing/ nearly perpendicular shock Power law extrapolation Shock crossings: Transparency and further energization Understand trapped particle population at quasi-perpendicular shock Goals and deliverables

Test Particle Contribution Generic Results: model shock with turbulence Example: M A = 2,  Bn = 85 o, shock width = 0.1 c/  p Legend:(here: shock in x-z plane) X position vs. timeY position vs. time X vs. Y positionsV x velocity vs. time V x vs. V y velocitiesZ vs. y positions Z velocity vs. time energy vs. time

Test Particle Contribution Shock-interaction of ions: - accelerated at another shock, - or mirrored, e.g.,in converging fields behind (sunward of) shock “transparency” M A = 3.0,  Bn = 80 o

Turbulent medium: sigma= 0.1, M=3, theta=80, W= 225keV Turbulent shock –> significant effect on medium energy ions

Test Particle Contribution In presence of turbulence, as expected, ions can be further energized during second encounter Depending on level of turbulence and spectrum, very energetic particles may not be significantly affected by shock Transmission is strongly pitch-angle dependent  Yan Li will study observationally trapping/ pitch-angle distributions of energized ions at q-perp shocks

Energetic Storm Particle (ESP) Events Overview/ Relevance to CISM Hybrid Simulations of Spatio- Temporal Evolution Integration into CISM SEP Model: - empirical model - integration of simulation results

Energetic Storm Particle (ESP) Events Hybrid Simulations of Spatio-Temporal Evolution

Energetic Storm Particle (ESP) Events Integration into CISM SEP Model: - empirical model - integration of simulation results Yan observational study: - when/why high energies - distinguish bulk vs. spike

Summary Hybrid simulations will provide shock source description (peak flux, power-law index, pitch-angle distribution) for entire parameter space ESP events require to be integrated into CISM SEP model in a separate way. Hybrid simulations can directly contribute to quantifying ESP events.