X-ray emission from protostellar jet HH 154: the first evidence of a diamond shock?

Abstract

X-ray emission from about ten protostellar jets has been discovered and it appears as a feature common to the most energetic jets. Although X-ray emission seems to originate from shocks internal to jets, the mechanism forming these shocks remains controversial. One of the best studied X-ray jet is HH 154 that has been observed by Chandra over a time base of about 10 years. We analyze the Chandra observations of HH 154 by investigating the evolution of its X-ray source. We show that the X-ray emission consists of a bright stationary component and a faint elongated component. We interpret the observations by developing a hydrodynamic model describing a protostellar jet originating from a nozzle and compare the X-ray emission synthesized from the model with the X-ray observations. The model takes into account the thermal conduction and radiative losses and shows that the jet/nozzle leads to the formation of a diamond shock at the nozzle exit. The shock is stationary over the period covered by our simulations and generates an X-ray source with luminosity and spectral characteristics in excellent agreement with the observations. We conclude that the X-ray emission from HH 154 is consistent with a diamond shock originating from a nozzle through which the jet is launched into the ambient medium. We suggest that the physical origin of the nozzle could be related to the dense gas in which the HH 154 driving source is embedded and/or to the magnetic field at the jet launching/collimation region.

Accepted for publication in The Astrophysical Journal

References in corpus (3)

• The discovery of an expanding X-ray source in the HH 154 protostellar jet
• The X-ray puzzle of the L1551 IRS 5 jet
• X-rays from protostellar jets: emission from continuous flows

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• The small-scale HH34 IRS jet as seen by X-shooter
• Recollimation boundary layers as X-ray sources in young stellar jets
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• A Theoretical Model of X-ray Jets from Young Stellar Objects
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• Detection of X-rays from the jet-driving symbiotic star Hen 3-1341
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• High Energy Emission and its Variability in Young Stellar Objects
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