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arXiv 1704.01769astro-ph.GA
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星系模拟中尘埃消光曲线的演化

Evolution of dust extinction curves in galaxy simulation

Kuan-Chou Hou, Hiroyuki Hirashita, Kentaro Nagamine, Shohei Aoyama, Ikkoh Shimizu

摘要:

为了理解消光曲线的演化,我们计算了尘埃演化的星系使用平滑粒子流体动力学模拟纳入恒星尘埃生产,超新星冲击中的尘埃破坏,吸积和凝聚的颗粒生长,和粉碎颗粒破坏。粉尘种类被分离成含碳粉尘和硅酸盐。通过将颗粒群分为大增益和小增益来考虑粒度分布的演变,这使我们能够估计灭绝曲线。我们研究了消光曲线的位置,气体密度和星系中的金属丰度的依赖性,并发现消光曲线是平坦的$t \lesssim 0.3$陀螺仪,因为恒星尘埃生产占主导地位的总尘埃丰度。2175年的彗星撞击和远紫外线(FUV)的上升在尘埃通过吸积增长后变得突出。在$t \gtrsim 3$ Gyr,破碎在外盘和低密度区域有效地发挥作用,因此灭绝曲线显示出非常强烈的2175 Å凸起和陡峭的FUV上升。$t\gtrsim 3$ Gyr的消光曲线与银河系的消光曲线一致,这意味着我们成功地将必要的尘埃过程包括在模型中。由恒星反馈引起的外盘分量的消光曲线具有较弱的2175 μ m凸起和较平坦的FUV斜率。碳质尘埃的强烈贡献往往会使小麦哲伦云消光曲线中的FUV上升不足,这支持了星系中小碳质尘埃的选择性损失。年轻时的快照也解释了高红移类星体的消光曲线。

英文摘要:

To understand the evolution of extinction curve, we calculate the dust evolution in a galaxy using smoothed particle hydrodynamics simulations incorporating stellar dust production, dust destruction in supernova shocks, grain growth by accretion and coagulation, and grain disruption by shattering. The dust species are separated into carbonaceous dust and silicate. The evolution of grain size distribution is considered by dividing grain population into large and small gains, which allows us to estimate extinction curves. We examine the dependence of extinction curves on the position, gas density, and metallicity in the galaxy, and find that extinction curves are flat at $t \lesssim 0.3$ Gyr because stellar dust production dominates the total dust abundance. The 2175 Å bump and far-ultraviolet (FUV) rise become prominent after dust growth by accretion. At $t \gtrsim 3$ Gyr, shattering works efficiently in the outer disc and low density regions, so extinction curves show a very strong 2175 Å bump and steep FUV rise. The extinction curves at $t\gtrsim 3$ Gyr are consistent with the Milky Way extinction curve, which implies that we successfully included the necessary dust processes in the model. The outer disc component caused by stellar feedback has an extinction curves with a weaker 2175 Å bump and flatter FUV slope. The strong contribution of carbonaceous dust tends to underproduce the FUV rise in the Small Magellanic Cloud extinction curve, which supports selective loss of small carbonaceous dust in the galaxy. The snapshot at young ages also explain the extinction curves in high-redshift quasars.

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