An APEX survey of outflow and infall toward the youngest protostars in
  Orion
  We aim to characterize the outflow properties of a sample of early Class 0
phase low-mass protostars in Orion first identified by the Herschel Space
Observatory. We also look for signatures of infall in key molecular lines. CO
$J$=3-2 and $J$=4-3 maps toward 16 very young Class 0 protostars were obtained
using the Atacama Pathfinder EXperiment (APEX) telescope. We search the data
for line wings indicative of outflows and calculate masses, velocities, and
dynamical times for the outflows. We use additional HCO$^+$, H$^{13}$CO$^+$,
and NH$_3$ lines to look for infall signatures toward the protostars. We
estimate the outflow masses, forces, and mass-loss rates based on the CO
$J$=3-2 and $J$=4-3 line intensities for 8 sources with detected outflows. We
derive upper limits for the outflow masses and forces of sources without clear
outflow detections. The total outflow masses for the sources with clear outflow
detections are in the range between 0.03 and 0.16 $M_\odot$ for CO $J$=3-2, and
in the range between 0.02 and 0.10 $M_\odot$ for CO $J$=4-3. The outflow forces
are in the range between $1.57\times10^{-4}$ and $1.16\times10^{-3}$ $M_\odot$
km s$^{-1}$ yr$^{-1}$ for CO $J$=3-2 and in the range between
$1.14\times10^{-4}$ and $6.92\times10^{-4}$ $M_\odot$ km s$^{-1}$ yr$^{-1}$ for
CO $J$=4-3. Nine protostars in our sample show asymmetric line profiles
indicative of infall in HCO$^+$, compared to H$^{13}$CO$^+$ or NH$_3$. The
outflow forces of the protostars in our sample show no correlation with the
bolometric luminosity, unlike those found by some earlier studies for other
Class 0 protostars. The derived outflow forces for the sources with detected
outflows are similar to those found for other - more evolved - Class 0
protostars, suggesting that outflows develop quickly in the Class 0 phase.
