Charge Exchange Spectra of Hydrogenic and He-like Iron
arXiv:astro-ph/0508078 · doi:10.1086/496874
Abstract
We present H-like Fe XXVI and He-like Fe XXV charge-exchange spectra resulting from collisions of highly charged iron with N2 gas at an energy of 10 eV/amu in an electron beam ion trap. Although individual high-n emission lines are not resolved in our measurements, we observe that the most likely level for Fe25+ --> Fe24+ electron capture is n~9, in line with expectations, while the most likely value for Fe26+ --> Fe25+ charge exchange is significantly higher. In the Fe XXV spectrum, the K-alpha emission feature dominates, whether produced via charge exchange or collisional excitation. The K-alpha centroid is lower in energy for the former case than the latter (6666 versus 6685 eV, respectively), as expected because of the strong enhancement of emission from the forbidden and intercombination lines, relative to the resonance line, in charge-exchange spectra. In contrast, the Fe XXVI high-n Lyman lines have a summed intensity greater than that of Ly-alpha, and are substantially stronger than predicted from theoretical calculations of charge exchange with atomic H. We conclude that the angular momentum distribution resulting from electron capture using a multi-electron target gas is significantly different from that obtained with H, resulting in the observed high-n enhancement. A discussion is presented of the relevance of our results to studies of diffuse Fe emission in the Galactic Center and Galactic Ridge, particularly with ASTRO-E2/Suzaku.
arXiv comment16 pages, 4 figures (3 color), accepted by ApJ
References in corpus (7)
- Sherpa: a Mission-Independent Data Analysis Application
- XMM-Newton Observation of Solar Wind Charge Exchange Emission
- Diffuse X-ray Emission in a Deep Chandra Image of the Galactic Center
- Chandra Observations of the "Dark" Moon and Geocoronal Solar-Wind Charge Transfer
- Origin of the Hard X-ray Emission from the Galactic Plane
- Chandra Observations of MBM12 and Models of the Local Bubble
- Unusual Properties of X-Ray Emission near the Galactic Center
Cited by in corpus (21)
- Highly charged ions: optical clocks and applications in fundamental physics
- Iron line and diffuse hard X-ray emission from the starburst galaxy M82
- Iron and Nickel Line Diagnostics for the Galactic Center Diffuse Emission
- X-rays from solar system objects
- He-like ions as practical astrophysical plasma diagnostics: From stellar coronae to active galactic nuclei
- Suzaku Discovery of the Strong Radiative Recombination Continuum of Iron from the Supernova Remnant W49B
- A deep X-ray observation of M82 with XMM-Newton
- Possible Charge-Exchange X-Ray Emission in the Cygnus Loop Detected with Suzaku
- Laboratory measurements compellingly support charge-exchange mechanism for the 'dark matter' 3.5 keV X-ray line
- Solar Wind Charge Exchange: An Astrophysical Nuisance
- Line Ratios for Solar Wind Charge Exchange with Comets
- EBIT Charge-Exchange Measurements and Astrophysical Applications
- Spectral Study of the Galactic Ridge X-ray Emission with Suzaku
- Charge Exchange Induced X-ray Emission of Fe XXV and Fe XXVI via a Streamlined Model
- Diffuse X-Ray Sky in the Galactic Center
- Origin of the Galactic Diffuse X-ray Emission: Iron K-shell Line Diagnostics
- Critical Test of Simulations of Charge-Exchange-Induced X-Ray Emission in the Solar System
- Measurement of anomalously strong emission from the 1s-9p transition in the spectrum of H-like phosphorus following charge exchange with molecular hydrogen
- Can the excess in the FeXXVI Ly gamma line from the Galactic Center provide evidence for 17 keV sterile neutrinos?
- High-resolution Charge Exchange Spectra with L-shell Nickel Show Striking Differences from Models
- New X-ray views of the Galactic center observed with Suzaku