Cloud-shock interactions in the Cygnus Loop
Abstract
Understanding the interactions of supernova remnants with the ambient interstellar medium is an important component for unraveling the dynamics and evolution of the interstellar medium. Because of the inhomogeneity of the interstellar medium the blast wave encounters varying densities, whether interstellar clouds or swept-up stellar wind bubbles. When a supernova blast wave encounters regions of denser interstellar material, a slower shock is driven into the cloud, and the reflected wave further heats previously shocked material. As the blast wave refracts around the obstacle, the overpressure drives shocks into the cloud, and the shear flow excites Kelvin-Helmholtz instabilities. The Cygnus Loop is a particularly fine laboratory for these studies because of its large angular scale (providing access to spatial scales of order 1e16 cm), and low extinction, making possible detailed observations in the optical and UV, in addition to soft X-rays. We present an analysis of X-ray observations of the Cygnus Loop, and compare the morphology of the interaction to numerical simulations of shock interactions with clouds. Because of the extreme softness of the X-ray emission (predominantly the Oxygen H-like and He-like lines), the analysis of the Chandra X-ray Observatory data is sensitive to the low-energy calibration. We present analyses incorporating the recent improvements in the Chandra calibration of the low-energy response. This work was supported by NASA grants G01-2060X and NAG5-9978, and by NASA contract NAS8-39073.
- Publication:
-
35th COSPAR Scientific Assembly
- Pub Date:
- 2004
- Bibcode:
- 2004cosp...35.3222G