Thomson Scattering in a Strong Magnetic Field

Canuto, V.; Lodenquai, J.; Ruderman, M.

doi:10.1103/physrevd.3.2303

Cited by 143 publications

(113 citation statements)

References 9 publications

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“…Furthermore, the cross section values reported in Table 2 confirm that k T T ? , as expected (see x 6.2 and Canuto et al 1971). Compared to the behavior obtained in our model, we expect that utilization of the exact cross sections given by equations (2) and (4) would tend to increase the efficiency of thermal Comptonization relative to the bulk process for photons with energy close to the cyclotron energy c .…”

Section: Discussionsupporting

confidence: 87%

“…Note the substantial decrease in the opacity of the gas along the magnetic field indicated by equation (6), which is consistent with results presented by Canuto et al (1971). In our calculations, the perpendicular scattering cross section ?…”

Section: Magnetic Effectssupporting

confidence: 91%

“…In general, we expect that k T T ? (e.g., Canuto et al 1971), and this result is verified when specific numerical models are developed. We also confirm that the values obtained for k are reasonably consistent with the dependence on the mean photon energy expressed by equation (6).…”

Section: Scattering Cross Sectionsmentioning

confidence: 54%

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Thermal and Bulk Comptonization in Accretion‐powered X‐Ray Pulsars

Becker

Wolff

2007

ApJ

283

361

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We develop a new theoretical model for the spectral formation process in accretion-powered X-ray pulsars based on a detailed treatment of the bulk and thermal Comptonization occurring in the accreting, shocked gas. A rigorous eigenfunction expansion method is employed to obtain the analytical solution for the Green's function describing the scattering of radiation injected into the column from a monochromatic source located at an arbitrary height above the stellar surface. The emergent spectrum is calculated by convolving the Green's function with source terms corresponding to bremsstrahlung, cyclotron, and blackbody emission. The energization of the photons in the shock, combined with cyclotron absorption, naturally produces an X-ray spectrum with a relatively flat continuum shape and a high-energy quasi-exponential cutoff. We demonstrate that the new theory successfully reproduces the phaseaveraged spectra of the bright pulsars Her X-1, LMC X-4, and Cen X-3. In these luminous sources, it is shown that the emergent spectra are dominated by Comptonized bremsstrahlung emission.

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Section: Discussionsupporting

confidence: 87%

Section: Magnetic Effectssupporting

confidence: 91%

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Thermal and Bulk Comptonization in Accretion‐powered X‐Ray Pulsars

Becker

Wolff

2007

ApJ

283

361

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“…Photons are either in ordinary or extra-ordinary polarization mode. The modes differ in the orientation of a photon's electric field vector with respect to the plane defined by the direction of motion and the external magnetic field (Canuto et al 1971;Mészáros & Ventura 1978;Becker & Wolff 2007).…”

Section: Motivationmentioning

confidence: 99%

Cyclotron resonant scattering feature simulations

Schwarm

Schoenherr

Falkner

et al. 2016

A&A

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Context. Electron cyclotron resonant scattering features (CRSFs) are observed as absorption-like lines in the spectra of X-ray pulsars. A significant fraction of the computing time for Monte Carlo simulations of these quantum mechanical features is spent on the calculation of the mean free path for each individual photon before scattering, since it involves a complex numerical integration over the scattering cross section and the (thermal) velocity distribution of the scattering electrons. Aims. We aim to numerically calculate interpolation tables which can be used in CRSF simulations to sample the mean free path of the scattering photon and the momentum of the scattering electron. The tables also contain all the information required for sampling the scattering electron's final spin. Methods. The tables were calculated using an adaptive Simpson integration scheme. The energy and angle grids were refined until a prescribed accuracy is reached. The tables are used by our simulation code to produce artificial CRSF spectra. The electron momenta sampled during these simulations were analyzed and justified using theoretically determined boundaries.Results. We present a complete set of tables suited for mean free path calculations of Monte Carlo simulations of the cyclotron scattering process for conditions expected in typical X-ray pulsar accretion columns (0.01 ≤ B/B crit ≤ 0.12, where B crit = 4.413 × 10 13 G, and 3 keV ≤ k B T ≤ 15 keV). The sampling of the tables is chosen such that the results have an estimated relative error of at most 1/15 for all points in the grid. The tables are available online (see link in footnote, page 1).

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“…When this condition is satisfied, the Thomson cross section is greatly enhanced, by a factor >-w5/(w5 -w~/,2) (Canuto, Lodenquai & Ruderman 1971) dependent on the polarization of the photon (Melrose & Sy 1972). The maximum enhancement factor is '" w~/r2, where r is the width of the cyclotron resonance.…”

Section: Melrosementioning

confidence: 97%