  Multimessenger observations may hold the key to learn about the most
energetic sources in the universe. The recent construction of large scale
observatories opened new possibilities in testing non thermal cosmic processes
with alternative probes, such as high energy neutrinos and gravitational waves.
We propose to combine information from gravitational wave detections, neutrino
observations and electromagnetic signals to obtain a comprehensive picture of
some of the most extreme cosmic processes. Gravitational waves are indicative
of source dynamics, such as the formation, evolution and interaction of compact
objects. These compact objects can play an important role in astrophysical
particle acceleration, and are interesting candidates for neutrino and in
general high-energy astroparticle studies. In particular we will concentrate on
the most promising gravitational wave emitter sources: compact stellar
remnants. The merger of binary black holes, binary neutron stars or black
hole-neutron star binaries are abundant gravitational wave sources and will
likely make up the majority of detections. However, stellar core collapse with
rapidly rotating core may also be significant gravitational wave emitter, while
slower rotating cores may be detectable only at closer distances. The joint
detection of gravitational waves and neutrinos from these sources will probe
the physics of the sources and will be a smoking gun of the presence of hadrons
in these objects which is still an open question. Conversely, the non-detection
of neutrinos or gravitational waves from these sources will be fundamental to
constrain the hadronic content.
