利用多成像类星体的天体测量弱引力透镜发现亚恒星暗物质晕
Discovering Substellar Dark Matter Halos with Astrometric Weak Lensing of Multiply Imaged Quasars
- Stanford University（斯坦福大学）
- Johns Hopkins University（约翰斯·霍普金斯大学）
- The University of Tokyo（东京大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究提出用多成像类星体的天体测量弱引力透镜探测亚恒星暗物质晕，可将引力透镜灵敏度延伸至比迄今最小暗物质结构低12-14个数量级，还能约束暗物质粒子质量等关键参数。
AI中文摘要：
我们提出将多成像类星体的时域天体测量弱引力透镜作为探测亚恒星暗物质（DM）晕的探针。在ΛCDM模型中，每个宏像的光子路径会穿过大量微晕，这些微晕共同产生具有可计算红功率谱的随机质心运动。穿越时间超过观测时长的晕会在像对之间产生相对角加速度。对于尺寸为0.01-1 pc（ΛCDM模型中质量为10⁻⁶-1 M⊙）的亚晕，该响应最强，将引力透镜灵敏度延伸至比迄今探测到的最小DM结构低12至14个数量级。我们对两个基准系统的十年观测（300个历元）进行灵敏度预测：星系透镜的四重像B1422+231，采用扩展路径强度相关（EPIC）的每历元0.1 μas精度；宽分离的星系团透镜三重像SDSS J1029+2623，采用1 μas精度。在图像位置处投影质量密度的一半由微晕构成的（乐观）假设下，角加速度通道对星系透镜的标准ΛCDM微晕群体达到约10的方差信噪比，对星系团达到约1的信噪比。若获得正检测，将：将DM粒子质量的普遍下界提高至费米子≥400 keV、玻色子≥10⁻¹² eV；将DM动力学退耦温度约束至≥10 MeV；并在原初曲率功率谱的15-20个e-folds上以0.01的精度对谱指数的变化敏感。在特征明确的透镜中获得可靠的零结果，将约束微晕的存活能力和/或暗示上述不等式被违反。这些信号推动对多成像类星体进行0.1-1 μas的高精度差分天体测量观测。
英文摘要：
We propose time-domain astrometric weak lensing of multiply imaged quasars as a probe of substellar dark matter (DM) halos. In $Λ$CDM, each macro-image's light traverses many microhalos, producing a stochastic centroid motion with a calculable red power spectrum. Halos with crossing times longer than the survey impart a relative angular acceleration between image pairs. The response peaks at subhalo scale radii 0.005-2 pc and masses $3\times10^{-6}$-$10^2\,M_\odot$, 12-14 orders of magnitude below the smallest detected DM structures, down to the damping cutoffs of a 100 GeV thermal relic. We forecast the sensitivity of ten-year campaigns with 300 epochs for two benchmark systems: the galaxy-lensed quadruple B1422+231 at a 0.1 $μ$as per-epoch precision forecast for extended-path intensity correlation, and the cluster-lensed triple SDSS J1029+2623 at 1 $μ$as. The angular-acceleration channel reaches the standard $Λ$CDM microhalo population with a variance signal-to-noise ratio of order ten for the galaxy lens (order unity after stellar microlensing subtraction) and 0.35 for the cluster under the optimistic assumption that 10% of the projected mass density at the image positions resides in surviving microhalos. A positive detection would: raise universal lower bounds on the DM particle mass to $\gtrsim400$ keV for fermions and $\gtrsim10^{-12}$ eV for bosons; constrain the DM kinetic decoupling temperature to $\gtrsim 10$ MeV; and be sensitive to the running of the spectral tilt at the 0.01 level over 15-20 e-folds of the primordial curvature power spectrum. A robust null result across well-characterized lenses would constrain microhalo survival and/or imply violations of the above inequalities. These signatures motivate differential astrometric observations with extreme 0.1-1 $μ$as light-centroiding precision on multiply imaged quasars. [Abridged]
