On standardizing kilonovae and their use as standard candles to measure
  the Hubble constant
  The detection of GW170817 is revolutionizing many areas of astrophysics with
the joint observation of gravitational waves and electromagnetic emissions.
These multi-messenger events provide a new approach to determine the Hubble
constant, thus, they are a promising candidate for mitigating the tension
between measurements of Type Ia supernovae via the local distance ladder and
the Cosmic Microwave Background. In addition to the "standard siren" provided
by the gravitational-wave measurement, the kilonova itself has characteristics
that allow to improve existing measurements or to perform yet another,
independent measurement of the Hubble constant without gravitational-wave
information. Here, we employ standardization techniques borrowed from the
type-Ia community and apply them to kilonovae, not using any information from
the gravitational-wave signal. We use two versions of this technique, one
derived from direct observables measured from the lightcurve, and the other
based on inferred ejecta parameters, e.g., mass, velocity, and composition, for
two different models. These lead to Hubble Constant measurements of $H_0 =
109^{+49}_{-35}$\,km $\mathrm{s}^{-1}$ $\mathrm{Mpc}^{-1}$ for the measured
analysis, and $H_0 = 85^{+22}_{-17}$\,km $\mathrm{s}^{-1}$ $\mathrm{Mpc}^{-1}$
and $H_0 = 79^{+23}_{-15}$\,km $\mathrm{s}^{-1}$ $\mathrm{Mpc}^{-1}$ for the
inferred analyses. This measurement has error bars within ~$\sim$\,2 to the
gravitational-wave measurements ($H_0=74^{+16}_{-8}$\,km $\mathrm{s}^{-1}$
$\mathrm{Mpc}^{-1}$), showing its promise as an independent constraint on
$H_0$.
