How are HI Disks Fed? Probing the Drivers of Regulated Galaxy Growth

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Disk galaxies form stars through clouds of cold gas in their disks. As the stars form, the cold gas content is reduced. In order for galaxies to continue to form stars, they must acquire cold gas from outside. The process of accreting gas from intergalactic space is called condensation. This project will use observations from the Very Large Array (VLA) and the Hubble Space Telescope to map out the cold disk gas and the infalling intergalactic gas in order to better understand the process of condensation. The project will target 35 nearby disk galaxies for their observations and will compare the results with computer simulations of the growth and evolution of galaxies. The data from these observations will be converted to 3D visualizations for use in public and classroom settings.The project will use 21-cm data from the VLA and QSO absorption spectroscopy to trace the rotating HI disk to large galactic radii so that they can identify gas clumps that are inconsistent with the rotation of the disk. They will look for a correlation between the incidence of condensing clouds and the prevalence of young stars and stellar feedback. The VLA maps will be compared to mock images from simulations in order to estimate the source of the condensing clouds. The project will produce data products that will be available to the astronomical community through the VLA-Disk website. They will also produce interactive 3D visualizations for use in public outreach and within the classroom. Use of these interactive tools will be introduced to local high-school teachers at an annual StarLab workshop and their effectiveness will be evaluated through surveys of the teachers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.