AI 中文总结
该研究表征FRB20230907D的前景环境，结合多波段数据识别出两个前景星系团，通过修正NFW轮廓估算其色散量贡献，结合其他结构可解释该FRB的过量色散量，凸显多波段数据的重要性。
AI 中文摘要
我们对FRB20230907D的前景环境进行了表征，该FRB定位在红移z=0.464的星系，其观测色散量为DM_obs=1031 pc cm⁻³。在其红移处，FRB20230907D超出了Macquart关系（宇宙学色散量与源红移之间的预期关系），表明该视线方向存在显著的过量色散量。我们利用Subaru/PFS和SDSS光谱、已发布的星系团表、Rubin/LSST成像数据以及eROSITA X射线数据，对可能导致该过量的前景结构进行表征。通过朋友-朋友搜索，我们在z≃0.09处识别出一个质量巨大的前景系统，其M_200≃5.2×10¹⁴ M_⊙，而低红移星表则在z≃0.02565处揭示了另一个星系团。假设晕气体遵循修正的NFW晕密度轮廓，我们估算这两个系统在观测者坐标系下的贡献分别为150⁺¹¹⁰₋₇₀ pc cm⁻³和80⁺⁶⁰₋₄₀ pc cm⁻³。结合银河系、弥散星系际介质、室女座星系团、M49星系团以及宿主星系的贡献，这些前景结构可在不确定性范围内解释FRB20230907D的过量色散量，凸显了密集前景光谱观测和多波段数据的重要性。
英文摘要
We characterize the foreground environment of FRB20230907D, localized to a galaxy at $z=0.464$, which has an observed dispersion measure of ${\rm DM}_{\rm obs}=1031~{\rm pc~cm^{-3}}$. At its redshift, FRB20230907D lies above the Macquart relation, the expected relation between cosmological dispersion measure and the source redshift, indicating a substantial excess DM along this line of sight. We use Subaru/PFS and SDSS spectroscopy, published group catalogs, Rubin/LSST imaging, and eROSITA X-ray data to characterize the foreground structures that may account for this excess. A friends-of-friends search identifies a massive foreground system at $z\simeq0.09$ with $M_{200}\simeq5.2\times10^{14}~M_\odot$, while low redshift catalogs reveal an additional group at $z\simeq0.02565$. Assuming that the halo gas follows a modified-NFW halo density profile, we estimate observer frame contributions of $150^{+110}_{-70}~{\rm pc~cm^{-3}}$ and $80^{+60}_{-40}~{\rm pc~cm^{-3}}$ from these systems, respectively. Together with the Milky Way, diffuse intergalactic medium, Virgo cluster, M49 group, and host galaxy contributions, these foreground structures can account for the excess dispersion measure of FRB20230907D within uncertainties. This highlights the importance of dense foreground spectroscopy and multi-wavelength data.
Comments28 pages, 16 figures
