Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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COSMIC RAY ACCELERATION AT COSMOLOGICAL SHOCKS

  • KANG HYESUNG (Department of Earth Sciences, Pusan National University) ;
  • JONES T. W. (Department of Astronomy, University of Minnesota)
  • Published : 2004.12.01
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Abstract

Cosmological shocks form as an inevitable consequence of gravitational collapse during the large scale structure formation and cosmic-rays (CRs) are known to be accelerated at collisionless shocks via diffusive shock acceleration (DSA). We have calculated the evolution of CR modified shocks for a wide range of shock Mach numbers and shock speeds through numerical simulations of DSA in 1D quasi-parallel plane shocks. The simulations include thermal leakage injection of seed CRs, as well as pre-existing, upstream CR populations. Bohm-like diffusion is assumed. We show that CR modified shocks evolve to time-asymptotic states by the time injected particles are accelerated to moderately relativistic energies (p/mc $\ge$ 1), and that two shocks with the same Mach number, but with different shock speeds, evolve qualitatively similarly when the results are presented in terms of a characteristic diffusion length and diffusion time. We find that $10^{-4} - 10^{-3}$ of the particles passed through the shock are accelerated to form the CR population, and the injection rate is higher for shocks with higher Mach number. The CR acceleration efficiency increases with shock Mach number, but it asymptotes to ${\~}50\%$ in high Mach number shocks, regardless of the injection rate and upstream CR pressure. On the other hand, in moderate strength shocks ($M_s {\le} 5$), the pre-existing CRs increase the overall CR energy. We conclude that the CR acceleration at cosmological shocks is efficient enough to lead to significant nonlinear modifications to the shock structures.

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References

  1. Bell, A. R. 1978, The acceleration of cosmic rays in shock fronts. I, MNRAS, 182, 147 https://doi.org/10.1093/mnras/182.2.147
  2. Berezhko, E., Ksenofontov, L., & Yelshin, V. 1995, Efficiency of CR acceleration in supernova remnants, Nuclear Physic B., 39, 171
  3. Berezhko E. G., & V$\ddot{o}$lk H. J. 2000, Kinetic theory of cosmic ray and gamma-ray production in supernova remnants expanding into wind bubbles, A&Ap, 357, 283
  4. Bowyer, S., Bergh$\ddot{o}$fer, T. W., & Korpelra, E., 1999, Extreme-Ultraviolet Emission in Abell 1795, Abell 2199, and the Coma Cluster, ApJ, 526, 592 https://doi.org/10.1086/308034
  5. Blandford, R. D., & Eichler, D. 1987, Particle Acceleration at Astrophysical Shocks - a Theory of Cosmic-Ray Origin, Phys. Rept., 154, 1 https://doi.org/10.1016/0370-1573(87)90134-7
  6. Drury, L. O'C. 1983, An Introduction to the Theory of Shock Acceleration of Energetic Particles in Tenuous Plasmas, Rept. Prog. Phys., 46, 973 https://doi.org/10.1088/0034-4885/46/8/002
  7. Feretti L., Fusco-Femiano R., Giovannini G., Govoni F., 2001, The giant radio halo in Abell 2163, A&Ap 373, 106 https://doi.org/10.1051/0004-6361:20010581
  8. Fusco-Femiano, R., Dal Fiume, D., Feretti, L., Giovannini, G., Grandi, P., Matt, G., Molendi, S. & Santangelo, A. 1999, Hard X-Ray Radiation in the Coma Cluster Spectrum, ApJ, 513, L21 https://doi.org/10.1086/311902
  9. Gieseler U. D. J., Jones T. W., & Kang H. 2000, Time dependent cosmic-ray shock acceleration with self-consistent injection, A&Ap, 364, 911
  10. Giovannini, G. & Feretti, L. 2000, Halo and relic sources in clusters of galaxies, New Astronomy, 5, 335 https://doi.org/10.1016/S1384-1076(00)00034-8
  11. Jones, T. W. & Kang, H. 2005, Simulating Particle Acceleration in Modified Shocks Using a New Coarse-grained Finite Momentum-Volume Scheme, in preparation
  12. Kang, H., 2003, Acceleration of Cosmic Rays at Cosmic Shocks, Journal of Korean Astronomical Society, 36, 1
  13. Kang, H., & Jones, T. W. 1991, Numerical studies of diffusive particle acceleration in supernova remnants, MNRAS, 249, 439 https://doi.org/10.1093/mnras/249.3.439
  14. Kang, H., & Jones, T. W., 2002, Acceleration of Cosmic Rays at Large Scale Cosmic Shocks in the Universe, Journal of Korean Astronomical Society, 35, 159 https://doi.org/10.5303/JKAS.2002.35.4.159
  15. Kang, H., Jones, T. W., & Gieseler, U. D. J, 2002, Numerical Studies of Cosmic-Ray Injection and Acceleration, ApJ, 579, 337 https://doi.org/10.1086/342724
  16. Kang, H., Jones, T. W., LeVeque, R. J., & Shyue, K. M. 2001, Time Evolution of Cosmic-Ray Modified Plane Shocks, ApJ, 550, 737 https://doi.org/10.1086/319804
  17. Loeb, A. & Waxmann, E. 2000, Cosmic-ray background from structure formation in the intergalactic medium, Nature, 405, 156 https://doi.org/10.1038/35012018
  18. Lucek, S. G., & Bell, A. R. 2000, Non-linear amplification of a magnetic field driven by cosmic ray streaming, MNRAS, 314, 65 https://doi.org/10.1046/j.1365-8711.2000.03363.x
  19. Malkov M. A., & Drury, L. O'C. 2001, Nonlinear theory of diffusive acceleration of particles by shock waves, Rep. Prog. Physr. 64, 429 https://doi.org/10.1088/0034-4885/64/4/201
  20. Malkov, M. A., & V$\ddot{o}$lk H.J. 1998, Diffusive ion acceleration at shocks: the problem of injection, Adv. Space Res. 21, 551 https://doi.org/10.1016/S0273-1177(97)00961-7
  21. Miniati, F., Ryu, D., Kang, H., Jones, T. W., Cen, R., & Ostriker, J. 2000, Properties of Cosmic Shock Waves in Large-Scale Structure Formation, ApJ, 542, 608 https://doi.org/10.1086/317027
  22. Miniati, F., 2002 Inter-galactic Shock Acceleration and the Cosmic Gamma-ray Background, MNRAS, 337, 199 https://doi.org/10.1046/j.1365-8711.2002.05903.x
  23. Quest, K. B. 1988, Theory and simulation of collisionless parallel shocks, J. Geophys. Res. 93, 9649 https://doi.org/10.1029/JA093iA09p09649
  24. Ryu, D., Kang, H., Hallman, E., & Jones, T. W. 2003, Cosmological Shock Waves and Their Role in the Large Scale Structure of the Universe, ApJ, 593, 599 https://doi.org/10.1086/376723
  25. Sarazin, C. L., & Lieu, R., 1998, Extreme-Ultraviolet Emission from Clusters of Galaxies: Inverse Compton Radiation from a Relic Population of Cosmic Ray Electrons?, ApJ, 494, L177 https://doi.org/10.1086/311196
  26. Skilling, J. 1975, Cosmic ray streaming. I - Effect of Alfven waves on particles, MNRAS, 172, 557 https://doi.org/10.1093/mnras/172.3.557

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