Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Fan Beam Model for Radio Pulsars. I. Observational Evidence   We propose a novel beam model for radio pulsars based on the scenario that
the broadband and coherent emission from secondary relativistic particles, as
they move along a flux tube in a dipolar magnetic field, forms a radially
extended sub-beam with unique properties. The whole radio beam may consist of
several sub-beams, forming a fan-shaped pattern. When only one or a few flux
tubes are active, the fan beam becomes very patchy. This model differs
essentially from the conal beam models in the respects of beam structure and
predictions on the relationship between pulse width and impact angle $\beta$
(the angle between line of sight and magnetic pole) and the relationship
between emission intensity and beam angular radius. The evidence for this model
comes from the observed patchy beams of precessional binary pulsars and three
statistical relationships found for a sample of 64 pulsars, of which $\beta$
were mostly constrained by fitting polarization position angle data with the
Rotation Vector Model. With appropriate assumptions, the fan beam model can
reproduce the relationship between 10\% peak pulse width and $|\beta|$, the
anticorrelation between the emission intensity and $|\beta|$, and the upper
boundary line in the scatter plot of $|\beta|$ versus pulsar distance. An
extremely patchy beam model with the assumption of narrowband emission from one
or a few flux tubes is studied and found unlikely to be a general model. The
implications of the fan beam model to the studies on radio and gamma-ray pulsar
populations and radio polarization are discussed.

34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys