Oh, KyuseokKyuseokOhSchawinski, KevinKevinSchawinskiKoss, MichaelMichaelKossTrakhtenbrot, BennyBennyTrakhtenbrotLamperti, IsabellaIsabellaLampertiRicci, ClaudioClaudioRicciMushotzky, RichardRichardMushotzkyVeilleux, SylvainSylvainVeilleuxBerney, SimonSimonBerneyCrenshaw, D. MichaelD. MichaelCrenshawGehrels, NeilNeilGehrelsHarrison, FionaFionaHarrisonMASETTI, NICOLANICOLAMASETTISoto, Kurt T.Kurt T.SotoStern, DanielDanielSternTreister, EzequielEzequielTreisterUeda, YoshihiroYoshihiroUeda2020-08-062020-08-0620170035-8711http://hdl.handle.net/20.500.12386/26703We investigate the observed relationship between black hole mass (M<SUB>BH</SUB>), bolometric luminosity (L<SUB>bol</SUB>) and Eddington ratio (λ<SUB>Edd</SUB>) with optical emission-line ratios ([N II] λ6583/Hα, [S II] λλ6716, 6731/Hα, [O I] λ6300/Hα, [O III] λ5007/Hβ, [Ne III] λ3869/Hβ and He II λ4686/Hβ) of hard X-ray-selected active galactic nuclei (AGN) from the BAT AGN Spectroscopic Survey. We show that the [N II] λ6583/Hα ratio exhibits a significant correlation with λ<SUB>Edd</SUB> (R<SUB>Pear</SUB> = -0.44, p-value = 3 × 10<SUP>-13</SUP>, σ = 0.28 dex), and the correlation is not solely driven by M<SUB>BH</SUB> or L<SUB>bol</SUB>. The observed correlation between [N II] λ6583/Hα ratio and M<SUB>BH</SUB> is stronger than the correlation with L<SUB>bol</SUB>, but both are weaker than the λ<SUB>Edd</SUB> correlation. This implies that the large-scale narrow lines of AGN host galaxies carry information about the accretion state of the AGN central engine. We propose that [N II] λ6583/Hα is a useful indicator of Eddington ratio with 0.6 dex of rms scatter, and that it can be used to measure λ<SUB>Edd</SUB> and thus M<SUB>BH</SUB> from the measured L<SUB>bol</SUB>, even for high-redshift obscured AGN. We briefly discuss possible physical mechanisms behind this correlation, such as the mass-metallicity relation, X-ray heating, and radiatively driven outflows.STAMPAenArticle10.1093/mnras/stw24672-s2.0-85014644513000393647100015https://academic.oup.com/mnras/article/464/2/1466/22828552017MNRAS.464.1466OFIS/05 - ASTRONOMIA E ASTROFISICAScienze Fisiche Settori ERC (ERC) di riferimento::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_11 Relativistic astrophysics