A Robust Measure of Dark Matter Halo Ellipticities
arXiv:1607.03595 · doi:10.3847/2041-8205/826/2/L23
Abstract
In simulations of the standard cosmological model (LCDM), dark matter halos are aspherical. However, so far the asphericity of an individual galaxy's halo has never been robustly established. We use the Jeans equations to define a quantity which robustly characterizes a deviation from rotational symmetry. This quantity is essentially the gravitational torque and it roughly provides the ellipticity projected along the line of sight. We show that the Thirty Meter Telescope (TMT), with a single epoch of observations combined with those of the Gaia space telescope, can distinguish the LCDM value of the torque from zero for each Sculptor-like dwarf galaxy with a confidence between 0 and 5 sigma, depending on the orientation of each halo. With two epochs of observations, TMT will achieve a 5 sigma discovery of torque and so asphericity for most such galaxies, and so will provide a new and powerful test of the LCDM model.
6 pages, 4 pdf figures, accepted for publication in ApJL
References in corpus (5)
- Stellar Velocities in the Carina, Fornax, Sculptor and Sextans dSph Galaxies: Data from the Magellan/MMFS Survey
- Precise constraints on the dark matter content of Milky Way dwarf galaxies for gamma-ray experiments
- Merger traces in the spatial distribution of stellar populations in the Fornax dSph galaxy
- Gaia astrometric science performance - post-launch predictions
- What can Gaia (with TMT) say about Sculptor's Core?