论文标题
普朗克后的相互作用辐射及其对哈勃张力的影响
Interacting radiation after Planck and its implications for the Hubble Tension
论文作者
论文摘要
标准宇宙学预测，在物质辐射平等之前，约有41％的能量密度是在自由流中微子中。但是，在许多超出标准模型方案中，该组件的数量和自由流性质都已被修改。例如，这发生在具有新的中微子自我互动或具有相互作用光颗粒的其他黑暗扇区的模型中。我们考虑了标准宇宙学的几个扩展，其中包括由此类粒子物理模型激励的非免费流辐射组件，并使用最终的Planck数据释放来限制它们。该释放包含极化可能性的显着改善，这在区分自由流和相互作用的辐射物种方面起着重要作用。固定辐射中的总能量以匹配标准中微子解耦的期望，我们发现自由流辐射的比例必须为$ f_ \ mathrm {fs}> 0.8 $ 0.8 $在95％Cl（结合温度，极化，偏振和baryon声学振荡数据）。允许自由流和相互作用辐射的任意贡献，有效的新的非流程自由度的数量被限制为$ n_ \ mathrm {fld} <0.6 $ 95％Cl。还知道具有额外辐射的宇宙学可以缓解当前扩展率$ H_0 $的局部测量和CMB推理之间的差异。我们表明，与先前仅具有自由流的组件的模型相比，包括非散发辐射组件可以使辐射中的总能量密度更大，从而导致对宇宙学数据的拟合度略有改善。
Standard cosmology predicts that prior to matter-radiation equality about 41% of the energy density was in free-streaming neutrinos. In many beyond Standard Model scenarios, however, the amount and free-streaming nature of this component is modified. For example, this occurs in models with new neutrino self-interactions or an additional dark sector with interacting light particles. We consider several extensions of the standard cosmology that include a non-free-streaming radiation component as motivated by such particle physics models and use the final Planck data release to constrain them. This release contains significant improvements in the polarization likelihood which plays an important role in distinguishing free-streaming from interacting radiation species. Fixing the total amount of energy in radiation to match the expectation from standard neutrino decoupling we find that the fraction of free-streaming radiation must be $f_\mathrm{fs} > 0.8$ at 95% CL (combining temperature, polarization and baryon acoustic oscillation data). Allowing for arbitrary contributions of free-streaming and interacting radiation, the effective number of new non-free-streaming degrees of freedom is constrained to be $N_\mathrm{fld} < 0.6$ at 95% CL. Cosmologies with additional radiation are also known to ease the discrepancy between the local measurement and CMB inference of the current expansion rate $H_0$. We show that including a non-free-streaming radiation component allows for a larger amount of total energy density in radiation, leading to a mild improvement of the fit to cosmological data compared to previously discussed models with only a free-streaming component.
