scholarly journals Pulsar radio beams and emission altitudes

1996 ◽  
Vol 160 ◽  
pp. 287-288
Author(s):  
Jaroslaw Kijak ◽  
Janusz A. Gil
Keyword(s):  
Emission Region ◽  
Intensity Level ◽  
Pulse Profile ◽  
Pulsar Emission ◽  
Pulsar Radio ◽  
Pulsar Radiation ◽  
Measured Profile ◽  
Field Lines ◽  
The Relationship ◽  
Pulsar Radio Emission

We verify the relationship proposed by Kijak and Gil (1996) for the pulsar radio emission altitudes(see also Eq.3 in Gil & Krawczyk, 1996), using the pulse-profile Effelsberg raw data at 1.41 GHz. We measured profile pulse-widths at the lowest intensity level corresponding to 0.01% of the maximum intensity (Fig. 1b), using the polarlog-scale technique (Hankins and Fowler, 1986). We calculated opening angles (Fig. 1a) and emission altitudes (Fig. 1c) assuming that:i) pulsar radiation is narrow-band with radius-to-frequency mapping operating in the emission region,ii) pulsar emission is beamed tangentially to the dipolar magnetic field lines,iii) the extreme profile wings originate near or at the last open field lines.

scholarly journals Understanding the radio beam of PSR J1136+1551 through its single pulses

2019 ◽  
Vol 489 (1) ◽  
pp. 310-324 ◽  
Author(s):  
Lucy Oswald ◽  
Aris Karastergiou ◽  
Simon Johnston
Keyword(s):  
Magnetic Field ◽  
Single Pulse ◽  
Line Of Sight ◽  
Emission Region ◽  
Beam Model ◽  
Pulse Profile ◽  
Emission Frequency ◽  
Pulsar Emission ◽  
Field Lines ◽  
The Magnetic Field

ABSTRACT The frequency widening of pulsar profiles is commonly attributed to lower frequencies being produced at greater heights above the surface of the pulsar; so-called radius-to-frequency mapping (RFM). The observer’s view of pulsar emission is a 1D cut through a 3D magnetosphere: we can only see that emission which points along our line of sight. However, by comparing the frequency evolution of many single pulses positioned at different phases, we can build up an understanding of the shape of the active emission region. We use single pulses observed with the Giant Metrewave Radio Telescope to investigate the emission region of PSR J1136+1551 and test RFM. Assuming that emission is produced tangential to the magnetic field lines and that each emission frequency corresponds to a single height, we simulate the single pulse profile evolution resulting from the canonical conal beam model and a fan beam model. Comparing the results of these simulations with the observations, we conclude that the emission region of PSR J1136+1551 is better described by the fan beam model. The diversity of profile widening behaviour observed for the single pulses can be explained by orthogonally polarized modes propagating along differing frequency-dependent paths in the magnetosphere.

scholarly journals Triplicity of Pulsar Profiles and Orthogonal Polarization Modes

1987 ◽  
Vol 125 ◽  
pp. 58-58
Author(s):  
J. A. Gil
Keyword(s):  
Inner Core ◽  
Emission Region ◽  
Radius Of Curvature ◽  
Orthogonal Polarization ◽  
Pulsar Emission ◽  
Pulsar Radio ◽  
High Frequencies ◽  
The Mean ◽  
Radio Frequencies ◽  
Field Lines

A mechanism for generation of two concentric pulsar beams corresponding to the core and conal pulsar emission is proposed. The inner beam originates close to the star, where the radius of curvature of the dipolar magnetic field lines is suitable for coherent curvature emission at pulsar radio frequencies. Further from the star where the outer beam originates, the radius of curvature of dipolar lines is probably too large, but the actual curvature can be dominated by the toroidal component of field lines twisted back due to the pulsar rotation. One can show that for even moderate twisting the actual radius of curvature leads again to pulsar radio frequencies. Thus, the pulsar emission is a superposition of two beams originating at widely radially separated locations. When the observer's line-of-sight cuts both beams, a three-component profile should be observed. Because of the retardational time delay, the inner (core) component should appear late with respect to the profile midpoint, that is, closer to the traling component. Such an asymmetry is indeed observed in complex profile pulsars. In pulsar magnetosphere, the radius of curvature of dipolar field lines depends on the radius of the emission region in the opposite way than that of the toroidal lines. This explains why core and conal components dominate the mean profile at low and high frequencies, respectively.

