Astrophysics and Space Sciences Transactions www.astrophys-space-sci-trans.net 1810-6528 1810-6536 5 1 2009 10.5194/astra-5-15-2009 http://www.astrophys-space-sci-trans.net/5/15/2009/ http://www.astrophys-space-sci-trans.net/5/15/2009/astra-5-15-2009.html http://www.astrophys-space-sci-trans.net/5/15/2009/astra-5-15-2009.pdf 15 19 2009-06-04 Solar wind proton reflection and injection to the ACR regime at the parallel termination shock D. Verscharen verscharen@mps.mpg.de H.-J. Fahr Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Straße 2, 37191 Katlenburg-Lindau, Germany Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany Our recent kinetic model for the parallel solar wind termination shock describes the ion shock transit under the influence of a decelerating electrostatic potential and the turbulent wave-particle interaction with electrostatic plasma waves. Due to this diffusive interaction, a certain number of ions are reflected at the shock. These ions propagate with a bulk velocity comparable to the bulk velocity of the incoming solar wind backwards into the inner heliosphere. They undergo strong pitch-angle diffusion as they interact with the interplanetary Alfvénic turbulence similar to freshly ionized pick-up ions (PUIs). Their distribution function is hence isotropized to a shell in velocity space. Since their velocity magnitude in the wind frame is higher (about two times) than the estimated PUI velocity, part of the reflected and isotropized ions can directly enter an acceleration process (diffusive or stochastic, respectively) without the necessity of a pre-acceleration. This means that an additional self-initialized seed population for the injection into the anomalous cosmic ray (ACR) acceleration is shown to appear due to shock reflected solar wind ions. Achterberg, A. and Krulls, W M.: A fast simulation method for particle acceleration, Astron Astrophys., 265, L13–L16, 1992. Burlaga, L F., Ness, N F., Acuña, M H., Lepping, R P., Connerney, J E P., and Richardson, J D.: Magnetic fields at the solar wind termination shock, Nature, 454, 75–77, \doi10.1038/nature07029, 2008. Chalov, S V. and Fahr, H J.: Reflection of Pre-Accelerated Pick-up Ions at the Solar Wind Termination Shock: The Seed for Anomalous Cosmic Rays, Sol Phys., 168, 389–411, \doi10.1007/BF00148064, 1996. Chalov, S V. and Fahr, H J.: Interplanetary Pick-Up Ion Acceleration A Study of Anisotropic Phase-Space Diffusion, Astrophys Space~Sci., 264, 509–525, 1999. Chalov, S V., Fahr, H J., and Izmodenov, V.: Spectra of energized pick-up ions upstream. of the heliospheric termination shock I. The role of Alfvenic turbulences., Astron Astrophys., 304, 609–616, 1995. Decker, R B., Krimigis, S M., Roelof, E C., Hill, M E., Armstrong, T P., Gloeckler, G., Hamilton, D C., and Lanzerotti, L J.: Voyager 1 in the Foreshock, Termination Shock, and Heliosheath, Sci., 309, 2020–2024, \doi10.1126/science.1117569, 2005. Dworsky, A. and Fahr, H J.: Ion acceleration in connection with a modulated solar wind termination shock: phase space propagation and complete energy spectra, Astron Astrophys., 353, L1–L4, 2000. Fahr, H.-J. and Siewert, M.: Anisotropic unstable ion distribution functions downstream of the solar wind termination shock, Astrophysics and Space Sciences Transactions, 3, 21–27, 2007. Fahr, H.