Physical Properties of the Host Galaxies of Ca-rich Transients
  Calcium-rich (Ca-rich) transients are a new class of supernovae (SNe) that
are known for their comparatively rapid evolution, modest peak luminosities,
and strong nebular calcium emission lines. Currently, the progenitor systems of
Ca-rich transients remain unknown. Although they exhibit spectroscopic
properties not unlike core-collapse Type Ib/c SNe, nearly half are found in the
outskirts of their host galaxies that are predominantly elliptical, suggesting
a closer connection to the older stellar populations of SNe Ia. In this paper,
we present a compilation of publicly available multiwavelength observations of
all known and/or suspected host galaxies of Ca-rich transients ranging from FUV
to IR, and use these data to characterize their stellar populations with
prospector. We estimate several galaxy parameters including integrated star
formation rate, stellar mass, metallicity, and age. For nine host galaxies, the
observations are sensitive enough to obtain nonparametric star formation
histories, from which we recover SN rates and estimate probabilities that the
Ca-rich transients in each of these host galaxies originated from a
core-collapse vs. Type Ia-like explosion. Our work supports the notion that the
population of Ca-rich transients do not come exclusively from core-collapse
explosions, and must either be only from white dwarf stars or a mixed
population of white dwarf stars with other channels, potentially including
massive star explosions. Additional photometry and explosion site spectroscopy
of larger samples of Ca-rich host galaxies will improve these estimates and
better constrain the ratio of white dwarf vs. massive star progenitors of
Ca-rich transients.
