Study on the Possible Contribution of Galactic Cosmic Rays to the Galactic Halo Magnetic Field Xiaobo Qu, Yi Zhang, Liang Xue* Cheng Liu, Hongbo Hu Institute of High Energy Physics, CAS, Beijing, China * Shandong University, Ji’nan, China Presented By Xiaobo Qu ICRC2011, Beijing, China

OUTLINE Galactic magnetic field in halo Cosmic ray anisotropy Magnetic field induced by Cosmic ray flows Summary

Galactic magnetic field in halo The Galactic magnetic field (GMF) structure in the halo is revealed by the measures of the Faraday rotation of linearly polarized radiation from pulsars and extragalactic radio sources. The measurement suggests the GMF in the halo to be an anti-symmetric structure.

The anti-symmetric rotation measure sky (Han, 2009) ‘A0’ type dynamo in Galactic halo (poloidal field and toroidal field with reversed directions)

Sidereal time Anisotropy in two hemisphere Tibet III Icecube Tibet III: Amenomori, M., et al. 2006, Science, 314, 439 ICECUBE: Abbasi, R. U., et al. 2010, ApJ, 718, 194

Sidereal time Anisotropy in Galactic coordinate Tibet III Icecube Cosmic ray flow in three directions

Magnetic field induced by Cosmic ray flows Extend the anisotropy image observed in the solar vicinity to the whole Galaxy. Biot-Savart Law A0 dynamo J.L. Han,1997 X.B.Qu et al., arXiv:

Magnetic field induced by Cosmic ray flows Parameterized model: Sun, X. H. & Reich,W. 2010, Research in Astronomy and Astrophysics, 10, 1287

Magnetic field induced by Cosmic ray flows So far, this calculation only contains the contribution of CR particles with a positive charge, without considering the abundant CR particles with a negative charge in our Galaxy. Another causation is the simplified extension of the local anisotropy to the whole Galaxy.

Summary Qualitatively, the CR streams inferred from the anisotropy of the GCRs can generate a large- scale magnetic field with a poloidal and toroidal structures consistent with the observations. Quantitatively, the strength of GMF induced by the current related to particles with energy above 100 GeV is approximately 20 times larger than that observed.

Summary The anisotropy of the GCR provides a new measure to study the Galactic electric current as well as a new window to understand the origin of the GMF. The agreement in the magnetic field structure between the model and the observations indicates that the extension of the local anisotropy to the whole Galaxy is reasonable. This will help in further understanding the origin of the anisotropy of the GCRs.

Faraday rotation

The CR anisotropy is fairly stable in two samples. Three Componets ： I Tail-in; II Loss-cone III------Cygnus region ； Tibet measurement in two dimensions

the electric current is I=nqvS n is the density of charged particles. q is charge number of one charged particle. v is the directional movement velocity of cp. S is the cross section area of the current.

Compton-Getting Effect Δ I = (  + 2 ) v c cos  A.H. Compton and I.A. Getting, Phys. Rev. 47, 817(1935) Due to the solar motion around galactic center jE-E- 8 V=220km/s, 

4 TeV 6.2 TeV 12 TeV 50 TeV 300 TeV Celestial Cosmic Ray intensity map in five energy range <12TeV Energy independent >12TeV Fade away “ Tail-in” effect exists in 50TeV rule out the solar causation Energy dependence

Sidereal time anisotropy in 9 Phases ( ) >, M. Amenomori et al., ApJ 711, 119 (2010) Temporal Variations Stable Insensitive to solar activities Improved analysis method, more statistic.

Zenith On-source Off-source ——Global fitting method Equal Two dimension analysis method Zenith belt