论文标题
与Neutron Star合并的Kilonova相关的放射性伽马射线瞬态
Radioactively-Powered Gamma-Ray Transient Associated with a Kilonova from Neutron Star Merger
论文作者
论文摘要
GW170817/GRB170817A/AT2017GFO的ASOSOCITION为中子星合并提供了第一个直接证据，作为$ R $ $ $ - 过程的核合成的重要来源。伽马射线瞬态（GRT）将由新鲜合成的$ r $ process元素的放射性衰变提供动力。通过详细分析Kilonova弹出的组成和伽马射线不透明度，我们计算了一系列具有质量$ M _ {\ rm EJ} = 0.001 = 0.001 \ sim 0.05m _ {\ odot _ {\ odot vel的球形对称合并模型的GRT的光曲线和频谱ej} = 0.1 \ sim 0.4c $。发现GRT LightCurve的峰值取决于$ M _ {\ rm EJ} $和$ V _ {\ rm EJ} $ as $ t _ {\ rm PK} \ rm PK} \ lm pk} \ oft 0.5〜 {\ rm days} ej} /0.01M _ {\ odot}）^{1/2}（v _ {\ rm ej} /0.1c）^{ - 1} $和$ l _ {\ rm pk} \ rm pk} \ y Moun ej} /0.01M _ {\ odot}）^{1/2}（v _ {\ rm ej} /0.1c）$。大多数辐射光子在$ 100-3000 $ keV频段中，而光谱峰约为800〜KEV，用于不同的核物理输入。多普勒拓宽效果使线路特征模糊不清。采用文献中报告的弹出参数，我们检查了与AT2017GFO相关的可能GRT的检测概率。我们表明，在MEV频段（例如ETCC和Amego）中，既不能使用当前也不能用拟议的任务来令人信服地检测GRT。低伽马射线的通量，加上本地宇宙的极低事件速率，发现GRTS是一个巨大的挑战。
AAssociation of GW170817/GRB170817A/AT2017gfo provides the first direct evidence for neutron star mergers as significant sources of $r$-process nucleosynthesis. A gamma-ray transient (GRT) would be powered by the radioactive decay of the freshly-synthesized $r$-process elements. By analyzing the composition and gamma-ray opacity of the kilonova ejecta in details, we calculate the lightcurve and spectrum of the GRT for a range of spherically symmetric merger ejecta models with mass $M_{\rm ej}=0.001 \sim 0.05M_{\odot}$ and expansion velocity $v_{\rm ej}= 0.1\sim 0.4c$. It is found that the peak of the GRT lightcurve depends on $M_{\rm ej}$ and $v_{\rm ej}$ as $t_{\rm pk} \approx 0.5~{\rm days} ~ (M_{\rm ej}/0.01M_{\odot})^{1/2}(v_{\rm ej}/0.1c)^{-1}$ and $L_{\rm pk} \approx 2.0\times10^{41} ~{\rm erg~s} ^{-1} (M_{\rm ej}/0.01M_{\odot})^{1/2}(v_{\rm ej}/0.1c)$. Most radiating photons are in the $100-3000$ keV band and the spectrum peaks at about 800~keV for different nuclear physics inputs. The line features are blurred out by the Doppler broadening effect. Adopting the ejecta parameters reported in literature, we examine the detection probability of the possible GRT associated with AT2017gfo. We show that the GRT cannot be convincingly detected neither with current nor with the proposed missions in the MeV band, such as ETCC and AMEGO. The low gamma-ray flux, together with the extremely low event rate at local universe, makes a discovery of GRTs a great challenge.
