Probing the Dynamic Universe With the Motions of Stars and Galaxies

Paine, Jennie

Graduate Thesis Or Dissertation

Probing the Dynamic Universe With the Motions of Stars and Galaxies Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/js956h44z

Abstract

Observations of the motions of celestial objects have a variety of physical applications — from stellar dynamics to cosmology. This dissertation focuses on high precision measurements of proper motions and velocities of stars and galaxies and an exploration of their myriad applications. I first present a method for identifying extragalactic objects detected by Gaia astrometric mission, resulting in a catalog of over 500,000 active galactic nuclei. The proper motions of such an extragalactic astrometric catalog are sensitive to the galactocentric acceleration of the solar system and the isotropy of cosmic expansion, and I forecast the measurements of these effects with the Gaia catalog. Next, I use a nearby sample of galaxies to place limits on the magnitude of the proper motion signal caused by the linear velocity of the solar system, called secular parallax. I investigate the influence of peculiar velocities of nearby galaxies due to large scale structure on this measurement using simulated galaxy proper motions. Finally, I present a series of studies of stellar kinematics in the Galactic Center. I use radio observations of stellar SiO masers from the Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) to measure high resolution astrometry and spectra of a sample of 28 stars. I present the resulting 3D velocities of the stars, and the first limits on their 3D accelerations. The stellar kinematics trace the gravitational potential around the central supermassive black hole, and thus I calculate limits on the mass distribution within the inner 2 pc using the maser measurements. I will discuss the influence that confounding factors such as maser variability and undetected binary stars may have on these measurements.

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