scholarly journals Single-Pulse Intensity Fluctuations by Cross-Correlation with Longitude of the Average Profile

1992 ◽  
Vol 128 ◽  
pp. 271-277
Author(s):  
M.V. POPOV ◽  
W. Sieber
Keyword(s):  
Spectral Analysis ◽  
Radio Emission ◽  
Cross Correlation ◽  
Regular Structure ◽  
Single Pulse ◽  
Pulse Intensity ◽  
Pulse Radio ◽  
Average Profile ◽  
Intensity Fluctuations

Single-pulse radio emission from pulsars has been observed to vary both in intensity and position inside the pulse window. In some cases the variations show a rather regular structure (drifting subpulses). Such a regular structure can clearly be studied by fluctuation spectral analysis. The analysis has identified some particular peculiarities in the fluctuation spectra at different longitudes of the pulse window in many pulsars (Backer 1973, Page 1973, Popov and Smirnova 1982). In pulsars with complex integrated profiles (PSR 1919+21, PSR 1237+25) narrow features in the fluctuation spectra vary strongly with longitude, at some longitudes being quite undistinguishable.

scholarly journals Resolution of the PSR 1919+21 Magnetosphere Emitting Region

1992 ◽  
Vol 128 ◽  
pp. 287-289
Author(s):  
O. A. Kuz'min
Keyword(s):  
Radio Emission ◽  
Regular Structure ◽  
Phase Changes ◽  
Scintillation Spectrum ◽  
Radio Scintillation ◽  
Light Cylinder ◽  
Average Profile

AbstractRegular structure with 10 to 50kHz-scale was detected in the radio scintillation spectrum of PSR 1919+21. This regular structure may be a simple interferometric pattern formed by refractive multi-ray propagation between the pulsar and observer. It was found that the pulsar PSR 1919+21 radio emission scintillation spectrum phase changes significantly across the average profile. Within the refractive scattering scenario this phase-longitude dependence corresponds to a transversal shift of the magnetosphere emitting region of about 6 x 108 cm. The radio emission altitude is estimated to be near the light cylinder.

Multi-channel interference source detector

2021 ◽  
Author(s):  
V.N. Antipov ◽  
S.L. Ivanov ◽  
E.Е. Koltyshev ◽  
V.V. Mukhin ◽  
A.Yu. Frolov ◽  
...  
Keyword(s):  
Radio Emission ◽  
Radiation Pattern ◽  
Correlation Matrix ◽  
Cross Correlation ◽  
Emission Sources ◽  
Energy Correlation ◽  
Antenna Radiation Pattern ◽  
Channel Interference ◽  
Main Disadvantage ◽  
The Cross

Modern radars, along with the detection and measurement of target coordinates against the background of interference, must solve the problem of detecting radio emission sources and measuring their coordinates. Detection of interference, as well as targets, in the radar is provided in the main (total) channel based on the analysis of the rangefinder-Doppler portrait of the received signal. The main disadvantage of such a detector is that the interference coming along the side lobes of the sum antenna and falling into the dip of the antenna radiation pattern may not be detected. Therefore, the problem arises of developing and analyzing algorithms for detecting interference in a radar with several receiving channels. The article discusses the logical, energy, correlation and eigenvalues of the cross-correlation matrix of the received signals interference detectors for two receiving channels. Their characteristics are given. It is shown that two-channel interference detectors based on the analysis of the eigenvalues of the cross-correlation matrix have the highest efficiency. Energy and logical algorithms are quite a bit inferior to them. The developed algorithms make it possible to effectively detect radio emission sources even when they are in the dip of one of the antenna patterns.

scholarly journals Chaos and Strange Attractors in Pulsar Intensity Records

1992 ◽  
Vol 128 ◽  
pp. 326-328 ◽  
Author(s):  
Roger W. Romani ◽  
J. M. Rankin ◽  
D. C. Backer
Keyword(s):  
Strange Attractors ◽  
Dynamical Model ◽  
High Quality ◽  
Pulse Intensity ◽  
Flux Variability ◽  
Low Dimensionality ◽  
Intensity Fluctuations ◽  
Simple Dynamical Model ◽  
Significant Structure

AbstractWe have examined high quality Arecibo data of three pulsars for evidence of strange attractors in pulse-to-pulse intensity fluctuations. Significant structure was found for PSR 0823+26, and seems related to pulse drifting and nulling activity. The low dimensionality of the possible attractor suggest that a simple dynamical model can explain this component of the flux variability.