-J. and Verscharen, D.: Ion reflections from the parallel MHD termination shock and a possible injection mechanism into the Fermi-1 acceleration, Astron Astrophys., 487, L21–L24, \doi10.1051/0004-6361:200810217, 2008. Fahr, H J., Scherer, K., Potgieter, M S., and Ferreira, S E S.: Longitudinal variation of the pickup-proton-injection efficiency and rate at the heliospheric termination shock, Astron Astrophys., 486, L1–L4, \doi10.1051/0004-6361:200809561, 2008. Gardiner, C W.: Handbook of stochastic methods for physics, chemistry and the natural sciences, Springer, Berlin, 1994. Gosling, J T., Thomsen, M F., Bame, S J., Feldman, W C., Paschmann, G., and Sckopke, N.: Evidence for specularly reflected ions upstream from the quasi-parallel bow shock, Geophys Res Lett., 9, 1333–1336, \doi10.1029/GL009i012p01333, 1982. Kadomtsev, B B.: Plasma turbulence, New York: Academic Press, 1965, 1965. Kallenbach, R., Hilchenbach, M., Chalov, S V., Le Roux, J A., and Bamert, K.: On the "injection problem" at the solar wind termination shock, Astron Astrophys., 439, 1–22, \doi10.1051/0004-6361:20052874, 2005. Krasnoselskikh, V V., Lembège, B., Savoini, P., and Lobzin, V V.: Nonstationarity of strong collisionless quasiperpendicular shocks: Theory and full particle numerical simulations, Phys Plasmas, 9, 1192–1209, \doi10.1063/1.1457465, 2002. Lee, L C., Wu, C S., and Hu, X W.: Increase of ion kinetic temperature across a collisionless shock. I - A new mechanism, Geophys Res Lett., 13, 209–212, \doi10.1029/GL013i003p00209, 1986. Li, H., Wang, C., and Richardson, J D.: Properties of the termination shock observed by Voyager 2, Geophys Res Lett., 35, 19 107, \doi10.1029/2008GL034869, 2008.\vadjust Lifshitz, E M. and Pitaevskii, L P.: Physical kinetics, Course of theoretical physics, Oxford: Pergamon Press, 1981, 1981. Lucek, E A., Horbury, T S., Dandouras, I., and Rème, H.: Cluster observations of the Earth's quasi-parallel bow shock, J Geophys Res., 113, 7, \doi10.1029/2007JA012756, 2008. McComas, D J. and Schwadron, N A.: An explanation of the Voyager paradox: Particle acceleration at a blunt termination shock, Geophys Res Lett., 33, 4102, \doi10.1029/2005GL025437, 2006. Meziane, K., Mazelle, C., Wilber, M., Lequéau, D., Eastwood, J., Rème, H., Dandouras, I., Sauvaud, J., Bosqued, J., Parks, G., Kistler, L., McCarthy, M., Klecker, B., Korth, A., Bavassano-Cattaneo, M., Lundin, R., and Balogh, A.: Bow shock specularly reflected ions in the presence of low-frequency electromagnetic waves: a case study, Ann Geophys., 22, 2325–2335, 2004. Parker, E N.: Dynamics of the Interplanetary Gas and Magnetic Fields., Astrophys J., 128, 664–676, \doi10.1086/146579, 1958. Quest, K B.: Theory and simulation of collisionless parallel shocks, J Geophys Res., 93, 9649–9680, \doi10.1029/JA093iA09p09649, 1988. Schwadron, N A., Lee, M A., and McComas, D J.: Diffusive Acceleration at the Blunt Termination Shock, Astrophys J., 675, 1584–1600, \doi10.1086/527026, 2008. Shevyrev, N N., Zastenker, G N., and Du, J.: Statistics of low-frequency variations in solar wind, foreshock and magnetosheath: INTERBALL-1 and CLUSTER data, Planet Space Sci., 55, 2330–2335, \doi10.1016/j.pss.2007.05.014, 2007. Siewert, M. and Fahr, H.-J.: Full Boltzmann-kinetical treatment of an ion plasma crossing an MHD shock: parallel and non-parallel cases, Astron Astrophys., 471, 7–15, \doi10.1051/0004-6361:20077413, 2007. Stone, E C., Cummings, A C., McDonald, F B., Heikkila, B C., Lal, N., and Webber, W R.: Voyager 1 Explores the Termination Shock Region and the Heliosheath Beyond, Sci., 309, 2017–2020, \doi10.1126/science.1117684, 2005. Treumann, R A. and Scholer, M.: The magnetosphere as a plasma laboratory, p. 1495, The Century of Space Science, Volume I, 2002. Verscharen, D. and Fahr, H.-J.: A kinetic description of the dissipative quasi-parallel solar wind termination shock, Astron Astrophys., 487, 723–729, \doi10.1051/0004-6361:200809950, 2008a. Verscharen, D. and Fahr, H.-J.: Self-initialised Fermi-1 acceleration by pitch-angle re-scattering of solar wind ions reflected from the parallel termination shock, Astrophys Space Sci Trans., 4, 51–58, 2008b.