Host Galaxy Properties and Offset Distributions of Fast Radio Bursts:
  Implications for their Progenitors
  We present observations and detailed characterizations of five new host
galaxies of fast radio bursts (FRBs) discovered with the Australian Square
Kilometre Array Pathfinder (ASKAP) and localized to $\lesssim 1''$. Combining
these galaxies with FRB hosts from the literature, we introduce criteria based
on the probability of chance coincidence to define a sub-sample of 10
highly-confident associations (at $z=0.03-0.52$), three of which correspond to
known repeating FRBs. Overall, the FRB host galaxies exhibit a broad,
continuous range of color ($M_u-M_r = 0.9 - 2.0$), stellar mass ($M_\star =
10^{8} - 6\times 10^{10}\,M_{\odot}$), and star-formation rate (${\rm SFR} =
0.05 - 10\,M_{\odot}\,{\rm yr}^{-1}$) spanning the full parameter space
occupied by $z<0.5$ galaxies. However, they do not track the color-magnitude,
SFR-$M_\star$, nor BPT diagrams of field galaxies surveyed at similar
redshifts. There is an excess of "green valley" galaxies and an excess of
emission-line ratios indicative of a harder radiation field than that generated
by star-formation alone. From the observed stellar mass distribution, we rule
out the hypothesis that FRBs strictly track stellar mass in galaxies ($>99\%$
c.l.). We measure a median offset of 3.3 kpc from the FRB to the estimated
center of the host galaxies and compare the host-burst offset distribution and
other properties with the distributions of long- and short-duration gamma-ray
bursts (LGRBs and SGRBs), core-collapse supernovae (CC-SNe), and Type Ia SNe.
This analysis rules out galaxies hosting LGRBs (faint, star-forming galaxies)
as common hosts for FRBs ($>95\%$ c.l.). Other transient channels (SGRBs, CC-
and Type Ia SNe) have host galaxy properties and offsets consistent with the
FRB distributions. All of the data and derived quantities are made publicly
available on a dedicated website and repository.
