恒星ストリームの特徴を物理学者が解明(Physicists explain a stellar stream’s distinctive features)

2025-01-06 カリフォルニア大学リバーサイド校(UCR)

＜関連情報＞

• https://news.ucr.edu/articles/2025/01/06/physicists-explain-stellar-streams-distinctive-features-0
• https://iopscience.iop.org/article/10.3847/2041-8213/ada02b

GD-1 恒星流摂動体は、コアが崩壊した自己相互作用暗黒物質ハローとして機能します The GD-1 Stellar Stream Perturber as a Core-collapsed Self-interacting Dark Matter Halo

Xingyu Zhang, Hai-Bo Yu, Daneng Yang, and Ethan O. Nadler
The Astrophysical Journal Letters  Published: 2025 January 3
DOI:10.3847/2041-8213/ada02b

Abstract

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 N-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 × 10⁸ M_⊙, 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 σ/m ≈ 30–100 cm² g⁻¹ at V_max~10kms⁻¹, 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.