天基引力波探测器中的标量暗物质：质心运动、尺度呼吸与TDI投影
Scalar dark matter in space-based gravitational-wave detectors: center-of-mass motion, size breathing, and TDI projection
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中文总结 AI 辅助
该研究针对天基引力波探测器，构建质心运动与端点尺度呼吸的链路响应模型，得出TDI投影规则，为判定测试质量呼吸的可忽略性及材料响应建模需求提供基准。
中文摘要 AI 辅助
超轻标量暗物质可通过两种机制使天基引力波探测器产生响应：一是自由下落的测试质量所带的标量电荷，二是标量场诱导的局域固体长度尺度变化。现有天基探测器的预测通常将前者建模为质心力，而地面干涉仪研究表明，标量场还可通过材料和光程转换发挥作用。我们探究将单向多普勒测量组合为延迟时间延迟干涉测量（TDI）可观测量后，局域材料响应的哪一部分会保留下来。为此，我们针对类LISA、类太极和类天琴探测器，在统一的链路响应符号体系中构建了质心运动和端点尺度呼吸模型。主要结果是一条投影规则：在等臂、端点相同、标量场均匀的极限情况下，端点呼吸会以共模链路扰动的形式进入Michelson-X通道，并从保留的通道中被剔除。其主要泄漏由有限标量波矢、臂长不等或随时间变化、端点响应不同或辅助读出控制，且除局域尺度响应外，还带有额外的几何和延迟抑制。我们随后给出可复现的噪声、灵敏度及网络组合公式，并仅在明确的独立流和标量相干性假设下给出多任务改进结果。该结果为判定何时可忽略测试质量呼吸、何时必须对特定仪器的材料响应建模提供了可控基准。
英文摘要
Ultralight scalar dark matter can make space-based gravitational-wave detectors respond through both the scalar charge of freely falling test masses and scalar-induced changes of local solid length scales. Existing space-detector forecasts usually model the former as a center-of-mass force, while ground-based interferometer studies show that scalar fields can also act through material and optical-path transduction. We ask which part of a local material response survives after one-way Doppler measurements are assembled into delayed time-delay-interferometry observables. To this end, we formulate center-of-mass motion and endpoint-size breathing in a common link-response notation for LISA-, Taiji-, and TianQin-like detectors. The main result is a projection rule: in the equal-arm, identical-endpoint, common-field limit, endpoint breathing enters Michelson-$X$ as a common-mode link perturbation and is removed from the retained channel. Its leading leakage is controlled by finite scalar wave vector, unequal or time-dependent arms, nonidentical endpoint response, or auxiliary readouts, and carries extra geometric and delay suppressions beyond the local size response. We then give reproducible noise, sensitivity, and network-combination formulas, and quote multi-mission improvements only under explicit independent-stream and scalar-coherence assumptions. The result provides a controlled baseline for deciding when test-mass breathing can be neglected and when instrument-specific material response must be modeled.
