Protostellar jets: the revolution with ALMA

Fast and collimated molecular jets as well as slower wide-angle outflows
are observed since the earliest stages of the formation of a new star, when the
protostellar embryo accretes most of its final mass from the dense parental
envelope. Early theoretical studies suggested that jets have a key role in this
process as they can transport away angular momentum thus allowing the star to
form without reaching its break-up speed. However, an observational validation of
these theories is still challenging as it requires to investigate the interface between
jets and disks on scales of fractions to tens of AUs. For this reason, many questions
about the origin and feedback of protostellar jets remain unanswered, e.g. are
jets ubiquitous at the earliest stages of star formation? Are they launched by a
magneto-centrifugal mechanism as suggested by theoretical models? Are they
able to remove (enough) angular momentum? What is the jet/outflow feedback
on the forming star-disk system in terms of transported mass/momentum and
shock-induced chemical alterations?
The advent of millimetre interferometers such as NOEMA and ALMA with
their unprecedented combination of angular resolution and sensitivity are now
unraveling the core of pristine jet-disk systems. While NOEMA allows to obtain
the first statistically relevant surveys of protostellar jet properties and ubiquity,
recent ALMA observations provide the first solid signatures of jet rotation
and new insight on the chemistry of the protostellar region. I will review the most recent and exciting results obtained in the field and show how millimetre
interferometry is revolutionising our comprehension of protostellar jets.