Magnetic field strengths in the hotspots of 3C 33 and 111 |
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Authors: | Hardcastle Birkinshaw & Worrall |
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Institution: | Department of Physics, University of Bristol, Tyndall Avenue, Bristol BS8 1TL,;Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA |
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Abstract: | We report on ROSAT HRI observations of the nearby powerful radio galaxies 3C 33 and 111, which both have detected optical hotspots. We find nuclear X-ray sources in both objects, but no X-ray emission from the hotspots. This confirms the presence of a high-energy cut-off in the spectrum of synchrotron-emitting electrons. Since these electrons necessarily scatter the synchrotron photons by the inverse Compton process, our upper limits on the X-ray fluxes of the hotspots allow us to set lower limits of a few nanotesla on their magnetic flux density, close to or greater than the fields implied by equipartition of energy between radiating particles and magnetic field. |
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Keywords: | magnetic fields radiation mechanisms: non-thermal galaxies: individual: 3C 33 galaxies: individual: 3C 111 X-rays: galaxies |
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