Evolution of extinction curves in galaxies
Evolution of extinction curves in galaxies
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DOI：
10.1093/mnras/stu208
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发表时间：
2014-01
影响因子：
4.8
通讯作者：
R. Asano;T. Takeuchi;H. Hirashita;T. Nozawa
中科院分区：
文献类型：
--
作者：
R. Asano;T. Takeuchi;H. Hirashita;T. Nozawa
我们根据颗粒尺寸分布的演化模型研究星系消光曲线的演化。在这个模型中，我们考虑了各种过程：超新星 II 和 AGB 恒星形成的尘埃、ISM 中超新星激波造成的尘埃破坏、颗粒表面的金属吸积（称为颗粒生长）、破碎和凝结。我们发现，在星系演化的最早阶段，灭绝曲线是平坦的。由于星系富含尘埃，破碎可以有效地产生大量小颗粒（$a \la 0.01\;\mu$m）。然后，晶粒生长在小晶粒半径处变得有效，在晶粒尺寸分布上形成 $a \sim 10^{-3}${--}$10^{-2}\;\mu$m 处的凸起。因此，紫外线 (UV) 波长处的消光曲线变得陡峭，并且消光曲线上 $1/\lambda \sim 4.5\;\mu{\rm m}^{-1}\;(\lambda: \mbox{wavelength})$ 处的凸起变得显着。一旦凝固变得有效，消光曲线就会变得更加平坦，但与银河系消光曲线相比，紫外线消光仍然过多。这种差异可以通过引入更强的凝结作用来解决。因此，破碎和凝固之间的相互作用对于重现银河系灭绝曲线可能很重要。
We investigate the evolution of extinction curves in galaxies based on our evolution model of grain size distribution. In this model, we considered various processes: dust formation by SNe II and AGB stars, dust destruction by SN shocks in the ISM, metal accretion onto the surface of grains (referred to as grain growth), shattering and coagulation. We find that the extinction curve is flat in the earliest stage of galaxy evolution. As the galaxy is enriched with dust, shattering becomes effective to produce a large abundance of small grains ($a \la 0.01\;\mu$m). Then, grain growth becomes effective at small grain radii, forming a bump at $a \sim 10^{-3}${--}$10^{-2}\;\mu$m on the grain size distribution. Consequently, the extinction curve at ultraviolet (UV) wavelengths becomes steep, and a bump at $1/\lambda \sim 4.5\;\mu{\rm m}^{-1}\;(\lambda: \mbox{wavelength})$ on the extinction curve becomes prominent. Once coagulation becomes effective, the extinction curves become flatter, but the UV extinction remains overproduced when compared with the Milky Way extinction curve. This discrepancy can be resolved by introducing a stronger contribution of coagulation. Consequently, an interplay between shattering and coagulation could be important to reproduce the Milky Way extinction curve.