Change of the relative line strengths due to the resonance induced population transfer between Fe XVII and FeXVI ions

Wu, Chensheng; Gao, Xiang

doi:10.1038/s41598-019-43916-x

Cited by 12 publications

(17 citation statements)

References 40 publications

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“…We note that for Fe xvii, the atomic data for the line are under debate, with theoretical calculations and experiments finding different values (e.g., Gu et al 2007;de Plaa et al 2012;Bernitt et al 2012;Wu & Gao 2019;Gu et al 2019). Indeed the Kaastra (2018) wavelength and oscillator strength that we use for this ion do not agree with the Verner et al (1996) values.…”

Section: Ews From the Simulated Datamentioning

confidence: 65%

The warm-hot circumgalactic medium around EAGLE-simulation galaxies and its detection prospects with X-ray and UV line absorption

Wijers

Schaye

Oppenheimer

2020

Monthly Notices of the Royal Astronomical Society

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We use the EAGLE cosmological simulation to study the distribution of baryons, and FUV (O vi), EUV (Ne viii) and X-ray (O vii, O viii, Ne ix, and Fe xvii) line absorbers, around galaxies and haloes of mass $\, \rm {M}_{\rm {200c}}= 10^{11}$–$10^{14.5} \, \rm {M}_{\odot }$ at redshift 0.1. EAGLE predicts that the circumgalactic medium (CGM) contains more metals than the interstellar medium across halo masses. The ions we study here trace the warm-hot, volume-filling phase of the CGM, but are biased towards temperatures corresponding to the collisional ionization peak for each ion, and towards high metallicities. Gas well within the virial radius is mostly collisionally ionized, but around and beyond this radius, and for O vi, photo-ionization becomes significant. When presenting observables we work with column densities, but quantify their relation with equivalent widths by analysing virtual spectra. Virial-temperature collisional ionization equilibrium ion fractions are good predictors of column density trends with halo mass, but underestimate the diversity of ions in haloes. Halo gas dominates the highest column density absorption for X-ray lines, but lower-density gas contributes to strong UV absorption lines from O vi and Ne viii. Of the O vii (O viii) absorbers detectable in an Athena X-IFU blind survey, we find that 41 (56) per cent arise from haloes with $\, \rm {M}_{\rm {200c}}= 10^{12.0 \rm {-}13.5} \, \rm {M}_{\odot }$. We predict that the X-IFU will detect O vii (O viii) in 77 (46) per cent of the sightlines passing $\, \rm {M}_{\star }= 10^{10.5 \rm {-}11.0} \, \rm {M}_{\odot }$ galaxies within $100 \, \rm {pkpc}$ (59 (82) per cent for $\, \rm {M}_{\star }> 10^{11.0} \, \rm {M}_{\odot }$). Hence, the X-IFU will probe covering fractions comparable to those detected with the Cosmic Origins Spectrograph for O vi.

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Section: Ews From the Simulated Datamentioning

confidence: 65%

The warm-hot circumgalactic medium around EAGLE-simulation galaxies and its detection prospects with X-ray and UV line absorption

Wijers

Schaye

Oppenheimer

2020

Monthly Notices of the Royal Astronomical Society

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“…In this Letter, we report on new measurements of resonantly excited Fe XVI and Fe XVII with a synchrotron source at tenfold improved spectral resolution and millionfold lower peak photon flux than in [25], suppressing nonlinear dynamical effects [32,34,38] and undesired ion population transfers [35]. We also carry out improved large-scale calculations using three different advanced approaches [39][40][41], all showing a five-sigma departure from our experimental results.…”

mentioning

confidence: 73%

“…Nonetheless, at the high peak brilliance of the LCLS XFEL, nonlinear excitation dynamics [32,33] or nonequilibrium time evolution [34] might have affected the result of Bernitt et al [25]. An effect of resonance-induced population transfer between Fe XVI and Fe XVII ions was also postulated [35] since the Fe XVI line C (½ð2p 5 Þ 1=2 3s3d 5=2 J¼3=2 → ½2p 6 3s J¼1=2 ) appeared blended with the Fe XVII line 3D. A recent semiempirical calculation [36] reproduces the LCLS results [25] by finetuning relativistic couplings and orbital relaxation effects, but its validity has been disproved [37].…”

