scholarly journals On the radio frequency dependence of the pulse delay phenomenon in PSR B0943+10

2021 ◽  
Author(s):  
S A Suleymanova ◽  
A N Kazantsev ◽  
J M Rankin ◽  
S V Logvinenko
Keyword(s):  
Amplitude Ratio ◽  
Wide Frequency Range ◽  
Special Method ◽  
Pulse Profile ◽  
Pulse Delay ◽  
Pulse Phase ◽  
Exponential Change ◽  
Arecibo Observatory ◽  
Delay Phenomenon ◽  
Vacuum Gap

Abstract We report the result of measurements of a gradual shift of the integrated pulses towards later spin phase of the anomalous pulsar B0943+10 at the high radio frequencies. We have used observations from the Arecibo Observatory and the GMRT at 327 and 325 MHz correspondingly. For the measurements we have proposed a special method for calculating the correct positions of the partially merged two components of the pulse profile shape with significant temporal changes in their amplitude ratio. The exponential change in the pulse phase with an amplitude of 4 ms and characteristic time of about 1 hour has been found. Comparison of our measurements at 325 and 327 MHz with those at the lower frequencies of 25–80, 62 and 112 MHz have shown that the character of the process does not depend on frequency across a wide frequency range. The result is very important for constraining the nature of the delay. It supports the assumption that the process results from changes in the vacuum gap near the surface of the pulsar. The further correlation between changes in the pulse phase and its intensity is discussed.

scholarly journals Pulsar Discovery by Global Volunteer Computing: Fig. 1

Science ◽  
2010 ◽  
Vol 329 (5997) ◽  
pp. 1305-1305 ◽  
Author(s):  
B. Knispel ◽  
B. Allen ◽  
J. M. Cordes ◽  
J. S. Deneva ◽  
D. Anderson ◽  
...  
Keyword(s):  
Survey Data ◽  
Large Data ◽  
Large Data Sets ◽  
Volunteer Computing ◽  
Data Sets ◽  
Pulse Profile ◽  
Computing Power ◽  
Spin Period ◽  
Arecibo Observatory ◽  
Computer Power

Einstein@Home aggregates the computer power of hundreds of thousands of volunteers from 192 countries to mine large data sets. It has now found a 40.8-hertz isolated pulsar in radio survey data from the Arecibo Observatory taken in February 2007. Additional timing observations indicate that this pulsar is likely a disrupted recycled pulsar. PSR J2007+2722’s pulse profile is remarkably wide with emission over almost the entire spin period; the pulsar likely has closely aligned magnetic and spin axes. The massive computing power provided by volunteers should enable many more such discoveries.

scholarly journals Microstructure Crosscorrelation in Pulses Simultaneously Observed at Frequencies Separated by up to 1 GHz

1981 ◽  
Vol 95 ◽  
pp. 191-196
Author(s):  
Valentin Boriakoff ◽  
Dale C. Ferguson
Keyword(s):  
Component Separation ◽  
Pulse Profile ◽  
Double Peak ◽  
Arecibo Observatory

Microstructure crosscorrelation of pulses observed simultaneously at various separations in frequency in the range of 196 to 1420 MHz was done for PSR 0950+08 and PSR 1133+16 at the Arecibo Observatory. Microstructure and subpulse components were identified in the crosscorrelations, and their behaviour vs. pulse longitude was studied. Drastic differences in the subpulse and micropulse behaviour are noted, related in particular to component separation in the double peak average pulse profile of PSR 1133+16. Here the subpulses follow the average pulse profile component separation but the microstructure does not. Interpretation and constraints in terms of some current theories are also presented.

scholarly journals The Polarization of the Crab Pulsar with HST

1996 ◽  
Vol 160 ◽  
pp. 301-302
Author(s):  
Joseph F. Dolan ◽  
Patricia T. Boyd ◽  
Robert J. Hill ◽  
F. Graham-Smith ◽  
A. G. Lyne ◽  
...  
Keyword(s):  
Time Resolution ◽  
Linear Polarization ◽  
High Speed ◽  
Hubble Space Telescope ◽  
Position Angle ◽  
Crab Pulsar ◽  
Pulse Profile ◽  
Space Telescope ◽  
Pulse Phase ◽  
Sample Time

The linear polarization of the Crab pulsar as a function of pulse phase was observed by the High Speed Photometer on the Hubble Space Telescope in March, 1993. Observations were obtained in a bandpass centered on 2770 A using a 0.25 ms sample time, corresponding to a time resolution of 0.0075 in pulse phase. The UV polarization of the pulsar [Fig. 1] is strikingly similar to that observed in the visible (cf. Smith et al. 1988). The same values of polarization and the same swing of position angle occur through the main and secondary pulses. The polarization pulse profile must be essentially wavelength independent at frequencies above the infrared.

NUSTAR and Swift observations of AMXP Swift J1756.9−2508 during its 2018 outburst

2019 ◽  
Vol 489 (4) ◽  
pp. 5858-5865
Author(s):  
Binay Rai ◽  
Bikash Chandra Paul
Keyword(s):  
Spectral Analysis ◽  
Power Law ◽  
Power Law Model ◽  
Pulse Profile ◽  
Spectral Parameters ◽  
Time Resolved ◽  
Pulse Phase ◽  
Photon Index ◽  
Hard State ◽  
Orbital Phase

ABSTRACT We present here the timing and spectral analysis of the accreting millisecond pulsar (AMXP) SwiftJ1756.9−2508 during its recent outburst in 2018 using Swift and NUSTAR observations. The simultaneous fitting of the Swift and NUSTAR spectra indicates that the source was in the hard state with a cut-off energy of about 74.58 keV. We also study in detail the pulse profile of the AMXP and its dependence on energy. The colour–colour diagram of the source is different from those previously reported. We performed phase- and time-resolved spectral analysis using NUSTAR data. Pulse phase-resolved spectra were fitted with a power-law model and significant changes in the spectral parameters with pulse phase were observed. The orbital phase and time-resolved spectra were fitted with a cut-off power-law model. The column density and photon index obtained from orbital phase spectral analysis were found to show some anticorrelation with the flux. Through time-resolved spectral analysis, we observed that the spectral parameters show positive correlation with each other and with the flux. We do not observe a softening of the spectrum with time. No emission lines or Compton bump were observed in the spectrum of the AMXP.

scholarly journals Joint observation of coherent coda waves at surface and underground arrays

2013 ◽  
Vol 194 (1) ◽  
pp. 367-371
Author(s):  
Mario La Rocca ◽  
Edoardo Del Pezzo ◽  
Danilo Galluzzo ◽  
Roberto Scarpa
Keyword(s):  
Amplitude Ratio ◽  
Wide Frequency Range ◽  
Body Waves ◽  
Coda Wave ◽  
Coherent Signals ◽  
Small Aperture ◽  
Data Set ◽  
Frequency Bands ◽  
Regional Seismicity ◽  
Aperture Arrays

Abstract Local and regional seismicity jointly recorded by two dense small aperture arrays, one installed at surface and one at 1.3 km depth, constitutes an interesting data set useful for coda observations. Applying array techniques to earthquakes recorded at the two arrays we measure slowness, backazimuth and correlation coefficient of the coherent coda wave signals in five frequency bands in the range 1–10 Hz. Slowness distributions show marked differences between surface and underground, with slow signals at surface (slowness greater than 1.0 s km−1) that are not observed underground. We interpret these coherent signals as surface waves produced by the interaction of body waves with the free surface characterized by rough topography. The backazimuth values measured in the frequency bands centred at 1.5 and 3 Hz are almost uniformly distributed between 0 and 360°, while those measured at higher frequencies show different distributions between surface and underground. On the contrary, the earthquake envelopes show very similar coda shapes between surface and underground recordings, with an almost constant coda-amplitude ratio (between 4 and 8) in a wide frequency range.

Hit and False-Alarm Rates of Selected ABR Indices in Differentiating Cochlear Disorders From Acoustic Tumors

1996 ◽  
Vol 5 (1) ◽  
pp. 90-96 ◽  
Author(s):  
Frank E. Musiek ◽  
Cynthia A. McCormick ◽  
Raymond M. Hurley
Keyword(s):  
False Alarm ◽  
Amplitude Ratio ◽  
High Specificity ◽  
Auditory Brainstem ◽  
Latency Difference ◽  
Cochlear Pathology ◽  
Brainstem Response ◽  
Absolute Latency ◽  
Two Indices ◽  
Low Sensitivity

We performed a retrospective study of 26 patients with acoustic tumors and 26 patients with otologically diagnosed cochlear pathology to determine the sensitivity (hit rate), specificity (false-alarm rate), and efficiency of six auditory brainstem response indices. In addition, a utility value was determined for each of these six indices. The I–V interwave interval, the interaural latency difference, and the absolute latency of wave V provided the highest hit rates, the best A’ values and good utility. The V/I amplitude ratio index provided high specificity but low sensitivity scores. In regard to sensitivity and specificity, using the combination of two indices provided little overall improvement over the best one-index measures.

Arecibo Observatory: another great lost in 2020

Nature ◽  
2020 ◽  
Vol 588 (7839) ◽  
pp. 539-539
Author(s):  
Abel Méndez
Keyword(s):  
Arecibo Observatory

CONSTRUCTION PRINCIPLES OF TECHNICALLY INVARIANT QUARTZ GENERATORS BASED ON THE DOUBLE-LOOP PULSE PHASE LOCKING SYSTEMS

2019 ◽  
Vol 78 (13) ◽  
pp. 1167-1177
Author(s):  
S. K. Pidchenko ◽  
A. A. Taranchuk ◽  
A. Totsky ◽  
V. B. Sharonov
Keyword(s):  
Phase Locking ◽  
Double Loop ◽  
Pulse Phase
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