Zhang Xingyu, Yu Hai-Bo, Yang Daneng, Nadler Ethan O
Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China;
Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA;
Astrophys J Lett. 2025 Jan 10;978(2):L23. doi: 10.3847/2041-8213/ada02b. Epub 2025 Jan 3.
The GD-1 stellar stream exhibits spur and gap structures that may result from a close encounter with a dense substructure. When interpreted as a dark matter subhalo, the perturber is denser than predicted in the standard cold dark matter (CDM) model. In self-interacting dark matter (SIDM), however, a halo could evolve into a phase of gravothermal collapse, resulting in a higher central density than its CDM counterpart. We conduct high-resolution controlled -body simulations to show that a collapsed SIDM halo could account for the GD-1 perturber's high density. We model a progenitor halo with a mass of 3 × 10 , motivated by a cosmological simulation of a Milky Way analog, and evolve it in the Milky Way's tidal field. For a cross section per mass of / ≈ 30-100 cm g at , the enclosed mass of the SIDM halo within the inner 10 pc can be increased by more than 1 order of magnitude compared to its CDM counterpart, leading to a good agreement with the properties of the GD-1 perturber. Our findings indicate that stellar streams provide a novel probe into the self-interacting nature of dark matter.
GD - 1恒星流呈现出的分支和间隙结构可能是与致密子结构近距离相遇的结果。当将其解释为暗物质次晕时，扰动体比标准冷暗物质（CDM）模型预测的更致密。然而，在自相互作用暗物质（SIDM）中，一个晕可能会演化为引力热坍缩阶段，导致其中心密度高于CDM对应的晕。我们进行了高分辨率的受控体模拟，以表明坍缩的SIDM晕可以解释GD - 1扰动体的高密度。我们根据对银河系类似物的宇宙学模拟，构建了一个质量为3×10 的原晕，并在银河系的潮汐场中使其演化。对于 时每质量的横截面为 / ≈ 30 - 100 cm²/g，与CDM对应的晕相比，SIDM晕在内10秒差距内的包层质量可以增加超过1个数量级，这与GD - 1扰动体的性质非常吻合。我们的研究结果表明，恒星流为暗物质的自相互作用性质提供了一种新的探测手段。
