The Road to the Virgo Cluster: The DECam/IRAC Galaxy Environment Survey

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This is a proposal to move forward our understanding of the variety of processes that are responsible for observed galaxy properties, and how these vary with galaxy environment, e.g. galaxies that have few neighbors versus galaxies that are crowded closely together. This is important to help scientists to distinguish the relative importance of properties that contribute to the growth of galaxies, including environment as mentioned above, the amount and type of stars being formed in galaxies, and how the visible matter in galaxies interacts with the dark matter associated with them. The proposers will do a large survey of galaxies and their environments at distances that correspond to when the Universe was young, but mature enough that clusters of galaxies had formed and some galaxies had formed nearly all their stars. It is important to look at galaxies at this epoch, as that is when it is expected that environmental effects are strong.The PI proposes the development and implementation of several public outreach and curricular activities, to be carried out both by him and the supported postdoc. The PI is at an institution which has a significant population of under-represented minorities. The proposed integration of the project data into a lab for astronomy students is a great example of bringing research into the classroom, and it provides an opportunity for the postdoc to acquire experience in education and outreach. The PI also plans monthly public lectures for high school students.The proposal describes the first systematic survey of galaxy environment at z=0.8-1.5. The survey will combine deep optical imaging from 0.3-1 micron with deep near-IR imaging from 3-5 micron over an area more than 15 times that of the COSMOS survey. In this way, the new survey will open the redshift z=0.8-1.5 universe in a way that the Sloan Digital Sky Survey has opened the local universe at z=0.1. The team will measure the relation between galaxy stellar masses/halo masses and its dependence on environment and address the following questions. When do galaxy scaling laws appear and how do these depend on environment? What are the physical mechanisms that transform galaxies to red sequence galaxies with low mass-specific star-formation rates? How do these mechanisms depend on galaxy mass, environment, and redshift?