2016ApJ...831...37K -
Astrophys. J., 831, 37-37 (2016/November-1)
Study of Swift/BAT selected low-luminosity active galactic nuclei observed with Suzaku.
KAWAMURO T., UEDA Y., TAZAKI F., TERASHIMA Y. and MUSHOTZKY R.
Abstract (from CDS):
We systematically analyze the broadband (0.5-200 keV) X-ray spectra of hard X-ray (>10 keV) selected local low-luminosity active galactic nuclei (LLAGNs) observed with Suzaku and Swift/BAT. The sample consists of 10 LLAGNs detected with Swift/BAT with intrinsic 14-195 keV luminosities smaller than 1042 erg s–1 available in the Suzaku archive, covering a wide range of the Eddington ratio from 10–5 to 10–2. The overall spectra can be reproduced with an absorbed cut-off power law, often accompanied by reflection components from distant cold matter, and/or optically thin thermal emission from the host galaxy. In all of the objects, relativistic reflection components from the innermost disk are not required. Eight objects show a significant narrow iron-Kα emission line. Comparing their observed equivalent widths with the predictions from the Monte-Carlo-based torus model by Ikeda et al. (2009), we constrain the column density in the equatorial plane to be log NHeq>22.7, or the torus half-opening angle θoa < 70deg. We infer that the Eddington ratio (λEdd) is a key parameter that determines the torus structure of LLAGNs: the torus becomes large at λEdd >= 2 x 10–4, whereas at lower accretion rates it is little developed. The luminosity correlation between the hard X-ray and mid-infrared (MIR) bands of the LLAGNs follows the same correlation as for more luminous AGNs. This implies that mechanisms other than AGN-heated dust are responsible for the MIR emission in low Eddington ratio LLAGNs.
Abstract Copyright:
© 2016. The American Astronomical Society. All rights reserved.
Journal keyword(s):
galaxies: active - X-rays: galaxies - X-rays: galaxies
Simbad objects:
12
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