Gpc尺度上大型类星体群轴的相关取向
Correlated orientations of the axes of large quasar groups on Gpc scales
摘要：
类星体的光学和射电偏振，以及射电喷流的相关取向，已经在Gpc尺度上被报道，可能是由于自旋轴的内在排列。光学类星体偏振似乎优先对准或正交于主机大尺度结构，特别是大型类星体群（LQG）。使用71个红移为$1.0 \leq z \leq 1.8$的LQG样本，我们研究了LQG本身是否表现出相关取向。我们发现，LQG位置角（PA）是不太可能从一个均匀的分布（$p$ -值$0.008 \lesssim p \lesssim 0.07$）。LQG PA分布是双峰的，中值模式在$\barθ\sim45\pm2^{\circ}, 136\pm2^{\circ}$，非常接近的平均角的类星体射电偏振报告在两个地区与我们的LQG样本一致。我们量化PA数据中的对齐程度，发现LQG在非常大的尺度上是对齐和正交的。在$\sim 30^{\circ}$（1.6 Gpc）的典型角（适当）分离处，最大显著性为$\simeq 0.8\%$（$2.4σ$）。如果LQG的方向相关性是真实的，它代表了大尺度结构的排列，其尺度大于宇宙学模拟预测的尺度，并且至少比迄今为止观察到的任何一个都大一个数量级，除了类星体偏振/射电喷流排列。我们的结论是，LQG对齐有助于解释类星体偏振/射电喷流对齐，但提出了具有挑战性的问题的起源LQG相关性和假设的和谐宇宙模型。
英文摘要：
Correlated orientations of quasar optical and radio polarisation, and of radio jets, have been reported on Gpc scales, possibly arising from intrinsic alignment of spin axes. Optical quasar polarisation appears to be preferentially either aligned or orthogonal to the host large-scale structure, specifically large quasar groups (LQGs). Using a sample of 71 LQGs at redshifts $1.0 \leq z \leq 1.8$, we investigate whether LQGs themselves exhibit correlated orientation. We find that LQG position angles (PAs) are unlikely to be drawn from a uniform distribution ($p$-values $0.008 \lesssim p \lesssim 0.07$). The LQG PA distribution is bimodal, with median modes at $\barθ\sim45\pm2^{\circ}, 136\pm2^{\circ}$, remarkably close to the mean angles of quasar radio polarisation reported in two regions coincident with our LQG sample. We quantify the degree of alignment in the PA data, and find that LQGs are aligned and orthogonal across very large scales. The maximum significance is $\simeq 0.8\%$ ($2.4σ$) at typical angular (proper) separations of $\sim 30^{\circ}$ (1.6 Gpc). If the LQG orientation correlation is real, it represents large-scale structure alignment over scales larger than those predicted by cosmological simulations and at least an order of magnitude larger than any so far observed, with the exception of quasar-polarisation / radio-jet alignment. We conclude that LQG alignment helps explain quasar-polarisation / radio-jet alignment, but raises challenging questions about the origin of the LQG correlation and the assumptions of the concordance cosmological model.
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