EAPSI: Understanding Cosmic Dust in Lyman-Alpha Emitters

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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.