mentioning

confidence: 99%

“…This gives us the 3C=3D intensity ratio without having to infer a contribution of Fe XVI line C (in [25] still unresolved) from the intensity of the well-resolved Fe XVI A line. Thereby, we largely reduce systematic uncertainties and exclude the resonanceinduced population transfer mechanism [35] that may have affected the LCLS result [25].…”

mentioning

confidence: 99%

“…With modern [51][52][53]. Blue crosses: predictions [29,31,32,35,36,[54][55][56][57]. Note that the validity of theory [36] has been disputed [37].…”

mentioning

confidence: 99%

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High Resolution Photoexcitation Measurements Exacerbate the Long-Standing Fe XVII Oscillator Strength Problem

Kühn¹,

Shah²,

López‐Urrutia³

et al. 2020

Phys. Rev. Lett.

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For more than 40 years, most astrophysical observations and laboratory studies of two key soft x-ray diagnostic 2p − 3d transitions, 3C and 3D, in Fe XVII ions found oscillator strength ratios fð3CÞ=fð3DÞ disagreeing with theory, but uncertainties had precluded definitive statements on this much studied conundrum. Here, we resonantly excite these lines using synchrotron radiation at PETRA III, and reach, at a millionfold lower photon intensities, a 10 times higher spectral resolution, and 3 times smaller uncertainty than earlier work. Our final result of fð3CÞ=fð3DÞ ¼ 3.09ð8Þð6Þ supports many of the earlier clean astrophysical and laboratory observations, while departing by five sigmas from our own newest large-scale ab initio calculations, and excluding all proposed explanations, including those invoking nonlinear effects and population transfers.

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High-resolution X-ray spectra of the compact binary supersoft X-ray source CAL 87

Pei,

Zhang,

et al. 2024

A&A

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In this study we present an analysis of the archival X-ray data of the eclipsing supersoft X-ray binary CAL 87 observed with the Chandra Advanced CCD Imaging Spectrometer (ACIS) camera and Low Energy Transmission Grating (LETG) in 2001 August and with XMM-Newton in 2003 April. The high-resolution X-ray spectra are almost unchanged on the two different dates. The average unabsorbed X-ray luminosity during the exposure was 4.64$-$5.46$ $ ergs s$^ $ in 2001 and 4.54$-$4.82 $ $ ergs s$^ $ in 2003, with prominent and redshifted emission lines, mostly of nitrogen, oxygen, iron, and argon, contributing to at least 30<!PCT!> of the X-ray flux. The continuum X-ray flux is at least an order of magnitude too low for a hot hydrogen-burning white dwarf (WD). However, the continuum flux is consistent with Thomson-scattering reflecting about 5<!PCT!> of the light of a hydrogen-burning WD with effective temperature of 800,000 K and a mass of sim 1.2 M$_ It has been noted that a large Thomson-scattering corona explains the X-ray eclipse of CAL 87, in which the size of the eclipsed region is found to be on the order of a solar radius. The emission lines originate in an even more extended region beyond the eclipsed central X-ray source; the emission spectrum is very complex, with unusual line ratios.

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Change of the relative line strengths due to the resonance induced population transfer between Fe XVII and FeXVI ions

Cited by 12 publications

References 40 publications

The warm-hot circumgalactic medium around EAGLE-simulation galaxies and its detection prospects with X-ray and UV line absorption

The warm-hot circumgalactic medium around EAGLE-simulation galaxies and its detection prospects with X-ray and UV line absorption

High Resolution Photoexcitation Measurements Exacerbate the Long-Standing Fe XVII Oscillator Strength Problem

High-resolution X-ray spectra of the compact binary supersoft X-ray source CAL 87

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