On the X-ray feature associated with the Guitar nebula
Abstract
Context: A mysterious X-ray nebula, showing a remarkably linear geometry, was recently discovered close to the Guitar Nebula, the bow-shock nebula associated with B2224+65, which is the fastest pulsar known. The nature of this X-ray feature is unknown, and even its association with pulsar B2224+65 is unclear.
Aims: We attempt to develop a self-consistent scenario to explain the complex phenomenology of this object.
Methods: We assume that the highest energy electrons accelerated at the termination shock escape from the bow shock and diffuse into the ambient medium, where they emit synchrotron X-rays. The linear geometry should reflect the plane-parallel geometry of its ambient field.
Results: We estimate the Lorentz factor of the X-ray emitting electrons and the strength of the magnetic field. The former (≃10^8) is close to its maximum possible value, while the latter, at \cong45 {μ G}, is higher than typical interstellar values and must have been amplified in some way. The magnetic field must also be turbulent to some degree to trap the electrons sufficiently for synchrotron X-ray emission to occur effectively. We propose a self-consistent scenario in which, by some streaming instability, the electrons themselves generate a turbulent field in which they then diffuse. Some numerical coincidences are explained, and tests are proposed to verify our scenario.
Conclusions: Electron leaking may be common in the majority of pulsar bow-shock nebulae, even though the X-ray nebulosity in general is too diffuse to be detectable.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 2008
- DOI:
- 10.1051/0004-6361:200810666
- arXiv:
- arXiv:0809.2159
- Bibcode:
- 2008A&A...490L...3B
- Keywords:
-
- stars: pulsars: individual: B2224+65;
- ISM: individual objects: Guitar nebula;
- radiation mechanisms: non-thermal;
- Astrophysics
- E-Print:
- 4 pages. Accepted for publication in A&