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 The Thousand-Pulsar-Array programme on MeerKAT – I. Science objectives and first results

2020 ◽  
Vol 493 (3) ◽  
pp. 3608-3615 ◽  
Author(s):  
Simon Johnston ◽  
A Karastergiou ◽  
M J Keith ◽  
X Song ◽  
P Weltevrede ◽  
...  
Keyword(s):  
Radio Emission ◽  
Single Pulse ◽  
Wide Band ◽  
Radio Pulsars ◽  
Pulse Trains ◽  
First Results ◽  
Dispersion Measures ◽  
Large Survey ◽  
First Time

ABSTRACT We report here on initial results from the Thousand-Pulsar-Array (TPA) programme, part of the Large Survey Project ‘MeerTime’ on the MeerKAT telescope. The interferometer is used in the tied-array mode in the band from 856 to 1712 MHz, and the wide band coupled with the large collecting area and low receiver temperature make it an excellent telescope for the study of radio pulsars. The TPA is a 5 year project, which aims at to observing (a) more than 1000 pulsars to obtain high-fidelity pulse profiles, (b) some 500 of these pulsars over multiple epochs, and (c) long sequences of single-pulse trains from several hundred pulsars. The scientific outcomes from the programme will include the determination of pulsar geometries, the location of the radio emission within the pulsar magnetosphere, the connection between the magnetosphere and the crust and core of the star, tighter constraints on the nature of the radio emission itself, as well as interstellar medium studies. First, results presented here include updated dispersion measures, 26 pulsars with Faraday rotation measures derived for the first time, and a description of interesting emission phenomena observed thus far.

scholarly journals Organised polarisation variability in radio pulsars and consequences for emission theory

2017 ◽  
Vol 13 (S337) ◽  
pp. 79-82
Author(s):  
Cristina-Diana Ilie ◽  
Patrick Weltevrede
Keyword(s):  
Radio Emission ◽  
Single Pulse ◽  
Position Angle ◽  
Emission Mechanism ◽  
Radio Pulsars ◽  
High Quality ◽  
Special Cases ◽  
High Quality Sample ◽  
Linear Polarisation ◽  
Periodic Switching

AbstractThe aim of this work is to explore the connection between variability in single pulse intensity and periodic switching of the position angle (PA) of the linear polarisation and how this relates to the radio emission mechanism. There are five pulsars reported in the literature for which the PA is seen to periodically change in tandem with the variability in their pulse shapes. This behaviour is seemingly incompatible with two well established models of the radio emission mechanism. The purpose of this study is to investigate in a systematic way whether this phenomenon is common or if only happens in special cases, using a high-quality sample of pulsar data observed with the Parkes telescope. We show that the connection between polarisation variability and intensity variability is more common than previously expected.

scholarly journals Single Pulses from the Galactic Center Magnetar with the Very Large Array

2017 ◽  
Vol 13 (S337) ◽  
pp. 263-266
Author(s):  
S. Chatterjee ◽  
R. S. Wharton ◽  
J. M. Cordes ◽  
G. C. Bower ◽  
B. J. Butler ◽  
...  
Keyword(s):  
Galactic Center ◽  
Single Pulse ◽  
Line Of Sight ◽  
Time Variability ◽  
Dispersion Measure ◽  
Pulse Profile ◽  
Very Large Array ◽  
Pulse Behavior ◽  
Average Profile ◽  
Scattering Time

AbstractPhased VLA observations of the Galactic center magnetar J1745-2900 over 8-12 GHz reveal rich single pulse behavior. The average profile is comprised of several distinct components and is fairly stable over day timescales and GHz frequencies. The average profile is dominated by the jitter of relatively narrow pulses. The pulses in each of the four profile components are uncorrelated in phase and amplitude, although the occurrence of pulse components 1 and 2 appear to be correlated. Using a collection of the brightest individual pulses, we verify that the index of the dispersion law is consistent with the expected cold plasma value of 2. The scattering time is weakly constrained, but consistent with previous measurements, while the dispersion measure DM = 1763+3−10 pc cm−3 is lower than previous measurements, which could be a result of time variability in the line-of-sight column density or changing pulse profile shape over time or frequency.

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