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تسجيل مستخدم جديدThe Phase-resolved High Energy Spectrum of the Crab Pulsar
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We present a modified outer gap model to study the phase-resolved spectra of the Crab pulsar. A theoretical double peak profile of the light curve containing the whole phase is shown to be consistent with the observed light curve of the Crab pulsar by shifting the inner boundary of the outer gap inwardly to $sim 10$ stellar radii above the neutron star surface. In this model, the radial distances of the photons corresponding to different phases can be determined in the numerical calculation. Also the local electrodynamics, such as the accelerating electric field, the curvature radius of the magnetic field line and the soft photon energy, are sensitive to the radial distances to the neutron star. Using a synchrotron self-Compton mechanism, the phase-resolved spectra with the energy range from 100 eV to 3 GeV of the Crab pulsar can also be explained.
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Context{The high energy emission regions of rotation powered pulsars are studied using folded light curve (FLCs) and phase resolved spectra (PRS).} aims{This work uses the NICER observatory to obtain the highest resolution FLC and PRS of the Crab pul
sar at soft X-ray energies.} methods{NICER has accumulated about 347 ksec of data on the Crab pulsar. The data are processed using the standard analysis pipeline. Stringent filtering is done for spectral analysis. The individual detectors are calibrated in terms of long time light curve (LTLC), raw spectrum and deadtime. The arrival times of the photons are referred to the solar systems barycenter and the rotation frequency $ u$ and its time derivative $dot u$ are used to derive the rotation phase of each photon.} results{The LTLCs, raw spectra and deadtimes of the individual detectors are statistically similar; the latter two show no evolution with epoch; detector deadtime is independent of photon energy. The deadtime for the Crab pulsar, taking into account the two types of deadtime, is only approx 7% to 8% larger than that obtained using the cleaned events. Detector 00 behaves slightly differently from the rest, but can be used for spectral work. The PRS of the two peaks of the Crab pulsar are obtained at a resolution of better than 1/512 in rotation phase. The FLC very close to the first peak rises slowly and falls faster. The spectral index of the PRS is almost constant very close to the first peak.} conclusions{The high resolution FLC and PRS of the {{peaks}} of the Crab pulsar provide important constraints for the formation of caustics in the emission zone.}
We investigate polarization of high-energy emissions from the Crab pulsar in the frame work of the outer gap accelerator, following previous works of Cheng and coworkers. The recent version of the outer gap, which extends from inside the null charge
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We investigate polarization of high-energy emissions from the Crab pulsar in the frame work of the outer gap accelerator. The recent version of the outer gap, which extends from inside the null charge surface to the light cylinder, is used for examin
ing the light curve, the spectrum and the polarization characteristics, simultaneously. The polarization position angle curve and the polarization degree are calculated to compare with the Crab optical data. We show that the outer gap model explains the general features of the observed light curve, the spectrum and the polarization by taking into account the emissions from inside of the null charge surface and from tertiary pairs, which were produced by the high-energy photons from the secondary pairs. For the Crab pulsar, the polarization position angle curve indicates that the viewing angle of the observer measured from the rotational axis is greater than 90 degrees.
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