用快速射电暴探测宇宙网：II. 闪烁

中文摘要 AI 辅助

我们考虑了宇宙网天体（CWOs）中多相气体的形成，这些气体通过冷却和碎裂在宇宙片层和纤维的激波加热介质以及暗物质晕的星系周介质（CGM）中产生。这导致了与周围环境处于压力平衡的致密、低温（约10^4 K）、小尺度云片。这种电离的过密区域可以影响快速射电暴（FRBs）发射的无线电波的传播，使我们能够通过检查它们对观测到的FRB通量闪烁图案的影响来探测CWOs中的小尺度结构。虽然我们发现遇到含有冷云片的高温纤维或片层的概率相当小，且通常局限于高红移，但预期的高FRB发生率仍可能允许通过沿罕见视线的闪烁进行探测。我们建议将银河系（MW）星际介质的闪烁作为一个有前景的探针：CWO等离子体屏幕可以抑制它，从而对其冷气体性质施加约束。纤维和片层可以分别抑制来自红移z_S≳2和3的源的MW闪烁，而CGM中的冷湍流云片可以通过红移低至z_S~0.5的源进行探测，从而约束极低的体积填充因子f_v（例如，对于z_S≳2，f_v≳10^-5）。为了提供可检验的预测，我们估计了预期遇到可能将MW闪烁抑制到给定频率以下的CWOs的FRBs比例，并将其表示为平均河外色散量的函数。未来的FRB样本可以将这些约束映射到CWOs中云片的存在和性质（如密度、大小、f_v和湍流）的界限上。

英文摘要

We consider the formation of multiphase gas in cosmic web objects (CWOs) through cooling and fragmentation within the shock-heated medium of cosmic sheets and filaments, and the circumgalactic medium (CGM) of haloes. This leads to dense, cool ($\sim10^{4}\,\mathrm{K}$), small-scale cloudlets in pressure equilibrium with their surroundings. Such ionized overdensities can affect the propagation of radio waves emitted by fast radio bursts (FRBs), allowing us to probe the small-scale structure in CWOs by examining their impact on the scintillation pattern of the observed FRB flux. While we find that the probability of encountering a high-temperature filament or sheet with cold cloudlets is rather small and usually confined to high redshifts, the expected high rates of FRBs may still permit detection through scintillation along rare sightlines. We suggest scintillation from the Milky Way (MW) interstellar medium as a promising probe: CWO plasma screens can suppress it, placing constraints on their cold-gas properties. Filaments and sheets can suppress MW scintillation from sources at $z_\mathrm{S}\gtrsim2$ and $3$, respectively, while cold and turbulent cloudlets in the CGM can be probed by sources at redshifts as low as $z_\mathrm{S}\sim0.5$, constraining remarkably low volume-filling fractions, $f_\mathrm{v}$ (e.g. $f_\mathrm{v}\gtrsim10^{-5}$ for $z_\mathrm{S}\gtrsim2$). To provide testable predictions, we estimate the fraction of FRBs expected to encounter CWOs that may suppress MW scintillation below a given frequency, and express this as a function of the average extragalactic dispersion measure. Future FRB samples could map these constraints onto bounds on the existence and properties of cloudlets in CWOs, such as their density, size, $f_\mathrm{v}$, and turbulence.

发表机构

• Racah Institute of Physics, The Hebrew University（拉卡物理研究所，希伯来大学）
• University of Washington, Department of Astronomy（华盛顿大学天文学系）
• Astrophysics Research Center of the Open University (ARCO), The Open University of Israel（开放大学天体物理学研究中心（ARCO），以色列开放大学）
• Department of Natural Sciences, The Open University of Israel（自然科学与系，以色列开放大学）
• Department of Physics, The George Washington University（乔治华盛顿大学物理系）
• Department of Physics, University of California, Santa Barbara（加州大学圣塔芭芭拉分校物理系）

机构由 AI 辅助整理，请以论文原文为准。

补充信息

备注

19 page + 6 in appendix