The Origin of Supermassive Black Holes and their Influence on Dwarf Galaxies

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Black holes are incredibly dense and massive objects with powerful gravity. Astronomers have found convincing evidence that large galaxies, including our own Milky Way, have giant black holes in their centers. These objects can also emit large amounts of energy that can heat and push the gas in entire galaxies. For this reason, black holes can have a profound effect on galaxies over time. There are many questions, however, regarding giant black holes that remain unanswered: How do they form? How do they grow? Are they capable of permanently shutting down the formation of stars in galaxies? Can they affect the distribution of the mysterious dark matter surrounding the galaxies where they live? This project seeks to address these questions by studying a sample of the smallest galaxies - known as "dwarfs" - that contain central black holes. Dwarfs have peaceful formation and interacting histories that allow their central black holes to grow in a more passive way than in large galaxies. Therefore, they provide important clues about the formation of the first black holes in the early universe. Samples of dwarfs with and without energy-emitting black holes will be compared to assess the effects of black hole activity on the gas of these galaxies. Observations will also be compared with predictions of computer models that take into account how the universe evolves as a whole. The scientists involved in this project will also conduct an outreach program targeted to groups traditionally less involved in the sciences. Virtual reality multi-sensory resources will be created to help the deaf and the blind experience the universe. These products will be adapted to engage the large Hispanic community in Southern California, and exported to support the PI's ongoing efforts to teach astronomy to AIDS orphan children in Malawi, Africa.A joint observational/theoretical effort will study the growth of black holes in low mass galaxies with signatures of an active galactic nuclei (AGN). The target stellar mass is in the range between ten million and ten billion solar masses. The team will assemble a sample AGN candidate dwarfs and confirm whether they truly contain AGNs with the use of high spatial resolution spectroscopic observations in optical and near infrared wavelengths. New methods to estimate black hole masses in these elusive objects will be developed and applied to the sample. A matched control non-AGN sample will also be observed. The data will allow for the search and detection of outflows in these dwarfs; the comparison of AGN with non-AGN objects will provide the first estimates of the impact of black hole feedback on the gas content of dwarf galaxies. Other key structural properties of the hosts, such as color/metallicity gradients and kinematics, will be measured to explore other possible effects of feedback. Observational results will be compared to zoom-in cosmological numerical simulations of dwarfs run with different feedback models, including with and without AGN. Simulations will be used not only as predictions, but also to estimate uncertainties due to projection effects, beam size and spectral resolution. The goals of the project can be summarized in two points: 1) help constrain the demographics of black holes in dwarfs, 2) understand the impact of black hole feedback on the structural properties of these galaxies. The expected results of this project can potentially transform our understanding of feedback in dwarfs by shedding light on the energy coupling of black hole feedback to the interstellar medium and providing tight constraints on outflows that can be used to inform the next generation theoretical models of feedback. Further legacy that includes a detailed survey of the stellar properties and kinematics of dozens of dwarf galaxies within 200 Mpc is also expected.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.