The Development of an X-Ray Imaging Proportional Counter and an Analysis of Tycho's Supernova Remnant.

A soft X-ray imaging proportional counter was developed for use in X-ray astronomy. The detector, a drift multiwire proportional counter, determines the position of the site of X-ray absorption in the detector in two orthogonal directions using the center-of-gravity centroid determination technique. Spatial resolutions of 0.2 millimeters full width at half maximum and 0.5 millimeters full width at half maximum have been obtained at X-ray energies of 0.94 and 0.28 kiloelectron volts, respectively. Energy resolutions of 65 percent full width at half maximum and 110 percent full width at half maximum have been obtained at these energies. The detector and processing electronics were integrated into a rocket-borne X-ray telescope payload capable of providing angular resolutions of 1.0 arcminutes full width at half maximum and 1.3 arcminutes full width at half maximum at X-ray energies of 0.94 and 0.28 kiloelectron volts, respectively. X-ray imaging observations of Tycho's supernova remnant were obtained with the Einstein Observatory imaging proportional counter. The remnant appears as an incomplete shell of radius 3.5 parsecs in the adiabatic phase of evolution. The X-ray and radio shells are spatially coincident, although uncorrelated in intensity. The luminosity at a distance of 3 kiloparsecs is (5.3 (+OR-) 1.3) x 10('36) ergs per second. The current shock velocity is 3400 (+OR-) 140 kilometers per second. We find an initial blast energy of 2.5 x 10('51) ergs and an average ambient density in the vicinity of Tycho of approximately 3 atoms per cubic centimeter. We estimate the mass swept up by the expanding shock wave at about 20 solar masses. A range of 0.3 to 3 solar masses has been placed on the supernova ejected mass. The open shell structure and limb brightening of the remnant is consistent with expansion into an inhomogeneous medium. The initial energy allows us to place distance limits to Tycho of 1.3 and 4 kiloparsecs.