  Context. Outflows provide indirect means to get an insight on diverse star
formation associated phenomena. On scales of individual protostellar cores,
outflows combined with intrinsic core properties can be used to study the mass
accretion/ejection process of heavily embedded protostellar sources. Methods.
An area comprising 460"x230" of the Serpens cloud core has been mapped in 12 CO
J = 3\to 2 with the HARP-B heterodyne array at the James Clerk Maxwell
Telescope; J = 3\to 2 observations are more sensitive tracers of hot outflow
gas than lower J CO transitions; combined with the high sensitivity of the
HARP-B receptors outflows are sharply outlined, enabling their association with
individual protostellar cores. Results. Most of ~20 observed outflows are found
to be associated with known protostellar sources in bipolar or unipolar
configurations. All but two outflow/core pairs in our sample tend to have a
projected orientation spanning roughly NW-SE. The overall momentum driven by
outflows in Serpens lies between 3.2 and 5.1 x 10^(-1) M\odot km s^(-1), the
kinetic energy from 4.3 to 6.7 x 10^(43) erg and momentum flux is between 2.8
and 4.4 x 10^(-4) M\odot km s^(-1) yr^(-1). Bolometric luminosities of
protostellar cores based on Spitzer photometry are found up to an order of
magnitude lower than previous estimations derived with IRAS/ISO data.
Conclusions. We confirm the validity of the existing correlations between the
momentum flux and bolometric luminosity of Class I sources for the homogenous
sample of Serpens, though we suggest that they should be revised by a shift to
lower luminosities. All protostars classified as Class 0 sources stand well
above the known Class I correlations, indicating a decline in momentum flux
between the two classes.
