爱因斯坦望远镜时代利用明亮引力波源精确测量哈勃常数 $H_0$ 的道路
The road towards precision measurements of $H_0$ with bright sirens in the Einstein Telescope era
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中文总结 AI 辅助
研究利用爱因斯坦望远镜模拟双中子星合并及电磁对应体，预测明亮引力波源目录对哈勃常数的约束能力。通过构建不同模拟目录分析发现，独立探测时低红移事件贡献大，纳入外部信息可减少简并性，所需事件数大幅降低，凸显电磁对应体识别及互补探测的重要性。
中文摘要 AI 辅助
引力波标准源提供了宇宙膨胀的独立探测手段，因为其光度距离可直接从引力波信号推断得出，对于明亮引力波源，源红移可通过识别电磁对应体获得。本文利用爱因斯坦望远镜探测到的模拟双中子星合并及其相关电磁对应体，预测了未来明亮引力波源目录对哈勃常数的约束能力。我们构建了具有不同事件数量和红移分布的模拟目录，以GW170817作为参考明亮引力波源，并在平坦的 $\Lambda$CDM 宇宙学中分析所得约束。结果表明，当明亮引力波源作为独立探测手段时，大部分关于 $H_0$ 的信息由低红移事件提供，对于 $z \sim 1$ 以上的源，精度提升趋于饱和；在该红移之上，明亮引力波源的约束能力受与 $\Omega_m$ 的简并性限制，阻碍了 $H_0$ 精度的进一步提高。在这种情况下，大约需要90个低红移明亮引力波源才能达到 $\sigma_{H_0} \sim 1\,{\rm km\,s^{-1}\,Mpc^{-1}}$，而大约45个就足以达到 $\sigma_{H_0} \sim 2\,{\rm km\,s^{-1}\,Mpc^{-1}}$。当纳入外部重子声学振荡信息以减少 $H_0 - \Omega_m$ 的简并性时，中等红移的引力波源变得更具信息量，所需事件数量大幅减少，对于 $\sigma_{H_0} \sim 1\,{\rm km\,s^{-1}\,Mpc^{-1}}$ 和 $\sigma_{H_0} \sim 2\,{\rm km\,s^{-1}\,Mpc^{-1}}$ 分别约为20个和15个明亮引力波源。这些结果凸显了电磁对应体识别和互补背景探测在使明亮引力波源成为哈勃张力的有竞争力、独立于距离阶梯的测试中的重要性。
英文摘要
Gravitational-wave standard sirens provide an independent probe of cosmic expansion since their luminosity distances are inferred directly from the gravitational-wave signal and, for bright sirens (BSs), the source redshifts are obtained through the identification of electromagnetic counterparts. In this work, we forecast the constraining power of future bright siren catalogues on the Hubble constant using simulated binary-neutron-star mergers detected by the Einstein Telescope with associated electromagnetic counterparts. We construct mock catalogues with different numbers of events and redshift distributions, with GW170817 as a reference BS, and analyse the resulting constraints within a flat $Λ$CDM cosmology. We find that, when bright sirens are used as a standalone probe, most of the information on $H_0$ is provided by low-redshift events, with the improvement in precision saturating for sources above $z \sim 1$; beyond that redshift, the constraining power of BSs is increasingly limited by the degeneracy with $Ω_m$, which prevents further gains in precision on $H_0$. In this case, approximately $90$ low-redshift BSs are required to reach $σ_{H_0} \sim 1\,{\rm km\,s^{-1}\,Mpc^{-1}}$, while about $45$ are sufficient for $σ_{H_0} \sim 2\,{\rm km\,s^{-1}\,Mpc^{-1}}$. When external BAO information is included to reduce the $H_0 - Ω_m$ degeneracy, intermediate-redshift sirens become more informative and the required number of events decreases substantially, to roughly $20$ and $15$ BSs for $σ_{H_0} \sim 1\,{\rm km\,s^{-1}\,Mpc^{-1}}$ and $σ_{H_0} \sim 2\,{\rm km\,s^{-1}\,Mpc^{-1}}$, respectively. These results highlight the importance of both electromagnetic counterpart identification and complementary background probes in making BSs a competitive, distance-ladder-independent test of the Hubble tension.
