X-ray emission mechanisms in protostellar jets
Rosaria Bonito (Università di Palermo, Pizza del Parlamento 1, 90134
Palermo, Italy)
Salvatore Orlando (INAF -- Osservatorio Astronomico di Palermo)
Giovanni Peres (Università di Palermo)
Prompted by the recent detection of X-ray emission from Herbig-Haro objects, we
studied the interaction between a supersonic jet originating from a young
stellar object and the ambient medium with the aim to investigate the mechanisms
of X-ray emission. Our model takes into account the radiative losses from
optically thin plasmas and the Spitzer's thermal conduction including saturation
effects. We explored the parameter space defined by the density contrast between
the ambient density and the jet and by the Mach number to infer the
configurations which can give rise to X-ray emission. From the models, we
derived X-ray emission as predicted to be observed with Chandra/ACIS-I and
XMM-Newton/EPIC-pn, using the MEKAL spectral code and including the absorption
of interstellar medium. Here we discuss a representative case which produces,
without any ad-hoc assumption, X-ray emission with characteristics very similar
to those observed in the protostellar jet HH 154. We find that the X-ray
emission originates from a blob localized just behind the bow shock, moving with
velocity 500 km/s. We predict, therefore, a detectable proper motion of the
X-ray blob, interesting for future observations.