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H.L. Marshall, N.S. Schulz (MIT CSR)
Observations of PSR B0656+14 using the Chandra Low Energy Transmission Grating Spectrometer are presented. The zeroth order events are pulsed at an amplitude of 10 +/- 2% and the image may be slightly extended. The extended emission is modelled as a Gaussian with a diameter of about 1.5", for a linear size (at a distance of 300 pc) of 6.5e15 cm. In the absence of systematic errors in the detector point spread function, the extended emission comprises < 50% of the observed flux in the 0.2-2.0 keV band, for a luminosity of < 1e32 erg/s. The spectrum is well modelled by a soft blackbody with T = 8.0 +/- 0.3 x 1e5 K with a size of 8.8 +/- 0.7 km in addition to a harder component that is modelled with either a power law or a higher temperature blackbody. Time-resolved spectroscopy shows that there is a weak absorption feature at 0.266 keV (observed frame) in the off-pulse spectrum, relative to the on-pulse spectrum. In a model where the the spectrum pulses at the 10% level in a spectrally independent way, the feature is marginally significant. This line has an equivalent width of 0.16 Angstroms and a width of 0.17 Angstroms in the time-averaged spectrum with a significance of 4.1 sigma relative to the continuum. This feature might be the first transition ever detected from atoms in strong magnetic and gravitational fields.
The author(s) of this abstract have provided an email address for comments about the abstract: mailto:hermanm@space.mit.edu