Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Zwicky Transient Facility Census of the Local Universe I: Systematic
  search for Calcium rich gap transients reveal three related spectroscopic
  sub-classes   (Abridged) Using the Zwicky Transient Facility alert stream, we are
conducting a large campaign to spectroscopically classify all transients
occurring in galaxies in the Census of the Local Universe (CLU) catalog. The
aim of the experiment is to construct a spectroscopically complete,
volume-limited sample of transients coincident within 100" of CLU galaxies out
to 200 Mpc, and to a depth of 20 mag. We describe the survey design and
spectroscopic completeness from the first 16 months of operations. We present
results from a systematic search for Calcium rich gap transients in the sample
of 22 low luminosity (peak absolute magnitude $M > -17$), hydrogen poor events
found in the experiment (out of 754 spectroscopically classified SNe). We
report the detection of eight Calcium rich gap transients, and constrain their
volumetric rate to be at least $\approx 15\pm5$% of the SN Ia rate. Combining
this sample with ten events from the literature, we find a likely continuum of
spectroscopic properties ranging from events with SN Ia-like features (Ca-Ia
objects) to SN Ib/c-like features (Ca-Ib/c objects) at peak light. Within the
Ca-Ib/c events, we find two populations of events distinguished by their red
($g - r \approx 1.5$ mag) or green ($g - r \approx 0.5$ mag) spectral colors at
$r$-band peak, wherein redder events show strong line blanketing signatures,
slower light curves, weaker He lines and lower [Ca II]/[O I] in the nebular
phase. Together, we find that the spectroscopic continuum, volumetric rates and
striking old environments are consistent with the explosive burning of He
shells on low mass white dwarfs. We posit that Ca-Ia and red Ca-Ib/c objects
are consistent with the double detonation of He shells with high He burning
efficiency, while green Ca-Ib/c objects could arise from less efficient He
burning scenarios such as detonations in low density He shells or He shell
deflagrations.

7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics