scholarly journals Simultaneous Radio and X-Ray observations of Crab Pulsar

2017 ◽  
Vol 13 (S337) ◽  
pp. 309-310
Author(s):  
A. K. Basu ◽  
B. C. Joshi ◽  
D. Bhattacharya
Keyword(s):  
Radio Telescope ◽  
Intensity Distribution ◽  
Main Pulse ◽  
Electromagnetic Spectrum ◽  
Crab Pulsar ◽  
X Ray ◽  
Preliminary Results ◽  
Pulse Intensity

AbstractCrab Pulsar (PSR B0531+21) is known to emit pulsed emission in all bands of the electromagnetic spectrum. It also emits giant radio pulses (GRPs) frequently, which are roughly a hundred to million times brighter than the normal pulses. We aim to study whether there is a significant X-ray enhancement correlated with the occurrence of GRPs, using simultaneous observations with the ASTROSAT, the Giant Meterwave Radio telescope (1300 MHz) and the Ooty Radio telescope (325 MHz). This required determination of fixed pipeline offsets between different instruments. We find the offset between ASTROSAT and GMRT to be −30.181 ± 0.095 ms and that between ASTROSAT and ORT to be −18.4 ± 0.2 ms. Our preliminary results with 1300 MHz data also show a break in pulse intensity distribution at ~ 33 Jy in the main pulse and ~ 28 Jy in the inter-pulse.

Half-bare positron in the inner gap of a pulsar

2017 ◽  
Vol 7 (1-2) ◽  
pp. 36-41 ◽  
Author(s):  
S. Trofymenko ◽  
V. M. Kontorovich
Keyword(s):  
Transition Radiation ◽  
Main Pulse ◽  
Stellar Surface ◽  
Additional Contribution ◽  
Crab Pulsar ◽  
X Ray ◽  
Bare State ◽  
Curvature Radiation ◽  
Polar Gap ◽  
The One

The pulsed radiation from the Crab Pulsar consists of the main pulse (MP) and inter pulse (IP), as well as of the extra pulse components appearing at certain frequencies. One of the mysteries of these data, found by Moffett and Hankins twenty years ago, is the shift of the IP at high radio frequencies compared to lower ones and return to its previous position in the higher-frequency optical and X-ray range. In previous paper we proposed the explanation of these mysterious changes with the frequency, applying the idea of the reflection of curvature radiation by relativistic positrons from the stellar surface. Presently we focus on the additional contribution of transition radiation, emitted when positron hits the surface, to the total pulse produced by the particle. It is shown that due to the 'half-bare' state of positron in the polar gap the considered contribution is significantly suppressed comparing to the one of reflected curvature radiation.

Preliminary results of the X-ray structure determination of praseodymium nicotinate dihydrate

1972 ◽  
Vol 12 (5) ◽  
pp. 865-865
Author(s):  
I. K. Abdul'minev ◽  
L. A. Aslanov ◽  
M. A. Porai-Koshits
Keyword(s):  
Structure Determination ◽  
X Ray ◽  
Preliminary Results

scholarly journals Mapping the Emission Location of the Crab Pulsar’s Giant Pulses

2017 ◽  
Vol 13 (S337) ◽  
pp. 83-83
Author(s):  
Robert Main ◽  
Marten H. van Kerkwijk
Keyword(s):  
Spatial Resolution ◽  
Main Pulse ◽  
Electromagnetic Spectrum ◽  
High Flux ◽  
Crab Pulsar ◽  
Order Unity ◽  
Physical Location ◽  
Cylinder Radius ◽  
Giant Pulses ◽  
Physical Scale

AbstractThe Crab pulsar has a striking radio profile, dominated by two pulse components (the main pulse and interpulse) which are comprised of giant pulses. These pulses are randomly occurring, they extend to extremely high flux densities, and are closely aligned with emission across the entire electromagnetic spectrum. The Crab, like many pulsars, exhibits scintillation – a pattern in frequency and time arising from interfering scattered images. The pattern varies with location, with the physical scale over which it changes by order unity corresponding to the spatial resolution of the scattering surface. For the Crab, the scattering is in the nebula and the estimated spatial resolution is of order the light cylinder radius. Comparing scintillation spectra of the two components, we infer a difference in physical location of the same order.

Preliminary results of the x-ray structure determination of erbium isonicotinate dihydrate

1972 ◽  
Vol 12 (5) ◽  
pp. 866-867
Author(s):  
L. A. Aslanov ◽  
I. K. Abdul'minev ◽  
R. A. Chupakhina ◽  
M. A. Porai-Koshits
Keyword(s):  
Structure Determination ◽  
X Ray ◽  
Preliminary Results

scholarly journals Numerical simulations of the hard X-ray pulse intensity distribution at the Linac Coherent Light Source

2017 ◽  
Vol 24 (4) ◽  
pp. 738-743 ◽  
Author(s):  
Tom Pardini ◽  
Andrew Aquila ◽  
Sébastien Boutet ◽  
Daniele Cocco ◽  
Stefan P. Hau-Riege
Keyword(s):  
Numerical Simulations ◽  
Light Source ◽  
Intensity Distribution ◽  
Imaging Techniques ◽  
Coherent Light ◽  
Ray Optics ◽  
X Ray ◽  
Pulse Intensity ◽  
Linac Coherent Light Source ◽  
Coherent Light Source

Numerical simulations of the current and future pulse intensity distributions at selected locations along the Far Experimental Hall, the hard X-ray section of the Linac Coherent Light Source (LCLS), are provided. Estimates are given for the pulse fluence, energy and size in and out of focus, taking into account effects due to the experimentally measured divergence of the X-ray beam, and measured figure errors of all X-ray optics in the beam path. Out-of-focus results are validated by comparison with experimental data. Previous work is expanded on, providing quantitatively correct predictions of the pulse intensity distribution. Numerical estimates in focus are particularly important given that the latter cannot be measured with direct imaging techniques due to detector damage. Finally, novel numerical estimates of improvements to the pulse intensity distribution expected as part of the on-going upgrade of the LCLS X-ray transport system are provided. We suggest how the new generation of X-ray optics to be installed would outperform the old one, satisfying the tight requirements imposed by X-ray free-electron laser facilities.

Reflection of positron radiation from star surface and shift of inter pulse position in Crab pulsar

2017 ◽  
Vol 7 (1-2) ◽  
pp. 30-35 ◽  
Author(s):  
V. Kontorovich ◽  
S. Trofymenko
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Main Pulse ◽  
Stellar Surface ◽  
Crab Pulsar ◽  
X Ray ◽  
Unique Information ◽  
Radio Frequencies ◽  
Star Surface ◽  
The Magnetic Field

The pulsed radiation from the Crab pulsar consists of the main pulse (MP) and inter pulse (IP), as well as of the extra pulse components appearing at certain frequencies. It has been studied in many frequencies and contains unique information, which is not available for the majority of the pulsars. One of the mysteries of these data, found by Moffett and Hankins twenty years ago, is the shift of the IP at high radio frequencies compared to lower ones and return to its previous position in the more high-frequency optical and X-ray range. We propose the explanation of these mysterious changes with the frequency as a reflection of radiation by relativistic positrons from the stellar surface. The magnetic field of the pulsar in the pole must be inclined to the surface of the star and affects on the discussed processes.

scholarly journals QUANTITATIVE DETERMINATION OF INTENSITY DISTRIBUTION OF PRIMARY X-RAY SPECTRUM

1981 ◽  
Vol 30 (10) ◽  
pp. 1351
Author(s):  
GUO CHANG-LIN ◽  
JI ANG ◽  
TAO GUANG-YI
Keyword(s):  
Quantitative Determination ◽  
Intensity Distribution ◽  
X Ray

scholarly journals Timing offset calibration of CZTI instrument aboard ASTROSAT

2018 ◽  
Vol 617 ◽  
pp. A22 ◽  
Author(s):  
A. Basu ◽  
B. C. Joshi ◽  
D. Bhattacharya ◽  
A. R. Rao ◽  
A. Naidu ◽  
...  
Keyword(s):  
Radio Telescope ◽  
High Energy ◽  
Dispersion Measure ◽  
Electromagnetic Spectrum ◽  
Time Data ◽  
X Ray ◽  
Timing Offset ◽  
Time Alignment ◽  
Timing Noise ◽  
High Energy Emission

Aim: Both the radio and the high-energy emission mechanism in pulsars is not yet properly understood. A multiwavelength study is likely to help better understand of such processes. ASTROSAT, the first Indian space-based observatory, has five instruments aboard that cover the electromagnetic spectrum from infra-red (1300 Å) to hard X-ray (380 keV). The instrument relevant to our study is the Cadmium Zinc Telluride Imager (CZTI). CZTI is a hard X-ray telescope functional over an energy range of 20–380 keV. We aim to estimate the timing offset introduced in the data acquisition pipeline of the instrument, which will help in time alignment of high energy time-series with those from two other ground based observatories, viz. the Giant Meterwave Radio Telescope (GMRT) and the Ooty Radio Telescope (ORT). Method: PSR B0531+21 is a well studied bright pulsar with closely aligned radio and hard X-ray pulse profiles. We used simultaneous observations of this pulsar with the ASTROSAT, the ORT, and the GMRT. As the pulsar resides in a very turbulent environment and shows significant timing noise, it was specially observed using the ORT with almost daily cadence to obtain good timing solutions. We also supplemented the ORT data with archival Fermi data for estimation of timing noise. We obtained the phase connected timing solution of the pulsar by estimating its dispersion measure variations and the timing noise. The timing offset of ASTROSAT instruments was estimated from fits to pulse arrival time data at the ASTROSAT and the radio observatories. Results: We estimate the relative offset of ASTROSAT-CZTI with respect to GMRT to be −4716 ± 50 μs. The corresponding offset with the ORT was −29639 ± 50 μs and Fermi-LAT was −5368 ± 56 μs respectively.

Determination of dispersion and polarization of thermal plane waves in crystals

1971 ◽  
Vol 134 (3-4) ◽  
Author(s):  
P. L. La Fleur
Keyword(s):  
Intensity Distribution ◽  
Phonon Scattering ◽  
Reciprocal Lattice ◽  
Plane Waves ◽  
Lattice Points ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
Reciprocal Lattice Point ◽  
X Ray

AbstractThe dispersion of the thermal plane waves (phonons) in crystals can be determined from the x-ray diffraction intensity distribution around a reciprocal lattice point. In the method presented here no higher-order phonon-scattering corrections are necessary. It is shown furthermore that polarizations and dispersion of the phonons can be determined from the intensity distributions around six properly chosen reciprocal lattice points.

Determination of Grain Size for Different Texture Components by Statistical Fluctuations of Intensity, Registered in the Course of Texture Measurement

2010 ◽  
Vol 160 ◽  
pp. 135-140 ◽  
Author(s):  
Olga Krymskaya ◽  
Margarita Isaenkova ◽  
Yuriy Perlovich
Keyword(s):  
Grain Size ◽  
Intensity Distribution ◽  
Size Determination ◽  
Texture Measurement ◽  
X Ray ◽  
Statistical Fluctuations ◽  
Pole Figures ◽  
Different Temperatures

The method for grain size determination by statistical fluctuations of X-ray intensity, registered during measurement of texture pole figures, was developed. Niobium and bronze rods as well as tubes from Zr-1%Nb alloy, subjected to annealing at different temperatures, were studied. Description of the method, pole figures (PF), X-ray intensity distribution within PF circular sections, grain size values and their errors are presented.

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