Laboratory Measurements and Modeling of the Fe<scp>xvii</scp>X‐Ray Spectrum

Brown, G. V.; Beiersdörfer, P.; Liedahl, D. A.; Widmann, K.; Kahn, S. M.

doi:10.1086/305941

Cited by 170 publications

(199 citation statements)

References 57 publications

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“…This is in excellent agreement with the wavelength of a line observed with the SMM/FCS at 16.337 Å (Phillips et al 1982). Brown et al (1998) observed the line at 16.350 ± 0.008 Å, so it appears that this measurement is inaccurate. There is a line left unidentified by Parkinson and observed at 16.321 Å, with almost the expected intensity of the 1-7 line, so it seems likely that the Parkinson wavelength was also not correct.…”

Section: X-ray Observationssupporting

confidence: 79%

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Benchmarking atomic data for astrophysics: Fe XVII X-ray lines

Zanna¹

2011

A&A

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Recent R-matrix scattering calculations for electron impact excitation of Fe xvii are benchmarked against various X-ray solar observations. Quiescent active region observations are considered, together with a few SMM/FCS observations of active regions and flares analysed here. Extremely good agreement (within 10%) between expected and measured line intensities is found, with the exception of a few weaker lines that appear to be blended, and without the need to invoke opacity effects in the stronger line. The long-standing discrepancies that have been present when distorted wave (DW) calculations are adopted are now finally resolved. As was shown in the Fe xviii case, the differences with the DW calculations are caused by resonances that significantly increase the collision strengths of the 2p-3s transitions. The strong Fe xvii lines can now be reliably used to measure electron temperatures in the solar corona and other astrophysical sources. Emission measure modelling with the most recent atomic data of quiescent active region cores indicates O/Fe and Ne/Fe abundances reduced by factors of two to four compared to the latest compilation of "photospheric" abundances.

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Section: X-ray Observationssupporting

confidence: 79%

“…The assessed level energies have been presented in Del Zanna & Ishikawa (2009). In addition, the energies of the levels with n > 5 are obtained here from the laboratory wavelengths of Brown et al (1998).…”

Section: The Benchmark Methods and Atomic Datamentioning

confidence: 99%

Benchmarking atomic data for astrophysics: Fe XVII X-ray lines

Zanna¹

2011

A&A

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“…Theoretical energies and wavelengths are from CHIANTI (Dere et al 1997(Dere et al , 2009). The labelling for Fe xvii lines follows that of Brown et al (1998). ( In the case of collisional ionisation equilibrium the ionisation potential χ n is comparable to the initial energy of the electron E kT .…”

Section: Rgs: Phenomenological Spectral Analysismentioning

confidence: 99%

The X-ray spectral signatures from the complex circumnuclear regions in the Compton thick AGN NGC 424

Marinucci

Bianchi

Matt

et al. 2010

A&A

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Aims. Most of our knowledge of the circumnuclear matter in Seyfert galaxies is based on the X-ray spectra of the brightest Compton-thick Seyfert 2 galaxies. The complete obscuration of the nuclear radiation in these sources allows us to study all the components arising from reprocessing of the primary continuum in the circumnuclear matter in detail, while they are heavily diluted in unobscured sources, often down to invisibility. Methods. We present the XMM-Newton RGS and EPIC pn spectra of a long ( 100 ks) observation of one of the soft X-ray brightest Compton-thick Seyfert 2 galaxies, NGC 424. As a first step, we performed a phenomenological analysis of the data to derive the properties of all the spectral components. On the basis of these results, we fitted the spectra with self-consistent photoionisation models, produced with cloudy.Results. The high-energy part of the spectrum is dominated by a pure neutral Compton reflection component and a neutral iron Kα line, together with Kα emission from neutral Ni, suggesting a significant Ni/Fe overabundance. The soft X-ray RGS spectrum comes mostly from line emission from H-like and He-like C, N, O, and Ne, as well as from the Fe L-shell. The presence of narrow RRC from O viii, O vii, and C vi, the last two with resolved widths corresponding to temperatures around 5-10 eV, is a strong indication of a gas in photoionisation equilibrium, as confirmed by the prevalence of the forbidden component in the O vii triplet. Two gas phases with different ionisation parameters are needed to reproduce the spectrum with a self-consistent photoionisation model, any contribution from a gas in collisional equilibrium being no more than 10% of the total flux in the 0.35-1.55 keV band. When this self-consistent model is applied to the 0.5-10 keV band of the EPIC pn spectrum, a third photoionised phase is needed to account for emission lines with higher ionisation potential, although Kα emission from S xv and Fe xxvi remains under-predicted.

