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M. J. Ojeda

Publications and source records attributed to M. J. Ojeda.

2 recordsLinked to original sources

Angular Broadening of Nearby Pulsars

We conducted a very long baseline interferometric observation of 5 nearby pulsars and did not resolve the scattering disks of any of these sources. Using our upper limits on the angular diameters of these scattering disks and published values of the broadening times and proper motion velocities, we constrain the possible distributions of scattering material. The material responsible for scattering these sources is neither uniformly distributed nor concentrated at the surface of the Local Bubble. We argue that these pulsars themselves influence their environments to produce this scattering material.

astro-ph

Size of the Vela Pulsar's Radio Emission Region: 500 km

We use interstellar scattering of the Vela pulsar to determine the size of its emission region. From interferometric phase variations on short baselines, we find that radio-wave scattering broadens the source by 3.4+/-0.3 milliarcseconds along the major axis at position angle 81+/-3 degrees. The ratio of minor axis to major axis is 0.51+/-0.03. Comparison of angular and temporal broadening indicates that the scattering material lies in the Vela-X supernova remnant surrounding the pulsar. From the modulation of the pulsar's scintillation on very short baselines, we infer a size of 500 km for the pulsar's emission region. We suggest that radio-wave refraction within the pulsar's magnetosphere may plausibly explain this size.

astro-ph