The hard TeV spectrum of 1ES 0229+200: new clues from Swift
Abstract
The BL Lac object 1ES 0229+200 (z = 0.14) has been detected by the High Energy Stereoscopic System (HESS) during observations taking place in 2005-2006. The TeV spectrum, when corrected for the absorption of gamma-ray photons through the interaction with the extragalactic background light, is extremely hard, even if the most conservative level for the background is considered. The case of 1ES 0229+200 is very similar to that of 1ES 1101-232, for which a possible explanation, in the framework of the standard one-zone synchrotron-self Compton (SSC) model, is that the high-energy emission is SSC radiation of electrons distributed as a power law with a large value of the minimum energy. In this scenario, the hard TeV spectrum is accompanied by a very hard synchrotron continuum below the soft X-ray band. We will show that recent Swift observations of 1ES 0229+200 in the critical UV X-ray band support this model, showing the presence of the expected spectral break and hard continuum between the UV and the X-ray bands.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 2009
- DOI:
- 10.1111/j.1745-3933.2009.00724.x
- arXiv:
- arXiv:0905.0899
- Bibcode:
- 2009MNRAS.399L..59T
- Keywords:
-
- radiation mechanisms: non-thermal;
- galaxies: general;
- gamma-rays: observations;
- gamma-rays: theory;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 5 pages, 1 figure. Accepted for publication as a letter to MNRAS after minor revision