● V-1. SHINE Nova Scotia, August 2009. ● V-2. Acceleration of ACRs at a Blunt Termination Shock: 2-D Simulations. J. K ό ta University of Arizona Tucson, AZ 85721-0092, USA Thanks: J.R. Jokipii, J. Giacalone. [email protected] Difference between 1 & 2 D Shocks.
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SHINE Nova Scotia, August 2009
Acceleration of ACRs at a Blunt Termination Shock: 2-D Simulations
University of Arizona
Tucson, AZ 85721-0092, USA
Thanks: J.R. Jokipii, J. Giacalone
Difference between 1 & 2 D Shocks
● Are Anomalous Cosmic Rays (ACRs) indeed accelerated at the solar wind termination shock (TS) ?
● Bluntness of TS counts
● Topology between shock & field Lines counts (cannot be modeled in 1 D)
● Model still qualitative
Do not consider other important effects, like dynamical variations
Multiple intersection explains precursor anisotropies
Displacement of the ‘nose’ helps
ACR fluxes continued
to increase into the
● Temporal variaton
● Magnetic topology
(McComas & Schwadron,
Kόta & Jokipii)
● Combination of the two?
Can be a direct result of 2D topology
Could have been foreseen (Kόta & Jokipii, 2004)
McComas and Schwadron (2006)
Injection & Acceleration at Flanks
Short time for
Kóta and Jokipii, 2004
This Simulation: Shock & Injection stronger at nose, weaker toward tail
More TSP at nose (injection profile)
Less ACRs at nose (global feature)
Controlled by κ┴
ACR flux continues
to increase beyond TS
Cooled down to 100 keV
Starting energy 5 MeV
Flank 60 West
ACRs are `older’ deeper in the HS
Reverse method w larger κ Forward method w smaller κ
Less efficient- More efficient
● Magnetic field lines cross the blunt TS multiple times. This explains upstream anisotropies and :
● Two-population spectrum: ACRs start as TSPs at the nose and move toward the flanks during acceleration. Appear still modulated at the TS, and continue to increase into the heliosheath.
● 2-D Shock differs from 1-D shock (topology)
● Dependence on parameters (κ) still need to be explored .
- injection rate and/or shock ratio is higher at nose
Reason: unfavourable topology (natural cold spot)
Along shock front
Distance from shock
Global structure along shock front
organized by magnetic field
ACR fluxes continued to increase beyond TS
V. Hess 1912
Voyager-1 December 2004
Similar result from V-2 (2007)
VLISM: partially ionized
0.1/cc μG B ?