论文标题
与银河系矮人球形星系约束速度依赖性的自我互动暗物质
Constraining Velocity-dependent Self-Interacting Dark Matter with the Milky Way's dwarf spheroidal galaxies
论文作者
论文摘要
明亮的银河系（MW）矮球星系（DSPHS）的中央暗物质（DM）密度之间观察到的抗相关性及其轨道上心距离距离具有潜在的自我相互作用暗物质（SIDM）的潜在特征。在这项工作中，我们通过分析单位质量的SIDM散射横截面范围（$σ/m_χ$）来研究这种可能性，能够解释这种抗相关性。我们模拟了MW周围DSPHS亚李的轨道演化，假设重力电位的分析形式，采用了Gaia任务的适当运动，包括对重力潮汐剥离的一致表征。使用重量热流体形式主义对次霍斯密度曲线的演变进行建模，其中DM粒子碰撞诱导的热传导取决于$σ/m_χ$。我们发现，诸如Carina和fornax之类的DSPHS模型重现了观察到的中央DM密度，固定$σ/m_χ$在$ 30 $和50 $ cm $^{2} $ g $^{2} $ g $^{-1} $之间，而其他dsphs则更大的dsphs偏爱$ 70 $ $ $ $ $ $ cmm $ cmm $ cmm，这些横截面与每个Subhalo核心内DM颗粒的平均碰撞速度相关，因此以大型横截面建模的系统具有较低的碰撞速度。我们与SIDM粒子模型符合横截面的相关性，其中质量$m_χ= 0.648 \ pm 0.154 $ GEV在交换质量$ $ m_ϕ = 0.636 \ pm 0.055 $ MEV的情况下相互作用，并用Yukawa的电势描述了自我交互。结果是一个横截面的关系，该关系解释了MW DSPH卫星的不同DM轮廓，并且与较大尺度上的观察性约束一致。
The observed anti-correlation between the central dark matter (DM) densities of the bright Milky Way (MW) dwarf spheroidal galaxies (dSphs) and their orbital pericenter distances poses a potential signature of self-interacting dark matter (SIDM). In this work we investigate this possibility by analysing the range of SIDM scattering cross section per unit mass, $σ/m_χ$, able to explain such anti-correlation. We simulate the orbital evolution of dSphs subhaloes around the MW assuming an analytical form for the gravitational potential, adopting the proper motions from the Gaia mission and including a consistent characterization of gravitational tidal stripping. The evolution of the subhaloes density profile is modelled using the gravothermal fluid formalism, where DM particle collisions induce thermal conduction that depends on $σ/m_χ$. We find that models of dSphs, such as Carina and Fornax, reproduce the observed central DM densities with fixed $σ/m_χ$ ranging between $30$ and $50$ cm$^{2}$g$^{-1}$, whereas other dSphs prefer larger values ranging between $70$ and $100$ cm$^{2}$g$^{-1}$. These cross sections correlate with the average collision velocity of DM particles within each subhalo's core, so that systems modelled with large cross sections have lower collision velocities. We fit the cross section-velocity correlation with a SIDM particle model, where a DM particle of mass $m_χ=0.648\pm 0.154$ GeV interacts under the exchange of a light mediator of mass $m_ϕ=0.636\pm 0.055$ MeV, with the self-interactions being described by a Yukawa potential. The outcome is a cross section-velocity relation that explains the diverse DM profiles of MW dSph satellites and is consistent with observational constraints on larger scales.
