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arXiv 2202.08491astro-ph.HE
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Cosmic-ray谱的三分量模型和偶极各向异性

A Three-component Model for Cosmic-ray Spectrum and Dipole Anisotropy

Yiran Zhang, Siming Liu, Houdun Zeng

摘要:

利用三分量多尺度扩散模型,我们证明了宇宙线(CR)质子和氦谱和偶极各向异性可以用合理的参数来解释。该模型包括一个与产生Geminga脉冲星的超新星遗迹(SNR)相关的附近源,一个位于银河系中心的源,以及一个与银河系盘相关的组件。TeV以下的CR通量主要由盘分量决定。中心源与连续注入的CR开始约1800万年前是需要解释的各向异性超过100 TeV。假设所有SNR注入的CR谱都是普适的,附近的源可以通过星际磁场的缓慢扩散在地球上产生TeV的谱凸,这需要在磁力线和朝向源的视线之间有一个角度$ θ\approx 5^{\circ} $,并且具有阿尔文马赫数$ M_{\text{A}}\approx 0.1 $的弱磁湍流。考虑到这种磁场对银河尺度各向异性的调制,在准局域方法中,磁场可以指向赤道坐标系中关于$ -90^{\circ} $的赤经和关于$ -7.4^{\circ} $的赤经。

英文摘要:

Using a three-component, multi-scale diffusion model, we show that the cosmic-ray (CR) proton and helium spectra and the dipole anisotropy can be explained with reasonable parameters. The model includes a nearby source associated with the supernova remnant (SNR) that gave rise to the Geminga pulsar, a source at the Galactic center, and a component associated with the Galactic disk. The CR flux below TeV is dominated by the disk component. The center source with a continuous injection of CRs starting about 18 Myr ago is needed to explain the anisotropy above 100 TeV. With the assumption of universal CR spectra injected by all SNRs, the nearby source can produce a TeV spectral bump observed at Earth via slow diffusion across the interstellar magnetic field, which needs to have an angle $ θ\approx 5^{\circ} $ between the field line and the line of sight toward the source, and have weak magnetic turbulence with the Alfvén Mach number $ M_{\text{A}}\approx 0.1 $. Considering the modulation of the Galactic-scale anisotropy by this magnetic field, in a quasi-local approach the field may be directed at a right ascension about $ -90^{\circ} $ and a declination about $ -7.4^{\circ} $ in the equatorial coordinate system.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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