2004/02/13 by G. C. Dewangan, R. E. Griffiths, T. Di Matteo +3 · 2 citations
Physics and Astronomy · #Accretion (finance) #Accretion disc #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Black hole (networking) #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geometry #Ion #Ionization #Line (geometry) #Luminosity #Physics #Spectral line #astro-ph
paper · pdf · doi:10.1086/383607
published as Astrophys.J. 607 (2004) 788-793 · 8 pages, uses emulateapj5, To apear in ApJ
arxiv created 2004/02/13 · openalex publication_date 2004/05/19 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report on the XMM-Newton spectroscopy of the low-luminosity active galaxies (LLAGNs) M81 and NGC 4579, both of which have known black hole masses and well-sampled spectral energy distributions (SEDs). The iron Kα line profiles from both LLAGNs can be described in terms of two components: a narrow line at 6.4 keV, and a moderately broad line (FWHM ~ 2 × 10 4 km s -1 ) arising from highly ionized, He-like or H-like species ( E ~ 6.8 keV). We interpret the broad lines arising from an accretion disk, the inner edge of which is restricted to large radii ( r in ~ 100 r g ). However, the Eddington ratio, L / L Edd , of these sources is 3-4 orders of magnitude lower than that required to photoionize a cold disk to He-like iron. We suggest that the lines can be explained as collisionally ionized X-ray lines arising from the transition region between a hot (radiatively inefficient) flow in the inner regions and a cold disk outside r ~ 100 r g . The accretion flow geometry probed by our XMM-Newton observations is consistent with the truncated disk models proposed to explain the SED of LLAGNs.