Constraints on magnetic field strength in the remnant SN1006 from its nonthermal images

TL;DR

This paper presents model-independent methods to constrain the magnetic field strength in SN1006 using multi-band images, finding it to be less than a few hundred micro Gauss and highlighting the potential of future high-resolution gamma-ray data.

Contribution

It introduces analytical approximations for estimating magnetic field strength from radio, X-ray, and gamma-ray images of supernova remnants, applicable with well-resolved data.

Findings

Magnetic field in SN1006 limbs is less than a few hundred micro Gauss.

Radio, X-ray, and gamma-ray surface brightness ratios can constrain magnetic fields.

Future high-resolution gamma-ray observations can provide more precise magnetic field estimates.

Abstract

Images of SN1006 have a number of important properties. For instance, the bright limbs coincide spatially in various bands, they have different brightness, and the contrast of brightness varies from radio to gamma-rays. The reasons of such properties and the role of the magnetic field strength are discussed. Simple, almost model-independent methods and analytical approximations for the derivation of the strength of magnetic field from the comparison of radio, X-rays and TeV images of SNR are presented. The methods require the TeV image to be well resolved and accurate, at least to the level of the radio and X-ray maps, in order to put reasonable constraints on magnetic field. If we apply it to the present HESS data, they limit the strength of magnetic field in limbs of SN1006 to values lower than few hundreds micro Gauss. If applied to the Fermi-LAT band, the model predicts same position and same ratio of the surface brightness for GeV photons as for the radio band. We conclude that TeV and GeV future high-resolution data may be very informative about the MF of SN1006.