Making Testable Predictions For the LSST Era
As highlighted in the LSST Science Book, one of the many exciting possibilities for Milky Way science in the LSST era is defining a complete sample of ultra-faint dwarf galaxies out to the virial radius. In preparation for LSST, we have made testable predictions for the number and spatial distribution of Milky Way dwarf galaxies to be discovered in the LSST and DES footprints, given several toy models for how dwarf galaxies populate sub-halos.
Because it is currently unclear how unresolved galaxies might limit the study of low-surface brightness stellar structures at very faint magnitudes, these figures, from Hargis, Willman & Peter, make predictions for a range of possible effective survey depths. With single epoch observations, we expect all dwarfs with L > 1000 LSun to be discovered, for a total of ~20-30 throughout the LSST footprint. The predicted number of hyperfaint (L < 1000 LSun) dwarfs to be detected is far more uncertain, but more than 100 may be discovered in LSST coadded observations.
Comparison between dwarf galaxy discoveries and these predictions will help discriminate between different models of dark matter + galaxy formation. Related, ongoing projects that need more people to support include:
- investigating both morphology- and color-based star-galaxy separation algorithms and
- making testable predictions for other hallmark LSST resolved stellar investigations.
Contact Beth Willman for more information or to find out how to participate.