Neutron star model atmospheres - a comparison with MXB 1728-34

Foster, A.; Ross, R. R.; Fabian, A. C.

doi:10.1093/mnras/221.2.409

Cited by 28 publications

(30 citation statements)

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“…An extensive study of the burst properties of 96 bursts was done by Basinska et al (1984) with the Y -axis detectors on board SAS 3. Radius expansion bursts were reported by Basinska et al (1984), Inoue (1988), Foster, Fabian, & Ross (1986), and Day & Tawara (1990). The source has been classiÐed by Hasinger & van der Klis (1989) as an atoll source based on timing and spectral observations with the EXOSAT satellite.…”

Section: Introductionmentioning

confidence: 87%

“…For the Ðts we implement a systematic error of 1%. We Ðx the hydrogen column density, to the value of 2.5 ] 1022 atoms cm~2 N H , (Ho †man et al 1976 ;Grindlay & Hertz 1981 ;Foster et al 1986 ;Di Salvo et al 2000).…”

Section: Spectral Analysismentioning

confidence: 99%

“…The source has been classiÐed by Hasinger & van der Klis (1989) as an atoll source based on timing and spectral observations with the EXOSAT satellite. The distance to the source is about 4 kpc (van Paradijs 1978 ;Foster et al 1986 ;Di Salvo et al 2000). No optical counterpart has been identiÐed (Liller 1977).…”

Section: Introductionmentioning

confidence: 99%

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An Atlas of Burst Oscillations and Spectral Properties in 4U 1728−34

Straaten

Klis

Kuulkers

et al. 2001

ApJ

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We study correlations between the burst properties and the position in the color-color diagram of the low mass X-ray binary 4U 1728[34 using 21 bursts found in two data sets obtained with the Rossi X-Ray T iming Explorer. Using spectral Ðts we analyze the spectral evolution during the bursts and determine the burst peak Ñux, temperature, rise time, and Ñuence. Using dynamical power spectra, we study the properties of the D363 Hz burst oscillations. We Ðnd correlations between Ñuence, peak Ñux, the occurrence of radius expansion, and the presence of burst oscillations and the position of the source in the color-color diagram. The radius expansion bursts with and without burst oscillations di †er both with respect to where they occur in the color-color diagram and in how the radius expansion takes place. We compare our results with those of a similar study by Muno and coworkers for KS 1731[26. Both KS 1731[260 and 4U 1728[34 show more or less the same behavior with respect to the dependence of the presence/absence of the burst oscillations on the position of the source in the color-color diagram, but the dependence of most of the spectral burst parameters on the position in the color-color diagram is clearly di †erent. We Ðnd that the systematic absence in 4U 1728[34 of burst oscillations in the "" island ÏÏ state of the color-color diagram is not explained by the bursts involving mixed H-He burning, as Cumming & Bildsten found may be the case in KS 1731[260.

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Section: Introductionmentioning

confidence: 87%

Section: Spectral Analysismentioning

confidence: 99%

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An Atlas of Burst Oscillations and Spectral Properties in 4U 1728−34

Straaten

Klis

Kuulkers

et al. 2001

ApJ

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“…Of the two, GX 354[0 is the better studied, particularly since its discovery as a burst source (Lewin 1976 ;Ho †man et al 1976). Previous observations of GX 354[0 with Einstein, EXOSAT , Ginga, and ROSAT have shown a spectrum that can be Ðt with either a thermal bremsstrahlung of kT D 13È18 keV or a power law of photon index D 1.7È2.1 (Grindlay & Hertz 1981 ;White et al 1986 ;Day & Tawara 1990 ;Foster, Ross, & Fabian 1986 ;Schulz 1999). The column density is large but uncertain, ranging from 1.5 ] 1022 to 3.5 ] 1022 cm~2 (Basinska et al 1984 ;Schulz 1999).…”

Section: Introductionmentioning

confidence: 99%

ASCAObservations of GX 354−0 and KS 1731−260

Narita

Grindlay

Barret

2001

ApJ

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We report on ASCA observations of the low-mass X-ray binaries GX 354[0 and KS 1731[260. The spectrum of GX 354[0 is best described as a power law or a Comptonized spectrum with q D 5 and kT D 8 keV and a residual at D6.5 keV. The residual may be a disk reÑection or a Compton-broadened Gaussian line from the hot inner advection-dominated accretion ÑowÈlike coronal region. The absorption column density to the source is 2.9 ] 1022 cm~2. No soft thermal component was detected. The spectrum from KS 1731[260 is softer, and it is best Ðt with a two-component model with a column density of 1.1 ] 1022 cm~2. The likely interpretation is emission from a Comptonizing cloud with an optical depth q [ 12 and either a neutron star or a disk blackbody emission. We discuss the likely location of the Comptonizing cloud for both sources within the context of several proposed emission models.

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“…The influence of Compton scattering on the atmospheres of X-ray bursters has been discussed in several papers (see e.g. Ebisuzaki et al 1984;and Foster et al 1986). Consistent models of the atmosphere with Compton scattering have been presented by London et al (1986), Ebisuzaki (1987), and Ross & Fabian (1993).…”

Section: Introductionmentioning

confidence: 99%

Model atmospheres and X-ray spectra of bursting neutron stars

Majczyna¹,

Madej

Różáńska³

2005

A&A

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Abstract. This paper presents the set of plane-parallel model atmosphere equations for a very hot neutron star (X-ray burst source). The model equations assume both hydrostatic and radiative equilibrium, and the equation of state of an ideal gas in local thermodynamic equilibrium (LTE). The equation of radiative transfer includes terms describing Compton scattering of photons on free electrons in fully relativistic thermal motion, for photon energies approaching m e c 2 . Model equations take into account many bound-free and free-free energy-dependent opacities of hydrogen, helium, and the iron ions, and also a dozen boundbound opacities for the highest ions of iron. We solve model equations by partial linearisation and the technique of variable Eddington factors. Large grid of H-He-Fe model atmospheres of X-ray burst sources has been computed for 10 7 ≤ T eff ≤ 3 × 10 7 K, a wide range of surface gravity, and various iron abundances. We demonstrate that the spectra of X-ray bursters with iron present in the accreting matter differ significantly from pure H-He spectra (published in an earlier paper), and also from blackbody spectra. Comptonized spectra with significant iron abundance are generally closer to blackbody spectra than spectra of H-He atmospheres. The ratio of color to effective temperatures in our grid always remains in the range 1.2 < T c /T eff < 1.85. The present grid of model atmospheres and theoretical X-ray spectra will be used to determine the effective temperatures, radii and M/R ratios of bursting neutron stars from observational data.

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Neutron star model atmospheres - a comparison with MXB 1728-34

Cited by 28 publications

References 0 publications

An Atlas of Burst Oscillations and Spectral Properties in 4U 1728−34

An Atlas of Burst Oscillations and Spectral Properties in 4U 1728−34

ASCAObservations of GX 354−0 and KS 1731−260

Model atmospheres and X-ray spectra of bursting neutron stars

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