AI 中文总结
研究正电子起源，通过将宇宙光子背景分解为灰体函数，计算红移\(z \leq 10\)时γ-γ对产生的电子-正电子对产生率及相关辐射，得出对产生率变化规律和总宇宙对产生率，其结果对宇宙伽马射线背景研究有重要意义。
AI 中文摘要
正电子的起源是天体物理学中尚未解决的谜题之一，因为大多数来源仍未确定。宇宙光子背景（CPB）是跨越整个电磁光谱的各向同性辐射。CPB自身相互作用可能是正电子和二次发射的一个有前景的来源。我们计算了红移\(z \leq 10\)时CPB自身γ-γ对产生的电子-正电子对产生率，并确定了湮灭光谱、逆康普顿发射和轫致辐射。CPB被分解为灰体函数之和，每个灰体函数根据源类型光度函数和红移进行演化。我们通过在演化的CPB上积分角度和能量相关的截面来计算对产生率。然后考虑宇宙学、星系际、能量损失函数，将每个红移处产生的对传播到\(z = 0\)。按红移计算光子发射，然后沿视线积分以得到当今宇宙伽马射线背景（CGB）的贡献。由此产生的对产生发射率从\(z = 0\)时约\(2×10^{-36}\)急剧增加到\(z = 2.7\)时的峰值\(1.8×10^{-31}\,\mathrm{e^\pm\,cm^{-3}\,s^{-1}}\)，然后再次下降。这导致高达红移\(10\)时的总宇宙对产生率约为\(10^{54}\,\mathrm{e^\pm\,s^{-1}}\)。CPB上经历逆康普顿散射的对的二次发射对CGB有相当大的贡献。宇宙学γ-γ吸收产生的对提供了一个需要在任何CGB研究中考虑的最小二次发射水平。特别是在1 MeV到1 GeV范围内，这种背景可占CGB总发射的20%，并可能大幅缩小MeV观测与模型之间的差距。
英文摘要
The origin of positrons is one of the unsolved puzzles in astrophysics as the majority of sources are still unidentified. The Cosmic Photon Background (CPB) is the isotropic radiation spanning the entire electromagnetic spectrum. Interactions of the CPB with itself may pose a promising source of positrons and secondary emission. We calculate the electron-positron pair production rate from the $γ$-$γ$ pair-production of the CPB with itself for redshifts $z \leq 10$, and determine the annihilation spectrum, Inverse Compton emission, and bremsstrahlung. The CPB is decomposed into a sum of gray body functions, of which each is being evolved according to source type luminosity functions and redshift. We compute the pair-production rate by integrating the angle- and energy-dependent cross section over the evolving CPB. The pairs produced at each redshift are then propagated towards $z=0$, taking into account a cosmological, intergalactic, energy loss function. The photon emission is calculated per redshift and then line-of-sight integrated towards a contribution of the Cosmic Gamma-Ray Background (CGB) today. The resulting pair-production emissivity increases steeply from $z=0$ of about $2 \times 10^{-36}$ to a peak of $1.8 \times 10^{-31}\,\mathrm{e^\pm\,cm^{-3}\,s^{-1}}$ at $z=2.7$, then declines again. This yields a total cosmic pair-production rate on the order of $10^{54}\,\mathrm{e^\pm\,s^{-1}}$ up to redshift $10$. The secondary emission of pairs experiencing Inverse Compton scattering off the CPB results in a sizable contribution to the CGB. The pairs from cosmological $γ$-$γ$ absorption provide a minimum level of secondary emission which needs to be taken into account for any CGB study. Especially in the range from 1 MeV to 1 GeV, this background can make up 20% of the total CGB emission and may substantially reduce the gap between MeV observations and models.
Comments11 pages, 10 figures, 2 tables, accepted by A&A
