This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Dr Valluri will study stellar motions in galaxies that are triaxial or have barred disks, and harbor supermassive black holes at their centers. Most elliptical galaxies are triaxial, and roughly half of all disk galaxies are barred. Despite this, the masses of their central black holes are generally determined by fitting axisymmetric (or even spherical) galaxy models to the observational data. Dr Valluri will start by investigating orbits in model triaxial potentials, finding the underlying frequencies of the regular orbits to classify them into their major families, and mapping out the regions where orbits are chaotic. She will then use the same technique on the orbits of particles in gravitational N-body simulations of rotating triaxial and barred galaxies, both with and without a central black hole. Finally, she will improve her current axisymmetric Schwarzschild code to include triaxiality and figure rotation. This code generates gravitationally self-consistent models that will be used to estimate the masses of the black holes at the centers of well-observed nearby galaxies.
An undergraduate student will participate in the research. The anticipated results are of broad scientific interest, since mass estimates for galaxy-center black holes are used to constrain the efficiency with which active galactic nuclei radiate energy, and to estimate how often the merger of binary supermassive black holes should be detectable by gravitational wave experiments. Dr Valluri will lead a discussion and mentoring group for women graduate students and undergraduate students in her department. She will also carry out hands-on astronomy projects for K-12 students in collaboration with the University of Michigan's Museum of Natural History and Planetarium.
