Abstract
The radiative lines of cosmically abundant H-like ions (Z < 30) are observed in most astronomical spectra where they are used to determine the properties of the emitting plasma (electronic temperature, density, abundance, and structure). With the launching in the late 90s of the space probes Chandra and XMM-Newton to observe X-ray spectra, the radiative properties (wavelength, transition probability and electron excitation collision strength) of hydrogenic lines in highly ionized elements with nuclear charges in the range 8 < Z < 30 have acquired a singular importance. The computation of the atomic properties of H-like ions in intermediate coupling implies solutions of the Dirac equation or the use of an approximate relativistic Hamiltonian such as the the one by Breit-Pauli. Despite the simplicity of these systems, there is not a complete (n < 10, say) and accurate atomic database, as required in X-ray astrophysical applications. We report a calculation of relativistic A-values for E_i (i ≤ 3) and M_j (j ≤ 2) transitions in H-like ions with Z ≤ 30 using the atomic structure codes AUTOSTRUCTURE and GRASP. Detailed comparisons are carried out with previous data sets in order to determine accuracy levels. This database will help to revaluate the spectra of standard astronomical X-ray sources, such as active galactic nuclei, X-ray binaries and black hole candidates.
