ROSAT PSPC OBSERVATIONS OF THE REMNANT OF SN-1006

We report soft X-ray observations (similar to 0.1-2.4 keV) of the remn ant of the AD 1006 supernova, obtained with the ROSAT PSPC in 1993 Jan uary. These data provide the best spectrally resolved X-ray images of the whole remnant yet recorded. The hard and soft components of the re mnant known from previous observations are now very clearly defined. A nalysis of the radial surface-brightness profiles demonstrates that th e hard flux is confined to thin sheets located in two 'aegis' which ca p the sides of the remnant at the north-east and south-west limbs. The interior flux is softer and is located in a shell which extends inwar ds to about 0.6 of the shock radius. The spectral analysis is characte rized by two components, a thermal plasma and a power-law continuum. T he power-law component is associated with the thin sheets which domina te in the aegis, and the thermal component comes from the interior. Ap art from the aegis, the spatial distribution of X-ray-emitting materia l is approximately as expected from an isothermal Sedov model. We conc lude that the remnant is at a distance of 0.7 +/- 0.1 kpc, that the ma ss is 1.7 +/- 0.7 M., and that the thermal energy of the observed plas ma is (2.4 +/- 1.0) x 10(49) erg. The ambient density is 0.40 +/- 0.06 cm(-3), the mean shock radius is 3.6 +/- 0.5 pc, and the present shoc k velocity is (1.4 +/- 0.2) x 10(3) km s(-1). The column density to th e remnant is (3.9 - 5.7) x 10(20) cm(-2), yielding a mean density alon g the line of sight of 0.19 - 0.28 cm(-3). It is likely that the therm al plasma is not in ionization equilibrium. We suggest that the aegis are formed by relativistic electrons, beamed from an otherwise unseen central object, interacting with the wound-up magnetic field in the po st-shock region. The luminosity required from the central source is > 1.2 x 10(34) erg s(-1). The high velocity dispersion of the cold iron seen in absorption in the UV spectrum of the sbOB star (the so-called S-M star) near the centre of the remnant indicates that the bulk of th is material must be outside the shock radius. The estimated kinetic en ergy in this cold halo is 2 x 10(49) erg, so the total initial energy of the supernova was > 4.4 x 10(49) erg.