Radio pulsar B0950++08: Radiation in Magnetosphere and Sparks above Surface

The nearby radio pulsar B0950$+$08 with full duty cycle is targeted by the Five-hundred-meter Aperture Spherical radio Telescope (FAST, 110 minutes allocated), via adopting polarization calibration on two ways of baseline determination, in order to understand its magnetospheric radiation geometry as well as the polar cap sparking. % The radiation of the main pulse could not be informative of magnetic field line planes due to its low linear polarization ($<10 \%$) and the position angle jumps, and the polarization position angle in the pulse longitudes whose linear fractions are larger than $\sim 30 \%$ is thus fitted in the classical rotating vector model (RVM). % The best RVM fit indicates that the inclination angle, $\alpha$, and the impact angle, $\beta$, of this pulsar are $100.5^{\circ}$ and $-33.2^{\circ}$, respectively, suggesting that the radio emission comes from two poles. % Polar cap sparking in the vacuum gap model, either the annular gap or the core gap, is therefore investigated in this RVM geometry, resulting in a high-altitude magnetospheric emission at heights from $\sim 0.25R_{\rm LC}$ to $\sim 0.56R_{\rm LC}$, with $R_{\rm LC}$ the light cylinder radius. % It is evident that both sparking points of the main and inter pulses are located mainly away from the magnetic pole, that is meaningful in the physics of pulsar surface and is even relevant to pulsar's inner structure.Comment: 13 pages, 9 figures, submitte

Radio Pulsar B0950+08: Radiation in the Magnetosphere and Sparks above the Surface

We observed the nearby radio pulsar B0950+08, which has a 100% duty cycle, using the Five-hundred-meter Aperture Spherical Radio Telescope. We obtained the polarization profile for its entire rotation, which enabled us to investigate its magnetospheric radiation geometry and the sparking pattern of the polar cap. After we excluded part of the profile in which the linear polarization factor is low (≲30%) and potentially contaminated by jumps in position angle, the rest of the swing in polarization position angle fits a classical rotating vector model (RVM) well. The best-fit RVM indicates that the inclination angle, α , and the impact angle, β , of this pulsar, are 100.°5 and −33.°2, respectively, suggesting that the radio emission comes from two poles. We find that, in such RVM geometry, either the annular vacuum gap model or the core vacuum gap model would require that the radio emissions come from a high-altitude magnetosphere with heights from ∼0.25 R _LC to ∼0.56 R _LC , with R _LC being the light cylinder radius. Both the main and interpulses’ sparking points are located away from the magnetic pole, which could relate to the physical conditions on the pulsar surface

Single Pulse Studies of PSR B0950+08 with FAST

We report detailed polarization and single-pulse studies of PSR B0950+08 with the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) at 1250 MHz. Significant bridge emission was observed between the inter-pulse and the main pulse and the height of the bridge decreased with increase in frequency. Our results support the interpretation that both the inter-pulse and the main pulse of this pulsar are from the same magnetic pole. From the relative peak flux density and the relative energy distribution, we conclude that no giant pulse was detected in PSR B0950+08. Our results provide opportunities to study the origin of the emission from PSR B0950+08 and offer new insights into the origins of pulsar emission and bridge emission