Cosmic-ray protons accelerated at cosmological shocks and their impact on groups and clusters of galaxies

被引:120
作者
Miniati, F
Ryu, DS
Kang, HS
Jones, TW
机构
[1] Max Planck Inst Astrophys, D-85740 Garching, Germany
[2] Univ Minnesota, Dept Astron, Minneapolis, MN 55455 USA
[3] Chungnam Natl Univ, Dept Astron & Space Sci, Taejon 305764, South Korea
[4] Pusan Natl Univ, Dept Earth Sci, Pusan 609735, South Korea
关键词
acceleration of particles; gamma rays : theory; large-scale structure of universe; methods : numerical; shock waves; X-rays : galaxies : clusters;
D O I
10.1086/322375
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We investigate the production of cosmic-ray (CR) protons at cosmological shocks by performing, for the first time, numerical simulations of large-scale structure formation that include directly the acceleration, transport, and energy losses of the high-energy particles. CRs are injected at shocks according to the thermal leakage model and, thereafter, accelerated to a power-law distribution as indicated by the test particle limit of the diffusive shock acceleration theory. The evolution of the CR protons accounts for losses owing to adiabatic expansion/compression, Coulomb collisions, and inelastic p-p scattering. Our results suggest that CR protons produced at shocks formed in association with the process of large-scale structure formation could amount to a substantial fraction of the total pressure in the intracluster medium. Their presence should be easily revealed by GLAST (Gamma-Ray Large-Area Space Telescope) through detection of gamma -ray flux from the decay of pi (o) produced in inelastic p-p collisions of such CR protons with nuclei of the intracluster gas. This measurement will allow a direct determination of the CR pressure contribution in the intracluster medium. We also find that the spatial distribution of CR is typically more irregular than that of the thermal gas because it is more influenced by the underlying distribution of shocks. This feature is reflected in the appearance of our gamma -ray synthetic images. Finally, the average CR pressure distribution appears statistically slightly more extended than the thermal pressure.
引用
收藏
页码:59 / 69
页数:11
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