NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-18 T02:31:15 PDT
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For refcode 2011ApJ...739...64X:
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Copyright by American Astronomical Society. Reproduced by permission
2011ApJ...739...64X The Relation of Optical/Ultraviolet and X-Ray Emission in Low-luminosity Active Galactic Nuclei Xu, Ya-Di Abstract. We study the relation of optical/UV and X-ray emission in the low luminosity active galactic nuclei (LLAGNs), using a sample of 49 sources including 28 local Seyfert galaxies and 21 low-ionization nuclear emission-line regions with optical/UV spectral luminosity at wavelength {lambda} = 2500 A, 23.0 <= log L_{nu}(2500 A)_(erg s^-1^ Hz^-1^) <= 27.7, and X-ray spectral luminosity at 2 keV, 20.5 <= log L_{nu}(2 keV)_ <= 25.3. Strong correlations are found between the X-ray luminosity and the optical/UV-to-X-ray index, {alpha}_ox_, with the optical/UV luminosity, with slopes very similar to the findings for the luminous AGNs in previous works. The correlation between {alpha}_ox_ and L_{nu}(2 keV)_ is very weak, as is that found for the luminous AGNs in the majority of previous similar works. We also study the relation between {alpha}_ox_ and the Eddington ratio L_bol_/L_Edd_ for our sample and find a significant anti-correlation for the sources with L_bol_/L_Edd_ <~ 10^-3^, which is opposite to the correlation between the two variables for the luminous AGNs. Using the advection-dominated accretion flow (ADAF) model, we roughly reproduce this anti-correlationship for the two variables for the LLAGNs. This result strongly supports the ADAF as a candidate for the accretion mode in LLAGNs. Key words: accretion, accretion disks, galaxies: active, galaxies: nuclei, X-rays: galaxies
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