Magnetospheric Geometry in Pulsar B1929+10 from Radio/X-ray Phase Alignment
Abstract
We have conducted a study of two rotation-powered pulsars that emit at both radio and x-ray wavelengths, PSR B0531+21 and PSR B1929+10. Using absolute phase information, we have phase-aligned x-ray and radio profiles from these pulsars. Observations were done using the Green Bank 140ft telescope, and ASCA. The 0531+21 x-ray profile is sharp and lines up well with the radio profile confirming that the x-ray emission from this pulsar is magnetospheric in origin. The 1929+10 profile is approximately sinusoidal (Wang & Halpern, ApJ 4 82, L159) with the peak of the emission arriving 67+/- 23 degrees after the maximum in the radio emission. The controversy to which the PSR B1929+10 result adds fuel, is whether this ``inter"-pulsar, is an ``aligned" or ``orthogonal" rotator - describing the alignment of the magnetic axis to the rotation axis. Do the two peaks in the radio profile (the pulse and interpulse) come from a double crossing of a thin hollow cone nearly aligned with rotation axis (as in Lyne & Manchester, 1988, MNRAS, 234, 477; Phillips, 1990, ApJL, 361, L57; Blaskiewicz et al, 1991, ApJ 370, 643), or alternatively (as in Rankin and Rathnasree, 1998 preprint) do they come from from opposite poles of an ``orthogonal" rotator where the spin axis is perpendicular to the magnetic axis? The radio to x-ray alignment we find favors the former explanation: if the x-ray hot spot is the result of return currents to the surface from the outward current that generates radio emission, then in the ``double-crossing" model, the hot spot phase is expected to lie between the main pulse and interpulse as observed.
- Publication:
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American Astronomical Society Meeting Abstracts #192
- Pub Date:
- May 1998
- Bibcode:
- 1998AAS...192.6801S