Interstellar photoelectric absorption cross sections, 0.03-10 keV

Morrison, Richard J. S.; McCammon, D.

doi:10.1086/161102

Cited by 1,703 publications

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“…where N ph is the flux in photons s −1 cm −2 keV −1 , A the normalization in photons s −1 cm −2 keV −1 at 1 keV, E the photon energy, Γ the power-law photon index, N H the interstellar hydrogen column density, and σ the photo-electric absorption cross section from Morrison & McCammon (1983). N H was fixed to 3 × 10 21 cm −1 .…”

Section: Cross Calibration Of Different Instrumentsmentioning

confidence: 99%

Photospheric radius expansion X-ray bursts as standard candles

Kuulkers

Hartog

Zand³

et al. 2003

A&A

378

448

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Abstract. We examined the maximum bolometric peak luminosities during type I X-ray bursts from the persistent or transient luminous X-ray sources in globular clusters. We show that for about two thirds of the sources the maximum peak luminosities during photospheric radius expansion X-ray bursts extend to a critical value of 3.79±0.15×10 38 erg s −1 , assuming the total X-ray burst emission is entirely due to black-body radiation and the recorded maximum luminosity is the actual peak luminosity. This empirical critical luminosity is consistent with the Eddington luminosity limit for hydrogen poor material. Since the critical luminosity is more or less always reached during photospheric radius expansion X-ray bursts (except for one source), such bursts may be regarded as empirical standard candles. However, because significant deviations do occur, our standard candle is only accurate to within 15%. We re-evaluated the distances to the twelve globular clusters in which the X-ray bursters reside.

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Section: Cross Calibration Of Different Instrumentsmentioning

confidence: 99%

Photospheric radius expansion X-ray bursts as standard candles

Kuulkers

Hartog

Zand³

et al. 2003

A&A

378

448

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“…We tested a blackbody, a Bremsstrahlung and a second power law component. The three component models were combined with neutral galactic absorption using the cross-sections of Morrison & McCammon (1983) assuming galactic absorption with solar abundance and N H = 5.5 × 10 20 cm −2 (Turner et al 1993). The power law and the blackbody models give an unacceptable fit to the soft excess-emission, with a reduced χ 2 of respectively 1.28 and 1.40.…”

Section: Analysis Of the Soft Energy Rangementioning

confidence: 99%

XMM–Newtonobservations of the Seyfert 1 galaxy ESO 141–G55

Gondoin

Orr

Lumb

2003

A&A

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Abstract.We report on an observation of the Seyfert 1 galaxy ESO 141-G55 performed in October 2001 with the EPIC MOS cameras and Reflection Grating Spectrometers (RGS) on board the XMM-Newton observatory. We find the hard (3-10 keV) continuum slope, including reflection, to be somewhat flatter (Γ = 1.72 ± 0.06) than that of a typical broad-line Seyfert 1 galaxy. The spectrum shows a weak emission line at 6.45 ± 0.04 keV with a measured equivalent width of ≈40 eV. A broad spectral feature is observed around 7 keV that can be fitted by an absorption edge at 7.6 ± 0.1 keV. The extrapolation of the primary power law continuum to energies lower than 2 keV indicates the presence of a soft excess component contributing to 45 ± 3% of the overall flux in the 0.3−2.0 keV energy range. This soft-excess cannot be explained solely by enhanced reflection from a highly ionized disk.

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“…Again, we mention here only two examplary works used very often for analysis of X-ray spectra. Morrison & McCammon (1983) did a polynomial fit of the effective absorption crosssection per hydrogen atom based on measured atomic ab- Fig. 1 The effect of different abundances and crosssections on the absorption towards soft X-ray sources For the same neutron star (blackbody of 90 eV, 11.67 km radius, and 1.48 Solar masses) the ratio of the X-ray fluxes (as would be expected to be observed by ROSAT) resulting from the two XSP EC routines 'tbabs' and 'wabs' are calculated for different distances.…”

Section: Abundances and Cross-sectionsmentioning

confidence: 99%

“…sorption cross-sections by Henke et al (1982) and abundances mostly from Anders & Ebihara (1982). With the exception of oxygen, Morrison & McCammon (1983) assume the elements to be either entirely in the gas phase or completely depleted into dust grains. The recent improved absorption treatment by Wilms et al (2000) takes into account newer element abundances as noted above and more recent photoionization cross-section calculations by e.g.…”

Section: Abundances and Cross-sectionsmentioning

confidence: 99%

“…Besides this updated database Wilms et al (2000) considered furthermore a simple spherical composite dust grain model in an MRN distribution (Mathis et al 1977). Both models are implemented in XSP EC and can be used via the routines 'wabs' (Morrison & McCammon 1983) or 'tbabs' (Wilms et al 2000). The various absorption descriptions can lead to different results (see Fig.…”

Section: Abundances and Cross-sectionsmentioning

confidence: 99%

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The Magnificent Seven in the dusty prairie

Posselt

Попов

Haberl

et al. 2007

Isolated Neutron Stars: From the Surface to the Interior

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The Magnificent Seven have all been discovered by their exceptional soft X-ray spectra and high ratios of X-ray to optical flux. They all are considered to be nearby sources. Searching for similar objects with larger distances, one expects larger interstellar absorption resulting in harder X-ray counterparts. Current interstellar absorption treatment depends on chosen abundances and scattering cross-sections of the elements as well as on the 3D distribution of the interstellar medium. After a discussion of these factors we use the comprehensive 3D measurements of the Local Bubble by Lallement et al. (2003) to construct two simple models of the 3D distribution of the hydrogen column density. We test these models by using a set of soft X-ray sources with known distances. Finally, we discuss possible applications for distance estimations and population synthesis studies.

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Interstellar photoelectric absorption cross sections, 0.03-10 keV

Cited by 1,703 publications

References 0 publications

Photospheric radius expansion X-ray bursts as standard candles

Photospheric radius expansion X-ray bursts as standard candles

XMM–Newtonobservations of the Seyfert 1 galaxy ESO 141–G55

The Magnificent Seven in the dusty prairie

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