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Full-Text Articles in Physical Sciences and Mathematics
Evolution Of Broad-Line Emission From Active Galactic Nuclei, Moshe Elitzur, Luis C. Ho, Jonathan R. Trump
Evolution Of Broad-Line Emission From Active Galactic Nuclei, Moshe Elitzur, Luis C. Ho, Jonathan R. Trump
Physics and Astronomy Faculty Publications
Apart from viewing-dependent obscuration, intrinsic broad-line emission from active galactic nuclei (AGN) follows an evolutionary sequence: type 1 → 1.2/1.5 → 1.8/1.9 → 2 as the accretion rate on to the central black hole is decreasing. This spectral evolution is controlled, at least in part, by the parameter Lbol/M2/3, where Lbol is the AGN bolometric luminosity and M is the black hole mass. Both this dependence and the double-peaked profiles that emerge along the sequence arise naturally in the disc-wind scenario for the AGN broad-line region.
Interpreting The Ionization Sequence In Agn Emission-Line Spectra, Chris T. Richardson, James T. Allen, Jack A. Baldwin, Paul C. Hewett, Gary J. Ferland
Interpreting The Ionization Sequence In Agn Emission-Line Spectra, Chris T. Richardson, James T. Allen, Jack A. Baldwin, Paul C. Hewett, Gary J. Ferland
Physics and Astronomy Faculty Publications
We investigate the physical cause of the great range in the ionization level seen in the spectra of narrow-lined active galactic nuclei (AGN). We used a recently developed technique called mean field independent component analysis to identify examples of individual Sloan Digital Sky Survey galaxies whose spectra are not dominated by emission due to star formation (SF), which we therefore designate as AGN. We assembled high signal-to-noise ratio (S/N) composite spectra of a sequence of these AGN defined by the ionization level of their narrow-line regions (NLR), and extending down to very low ionization cases. We then used a local …
A Transition Mass For Black Holes To Show Broad Emission Lines, Susmita Chakravorty, Martin Elvis, Gary J. Ferland
A Transition Mass For Black Holes To Show Broad Emission Lines, Susmita Chakravorty, Martin Elvis, Gary J. Ferland
Physics and Astronomy Faculty Publications
Although the supermassive (AGN) and stellar mass (BHBs) black holes have many properties in common, the broad emission lines (BELs) are exclusively signatures of the active galactic nuclei (AGN). Based on the detection of these lines from Sloan Digital Sky Survey (SDSS) data bases, there seems to be no AGN with mass MBH ≲ 105 M⊙. In this paper, we investigate if such low-mass black holes are really non-existent or they are undetected because the BELs in them are not produced efficiently. Using the ionizing spectral energy distribution for a wide range of black hole mass, …