论文标题
银河二进制中子星级合并残留物中R过程核合成的γ射线诊断
Gamma-ray Diagnostics of r-process Nucleosynthesis in the Remnants of Galactic Binary Neutron-Star Mergers
论文作者
论文摘要
我们对二进制中子星合并（NSMS）的$ r $ $ process核进行完整的核网络数值计算，目的是估计$γ$ ray-ray-ray的排放量，从银河NSMS的残余物中最高$ 10^6美元。采用4,070个核的核合成计算，以在0.10和0.45之间提供电子分数$ y _ {\ rm e} $的元素组成比。模拟了3,237个不稳定核的衰减过程以提取$γ$ -Ray光谱。结果，NSM在$γ$ ray带中具有不同的光谱颜色，来自其他各种天文学对象，年龄不到$ 10^5 $年。 In addition, we propose a new line-diagnostic method for $Y_{\rm e}$ that uses the line ratios of either $^{137{\rm m}}$Ba/$^{85}$K or $^{243}$Am/$^{60{\rm m}}$Co, which become larger than unity for young and old $r$-process站点分别为低$ y _ {\ rm e} $环境。从$γ$ - 射线观察到年龄的函数的距离限制的估计，在sub-mev频段中的高灵敏度，约为$ 10^{ - 9} $ photons s $^{ - 1} $ cm $ $^{ - 2} $^{ - 2} $或$ 10^{ - 15} $ 10^{ - 15} $ erg s $^$ 1}如果我们假设\ citet {2019apj ... 880 ... 23W}的NSMS人口在我们的银河系中的残留物。 $ 10^{ - 8} $ - $ 10^{ - 7} $ photons S $^{ - 1} $ CM $^{ - 2} $或$ 10^{ - 14} $ - $ 10^{ - $ 10^{ - 13} $ 10^{ - 13} $ erg s $ cm^{ - 1} $ cm^$ cm $ cm cm^into 70在NSM速率的假设30 myr $^{ - 1} $的假设下，至少一个NSM残留物的排放。还研究了$γ$ ray任务以观察银河NSM的可行性。
We perform a full nuclear-network numerical calculation of the $r$-process nuclei in binary neutron-star mergers (NSMs), with the aim of estimating $γ$-ray emissions from the remnants of Galactic NSMs up to $10^6$ years old. The nucleosynthesis calculation of 4,070 nuclei is adopted to provide the elemental composition ratios of nuclei with an electron fraction $Y_{\rm e}$ between 0.10 and 0.45 . The decay processes of 3,237 unstable nuclei are simulated to extract the $γ$-ray spectra. As a result, the NSMs have different spectral color in $γ$-ray band from various other astronomical objects at less than $10^5$ years old. In addition, we propose a new line-diagnostic method for $Y_{\rm e}$ that uses the line ratios of either $^{137{\rm m}}$Ba/$^{85}$K or $^{243}$Am/$^{60{\rm m}}$Co, which become larger than unity for young and old $r$-process sites, respectively, with a low $Y_{\rm e}$ environment. From an estimation of the distance limit for $γ$-ray observations as a function of the age, the high sensitivity in the sub-MeV band, at approximately $10^{-9}$ photons s$^{-1}$ cm$^{-2}$ or $10^{-15}$ erg s$^{-1}$ cm$^{-2}$, is required to cover all the NSM remnants in our Galaxy if we assume that the population of NSMs by \citet{2019ApJ...880...23W}. A $γ$-ray survey with sensitivities of $10^{-8}$--$10^{-7}$ photons s$^{-1}$ cm$^{-2}$ or $10^{-14}$--$10^{-13}$ erg s$^{-1}$ cm$^{-2}$ in the 70--4000 keV band is expected to find emissions from at least one NSM remnant under the assumption of NSM rate of 30 Myr$^{-1}$. The feasibility of $γ$-ray missions to observe Galactic NSMs are also studied.
