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| Paper: |
Iron K Line Diagnostics in Active Galactic Nuclei |
| Volume: |
373, The Central Engine of Active Galactic Nuclei |
| Page: |
109 |
| Authors: |
Yaqoob, T. |
| Abstract: |
We discuss some topical issues related to the study of Fe K emission lines in active galactic nuclei (AGNs). We show remarkable agreement between non-contemporaneous ASCA and Chandra grating data and explain why there has been terrible confusion about the ASCA and post-ASCA results on the relativistic components of the Fe K line emission. We point out that in fact the number of sources (not the percentage) that have been reported to exhibit relativistic effects in the Fe K line is now larger than it was in the ASCA era. Thus, the case for Constellation-X as a probe of strong gravity is even more compelling than it was a decade ago. One of the primary goals of these studies is to establish the foundations for future missions to map the spacetime metric around black holes. A prerequisite first step is to measure the black hole angular momentum in a robust manner that does not rely on assumptions about the accreting system. In addition, probing the Fe K lines out to high redshifts will pave the way for studying the accretion history and evolution of supermassive black holes. However, we point out some issues that need to be resolved, pertaining to spin measurement and to the relativistic Fe K line emission found from AGN in deep X-ray surveys. |
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