NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-25 T19:29:01 PDT
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For refcode 2016MNRAS.459L.100L:
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NED Abstract

Copyright by Royal Astronomical Society. 2016MNRAS.459L.100L Clumpy tori around type II active galactic nuclei as revealed by X-ray fluorescent lines Liu, Jiren; Liu, Yuan; Li, Xiaobo; Xu, Weiwei; Gou, Lijun; Cheng, Cheng Abstract. The reflection spectrum of a torus around an active galactic nucleus (AGN) is characterized by X-ray fluorescent lines, which are most prominent for type II AGNs. A clumpy torus allows photons reflected from the back-side of the torus to leak through the front regions that are free of obscuration. The observed X-ray fluorescent lines are therefore sensitive to the clumpiness of the torus. We analysed a sample of type II AGNs observed with the Chandra High Energy Transmission Grating Spectrometer (HETGS), and measured the fluxes for the Si Kalpha and Fe Kalpha lines. The measured Fe Kalpha/Si Kalpha ratios, spanning a range between 5 and 60, are far smaller than the ratios predicted from simulations of smooth tori, indicating that the tori of the studied sources have clumpy distributions rather than smooth ones. We compared the measured Fe Kalpha/Si Kalpha ratios with simulation results of clumpy tori. The Circinus galaxy has a Fe Kalpha/Si Kalpha ratio of ~60, which is close to the simulation results for N = 5, where N is the average number of clumps along the line of sight. The Fe Kalpha/Si Kalpha ratios of the other sources are all below the simulation results for N = 2. Overall, this shows that the non-Fe fluorescent lines in the soft X-ray band are a potentially powerful probe of the clumpiness of tori around AGNs. Key words: galaxies: individual: Circinus, Mrk 3, NGC 1068, NGC 3393, NGC 7582, NGC 2992, NGC 4388, NGC 4507, 3C 445, galaxies: Seyfert, X-rays: galaxies
Retrieve 9 NED objects in this reference.
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