Yang Daneng, Yu Hai-Bo, An Haipeng
Department of Physics, Tsinghua University, Beijing 100084, China.
Department of Physics and Astronomy, University of California, Riverside, California 92521, USA.
Phys Rev Lett. 2020 Sep 11;125(11):111105. doi: 10.1103/PhysRevLett.125.111105.
Observations of ultradiffuse galaxies NGC 1052-DF2 and -DF4 show they may contain little dark matter, challenging our understanding of galaxy formation. Using controlled N-body simulations, we explore the possibility that their properties can be reproduced through tidal stripping from the elliptical galaxy NGC 1052, in both cold dark matter (CDM) and self-interacting dark matter (SIDM) scenarios. To explain the dark matter deficiency, we find that a CDM halo must have a very low concentration so that it can lose sufficient inner mass in the tidal field. In contrast, SIDM favors a higher and more reasonable concentration as core formation enhances tidal mass loss. Final stellar distributions in our SIDM benchmarks are more diffuse than the CDM one, and hence the former are in better agreement with the data. We further show that a cored CDM halo model modified by strong baryonic feedback is unlikely to reproduce the observations. Our results indicate that SIDM is more favorable for the formation of dark-matter-deficient galaxies.
对超扩散星系NGC 1052-DF2和-DF4的观测表明，它们可能只包含少量暗物质，这对我们对星系形成的理解提出了挑战。通过可控的N体模拟，我们探讨了在冷暗物质（CDM）和自相互作用暗物质（SIDM）两种情况下，能否通过椭圆星系NGC 1052的潮汐剥离来再现它们的特性。为了解释暗物质的缺乏，我们发现CDM晕必须具有非常低的浓度，以便它能在潮汐场中损失足够的内部质量。相比之下，SIDM更倾向于更高且更合理的浓度，因为核心形成会增强潮汐质量损失。我们的SIDM基准模型中的最终恒星分布比CDM模型中的更弥散，因此前者与数据的吻合度更好。我们进一步表明，由强重子反馈修正的有核CDM晕模型不太可能再现这些观测结果。我们的结果表明，SIDM更有利于形成暗物质缺乏的星系。