scholarly journals Profile Changes in the Binary Pulsar PSR 1913+16

1992 ◽  
Vol 128 ◽  
pp. 214-216
Author(s):  
J. M. Weisberg ◽  
J. H. Taylor
Keyword(s):  
General Relativity ◽  
Flux Density ◽  
Spin Axis ◽  
Line Of Sight ◽  
Emission Region ◽  
Pulse Profile ◽  
Pulsar Emission ◽  
Binary Pulsar ◽  
The Past ◽  
Profile Changes

AbstractAccording to general relativity, the spin axis of binary pulsar PSR 1913+16 should precess at a rate of 1.21 degrees per year. This precession will cause the pulse profile to change as our line of sight samples different pulsar latitudes. In order to search for this phenomenon, we have carefully monitored the pulse profile at 1408 MHz for 8.5 years. The ratio of flux density of the first to second pulse component has declined at a rate of approximately 1.65% per year, with some evidence of a steeper decrease over the past three years. We have detected no evidence for a change in the separation of the two components. We discuss the nature of the pulsar emission region in light of these results.

scholarly journals Evolution of Multipolar Magnetic Fields in Isolated Neutron Stars and its effect on Pulsar Radio Emission

2000 ◽  
Vol 177 ◽  
pp. 265-266
Author(s):  
D. Mitra ◽  
S. Konar ◽  
D. Bhattacharya ◽  
A. V. Hoensbroech ◽  
J. H. Seiradakis ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Neutron Stars ◽  
Pulse Shape ◽  
Position Angle ◽  
Emission Region ◽  
Pulsar Radio ◽  
Significant Frequency ◽  
The Magnetic Field ◽  
Pulsar Radio Emission

AbstractThe evolution of the multipolar structure of the magnetic field of isolated neutron stars is studied assuming the currents to be confined to the crust. Lower orders (≤ 25) of multipole are seen to evolve in a manner similar to the dipole suggesting little or no evolution of the expected pulse shape. We also study the multifrequency polarization position angle traverse of PSR B0329+54 and find a significant frequency dependence above 2.7 GHz. We interpret this as an evidence of strong multipolar magnetic field present in the radio emission region.

Orthogonal Polarization in Pulsar Radio Emission

1975 ◽  
Vol 2 (6) ◽  
pp. 334-336 ◽  
Author(s):  
R.N. Manchester
Keyword(s):  
Source Region ◽  
Position Angle ◽  
Orthogonal Polarization ◽  
Magnetic Pole ◽  
Pulse Profile ◽  
Pulsar Radio ◽  
Emission Process ◽  
Integrated Or ◽  
Pulsar Radio Emission ◽  
Different Parts

For many pulsars the integrated or mean pulse profile is highly polarized. Generally linear polarization dominates over circular and there is a continuous variation of position angle through the profile (e.g. Manchester 1971). In most models for the emission process the angle of polarization is related to the (projected) direction of magnetic fields in the source region. Several of the observed properties of pulsars, for example, the mode-changing phenomenon (Backer 1970) and the different spectral index of different components of the intergrated profile (Manchester 1971), suggest that different parts of the integrated profile are emitted in different (though closely related) parts of the source. The different observed position angles across the integrated profile would then result from different projected magnetic field directions in these different parts of the source. For many pulsars the observed position angle variations are closely represented by a path through a radial set of projected field directions such as would be obtained in the vicinity of a magnetic pole (cf. Radhakrishnan and Cooke 1969).

