AI 中文总结
研究超高能宇宙射线起源问题，通过构建星系样本，利用偶极比较和角交叉相关分析，考虑银河磁场偏转，发现 8 EeV 及以上 UHECR 各向异性主要由约 50 - 60 Mpc 内的源驱动，明确了其有效传播视界。
AI 中文摘要
超高能宇宙射线（UHECR）的起源仍是天体粒子物理学中的核心开放问题。高于数 EeV 时 UHECR 到达方向的大规模各向异性，以及最高能量处的光谱抑制，表明星系外源局限于附近宇宙的有限体积，但其有效空间尺度仍受 poorly 约束。我们旨在通过研究不同距离附近星系分布对观测到的大规模各向异性的再现程度，来约束能量 E >= 8 EeV 的 UHECR 的有效传播视界，同时考虑银河磁场偏转。我们从 GLADE+ 目录构建了体积受限的星系样本，扩展到 10000 km/s（约 150 Mpc），并使用偶极比较和与皮埃尔·奥格天文台 UHECR 通量图（E >= 8 EeV）的角交叉相关分析来表征各向异性信号的距离依赖性，还使用从银河磁场模型导出的偏转图对星系 - UHECR 相关性进行加权。我们发现，对于 cz < 4000 km/s（< 60 Mpc）内的星系，星系和 UHECR 偶极之间的角分离最小，此时星系偶极幅度也最大。星系 - UHECR 交叉相关信号主要由附近群体主导，在更大距离处迅速减弱。考虑银河磁场偏转将相关幅度提高了两倍多，表明磁效应显著塑造了观测到的各向异性。我们的结果表明观察到的 8 EeV 及以上 UHECR 的各向异性主要由约 50 - 60 Mpc 内的源驱动，与能量损失和磁偏转的预期一致，保留了附近星系外源物质分布的可测量印记。
英文摘要
The origin of ultra-high-energy cosmic rays (UHECR) remains a central open problem in astroparticle physics. The observed large-scale anisotropy of UHECR arrival directions above several EeV, together with the spectral suppression at the highest energies, suggests extragalactic sources confined to a limited volume of the nearby Universe, though the effective spatial scale of this contribution remains poorly constrained. We aim to constrain the effective propagation horizon of UHECR with energies E >= 8 EeV by studying how well the observed large-scale anisotropy is reproduced by the distribution of nearby galaxies at different distances, accounting for Galactic magnetic-field deflections. We construct volume-limited galaxy samples from the GLADE+ catalogue extending to 10000 km/s (~150 Mpc) and use both dipole comparisons and angular cross-correlation analyses with the Pierre Auger Observatory UHECR flux map (E >= 8 EeV) to characterize the distance dependence of the anisotropy signal, further weighting the galaxy-UHECR correlations using deflection maps derived from a Galactic magnetic field model. We find that the angular separation between the galaxy and UHECR dipoles is minimized for galaxies within cz < 4000 km/s (< 60 Mpc), where the galaxy dipole amplitude is also maximal. The galaxy-UHECR cross-correlation signal is dominated by this nearby population and weakens rapidly at larger distances. Accounting for Galactic magnetic field deflections enhances the correlation amplitude by more than a factor of two, indicating that magnetic effects significantly shape the observed anisotropy. Our results indicate that the observed anisotropy of UHECR of 8 EeV and above is primarily driven by sources within ~50-60 Mpc, consistent with expectations from energy losses and magnetic deflections, retaining a measurable imprint of the nearby extragalactic matter distribution.
Comments18 pages, 10 figures
