A High-Precision X-ray View from Trapped Ion Clouds to Astrophysical Plasmas

• Applicant: Dr. Moto Togawa
• Subject Area: Astrophysics and Astronomy ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 577849509

Observations of X-ray binaries by the recently launched X-ray observatory, XRISM, revealed so far unresolved spectral emission and absorption lines of highly charged iron ions (Fe15+ to Fe25+) in the 6 to 8 keV X-ray range. Their line shapes, energies and emission strengths can be used to diagnose plasma properties such as density, temperature, velocity and ionization balance. However, their analysis is limited by the accuracy of the available atomic data on which it is based. Particularly, the strong electron correlation in ions with open L-shell configurations makes predictions less reliable. I thus propose to perform laboratory high-precision absorption spectroscopy on such iron ions produced and trapped by an electron beam ion trap with monochromatic hard X-ray synchrotron radiation allowing transition energy measurements with few meV uncertainty. This translates to a velocity uncertainty of less than 1km/s. These measurements will on one side provide critically needed atomic reference data, and on the other benchmark advanced theory and modelling and enable the full scientific potential of XRISM’s high-resolution spectra.

• DFG Programme: Fellowship
• International Connection: Japan
• Host: Professor Hiroya Yamaguchi, Ph.D.