K-shell photoabsorption studies of the carbon isonuclear sequence

Abstract

K-shell photoabsorption cross sections for the isonuclear C i-C iv ions have been computed using the R-matrix method. Above the K-shell threshold, the present results are in good agreement with the independent-particle results of Reilman and Manson. Below threshold, we also compute the strong 1s → np absorption resonances with the inclusion of important spectator Auger broadening effects. For the lowest 1s → 2p, 3p resonances, comparisons to available C ii, C iii, and C iv experimental results show good agreement in general for the resonance strengths and positions. Our results also provide detailed information on the C i K-shell photoabsorption cross section including the strong resonance features, since very limited laboratory experimental data exist. The resultant R-matrix cross sections are then used to model the Chandra X-ray absorption spectrum of the blazar Mkn 421. © 2010. The American Astronomical Society. All rights reserved. Printed in the U.S.A.