EAPSI: Understanding Cosmic Dust in Lyman-Alpha Emitters

对宇宙时间内尘埃的研究是天文学和天体物理学的一个关键领域，其影响从星系演化和宇宙学到行星形成。尘埃是恒星死亡时形成的，并扩散到星际介质中;一些然后形成下一代恒星和行星，而大部分留在星际介质中。这些尘埃重新处理紫外线和可见光，吸收它们并重新发射能量到中红外和远红外。即使是少量或中等数量的尘埃也会极大地影响星系的观测特性。该奖项支持研究早期宇宙中星系的尘埃特性，这些星系被认为是银河系类型星系的祖先。这项研究最近才成为可能，因为阿塔卡马大型毫米波阵列（阿尔马）可以直接探测这些微小星系中尘埃的热辐射。该研究将与东京大学的Masami Ouchi教授合作进行，对这些星系进行首次研究，启动了一项可能多年取得成果的合作。具体而言，这项工作将使用光谱能量分布（SED）拟合，该拟合使用的是由康罗伊等人开发的灵活的恒星星族合成（FSPS）软件。FSPS使用了Draine和Lee的尘埃模型（2007）使用三个参数，尘埃质量，PAH分数和尘埃粒度分布来参数化宇宙尘埃。由于宇宙中的大部分光来自尘埃发射，因此了解这些性质以及它们在宇宙的一生中如何变化是至关重要的。利用深层阿尔马数据，我们可以探测来自莱曼阿尔法巡天中发现的众多星星形成星系的尘埃排放。这些莱曼α发射体通常是小的，低质量的星系，将形成银河系大小的星系。明亮的莱曼α线提供了一个很好的方法来寻找研究小星系，否则很难找到。了解它们的尘埃性质对于进一步了解这些星系和研究银河系的可能历史至关重要。这个NSF EAPSI奖是与日本科学促进协会合作资助的。

The study of dust over cosmic time is a key field of astronomy and astrophysics that has implications from galaxy evolution and cosmology to planet formation. Dust forms as stars die and is spread into the interstellar medium; some is then formed into the next generation of stars and planets, while a large fraction stays in the interstellar medium. This dust reprocesses ultraviolet and optical light, absorbing it and re-emitting the energy into the mid- and far-infrared. Even a small or moderate amount of dust can greatly affect the observed properties of galaxies. This award supports research to study the dust properties of galaxies in the early universe, which are thought to be progenitors to Milky Way type galaxies. This study has only become possible very recently with the commissioning of the Atacama Large Millimeter Array (ALMA), which can directly detect the thermal emission from dust in these tiny galaxies. The research will be conducted in partnership with Prof. Masami Ouchi of the University of Tokyo to do a first-of-a-kind study of these galaxies, initiating a collaboration with the potential to be fruitful for many years.Specifically, this work will use spectral energy distribution (SED) fitting using the Flexible Stellar Population Synthesis (FSPS) software developed by Conroy et al. FSPS uses the dust models of Draine and Lee (2007) to parametrize cosmic dust using three parameters, dust mass, PAH fraction, and dust grain size distribution. As most of the light in the universe is from dust emission, understanding these properties, and how they change over the lifetime of the universe, is of critical concern. Using deep ALMA data, we can probe for dust emission from the numerous star forming galaxies discovered in Lyman-alpha surveys in these fields. These Lyman-alpha emitters are generally small, low mass galaxies that will form into Milky Way sized galaxies. The bright Lyman-alpha line provides an excellent way to find a study small galaxies otherwise very difficult to find. Understanding their dust properties is crucial to further our understanding of these galaxies and investigate possible histories of the Milky Way. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.