Comparison of multiwavelength observations of 9 broad-band pulsars with the spectrum of the emission from an extended current with a superluminally rotating distribution pattern - Astrophysics > Astrophysics of GalaxiesReport as inadecuate




Comparison of multiwavelength observations of 9 broad-band pulsars with the spectrum of the emission from an extended current with a superluminally rotating distribution pattern - Astrophysics > Astrophysics of Galaxies - Download this document for free, or read online. Document in PDF available to download.

Abstract: The observed spectra of 9 pulsars for which multiwavelength data areavailable from radio to $X$- or $\gamma$-ray bands Crab, Vela, Geminga,B0656+14, B1055-52, B1509-58, B1706-44, B1929+10, and B1951+32 are comparedwith the spectrum of the radiation generated by an extended polarizationcurrent whose distribution pattern rotates faster than light {\it in vacuo}. Itis shown that by inferring the values of two free parameters from observationaldata values that are consistent with those of plasma frequency and electroncyclotron frequency in a conventional pulsar magnetosphere, and by adjustingthe spectral indices of the power laws describing the source spectrum invarious frequency bands, one can account {\em quantitatively} for the entirespectrum of each pulsar in terms of a single emission process. This emissionprocess a generalization of the synchrotron-\-Cerenkov process to avolume-distributed source in vacuum gives rise to an oscillatory radiationspectrum. Thus, the bell-shaped peaks of pulsar spectra in the ultraviolet or$X$-ray bands the features that are normally interpreted as manifestations ofthermal radiation appear in the present model as higher-frequency maxima ofthe same oscillations that constitute the emission bands observed in the radiospectrum of the Crab pulsar. Likewise, the sudden steepening of the gradient ofthe spectrum by -1, which occurs around $10^{18}-10^{21}$ Hz, appears as auniversal feature of the pulsar emission: a feature that reflects the transitof the position of the observer across the frequency-dependent Rayleighdistance. Inferred values of the free parameters of the present model suggest,moreover, that the lower the rotation frequency of a pulsar, the more weightedtowards higher frequencies will be its observed spectral intensity.



Author: H. Ardavan, A. Ardavan, J. Singleton, J. Fasel, W. Junor, J. Middleditch, M. R. Perez, A. Schmidt, P. Sengupta, P. Volegov

Source: https://arxiv.org/







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