X-ray emission from stellar jets by collision against high-density molecular clouds: an application to HH 248

TL;DR

This study models X-ray emission from stellar jets impacting dense molecular clouds, demonstrating that such interactions can produce detectable X-ray emission, and applies this to explain observations of HH 248.

Contribution

The paper presents hydrodynamic simulations of jet-cloud impacts and constrains physical conditions to explain X-ray emission observed in HH 248, linking jet interactions to X-ray sources.

Findings

Jets can produce plasma up to 10 MK, emitting X-rays.

X-ray emission is detectable only when jets impact dense clouds.

Model parameters match observed X-ray luminosity and emission measure.

Abstract

We investigate the plausibility of detecting X-ray emission from a stellar jet that impacts against a dense molecular cloud. This scenario may be usual for classical T Tauri stars with jets in dense star-forming complexes. We first model the impact of a jet against a dense cloud by 2D axisymmetric hydrodynamic simulations, exploring different configurations of the ambient environment. Then, we compare our results with XMM-Newton observations of the Herbig-Haro object HH 248, where extended X-ray emission aligned with the optical knots is detected at the edge of the nearby IC 434 cloud. Our simulations show that a jet can produce plasma with temperatures up to 10 MK, consistent with production of X-ray emission, after impacting a dense cloud. We find that jets denser than the ambient medium but less dense than the cloud produce detectable X-ray emission only at the impact onto the cloud. From the exploration of the model parameter space, we constrain the physical conditions (jet density and velocity, cloud density) that reproduce well the intrinsic luminosity and emission measure of the X-ray source possibly associated with HH 248. Thus, we suggest that the extended X-ray source close to HH 248 corresponds to the jet impacting on a dense cloud.