标题： 一个连续的银河轴子线源：23钠的显著案例 显示英文标题

标题： A Continuous Galactic Line Source of Axions: The Remarkable Case of 23Na

摘要： 我们认为，$^{23}$Na 是星系轴子的潜在重要来源。 在$\gtrsim 7 \times 10^8$K 的温度下——这是超新星和 ONeMg 白矮星的大质量前身星中碳燃烧的特征——$^{23}$Na 的 440 keV 第一激发态具有热填充性，其反复衰变将恒星能量泵入逃逸的轴子中。 奇数 A 核丰度在高温恒星环境中通常非常低（或由于燃耗而完全不存在）。 $^{23}$Na 是个例外：该同位素的 $\approx 0.1 M_\odot$ 在碳燃烧过程中合成，然后保持在 $\approx 10^9$K 下，时间最长可达 $6 \times 10^4$y。 使用MESA模拟，银河系模型，并通过对先祖质量、位置和演化阶段的采样，我们发现在地球上的连续通量为$\langle \phi_a \rangle \approx 22$/cm$^2$秒对于$g^\mathrm{eff}_{aNN} = 10^{-9}$。 这些轴子中的一部分在穿过银河系磁场时转化为光子，产生一个440 keV的特征线$\gamma$射线，可以被全天空探测器（如康普顿光谱仪和成像仪（COSI））探测到。 假设存在一个1$\mu$G 银河磁场和足够轻的轴子质量，我们发现COSI将在探测$| g_{aNN}^\mathrm{eff} g_{a \gamma \gamma} | \gtrsim1.8 \times 10^{-22}$GeV$^{-1}$方面，在进行两年的调查后达到$3\sigma$。 显示英文摘要

摘要： We argue that $^{23}$Na is a potentially significant source of galactic axions. For temperatures $\gtrsim 7 \times 10^8$K -- characteristic of carbon burning in the massive progenitors of supernovae and ONeMg white dwarfs -- the 440 keV first excited state of $^{23}$Na is thermally populated, with its repeated decays pumping stellar energy into escaping axions. Odd-A nuclear abundances are typically very low in high-temperature stellar environments (or absent entirely due to burn-up). $^{23}$Na is an exception: $\approx 0.1 M_\odot$ of the isotope is synthesized during carbon burning then maintained at $\approx 10^9$K for times ranging up to $6 \times 10^4$y. Using MESA simulations, a galactic model, and sampling over progenitor masses, locations, and evolutionary stages, we find a continuous flux at earth of $\langle \phi_a \rangle \approx 22$/cm$^2$s for $g^\mathrm{eff}_{aNN} = 10^{-9}$. Some fraction of these axions convert to photons as they propagate through the galactic magnetic field, producing a distinctive 440 keV line $\gamma$ ray detectable by all-sky detectors like the Compton Spectrometer and Imager (COSI). Assuming a 1$\mu$G galactic magnetic field and a sufficiently light axion mass, we find that COSI will be able to probe $| g_{aNN}^\mathrm{eff} g_{a \gamma \gamma} | \gtrsim1.8 \times 10^{-22}$ GeV$^{-1}$ at $3\sigma$ after two years of surveying.