The X-Ray Luminosities of Herbig-Haro Objects

The recent detection of X-ray emission from HH 2 and HH 154 with the Chandraand XMM-Newton satellites (respectively) have opened up an interesting, newobservational possibility in the field of Herbig-Haro objects. In order to beable to plan further X-ray observations of other HH objects, it is now ofinterest to be able to estimate their X-ray luminosities in order to choosewhich objects to observe. This paper describes a simple, analytic model forpredicting the X-ray luminosity of a bow shock from the parameters of the flow(i.e., the size of the bow shock, its velocity, and the pre-shock density). Theaccuracy of the analytic model is analyzed through a comparison with thepredictions obtained from axisymmetric, gasdynamic simulations of the leadingworking surface of an HH jet. We find that our analytic model reproduces theobserved X-ray luminosities of HH 2 and HH 154, and we propose that HH~80/81 isa good candidate for future observations with Chandra.Comment: 10 pages (8 text, 2 figures