X-ray pulsar models. I - Angle-dependent cyclotron line formation and comptonization

Mészáros, P.; Nagel, Werner

doi:10.1086/163594

Cited by 114 publications

(85 citation statements)

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“…Parenthetically, we note that slight variations of the line energy are also predicted for the case of homogeneous magnetic fields, as the location, depth, and shape of the CRSF are predicted to change with viewing angle, i.e., pulse phase (Mészáros & Nagel 1985;Isenberg et al 1998b;Araya & Harding 1999;Araya-Góchez & Harding 2000). The strongest of these effects are the emission wings of the fundamental CRSF caused by "photon spawning" (Araya & Harding 1999;Araya-Góchez & Harding 2000), where electrons excited into a higher Landau level by resonant scattering of a photon, decay into the ground state by emitting photons at an energy which is roughly that of the fundamental CRSF.…”

Section: Crsf Variabilitysupporting

confidence: 52%

“…For the high temperatures of the accretion column, the line width is expected to be dominated by thermal broadening. As shown, e.g., by Mészáros & Nagel (1985), the anisotropic velocity field of the electrons in the accretion column leads to fractional line widths of σ C E C ∝ kT e m e c 2 cos 2 θ…”

Section: Implications Of the Line Variabilitymentioning

confidence: 79%

“…The strong magnetic field (B ∼ 10 12 G) at the neutron stars' magnetic poles leads to the formation of cyclotron resonant scattering features (CRSFs, "cyclotron lines"). These lines result from resonant scattering of electrons in Landau levels in the ∼10 12 G magnetic field of neutron star (see Coburn et al 2002;Araya & Harding 1999;Mészáros & Nagel 1985, and references therein). The energy of the feature is nominally given by…”

Section: Introductionmentioning

confidence: 99%

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The variable cyclotron line of GX 301–2

Kreykenbohm

Wilms

Coburn

et al. 2004

Nuclear Physics B - Proceedings Supplements

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Abstract. We present pulse phase resolved spectra of the hypergiant high mass X-ray binary GX 301−2. We observed the source in 2001 October with RXTE continuously for a total on-source time of almost 200 ksec. We model the continuum with both, a heavily absorbed partial covering model and a reflection model. In either case we find that the well known cyclotron resonant scattering feature (CRSF) at ∼35 keV is -although present at all pulse phases -strongly variable over the pulse: the line position varies by 25% from 30 keV in the fall of the secondary pulse to 38 keV in the fall of the main pulse where it is deepest. The line variability implies that we are seeing regions of magnetic field strength varying between 3.4 × 10 12 G and 4.2 × 10 12 G.

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Section: Crsf Variabilitysupporting

confidence: 52%

Section: Implications Of the Line Variabilitymentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

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The variable cyclotron line of GX 301–2

Kreykenbohm

Wilms

Coburn

et al. 2004

Nuclear Physics B - Proceedings Supplements

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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%

“…CRSFs are due to resonant scattering of electrons in Landau levels in the strong magnetic field (B ∼ 10 12 G) of neutron stars (see Coburn et al 2001;Araya & Harding 1999;Mészáros & Nagel 1985, and references therein). The energy of the CRSF is given by E C = 11.6 keV × 1 1 + z × B 10 12 G…”

Section: Introductionmentioning

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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Variability in high‐mass X‐ray binaries

et al. 2019

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Strongly magnetized, accreting neutron stars show periodic and aperiodic variability over a wide range of time scales. By obtaining spectral and timing information on these different time scales, we can have a closer look into the physics of accretion close to the neutron star and the properties of the accreted material. One of the most prominent time scales is the strong pulsation, i.e., the rotation period of the neutron star itself. Over one rotation, our view of the accretion column and the X-ray producing region changes significantly. This allows us to sample different physical conditions within the column but at the same time requires that we have viewing-angle-resolved models to properly describe them. In wind-fed high-mass X-ray binaries, the main source of aperiodic variability is the clumpy stellar wind, which leads to changes in the accretion rate (i.e., luminosity) as well as absorption column. This variability allows us to study the behavior of the accretion column as a function of luminosity, as well as to investigate the structure and physical properties of the wind, which we can compare to winds in isolated stars.

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X-ray pulsar models. I - Angle-dependent cyclotron line formation and comptonization

Cited by 114 publications

References 0 publications

The variable cyclotron line of GX 301–2

The variable cyclotron line of GX 301–2

Confirmation of two cyclotron lines in Vela X-1

Variability in high‐mass X‐ray binaries

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