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“…Brown et al (1998) employed an electron beam ion trap (EBIT) to measure transitions of Fe xvii in the 9-17.8 Å range and applied distorted wave calculations to model the experimental data. They determined that the ratio of the 15.014 line to the 15.261 line, averaged over the energies in the experiment, was 3:04 AE 0:12.…”

Section: Optical Depths Of the Coronal Plasmamentioning

confidence: 99%

Chandra,Extreme Ultraviolet Explorer, and Very Large Array Observations of the Active Binary System σ²Coronae Borealis

Osten

Ayres

Brown

et al. 2003

ApJ

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We present the results of a coordinated observing campaign on the short-period RS CVn binary 2 Coronae Borealis (F6V þ G0V; P orb ¼ 1:14 days) with the Very Large Array, the Extreme Ultraviolet Explorer, and the Chandra X-Ray Observatory High-Energy Transmission Grating Spectrometer. The radio emission is consistent with previously determined quiescent gyrosynchrotron properties. Multiple flares were seen with Extreme Ultraviolet Explorer, five occurring within two consecutive orbital periods. The first of these flares was observed with Chandra. The Chandra observations of 2 CrB showed no systematic variations of line fluxes, widths, or Doppler shifts with orbital phase, nor any response in line width or offset due to the flare. This is consistent with both stars being equally active coronal emitters. We have developed a self-consistent method of spectral analysis to derive information from the line and continuum emissions concerning the distribution of plasma with temperature and elemental abundances. A bimodal temperature distribution is appropriate for both quiescent and flare intervals, with a stable peak at 6-8 MK and another variable enhancement at higher temperatures, with evidence for significant contribution from temperatures up to 50 MK during the flare, compared to 30 MK during quiescence. The iron abundance is subsolar during quiescence but is enriched by about a factor of 2 during a large flare seen with Chandra. The noble gas elements neon and argon show elevated abundances with respect to iron, but there is no clear evidence for any first ionization potential-based abundance pattern during quiescence or the flare. We have determined coronal electron densities from the helium-like ions O vii, Ne ix, Mg xi, and Si xiii, which imply densities !10 10 cm À3 . There is a small enhancement in the electron densities derived for the flare, but it is not statistically significant. We call attention to electron temperature constraints provided by the ratios of 1s 2 1 S 0 -1snp 1 P 1 transitions of the helium-like ions O vii, Ne ix, Mg xi, and Si xiii. The derived coronal electron pressures change by 1-2 orders of magnitude over a 25% change in temperature, implying nonisobaric coronal conditions. We find no evidence for significant departures from the effectively thin coronal assumption. The electron densities inferred from the soft X-ray spectra are inconsistent with cospatial gyrosynchrotron emission; further observations are necessary to discriminate the relative locations of the radio and soft X-ray-emitting plasma.

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Laboratory Measurements and Modeling of the FexviiX‐Ray Spectrum

Cited by 170 publications

References 57 publications

Benchmarking atomic data for astrophysics: Fe XVII X-ray lines

Benchmarking atomic data for astrophysics: Fe XVII X-ray lines

The X-ray spectral signatures from the complex circumnuclear regions in the Compton thick AGN NGC 424

Chandra,Extreme Ultraviolet Explorer, and Very Large Array Observations of the Active Binary System σ²Coronae Borealis

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Laboratory Measurements and Modeling of the FexviiX‐Ray Spectrum

Cited by 170 publications

References 57 publications

Benchmarking atomic data for astrophysics: Fe XVII X-ray lines

Benchmarking atomic data for astrophysics: Fe XVII X-ray lines

The X-ray spectral signatures from the complex circumnuclear regions in the Compton thick AGN NGC 424

Chandra,Extreme Ultraviolet Explorer, and Very Large Array Observations of the Active Binary System σ2Coronae Borealis

Contact Info

Product

Resources

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Chandra,Extreme Ultraviolet Explorer, and Very Large Array Observations of the Active Binary System σ²Coronae Borealis