X-Ray Emission from Stellar Jets by Collision against High-density Molecular Clouds: an Application to HH 248

We investigate the plausibility of detecting X-ray emission from astellar jet that impacts a dense molecular cloud, a scenario that may betypical for classical T Tauri stars with jets in dense star-formingcomplexes. We first model the impact of a jet against a dense cloudusing two-dimensional axisymmetric hydrodynamic simulations, exploringdifferent configurations of the ambient environment. Then, we compareour results with XMM-Newton observations of the Herbig-Haro objectHH 248, where extended X-ray emission aligned with the optical knots isdetected at the edge of the nearby IC 434 cloud. Our simulations showthat a jet can produce plasma with temperatures up to 10$^7$ K,consistent with production of X-ray emission, after impacting a densecloud. We find that jets denser than the ambient medium but less densethan the cloud produce detectable X-ray emission only at impact with thecloud. From an exploration of the model parameter space, we constrainthe physical conditions (jet density and velocity and cloud density)that reproduce the intrinsic luminosity and emission measure of theX-ray source possibly associated with HH 248 well. Thus, we suggest thatthe extended X-ray source close to HH 248 corresponds to a jet impactinga dense cloud.