标题： 超轻轴子引起的振荡度规摄动的脉冲星测时阵列信号 显示英文标题

标题： Pulsar Timing Array Signature from Oscillating Metric Perturbations due to Ultra-light Axion

摘要： 一个一致振荡的超轻轴子可以表现为暗物质。特别是，其一致振荡的压力扰动可以激发一个振荡标量度规扰动，其特征振荡频率是轴子康普顿频率的两倍。在质量范围为$10^{(-24,-21)}{\rm eV}$的候选者可以在当前和未来的脉冲星测时阵列（PTA）项目所测试的频率范围内提供信号。涉及高度非线性环境中的压力扰动，这种分析需要相对论性和非线性处理。在这里，我们在弱引力和爱因斯坦引力的零剪切规范下的慢运动极限下，严格推导了这一效应，并表明暗物质的速度势决定了振荡的相位和频率变化。与速度场相关的单色 PTA 信号会证实这一预测，例如通过交叉关联 PTA 结果与未来本地速度流测量结果来实现。 显示英文摘要

摘要： A coherently oscillating ultra-light axion can behave as dark matter. In particular, its coherently oscillating pressure perturbations can source an oscillating scalar metric perturbation, with a characteristic oscillation frequency which is twice the axion Compton frequency. A candidate in the mass range $10^{(-24,-21)}{\rm eV}$ can provide a signal in the frequency range tested by current and future Pulsar Timing Array (PTA) programs. Involving the pressure perturbations in a highly nonlinear environment, such an analysis demands a relativistic and nonlinear treatment. Here, we provide a rigorous derivation of the effect assuming weak gravity and slow-motion limit of Einstein's gravity in zero-shear gauge and show that dark matter's velocity potential determines the oscillation phase and frequency change. A monochromatic PTA signal correlated with the velocity field would confirm the prediction, for example, by cross-correlating the PTA results with the future local velocity flow measurements.