scholarly journals Single Pulse Analysis of the Core-Dominated Pulsar B0611+22

2000 ◽  
Vol 177 ◽  
pp. 175-176
Author(s):  
Jeffrey S. Kern
Keyword(s):  
Single Pulse ◽  
Emission Region ◽  
Surprising Result ◽  
Polar Cap ◽  
Pulsar Radio ◽  
The Core ◽  
Dependent Behavior ◽  
Region I ◽  
Pulse Analysis ◽  
Pulsar Radio Emission

AbstractSingle pulse studies of pulsar radio emission provide a window into the time dependent behavior of the radio loud region. I have analyzed a series of precision polarimetric observations of pulsar B0611+22 to determine the geometry of the emission region. The observations are consistent with a central core emission region, and a periodically present conal component. This identification leads to the surprising result that all emission is from the leading half of the polar cap.

scholarly journals Single Pulses and the Plasma-physical Processes of Pulsar Radio Emission

2017 ◽  
Vol 13 (S337) ◽  
pp. 73-78
Author(s):  
Joanna M. Rankin
Keyword(s):  
Radio Emission ◽  
Pulse Sequences ◽  
Single Pulse ◽  
Physical Processes ◽  
Pulsar Emission ◽  
Pulsar Radio ◽  
Cone Model ◽  
Chart Recorder ◽  
Polarization Characteristics ◽  
Pulsar Radio Emission

AbstractPulsars were discovered on the basis of their individual pulses, first by Jocelyn Bell and then by many others. This was chart-recorder science as computers were not yet in routine use. Single pulses carry direct information about the emission process as revealed in the detailed properties of their polarization characteristics. Early analyses of single pulses proved so dizzyingly complex that attention shifted to study of average profiles. This is turn led to models of pulsar emission beams—in particular the core/double-cone model—which now provides a foundation for understanding single-pulse sequences. We mention some of the 21stC single-pulse surveys and conclude with a brief discussion of our own recent analyses leading to the identification of the pulsar radio-emission mechanism of both slow and millsecond pulsars.

scholarly journals An Empirical Theory of Pulsar Emission

1992 ◽  
Vol 128 ◽  
pp. 132-139
Author(s):  
Joanna M. Rankin
Keyword(s):  
Emission Characteristics ◽  
Pencil Beam ◽  
Empirical Theory ◽  
Polar Cap ◽  
Pulsar Emission ◽  
The Core ◽  
Pulsar Radiation ◽  
Starting Point ◽  
Major Species ◽  
Field Lines

AbstractA system of pulsar profile classification is used as a starting point to study the emission characteristics of pulsars. Two types or mechanisms of pulsar radiation are identified which combine geometrically to produce five major species of profile. The core emission, which forms a pencil beam of radiation, is apparently produced close to the stellar surface throughout the entire polar cap region by low γ particles. The conal emission, which consists of a hollow conical beam, then seems to be emitted at heights of 10 to 20 stellar radii by currents of high γ particles travelling along some of the most peripheral of the “open” field lines.

scholarly journals Search for a Correlation Between Radio Giant Pulses and VHE Photons of the Crab Pulsar

10.14311/1472 ◽  
2011 ◽  
Vol 51 (6) ◽  
Author(s):  
N. Lewandowska ◽  
D. Elsäesser ◽  
K. Mannheim
Keyword(s):  
Radio Emission ◽  
Special Form ◽  
Electromagnetic Spectrum ◽  
Crab Pulsar ◽  
Pulsar Emission ◽  
Pulsar Radio ◽  
Giant Pulses ◽  
Pulse Structure ◽  
Unique Source ◽  
Pulsar Radio Emission

The Crab pulsar is a unique source of pulsar radio emission. Its regular pulse structure is visible over the entire electromagnetic spectrum from radio to GeV ranges. Among the regular pulses, radio giant pulses (GPs) are known as a special form of pulsar radio emission. Although the Crab pulsar was discovered by its GPs, their origin and emission mechanisms are currently not understood. Within the framework of this report we give a review on radio GPs and present a new idea on how to examine the characteristics of this as yet not understood kind of pulsar emission.

Sign in / Sign up

Export Citation Format

Share Document