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

Abstract

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 $f(3C)/f(3D)$ 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 $f(3C)/f(3D)=3.09(8)(6)$ 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.

arXiv commentMain text (6 pages, 3 figures), Supplmentary Material (8 pages, 4 figure), Published in Physical Review Letters

References in corpus (28)

• Updated Atomic Data and Calculations for X-ray Spectroscopy
• The Quiescent Intracluster Medium in the Core of the Perseus Cluster
• The Chandra High Energy Transmission Grating: Design, Fabrication, Ground Calibration and Five Years in Flight
• High Resolution Observations of the Elliptical Galaxy NGC 4636 with the Reflection Grating Spectrometer On-Board XMM-Newton
• High Resolution X-Ray Spectra of Capella: Initial Results from the Chandra High Energy Transmission Grating Spectrometer
• Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi
• The Chandra Iron-L X-Ray Line Spectrum of Capella
• X-ray resonant photoexcitation: line widths and energies of Kα transitions in highly charged Fe ions
• The Heidelberg compact electron beam ion traps
• Estimating turbulent velocities in the elliptical galaxies NGC 5044 and NGC 5813
• AMBiT: A program for high-precision relativistic atomic structure calculations
• The X-ray spectrum of Fe XVII revisited with a multi-ion model
• The Iron Unresolved Transition Array in Active Galactic Nuclei
• Polarization measurement of dielectronic recombination transitions in highly charged krypton ions
• Lower entropy bounds and particle number fluctuations in a Fermi sea
• Are stellar coronae optically thin in X-rays? - A systematic investigation of opacity effects
• QED shifts in multivalent heavy ions
• A Census of X-ray gas in NGC 1068: Results from 450ks of Chandra HETG Observation
• Influence of Resonances on Spectral Formation of X-Ray Lines in Fe XVII
• The Transparency of Solar Coronal Active Regions
• X-ray spectra of the Fe-L complex
• Polarization of K-shell dielectronic recombination satellite lines of Fe XIX-XXV and its application for diagnostics of anisotropies of hot plasmas
• Breit-Pauli R-matrix calculations for electron impact excitation of Fe XVII: a benchmark study
• Revealing O VII from stacked X-ray grating spectra of clusters, groups and elliptical galaxies
• Astrophysical line diagnosis requires non-linear dynamical atomic modeling
• Revisiting the Fe XVII line emission problem: laboratory measurements of the 3s-2p and 3d-2p line-formation channels
• X-ray fluorescence spectrum of highly charged Fe ions driven by strong free-electron-laser fields
• Non-Equilibrium Modeling of the Fe XVII 3C/3D ratio for an Intense X-ray Free Electron Laser

Cited by in corpus (17)

• Atomic Data Assessment with PyNeb
• New Measurement Resolves Key Astrophysical Fe XVII Oscillator Strength Problem
• X-ray spectra of the Fe-L complex II: atomic data constraints from EBIT experiment and X-ray grating observations of Capella
• Deep-learning approach for the atomic configuration interaction problem on large basis sets
• Resonance-enhanced multiphoton ionization in the x-ray regime
• Observation of strong two-electron--one-photon transitions in few-electron ion
• Comprehensive Laboratory Measurements Resolving the LMM Dielectronic Recombination Satellite Lines in Ne-like Fe XVII Ions
• High-Precision Transition Energy Measurements of Neon-like Fe XVII Ions
• High-brilliance ultra-narrow-band x-rays via electron radiation in colliding laser pulses
• Combination of the Perturbation Theory with Configuration Interaction Method
• Natural-linewidth measurements of the 3C and 3D soft-x-ray transitions in Ni XIX
• QED calculations of the E1 transition amplitude in neon-like iron and nickel
• High resolution X-ray spectra of the compact binary supersoft X-ray source CAL 87
• QED approach to valence-hole excitation in closed shell systems
• Fe XVII $2p$-$3s$ line ratio diagnostic of shock formation radius in O stars
• The XSTAR Atomic Database
• Scalable codes for precision calculations of properties of complex atomic systems