Bremsstrahlung Emissivity of a Proton-Electron Plasma in a Strong Magnetic Field

Riffert, H.; Klingler, Markus; Ruder, H.

doi:10.1103/physrevlett.82.3432

Cited by 14 publications

(16 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Coburn et al 2002). The centroid energy of the fundamental cyclotron line is at ∼11 keV, and up to six harmonics have been observed and reported in the literature (Wheaton et al 1979;White et al 1983;Heindl et al 1999;Santangelo et al 1999;F09). This is a peculiar characteristic of 4U 0115+63 as in all other sources displaying cyclotron lines only the second harmonic is usually detected (the only exception being V 0332+53, which also showed evidence of the third cyclotron line harmonic; Coburn et al 2002;Orlandini 2004;Tsygankov et al 2006;Caballero et al 2007).…”

Section: U 0115+63mentioning

confidence: 94%

“…The electron distribution function f (v) can be determined from the solution of the integro-differential Boltzmann equation with a particle diffusion term and a Coulomb scattering kernel (Riffert et al 1999). The proton-electron Coulomb interaction without photon emission tends to bring the electrons to a thermodynamical equilibrium situation, for which f (v) is a Maxwellian at the proton temperature T .…”

Section: Updated Compmag Modelmentioning

confidence: 99%

“…Through the definition of a proper Green function, these authors managed to approximate the complex magnetic bremsstrahlung emission of the electrons in the accretion flow (Riffert et al 1999, hereafter R99) as a combination of a line emission at the cyclotron energy and an ordinary bremsstrahlung emission at lower energies. The angular-dependent cross section of the magnetic Compton scattering was then computed by using weighted averages.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A new model for the X-ray continuum of the magnetized accreting pulsars

Farinelli

Ferrigno

Bozzo

et al. 2016

A&A

View full text Add to dashboard Cite

Context. Accreting highly magnetized pulsars in binary systems are among the brightest X-ray emitters in our Galaxy. Although a number of high-quality broad-band (0.1-100 keV) X-ray observations are available, the spectral energy distribution of these sources is usually investigated by adopting pure phenomenological models rather than models linked to the physics of accretion. Aims. In this paper, a detailed spectral study of the X-ray emission recorded from the high-mass X-ray binary pulsars Cen X-3, 4U 0115+63, and Her X-1 is carried out by using BeppoSAX and joined Suzaku +NuStar data, together with an advanced version of the compmag model, which provides a physical description of the high-energy emission from accreting pulsars, including the thermal and bulk Comptonization of cyclotron and bremsstrahlung seed photons along the neutron star accretion column.Methods. The compmag model is based on an iterative method for solving second-order partial differential equations, whose convergence algorithm has been improved and consolidated during the preparation of this paper. Results. Our analysis shows that the broad-band X-ray continuum of all considered sources can be self-consistently described by the compmag model. The cyclotron absorption features (not included in the model) can be accounted for by using Gaussian components. From the fits of the compmag model to the data we inferred the physical properties of the accretion columns in all sources, finding values reasonably close to those theoretically expected according to our current understanding of accretion in highly magnetized neutron stars.Conclusions. The updated version of the compmag model has been tailored to the physical processes that are known to occur in the columns of highly magnetized accreting neutron stars and it can thus provide a better understanding of the high-energy radiation from these sources. The availability of broad-band high-quality X-ray data, such as those provided by BeppoSAX in the past and currently from NuStar and other facilities, is crucial to fully exploit the potentialities of the model. The advent of the Astro-H mission, endowed with an unprecedented combination of high sensitivity and X-ray broad-band coverage, provides good perspectives to improve our understanding of accretion onto highly magnetized neutron stars through physical models like the one adopted here.

show abstract

Section: U 0115+63mentioning

confidence: 94%

Section: Updated Compmag Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A new model for the X-ray continuum of the magnetized accreting pulsars

Farinelli

Ferrigno

Bozzo

et al. 2016

A&A

View full text Add to dashboard Cite

show abstract

“…In our approach we treat the cyclotron and bremsstrahlung sources as separate emission mechanisms, although they can also be viewed as components of a single, generalized magnetobremsstrahlung process, as discussed by Riffert et al (1999).…”

Section: Photon Sources and Associated Spectramentioning

confidence: 99%

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

Becker

Wolff

2007

ApJ

284

361

View full text Add to dashboard Cite

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.

show abstract

“…The combination of these terms provides a good approximation of the free-free process in very strong magnetic fields (Riffert et al 1999). It should be emphasized that when the cyclotron energy is comparable to the plasma temperature, the cyclotron emission becomes the preferred cooling channel (Arons et al 1987).…”

Section: Summary Of the Column Emission Modelmentioning

confidence: 99%

Study of the accreting pulsar 4U 0115+63 using a bulk and thermal Comptonization model

Ferrigno

Becker

Segreto

et al. 2009

A&A

127

148

View full text Add to dashboard Cite

Context. Highly magnetized pulsars accreting matter in a binary system are bright sources in the X-ray band (0.1-100 keV). Despite the early comprehension of the basic emission mechanism, their spectral energy distribution is generally described by phenomenological or simplified models. Aims. We propose a study of the spectral emission from the high mass X-ray binary pulsar 4U 0115+63 by means of thermal and bulk Comptonization models based on the physical properties of such objects. Methods.For this purpose, we analyze the BeppoSAX data in the energy range 0.7-100 keV of the 1999 giant outburst, 12 days after the maximum. We focus first on the phase averaged emission, and then on the phase resolved spectra, by modeling the system using a two-component continuum. Results. At higher energy, above ∼7 keV, the emission is due to thermal and bulk Comptonization of the seed photons produced by cyclotron cooling of the accretion column, and at lower energy, the emission is due to thermal Comptonization of a blackbody source in a diffuse halo close to the stellar surface. Phase resolved analysis establishes that most of the emission in the main peak comes from the column, while the low energy component gives a nearly constant contribution throughout the phase. Conclusions. From the best fit parameters, we argue that the cyclotron emission is produced ∼1.7 km above the stellar surface, and escapes from the column near its base, where the absorption features are generated by the interaction with the magnetic field in the halo. We find that in 4U 0115+63, the observed spectrum is dominated by reprocessed cyclotron radiation, whereas in other bright sources with stronger magnetic fields such as Her X-1, the spectrum is dominated by reprocessed bremsstrahlung.

show abstract

Bremsstrahlung Emissivity of a Proton-Electron Plasma in a Strong Magnetic Field

Cited by 14 publications

References 10 publications

A new model for the X-ray continuum of the magnetized accreting pulsars

A new model for the X-ray continuum of the magnetized accreting pulsars

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

Study of the accreting pulsar 4U 0115+63 using a bulk and thermal Comptonization model

Contact Info

Product

Resources

About