论文标题
钨与硒是Spitzer观察到的Kilonova Nebular发射的潜在来源
Tungsten vs Selenium as a potential source of kilonova nebular emission observed by Spitzer
论文作者
论文摘要
预计由重元素的精细结构水平之间的过渡产生的红外发射线预计会产生基洛诺瓦星云发射。对于GW170817中的KilOnova，Spitzer Space望远镜在后期检测到了4.5 $ {\rmμm} $的强力发射，但在3.6 $ {\ rmμm} $中未检测到任何来源。该特殊的频谱表明，在4.5 $ {\ rmμm} $左右存在强线发射器，并且没有强的线路约为3.6 $ {\ rmμm} $。为了建模频谱，我们根据NIST数据库中实验校准的能量水平的LS耦合中的选择规则准备了线列表。此方法使能够通过精确的线波长生成合成光谱。我们发现，无论是否包括第一个R-Process峰值元素，频谱对丰度模式敏感。在这两种情况下，合成光谱都可以匹配观察到的数据，从而导致两种可能的解释。如果第一个峰值元素丰富，则SE III线将主导通量。如果否则，则具有OS III，RH III和CE IV的W III可以是主要来源。观察未来Kilonovae在更广泛的波长范围内的静脉光谱可以提供更确定的元素鉴定。
Infrared emission lines arising from transitions between fine structure levels of heavy elements are expected to produce kilonova nebular emission. For the kilonova in GW170817, strong emission at 4.5 ${\rm μm}$ at late times was detected by the Spitzer Space Telescope but no source was detected at 3.6 ${\rm μm}$. This peculiar spectrum indicates that there exist strong line emitters around 4.5 ${\rm μm}$ and the absence of strong lines around 3.6 ${\rm μm}$. To model the spectrum we prepare a line list based on the selection rules in LS coupling from the experimentally calibrated energy levels in the NIST database. This method enables to generate the synthetic spectra with accurate line wavelengths. We find that the spectrum is sensitive to the abundance pattern whether or not the first r-process peak elements are included. In both cases, the synthetic spectra can match the observed data, leading to two possible interpretations. If the first peak elements are abundant a Se III line dominates the flux. If otherwise, W III with Os III, Rh III, and Ce IV can be the main sources. Observing nebular spectra for the future kilonovae in a wider wavelength range can provide more conclusive elemental identification.
