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We investigate whether the broad wings of H2O emission identified withHerschel towards low-mass Class 0 and Class 1 protostars may be consistent withan origin in a dusty MHD disk wind, and the constraints it would set on theunderlying disk properties. We present synthetic H2O line profiles predictionsfor a typical MHD disk wind solution with various values of disk accretionrate, stellar mass, extension of the launching area, and view angle. We comparethem in terms of line shapes and intensities with the HIFI profiles observed bythe WISH Key Program. We find that a dusty MHD disk wind launched from 0.2--0.6AU AU to 3--25 AU can reproduce to a remarkable degree the observed shapes andintensities of the broad H2O component, both in the fundamental 557 GHz lineand in more excited lines. Such a model also readily reproduces the observedcorrelation of 557 GHz line luminosity with envelope density, if the infallrate at 1000 AU is 1--3 times the disk accretion rate in the wind ejectionregion. It is also compatible with the typical disk size and bolometricluminosity in the observed targets. However, the narrower line profiles inClass 1 sources suggest that MHD disk winds in these sources, if present, wouldhave to be slower and/or less water rich than in Class 0 sources. Inconclusion, MHD disk winds appear as a valid (though not unique) option toconsider for the origin of the broad H2O component in low-mass protostars. ALMAappears ideally suited to further test this model by searching for resolvedsignatures of the warm and slow wide-angle molecular wind that would bepredicted.

Molecule survival in magnetized protostellar disk winds. II. Predicted H2O line profiles versus Herschel/HIFI observations