论文标题
FRB的色散度量和散射：来自层间介质的贡献，前景光环和宿主
The dispersion measure and scattering of FRBs: Contributions from the intergalactic medium, foreground halos, and hosts
论文作者
论文摘要
我们使用宇宙学水动力学模拟研究了通过层间中层（IGM），前景和宿主光环的分散度度量（DM）和FRB的散射。我们发现，前景光晕引起的中位DM约为由IGM引起的30 \％，但差异较大。主机诱导的DM偏离对数正态分布，但在$ 1-3000 \ {\ rm {pc \，cm^{ - 3}}} $的范围内显示出中位数$ \ sim 100 \ {\ sim 100 \ {\ rmm {pc \ rm {pc \，cm^，cm^，cm^{ - 3}} $。然后，我们产生模拟的FRB来源，假设$ z \ sim 0-0.82 $在范围内具有均匀分布，以同时考虑IgM，前景和宿主光晕的传播效果。模拟来源的DM分布与观察非常吻合。模拟源的拟合DM-REDSHIFT关系可以粗略地估计与误差$ΔZ\ Lessim 0.15 $的观测事件的红移。假设内部和外部尺度的Kolmogorov湍流模型分别为1000 km至1 au和0.2-10 PC，那么在DM散布时间（$τ$）空间中模拟源的分布也可以与观察值相匹配。最后，我们估计这些媒介在DM和$τ$中的相对重要性。 IGM和主机晕是临时DM的主要和次要来源，$ \ rm {dm_ {exg}} $。同时，前景光环的贡献随着$ \ rm {dm_ {exg}} $的增加而增加。宿主和前景光环可能是散射最重要的媒介。从统计上讲，后者可以用$ \ rm {dm_ {exg}} \ gtrsim 200 \ {\ rm {pc \ \，cm^{ - 3}}} $主导事件的散射。
We investigate the dispersion measure(DM) and scattering of FRBs by the intergalactic-medium(IGM), foreground and host halos, using cosmological hydrodynamical simulation. We find that the median DM caused by foreground halos is around 30\% of that caused by the IGM, but has a much larger variance. The DM induced by hosts deviates from a log-normal distribution, but exhibits an extended distribution in the range of $1-3000 \ {\rm{pc\, cm^{-3}}}$ with a median value $\sim 100 \ {\rm{pc\, cm^{-3}}}$. Then we produce mock FRB sources, assuming a uniform distribution in the range $z\sim 0-0.82$, to consider the propagation effect of IGM, foreground and host halos on FRB signals simultaneously. The DM distribution of mock sources agrees well with the observation. The fitted DM-redshift relation of the mock sources can provide a rough estimation of the redshifts of observed events with errors $δz \lesssim 0.15$. The distribution of mock sources in the DM-scattering time($τ$) space can also match the observation, assuming a Kolmogorov turbulence model with the inner and outer scale is 1000 km to 1 AU, and 0.2-10 pc respectively. Finally, we estimate the relative importance of these medium on DM and $τ$ in our models. The IGM and host halos are the primary and secondary sources to the extragalactic DM, $\rm{DM_{exg}}$. Meanwhile, the contribution from foreground halos increases as $\rm{DM_{exg}}$ increases. The host and foreground halos may be the most important medium for scattering. Statistically, the latter may dominate the scattering of events with $\rm{DM_{exg}} \gtrsim 200 \ {\rm{pc\, cm^{-3}}}$.
