AI 中文总结
该研究提出色散空间中的FRB-星系互相关统计量，证明f×g统计量信息含量更高，可在多数FRB无红移时提取宇宙学信息，能提升信噪比并精确测量重子成团参数。
AI 中文摘要
将快速射电暴（FRB）的色散与星系进行互相关，可在无需FRB红移的情况下研究宇宙中重子的分布。为此，已提出两种角互功率谱统计量变体：一种是色散量（DM）与按红移分箱的星系密度之间的统计量$C^{Dg}_l(z_g)$（缩写为$D \times g$），另一种是按色散量分箱的FRB计数与按红移分箱的星系密度之间的统计量$C^{fg}_l(\textrm{DM}, z_g)$（缩写为$f \times g$）。本文表明，$D \times g$统计量可作为$f \times g$统计量的DM矩恢复，意味着后者的信息含量严格更高。通过在DM空间和星系红移空间进行切片，$f \times g$统计量可分离自由电子成团和FRB源成团的贡献。我们对与CHIME（1600个FRB）和即将开展的CHORD（20000个FRB）巡天分别与DESI Legacy Survey BGS样本、Euclid星系巡天交叉相关的FRB样本进行费舍尔预测。结果显示，与$D \times g$统计量相比，$f \times g$统计量的信噪比（S/N）在CHIME×DESI(LS)中约为12，在CHORD×Euclid中约为54；该统计量对FRB的红移分布更敏感，对简单参数化的预测误差约为10%；它还能以26%的精度（CHIME）和14%的精度（CHORD）测量反馈导致的重子成团对数截断标度$k_{cut}$。由于当前大多数FRB缺乏宿主证认，即便精确定位后，对大样本进行光学后续观测仍具挑战性，可预见未来多数FRB仍无法获得可靠红移，而$f \times g$统计量为在无红移的情况下提取最大宇宙学信息提供了手段。
英文摘要
Cross-correlating the dispersion of fast radio bursts (FRBs) with galaxies provides a means to study the distribution of the baryons in the Universe, even in the absence of FRB redshifts. To this end, two variants of angular cross-power spectrum statistics have been proposed: one between DM and galaxy density binned by redshift $C^{Dg}_l(z_g)$ (abbreviated $D \times g$), and one between FRB counts binned by dispersion measure (DM) and galaxy density binned by redshift $C^{fg}_l(\textrm{DM}, z_g)$ (abbreviated $f \times g$). Here we show the $D \times g$ statistic can be recovered as a DM-moment of $f \times g$, implying the latter is strictly more informative. By slicing in both DM space and galaxy redshift space, the $f\times g$ statistic separates contributions from the clustering of free electrons and from the clustering of FRB sources. We perform Fisher forecasts for FRB samples consistent with CHIME (1,600 FRBs) and the upcoming CHORD (20,000 FRBs) survey cross-correlated against the DESI Legacy Survey BGS sample and Euclid galaxy surveys, respectively. We show that, compared to the $D \times g$ statistic, the $f \times g$ statistic results in $S/N\approx 12$ for CHIME$\times$DESI(LS) and SNR $\approx 54$ for CHORD$\times$Euclid. The $f \times g$ statistics is more sensitive to the redshift distribution of FRBs with forecasted errors on a simple parameterization of order $10 \%$. It measures the logarithmic cutoff scale for clustering of baryons due to feedback $k_{cut}$ to 26\% precision with CHIME and 14\% precision with CHORD. Since most FRBs currently lack host identifications, and scaling optical followup to large samples will remain challenging even with precise localizations, reliable redshifts will be unavailable for most FRBs for the foreseeable future. The $f \times g$ statistic provides a means to extract maximum cosmological information in their absence.
Comments14 pages, 4 figures
