论文标题
旋转破坏对星系中晶粒尺寸分布演变的影响
Effects of rotational disruption on the evolution of grain size distribution in galaxies
论文作者
论文摘要
星际尘埃颗粒可以通过辐射扭矩旋转，产生的离心力可能足够强，可以破坏大型灰尘颗粒。我们研究了这种旋转破坏对星系中晶粒尺寸分布演变的影响。为此，我们通过假设旋转破坏是主要的小颗粒生产机制来修改以前的模型。我们发现，在以下两个方面，旋转破坏会对晶粒尺寸分布的演变产生很大的影响，尤其是对于复合材料和谷物地幔（带有拉伸强度$ \ sim 10^7 $ erg cm $^{ - 3} $）。首先，由于旋转破坏的时间尺度很短，因此即使在星系进化的早期阶段也会出现小颗粒的产生。因此，即使恒星产生大晶粒，小晶粒的丰度也可能足够大，可以浸入灭绝曲线。其次，旋转破坏对于确定最大晶粒半径很重要，这可以调节灭绝曲线的陡度。对于具有拉伸强度的紧凑型晶粒$ \ gtrsim 10^9 $ erg cm $^{ - 3} $，只有当辐射场与射线温度一样强（或者尘埃温度与预期的尘埃高）对Starburst银河系的预期，尺寸演变仅受旋转破坏的影响很大。对于紧凑的谷物，旋转破坏预测，最大晶粒半径将小于尘埃温度$ \ gtrsim 50 $ k的星系的最大粒度。
Interstellar dust grains can be spun up by radiative torques, and the resulting centrifugal force may be strong enough to disrupt large dust grains. We examine the effect of this rotational disruption on the evolution of grain size distribution in galaxies. To this goal, we modify our previous model by assuming that rotational disruption is the major small-grain production mechanism. We find that rotational disruption can have a large influence on the evolution of grain size distribution in the following two aspects especially for composites and grain mantles (with tensile strength $\sim 10^7$ erg cm$^{-3}$). First, because of the short time-scale of rotational disruption, the small-grain production occurs even in the early phase of galaxy evolution. Therefore, even though stars produce large grains, the abundance of small grains can be large enough to steepen the extinction curve. Secondly, rotational disruption is important in determining the maximum grain radius, which regulates the steepness of the extinction curve. For compact grains with tensile strength $\gtrsim 10^9$ erg cm$^{-3}$, the size evolution is significantly affected by rotational disruption only if the radiation field is as strong as (or the dust temperature is as high as) expected for starburst galaxies. For compact grains, rotational disruption predicts that the maximum grain radius becomes less than 0.2 $μ$m for galaxies with a dust temperature $\gtrsim 50$ K.
