Emission Beam Geometry of Selected Pulsars Derived from Average Pulse Polarization Data

By J. E. Everett, J. Weisberg. 2000

229 citations recorded by the source corpus.

By fitting the classical rotating vector model (RVM) to high-quality polarization data for selected radio pulsars, we find the inclination of the magnetic axis to the spin axis, α, as well as the minimum angle between the line of sight and the magnetic axis, β, for 10 objects. We give a full treatment of statistical errors in the fitting process. We also present a dictionary and conversion table of various investigators' geometric definitions to facilitate future comparisons. We compare our results with other RVM fits and with empirical/geometrical (E/G) approaches, and we examine the strengths and weaknesses of RVM fits and E/G investigations for the determination of pulsar emission beam geometry. Our fits to B0950+08 show that it is an orthogonal rotator with the main and interpulse radiation emitted from opposite magnetic poles, whereas earlier RVM fits indicated that it is an almost-aligned, single-magnetic pole emitter. We demonstrate that low-level emission across a wide longitude range, when properly weighted in the RVM fit, conclusively favors the former scenario. B0823+26 is also an orthogonal rotator. We find that B1929+10 emits into its wide observed range of longitudes from portions of a single cone that is almost aligned with the spin axis. This result agrees with other RVM fits but conflicts with the E/G findings of Rankin & Rathnasree. We determine that convergent RVM solutions can be found only for a minority of pulsars: generally those having emission over a relatively wide longitude range, and especially those pulsars having interpulse emission. In pulsar B0823+26, our preferred fit to data at all longitudes yields a solution differing by several σ from a fit to the main pulse/postcursor combination alone. For pulsar B0950+08, separate fits to the main pulse region, the interpulse region, and our preferred fit to almost all longitudes, converge to results differing by several times the formal uncertainties. These results indicate that RVM fits are easily perturbed by systematic effects in polarized position angles and that the formal uncertainties significantly underestimate the actual errors.

Subfields: Astronomy and Astrophysics, Oceanography

View Paper: https://www.semanticscholar.org/paper/9710544a65574b83812f0df6d98bc3f27a46dd04

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Citations in the corpus

The glitch-induced identity changes of PSR J1119−6127 (2010, background): “The edge effect is clearly observed for the Vela pulsar, PSR B1046–58 and B1706–44 (Johnston et al. 2001; Johnston & Romani 2002), PSR B1133+16 (Kramer et al. 2003), and PSR B0656+14.”
AN ATLAS FOR INTERPRETING γ-RAY PULSAR LIGHT CURVES (2008, background): “One possible complication arises if the altitude of the radio emission is large, where sweep-back and time-delay can alter the naive rotating-vector model predictions (Everett & Weisberg 2001).”
THE FIRST FERMI LARGE AREA TELESCOPE CATALOG OF GAMMA-RAY PULSARS (2009, background): “Similarly it has been argued that PSR J0659+1414 has a small viewing angle ζ 20◦ (Everett & Weisberg 2001) (but see Weltevrede & Wright (2009) for a discussion of uncertainties).”
The Crab pulsar in the 0.75-30 MeV range as seen by CGRO COMPTEL (2001, background): “…for both the magnetic inclination α and the viewing angle ζ, the angle between the spin axis and the observer’s line of sight, from radio and optical/UV observations cannot be reconciled (see for recent publications e.g. Graham-Smith et al. 1996; Moffett & Hankins 1999; Everett & Weisberg 2001).”
Evidence for alignment of the rotation and velocity vectors in pulsars. II. Further data and emission heights (2005, methodology): “PSR B0656+14 has PAv of 93 ◦ (Brisken et al. 2003b), and recent optical polarization measurements by Kern et al. (2003) match well with the RVM fit of Everett & Weisberg (2001) allowing a determination of PA0 of 98 ◦.”