The Mass and Age Distribution of Halo White Dwarfs in the Canada-France
  Imaging Survey
  We present optical spectroscopy for 18 halo white dwarfs identified using
photometry from the Canada-France Imaging Survey and Pan-STARRS1 DR1 3$\pi$
survey combined with astrometry from Gaia DR2. The sample contains 13 DA, 1 DZ,
2 DC, and two potentially exotic types of white dwarf. We fit both the spectrum
and the spectral energy distribution in order to obtain the temperature and
surface gravity, which we then convert into a mass, and then an age, using
stellar isochrones and the initial-to-final mass relation. We find a large
spread in ages that is not consistent with expected formation scenarios for the
Galactic halo. We find a mean age of 9.03$^{+2.13}_{-2.03}$ Gyr and a
dispersion of 4.21$^{+2.33}_{-1.58}$ Gyr for the inner halo using a maximum
likelihood method. This result suggests an extended star formation history
within the local halo population.
