Knotty protostellar jets as a signature of episodic protostellar
  accretion?
  We aim at studying the causal link between the knotty jet structure in CARMA
7, a young Class 0 protostar in the Serpens South cluster, and episodic
accretion in young protostellar disks. We used numerical hydrodynamics
simulations to derive the protostellar accretion history in gravitationally
unstable disks around solar-mass protostars. We compared the time spacing
between luminosity bursts \Delta\tau_mod, caused by dense clumps spiralling on
the protostar, with the differences of dynamical timescales between the knots
\Delta\tau_obs in CARMA 7. We found that the time spacing between the bursts
have a bi-modal distribution caused by isolated and clustered luminosity
bursts. The former are characterized by long quiescent periods between the
bursts with \Delta\tau_mod = a few * (10^3-10^4) yr, whereas the latter occur
in small groups with time spacing between the bursts \Delta\tau_mod= a few *
(10-10^2) yr. For the clustered bursts, the distribution of \Delta\tau_mod in
our models can be fit reasonably well to the distribution of \Delta\tau_obs in
the protostellar jet of CARMA 7, if a certain correction for the (yet unknown)
inclination angle with respect to the line of sight is applied. The K-S test on
the model and observational data sets suggests the best-fit values for the
inclination angles of 55-80 deg., which become narrower (75-80 deg.) if only
strong luminosity bursts are considered. The dynamical timescales of the knots
in the jet of CARMA 7 are too short for a meaningful comparison with the long
time spacings between isolated bursts in our models. The exact sequences of
time spacings between the luminosity bursts in our models and knots in the jet
of CARMA 7 were found difficult to match. (abridged)
