2000ApJ...542..386H

G328.4+0.2 is a moderately small (5'x5') Galactic radio supernova remnant (SNR) at a distance of at least 17 kpc that has been long suggested to be Crab-like. Here we report on the detection with ASCA of the X-ray emission from the SNR. The X-ray source is faint with an observed flux of (6.0±0.8)x10^–13 ergs.s^–1.cm^–2 over the 2-10 keV band. The emission is heavily cut off at low energies and no flux is detected below 2 keV. Spectral analysis confirms that the column density to the source is indeed large, N_H∼10²³ atoms.cm^–2, and consistent with the total column density of hydrogen through the Galaxy at this position. Good fits to the spectrum can be obtained for either thermal plasma or nonthermal power-law models, although the lack of detected line emission as well as other evidence argues against the former interpretation. The power-law index we find, α_P=2.9^+0.9_–0.8, is consistent with other Crab-like SNRs. In the radio band, G328.4+0.2 is nearly as luminous as the Crab Nebula, yet in the X-ray band, it is some 70 times fainter. Nevertheless, its inferred soft X-ray band luminosity is greater than all but the brightest pulsar-powered synchrotron nebulae and implies that G328.4+0.2 contains a rapidly spinning, as yet undetected, pulsar that is losing energy at a rate of ∼10³⁸ ergs.s^–1.