Evolution of effective dust extinction law of galaxies and its observational examination

利用斯巴鲁望远镜等最先进的仪器进行多波长电磁辐射观测的迅速发展要求进行辐射转移计算，以模拟各种天体的光谱。特别是，星系的光谱正在遭受灭绝的宇宙尘埃存在于星系的星际介质。本研究项目的主要目标是获得一个有效的尘埃消光定律，以纠正尘埃消光光谱，并获得消光定律的演变沿着星系的演变。然而，不幸的是，我从来没有达到这些主要目标，因为在尘埃颗粒的大小分布的困难。另一方面，一个新开发的星系演化模型以及辐射传输通用代码的开发和应用使我能够实现以下四个成果：（1）揭示了确定星系中尘埃含量的机制;（2）推导了星系际尘埃的光电加热率;（3）提出了一个新的考虑电离光子在星系和星系际介质中传输的星系光谱模型，（4）揭示了散射对原行星盘结构的影响，提出了利用散射光谱模型搜索冰尘的方法。

Rapid developments of multi-wavelength electro-magnetic radiation observations by state-of-the-art instruments like Subaru telescope requested radiation transfer calculations to model spectra of various celestial objects. In particular, spectra of galaxies are suffering from extinction by cosmic dust which exists in the interstellar medium in galaxies. The main objectives of this research project were to obtain an effective dust extinction law to correct the spectra for the dust extinction and to obtain an evolution of the extinction law along galaxy evolution. However, unfortunately, I never reached these main goals because of a difficulty in the size distribution of dust grains. On the other hand, a newly developed galaxy evolution model and development and application of a general purpose code for radiation transfer enabled me to achieve the following four outcomes: (1) revealing mechanism to determine dust content in galaxies, (2) derivation of the photo-electric heating rate by intergalactic dust, (3) proposing a new spectral model of galaxies taking into account ionizing photon transfer in galaxies and intergalactic medium, and (4) revealing effects of scattering on structure of proto-planetary disks and proposing a technique to search icy dust by using a scattering spectral model.