TY - JOUR
T1 - Implications of infalling Fe II-emitting clouds in active galactic nuclei
T2 - Anisotropic properties
AU - Ferland, Gary J.
AU - Hu, Chen
AU - Wang, Jian Min
AU - Baldwin, Jack A.
AU - Porter, Ryan L.
AU - Van Hoof, Peter A.M.
AU - Williams, R. J.R.
PY - 2009
Y1 - 2009
N2 - We investigate consequences of the discovery that Fe II emission in quasars, one of the spectroscopic signatures of "Eigenvector 1," may originate in infalling clouds. Eigenvector 1 correlates with the Eddington ratio L/L Edd so that Fe II/Hβ increases as L/L Edd increases. We show that the "force multiplier," the ratio of gas opacity to electron scattering opacity, is ∼103-104 in Fe II-emitting gas. Such gas would be accelerated away from the central object if the radiation force is able to act on the entire cloud. As had previously been deduced, infall requires that the clouds have large column densities so that a substantial amount of shielded gas is present. The critical column density required for infall to occur depends on L/L Edd, establishing a link between Eigenvector 1 and the Fe II/Hβ ratio. We see predominantly the shielded face of the infalling clouds rather than the symmetric distribution of emitters that has been assumed. The Fe II spectrum emitted by the shielded face is in good agreement with observations thus solving several long-standing mysteries in quasar emission lines.
AB - We investigate consequences of the discovery that Fe II emission in quasars, one of the spectroscopic signatures of "Eigenvector 1," may originate in infalling clouds. Eigenvector 1 correlates with the Eddington ratio L/L Edd so that Fe II/Hβ increases as L/L Edd increases. We show that the "force multiplier," the ratio of gas opacity to electron scattering opacity, is ∼103-104 in Fe II-emitting gas. Such gas would be accelerated away from the central object if the radiation force is able to act on the entire cloud. As had previously been deduced, infall requires that the clouds have large column densities so that a substantial amount of shielded gas is present. The critical column density required for infall to occur depends on L/L Edd, establishing a link between Eigenvector 1 and the Fe II/Hβ ratio. We see predominantly the shielded face of the infalling clouds rather than the symmetric distribution of emitters that has been assumed. The Fe II spectrum emitted by the shielded face is in good agreement with observations thus solving several long-standing mysteries in quasar emission lines.
KW - Accretion, accretion disks
KW - Atomic processes
KW - Galaxies: active
KW - Line: formation
KW - Quasars: emission lines
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U2 - 10.1088/0004-637X/707/1/L82
DO - 10.1088/0004-637X/707/1/L82
M3 - Article
AN - SCOPUS:77749330754
SN - 0004-637X
VL - 707
SP - L82-L86
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1 PART 2
ER -