Are runaway O-star bow shocks capable of accelerating cosmic rays?
Abstract
In the long-standing quest to understand the origin of cosmic rays and how they can acquire their enormous energies, particle acceleration by shock waves is thought to play a central role. Massive runaway stars moving supersonically through the interstellar medium (ISM) are known to produce bow shocks detected through their associated infrared (IR) emission, and it has been speculated that these bow shocks can accelerate particles to very high energies, even producing cosmic rays. Here, we present preliminary results of our Chandra observations of the field centered on the runaway star AE Aur and its well characterized bow shock. Previous XMM-Newton observations revealed an X-ray "blob", located near the well-known IR arc, possibly a nonthermal source consistent with models of inverse Compton scattering of dust IR photons by electrons accelerated within the bow shock. The previous conclusions for AE Aur were based on relatively poor spatial coincidence between the X-ray "blob" and the IR arc. In contrast, our Chandra data, while confirming the XMM-Newton results, neither show a spatial coincidence with the bow shock, nor confirm a non-thermal spectrum. We conclude that in the AE Aur case, there is no observational evidence for cosmic-ray (electron) acceleration by the shock.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E2784R