Synchrotron X-Ray Rims in Tycho's Supernova Remnant are Energy Dependent
Abstract
Several young supernova remnants exhibit thin X-ray bright rims of synchrotron radiation at their forward shocks. Thin rims have been taken to indicate that shock-accelerated electrons rapidly cool downstream of the shock, requiring strong magnetic field amplification. But, magnetic field damping immediately behind the shock could produce similarly thin rims. Synchrotron loss-limited rim widths should decrease with energy whereas damping limited rims should be relatively energy-independent. To discriminate between models, we measured rim widths around Tycho's supernova remnant in 5 energy bands using an archival 750 ks Chandra observation. Rims narrow with increasing energy, favoring loss-limited radiation over magnetic damping and corroborating similar observations in the remnant of SN 1006. Observed widths are best fit by electron transport models requiring amplified magnetic fields of ~200-1000 µG and particle diffusion coefficients ~1-100x Bohm values, consistent with prior work on Tycho's SNR. Non-negligible diffusion results in some degeneracy between magnetic field strength and diffusion coefficient in setting observed rim widths, but strong magnetic fields are required for all measurements. A different approach may be needed to better constrain diffusion at supernova remnant shocks.
- Publication:
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American Astronomical Society Meeting Abstracts #225
- Pub Date:
- January 2015
- Bibcode:
- 2015AAS...22514027T