利用星系偏振相关性测量超轻轴子相干性
Measuring Ultralight-Axion Coherence with Galaxy Polarization Correlations
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中文总结 AI 辅助
研究利用星系偏振旋转角的三维两点相关性测量超轻类轴子双折射场幅度及相干尺度，通过检测星系对相关性转折测特征动量尺度，幅度约束相关参数，对特定基准调查给出灵敏度等结果，提供了一种晚期探测方法。
中文摘要 AI 辅助
与光子耦合的超轻类轴子粒子会使遥远源的线性偏振发生旋转。我们提议利用星系偏振旋转角的三维两点相关性来测量这种双折射场的幅度及其空间相干尺度。对于具有各向同性高斯速度分布的非相对论性轴子成分，等时场相关性具有$e^{-1}$尺度$L_{\rm G}^{\rm phys}=\sqrt{6}/(m_a v_a)$。通过检测星系对相关性中的转折可测量特征动量尺度$m_a v_a$，相关性幅度则能约束$g_{a\gamma}\sqrt{\Omega_a/\Omega_{\rm DM}}$。对于一个在四分之一天空、红移至$z = 2$的$10^6$个偏振星系的基准调查，有效星系散射$\sigma_{\rm tot}=10^\circ$，我们发现对$m_a(10^{-3}c/v_a)\sim10^{-29}$至$10^{-27}\,{\rm eV}$范围内亚度相关旋转的$5\sigma$灵敏度，且在该范围大部分区域检测到的信号$\sigma[\log_{10}(m_a v_a)]\lesssim0.1$。这提供了一种与宇宙微波背景双折射和结构形成约束互补的几何晚期探测方法。
英文摘要
Ultralight axion-like particles coupled to photons rotate the linear polarization of distant sources. We propose using the three-dimensional two-point correlation of galaxy polarization-rotation angles to measure not only the amplitude of this birefringence field but also its spatial coherence scale. For a nonrelativistic ALP component with an isotropic Gaussian velocity distribution, the equal-time field correlation has an $e^{-1}$ scale $L_{\rm G}^{\rm phys}=\sqrt{6}/(m_a v_a)$, where $v_a$ is the three-dimensional rms ALP velocity dispersion. A detected turnover in the galaxy-pair correlation therefore measures the characteristic momentum scale $m_a v_a$, while the correlation amplitude constrains $g_{aγ}\sqrt{Ω_a/Ω_{\rm DM}}$. For a fiducial survey with $10^6$ polarized galaxies over a quarter of the sky to $z=2$ and effective per-galaxy scatter $σ_{\rm tot}=10^\circ$, we find $5σ$ sensitivity to sub-degree correlated rotations over $m_a(10^{-3}c/v_a)\sim10^{-29}$--$10^{-27}\,{\rm eV}$, with $σ[\log_{10}(m_a v_a)]\lesssim0.1$ for detected signals across much of this range. This provides a geometric late-time probe complementary to CMB birefringence and structure-formation constraints.
