scholarly journals Coherent radio emission from pulsars

1992 ◽  
Vol 341 (1660) ◽  
pp. 105-115 ◽  
Keyword(s):  
Radio Emission ◽  
Linear Acceleration ◽  
Wave Mode ◽  
High Brightness ◽  
Pulsar Radio ◽  
Pulsar Radiation ◽  
Indirect Emission ◽  
Kinetic Instability ◽  
Beam Instabilities ◽  
Pulsar Radio Emission

The high brightness temperature of pulsar radiation requires that the emission process be coherent. There are three possibilities in principle: emission by bunches; reactive instability, due to an intrinsically growing wave mode; and kinetic instability, which is maser action. The emission may be direct or indirect, depending on whether the radiation can escape to infinity through the pulsar magnetosphere, or must first be converted into another wave mode. Early models favoured either direct curvature emission by bunches or indirect emission due to a reactive beam instability, but before about 1980 it was realized that there are serious problems with both mechanisms. There are strong physical arguments against emission by bunches being viable, and the first detailed analysis suggested that the seemingly plausible alternative of maser curvature emission is impossible. Also the growth rates for beam instabilities were found too small to allow waves to grow effectively. Alternative emission mechanisms, including cyclotron and linear acceleration emissions, and variants on the existing mechanisms have been considered. In this paper the suggested emission mechanisms are reviewed from a plasma-physical viewpoint, and they are then compared to see how they might fit into a phenomenological model for pulsar radio emission.

scholarly journals Maser Theory of Pulsar Radiation

1971 ◽  
Vol 46 ◽  
pp. 414-428
Author(s):  
Hong-Yee Chiu
Keyword(s):  
Radio Emission ◽  
Plasma Emission ◽  
Emission Mechanism ◽  
Radio Flux ◽  
High Brightness ◽  
Pulsar Radio ◽  
Pulsar Radiation ◽  
Amplification Process ◽  
Coherent Plasma ◽  
Pulsar Radio Emission

In this paper we present an account of a theory of pulsar radio emission. The emission mechanism is via a maser amplification process. This theory avoids the difficulty of coherent plasma emission, that the bandwidth of radiation must be less than 1/2 λ. The high brightness radio temperature and the insensitivity of pulsar radio flux to pulsar periods can be easily accounted for.

scholarly journals Pulsar radio emission mechanisms: a critique

2020 ◽  
Vol 500 (4) ◽  
pp. 4530-4548
Author(s):  
D B Melrose ◽  
M Z Rafat ◽  
A Mastrano
Keyword(s):  
Radio Emission ◽  
Gaussian Distribution ◽  
Rest Frame ◽  
Particle Distribution ◽  
Lorentz Factor ◽  
Relativistic Case ◽  
Pulsar Radio ◽  
Kinetic Instability ◽  
Wave Properties ◽  
Pulsar Radio Emission

ABSTRACT We consider critically the three most widely favoured pulsar radio emission mechanisms: coherent curvature emission (CCE), beam-driven relativistic plasma emission (RPE), and anomalous Doppler emission (ADE). We assume that the pulsar plasma is 1D, streaming outwards with a bulk Lorentz factor γs ≫ 〈γ〉 − 1 ≳ 1, where 〈γ〉 is the intrinsic spread in the rest frame of the plasma. We argue that the formation of beams in a multicloud model is ineffective in the intrinsically relativistic case for plausible parameters because the overtaking takes too long. We argue that the default choice for the particle distribution in the rest frame is a Jüttner distribution and that relativistic streaming should be included by applying a Lorentz transformation to the rest-frame distribution, rather than the widely assumed relativistically streaming Gaussian distribution. We find that beam-driven wave growth is severely restricted by (a) the wave properties in pulsar plasma, (b) a separation condition between beam and background, and (c) the inhomogeneity of the plasma in the pulsar frame. The growth rate for the kinetic instability is much smaller and the bandwidth of the growing waves is much larger for a Jüttner distribution than for a relativistically streaming Gaussian distribution. No reactive instability occurs at all for a Jüttner distribution. We conclude that none of CCE, RPE, and ADE is tenable as the generic pulsar radio emission mechanism for ‘plausible’ assumptions about the pulsar plasma.

scholarly journals Characteristics of Pulsar Radio Emission at Single-pulse Resolution

2000 ◽  
Vol 177 ◽  
pp. 149-154
Author(s):  
Avinash A. Deshpande
Keyword(s):  
Radio Emission ◽  
Weighted Average ◽  
Single Pulse ◽  
Position Angle ◽  
Complex Nature ◽  
Stable States ◽  
Pulsar Radio ◽  
Emission Profile ◽  
Secondary State ◽  
Pulsar Radio Emission

Pulsar radio emission shows remarkably rich, but complex behavior in both intensity and polarization when considered on a pulse-to-pulse basis. A large number of pulses, when averaged together, tend to approach & define stable shapes that can be considered as distinct signatures of different pulsars. Such average profiles have shapes ranging from that describable as a simple one-component profile to those suggesting as many as 9 components. The components are understood as resulting from an average of many, often narrower, intities — the subpulses —that appear within the longitude range of a given component. The pulse components are thusformedand represent statistically an intensity-weighted average pattern of the radiation received as a function of longitude. The profile mode changes recognized in many pulsars suggest that the emission profile of a given pulsar may have two quasi-stable states, with one (primary) state more probable/brighter than the other (secondary) state. There are also (often associated) polarization modes that represent polarization states that are orthogonal to each other. The complex nature of orthogonaljumpsobserved in polarization position-angle sweeps may be attributable to possible superposition of two profile/polarization modes with orthogonal polarizations.

scholarly journals Parameters of microstructure and noiselike intensity fluctuation in pulsar radio emission measured with submicrosecond time resolution provided by the S2 VLBI recording/playback system

2000 ◽  
Vol 177 ◽  
pp. 179-180 ◽  
Author(s):  
M.V. Popov ◽  
V.I. Kondrat’ev ◽  
V.I. Altunin ◽  
N. Bartel ◽  
W. Cannon ◽  
...  
Keyword(s):  
Radio Emission ◽  
Data Acquisition ◽  
Radio Telescope ◽  
Time Resolution ◽  
Intensity Fluctuation ◽  
Data Acquisition System ◽  
Acquisition System ◽  
Pulsar Radio ◽  
Removal Technique ◽  
Pulsar Radio Emission

AbstractThree bright pulsars (B0950+08, B1133+16, and B1929+10) were observed with the 70-m radio telescope in Tidbinbilla at a frequency of 1650 MHz using the S2 Data Acquisition System which provided continuous recording of pulsar signals in two conjugate bands of B=16 MHz each. Parameters of microstructure have been analyzed using the predetection dispersion removal technique.

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.

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