2004/12/03 by Xin-Lin Zhou, Jian-Min Wang, Jian‐Min Wang · 3 citations
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geometry #Hubble space telescope #Line (geometry) #Luminosity #Physics #Population #Torus #astro-ph
paper · pdf · doi:10.1086/427871
published as Astrophys.J.618:L83-L86,2004 · 4 pages in emulateapj5.sty; 1 figure; 2 tables. Accepted by ApJL
arxiv created 2004/12/03 · openalex publication_date 2004/12/17 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We assemble a sample consisting of 66 active galactic nuclei (AGNs) from the literature and from the XMM-Newton archive in order to investigate the origin of the 6.4 keV narrow iron Kα line (NIKAL). The X-ray Baldwin effect of the NIKAL is confirmed in this sample. We find that the equivalent width (EW) of the NIKAL is more strongly inversely correlated with the Eddington ratio ( ) than with the 2-10 keV X-ray luminosity. Our sample favors the dusty torus origin, with the X-ray Baldwin effect being caused by the changing opening angle of the dusty torus. The EW- relation can be derived from a toy model of the dusty torus. If the unification scheme is valid in all AGNs, we can derive the Baldwin effect from the ratio of type II AGNs to the total population given by Chandra and Hubble Space Telescope deep surveys. Thus, the evolution of populations could be reflected in the NIKAL's Baldwin effect.