发表机构
Yale University（耶鲁大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究量化了暗物质晕三轴度对卫星轨道的影响，发现三轴度会导致卫星轨道近心距散射、偏差，混沌轨道仅在强扁化宿主中出现，宿主形状和取向的不确定性会显著影响卫星轨道推断，需纳入未来研究。
AI 中文摘要
卫星星系的近心距决定了它们的潮汐剥离、熄灭和存活，然而其轨道几乎普遍在球形宿主势场中计算，而暗物质晕通常是三轴的。我们逐轨道量化了这种简化带来的误差：在固定质量剖面下，我们在静态NFW宿主中积分了10^6个来自宇宙学下落分布的卫星，这些宿主的三轴度系统变化。三轴度几乎未改变近心距、远心距和轨道周期的总体中位数，但单个轨道的连续近心距散射比例达5%-23%，具体取决于宿主形状，且与轨道能量无关；在哈勃时间内达到的最小近心距系统性缩小最多21%，加剧了峰值潮汐质量损失。这种由三轴度驱动的轨道失相主要是规则的而非混沌的；在强扁化宿主中，混沌卫星轨道很常见且主导近心处的近心通过，但它们的发散时间尺度远超哈勃时间。通过在真实三轴宿主中直接反向积分重建的球形卫星轨道，在2-4 Gyr内发散了1/10的 virial半径，其中宿主未受约束的形状和未知绝对取向分别带来了相当的不确定性。对于银河系矮星系三角座II，仅未知的晕形状和取向就使推断出的近心距扩散约50%，是其报告不确定性的5倍，也是LMC诱导位移的10倍以上，并使其产生6%-70%的偏差。这种宿主形状不确定性可主导卫星轨道误差预算，应纳入未来的推断研究中。
英文摘要
The pericentric distances of satellite galaxies govern their tidal stripping, quenching, and survival, yet their orbits are almost universally computed in spherical host haloes, whereas dark matter haloes are generically triaxial. We quantify, orbit by orbit, the error this simplification incurs. We integrate $10^6$ satellites, drawn from a cosmological infall distribution, in static NFW hosts of systematically varying triaxiality at fixed mass profile. Triaxiality leaves the population medians of pericentre, apocentre, and orbital period essentially unchanged. Instead, successive pericentres of an individual orbit scatter by 5-23% depending on host shape, irrespective of orbital energy; the minimum pericentre distance reached within a Hubble time shrinks systematically by up to 21%, enhancing the peak tidal mass loss. This triaxiality-driven orbital dephasing is overwhelmingly regular rather than chaotic; chaotic satellite orbits are common and dominate the near-centre pericentric passages in strongly flattened hosts, but diverge on time-scales far exceeding the Hubble time. Satellite orbits spherically reconstructed via direct backward integration in a truly triaxial host diverge by a tenth of the virial radius within 2-4 Gyr, with comparable uncertainties sourced separately by the unconstrained shape of the host and by its unknown absolute orientation. For the Milky Way dwarf Triangulum II, the unknown halo shape and orientation alone spread the inferred pericentre by ~50%, five times its reported uncertainty and more than ten times the LMC-induced shift, and bias it by 6-70%. This host-shape uncertainty can dominate satellite orbital error budgets and should be incorporated in future inferences.
Comments16 pages, 9 figures, 1 table; Accepted for publication in MNRAS
