Radiative Transfer in a Strongly Magnetized Plasma - Part Two - Effects of Comptonization

Nagel, Werner

doi:10.1086/159464

Cited by 88 publications

(66 citation statements)

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“…Physical spectral models (see, e.g., Nagel, 1981;Meszaros and Nagel, 1985;Wolff, 2005, 2007) were constructed only for specific configurations of the emitting regions and are not able to explain in a self-consistent manner the variety of the observations. The interaction of the radiation with the accreted matter in strong magnetic and gravitational fields is a complex problem.…”

Section: Be Systems X-ray Pulsars and Properties Of Cyclotron Absorpmentioning

confidence: 99%

“…The plasma falls in the accretion column at almost the speed of light and heats to 10 8 K close to the neutron star surface (see, e.g. Basko and Sunyaev, 1976;Nagel, 1981;Meszaros and Nagel, 1985;Araya-Góchez and Harding, 2000;Nishimura, 2008;Mushtukov et al, 2015). Bulk and thermal Comptonization plays a key role in the formation of the non thermal X-ray emission (Becker and Wolff, 2007).…”

Section: Introductionmentioning

confidence: 99%

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High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

230

234

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High-mass X-ray binaries are fundamental in the study of stellar evolution, nucleosynthesis, structure and evolution of galaxies and accretion processes. Hard X-rays observations by INTEGRAL and Swift have broadened significantly our understanding in particular for the super-giant systems in the Milky Way, which number has increased by almost a factor of three. INTEGRAL played a crucial role in the discovery, study and understanding of heavily obscured systems and of fast X-ray transients. Most super-giant systems can now be classified in three categories: classical/obscured, eccentric and fast transient.The classical systems feature low eccentricity and variability factor of ∼ 10 3 , mostly driven by hydrodynamic phenomena occurring on scales larger than the accretion radius. Among them, systems with short orbital periods and close to Roche-Lobe overflow or with slow winds, appear highly obscured. In eccentric systems, the variability amplitude can reach even higher factors, because of the contrast of the wind density along the orbit. Four super-giant systems, featuring fast outbursts, very short orbital periods and anomalously low accretion rates, are not yet understood.Simulations of the accretion processes on relatively large scales have progressed and reproduce parts of the observations. The combined effects of wind

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Section: Be Systems X-ray Pulsars and Properties Of Cyclotron Absorpmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High-mass X-ray binaries in the Milky Way

Walter

Lutovinov

Bozzo

et al. 2015

Astron Astrophys Rev

230

234

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show abstract

“…Motivated by the Her X-1 line detection, Nagel (1980Nagel ( , 1981 and later Mészáros & Nagel (1985) employed Feautrier methods in order to solve the radiation transfer equation. They performed two sets of calculations, treating effects of anisotropy and Comptonization separately.…”

Section: Solving Difference Equationsmentioning

confidence: 99%

A model for cyclotron resonance scattering features

Schönherr

Wilms

Kretschmar

et al. 2007

A&A

146

200

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Aims. We study the physics of cyclotron line formation in the high-energy spectra of accreting X-ray pulsars. In particular, we link numerical predictions for the line profiles to results from observational data analysis. Therefore, first we investigate the theoretical predictions and the significance of our model parameters, and second we aim at the development of a model to fit cyclotron lines in observational data. Methods. Simulations were performed using Monte Carlo methods. The data were extracted with HEADAS 6.1.1 and INTEGRAL OSA 5.1. A convolution model for the cyclotron line shapes was implemented for the XSPEC spectral analysis software package and for data packages compatible with XSPEC local models. Results. We predict the shapes of cyclotron lines for different prescribed physical settings. The calculations assume that the line-forming region is a low-density electron plasma, which is of cylindrical or slab geometry and which is exposed to a uniform, sub-critical magnetic field. We investigate the dependence of the shape of the fundamental line on angle, geometry, optical depth and temperature. We also discuss variations of the line ratios for non-uniform magnetic fields. We have developed a new convolution and interpolation model to simulate line features regardless of any a priori assumed shape of the neutron star continuum. Fitting RXTE and INTEGRAL data of the accreting X-ray pulsar V0332+53 with this model gives a qualitative description of the data. Strong emission wings of the fundamental cyclotron feature as predicted by internally irradiated plasma geometries are in principle observable by todays instruments but are not formed in V0332+53, hinting at a bottom illuminated slab geometry for line formation.

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“…Although this problem has been investigated for many years, there still exists no convincing theoretical model for the continuum of accreting X-ray pulsars (Harding 1994, and references therein). Most probably, the formation of the overall spectral shape is dominated by resonant Compton scattering (Nagel 1981b;Mészáros & Nagel 1985;Brainerd & Mészáros 1991;Sturner & Dermer 1994;Alexander et al 1996). This should produce a roughly powerlaw continuum with an exponential cutoff at an energy characteristic of the scattering electrons.…”

Section: Spectral Modelsmentioning

confidence: 99%

Confirmation of two cyclotron lines in Vela X-1

Kreykenbohm

Coburn

Wilms

et al. 2002

A&A

112

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Abstract. We present pulse phase-resolved X-ray spectra of the high mass X-ray binary Vela X-1 using the Rossi X-ray Timing Explorer. We observed Vela X-1 in 1998 and 2000 with a total observation time of ∼90 ksec. We find an absorption feature at 23.3−0.6 keV in the main pulse, that we interpret as the fundamental cyclotron resonant scattering feature (CRSF). The feature is deepest in the rise of the main pulse where it has a width of 7.6 +4.4 −2.2 keV and an optical depth of 0.33 +0.06 −0.13 . This CRSF is also clearly detected in the secondary pulse, but it is far less significant or undetected during the pulse minima. We conclude that the well known CRSF at 50.9 +0.6 −0.7 keV, which is clearly visible even in phase-averaged spectra, is the first harmonic and not the fundamental. Thus we infer a magnetic field strength of B = 2.6 × 10 12 G.

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Radiative Transfer in a Strongly Magnetized Plasma - Part Two - Effects of Comptonization

Cited by 88 publications

References 0 publications

High-mass X-ray binaries in the Milky Way

High-mass X-ray binaries in the Milky Way

A model for cyclotron resonance scattering features

Confirmation of two cyclotron lines in Vela X-1

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