X-ray spectroscopy in the microcalorimeter era II: A new Diagnostic on Column Density from the Case A to B Transition in H- and He-like Iron

Abstract

The Soft X-ray Spectrometer (SXS) on board \textit{Hitomi}, with the unprecedented resolving power of R$\sim$1250, allowed the detection of members of the Fe XXV \ka\ complex emission spectra from the center of the Perseus Cluster. In this paper, we introduce a novel method of measuring the column density using the optically thin (Case A) to optically thick (Case B) transition for one- and two-electron systems. We compare the Fe XXV K$\alpha$ line ratios computed with CLOUDY with that from the \textit{Hitomi} observations in the outer region of the Perseus core using collision strengths from different atomic datasets, and obtain good agreement. We also show the effect of turbulence on Fe XXV K$\alpha$ line ratios and interplay between column density and metallicity. Besides, we discuss the atomic number dependence of transition probabilities for allowed and non-allowed transitions, which causes the highly charged He-like systems, such as Fe XXV, to behave fundamentally differently from He I.

References in corpus (6)

• Heating Hot Atmospheres with Active Galactic Nuclei
• The Quiescent Intracluster Medium in the Core of the Perseus Cluster
• Turbulent Heating in Galaxy Clusters Brightest in X-rays
• Structures in the Great Attractor Region
• X-ray spectroscopy in the microcalorimeter era I: Effects of Fe XXIV Resonance Auger Destruction on Fe XXV K$\alpha$ spectra
• H-, He-like recombination spectra III: $n$-changing collisions in highly-excited Rydberg states and their impact on the radio, IR and optical recombination lines

Cited by in corpus (7)

• X-ray metal line emission from the hot circumgalactic medium: probing the effects of supermassive black hole feedback
• Chemical abundances in the outskirts of nearby galaxy groups measured with joint Suzaku and Chandra observations
• X-ray spectroscopy in the microcalorimeter era III: line formation under Case A, Case B, Case C, and Case D in H- and He-like iron for a photoionized cloud
• X-ray spectroscopy in the microcalorimeter era I: Effects of Fe XXIV Resonance Auger Destruction on Fe XXV K$\alpha$ spectra
• Scientific Objectives of the Hot Universe Baryon Surveyor (HUBS) Mission
• X-ray spectroscopy in the microcalorimeter era 4: Optical depth effects on the soft X-rays studied with CLOUDY
• Spectroscopic modelling of two high-mass X-ray binaries, Cyg X--3 and 4U 1538--522