Back to Volume
Paper: Tidal Streams as Probes of the Galactic Potential
Volume: 194, Working on the Fringe: Optical and IR Interferometry from Ground and Space
Page: 15
Authors: Johnston, K. V.; Zhao, H. S.; Spergel, D. N.; Hernquist, L.
Abstract: We illustrate how SIM measurements of the motions of stars in tidal streams from Galactic satellites can be used to recover the potential of the Milky Way. We assume that the heliocentric radial velocities of these stars can be determined from supporting ground-based spectroscopic surveys, and that the mass and phase-space coordinates of the Galactic satellite with which they are associated will also be known to SIM accuracy. Using results from numerical simulations as trial data sets, we find that, if we assume the correct form for the Galactic potential, we can predict the distances to the stars as a consequence of the narrow distribution of energy expected along the streams. We develop an algorithm to evaluate the accuracy of any adopted potential by requiring that the satellite and stars recombine within a Galactic lifetime when their current phase-space coordinates are integrated backwards. When applied to a four-dimensional grid of triaxial logarithmic potentials, with varying circular velocities, axis ratios and orientation of the major-axis in the disk plane, the algorithm can recover the parameters used for the Milky Way in a simulated data set to within a few percent using only 100 stars in a tidal stream.
Back to Volume