XRISM Discovery of Multiple Ionized Fe-K Emission and Absorption Components in Centaurus A

Abstract We present the first clear detection of ionized Fe-K emission and absorption components in the nearby radio galaxy Centaurus A, revealed by the high-resolution XRISM/Resolve detector. In the 6.5–6.9 keV band, XRISM reveals multiple Fe xxv and Fe xxvi emission components. One is a broad (with a width of σ = 3000 km s −1 ) and redshifted (+3400 km s −1 ) component, originating at D = 0.02 pc from the central black hole. The other two components are narrow (with a width of σ = 500 km s −1 ) and exhibit redshifted and blueshifted velocities (+2600 and −1500 km s −1 ), originating from more distant regions ( D = 0.1 pc). The photoionized model explains the broader component, while the two narrower components can be explained by either photoionization or collisional ionization. One interpretation is that the broader component is an outflow at ∼10 2 R S (Schwarzschild radius) and the narrow component is a shock-heated plasma close to the torus, with a possible connection to the JWST-discovered outflow outside the torus. Two blueshifted absorption lines are detected at ∼7.1 keV (∼10 4 km s −1 ) and ∼10.6 keV (∼10 5 km s −1 ). The line significance of the 10.6 keV line is above 98%. The absorption line components might be attributed to the broad emission component. These results demonstrate the high potential of XRISM/Resolve to characterize ionized emission and absorption features in the Fe-K band. Our findings establish a new benchmark in the study of circumnuclear environments in low-luminosity radio galaxies, thereby contributing to a broader understanding of active galactic nuclei unification.