Year: 2016
Type: article
Abstract: ABSTRACT We show that the recently observed suppression of the gap between the broad-line region (BLR) and the narrow-line region (NLR) in some active galactic nuclei (AGNs) can be fully explained by an increase of the gas density in the emitting region. Our model predicts the formation of the intermediate-line region (ILR) that is observed in some Seyfert galaxies by the detection of emission lines with intermediate-velocity FWHM ∼ 700–1200 km s−1. These lines are believed to be originating from an ILR located somewhere between the BLR and NLR. As was previously proved, the apparent gap is assumed to be caused by the presence of dust beyond the sublimation radius. Our computations with the use of the cloudy photoionization code show that the differences in the shape of the spectral energy distribution from the central region of AGNs do not diminish the apparent gap in the line emission in those objects. A strong discontinuity in the line emission versus radius exists for all lines at the dust sublimation radius. However, increasing the gas density to ∼ cm−3 at the sublimation radius provides the continuous line emission versus radius and fully explains the recently observed lack of apparent gap in some AGNs. We show that such a high density is consistent with the density of upper layers of an accretion disk atmosphere. Therefore, the upper layers of the disk atmosphere can give rise to the formation of observed emission-line clouds.
Source: The Astrophysical Journal
Authors: T. P. Adhikari, A. Różańska, B. Czerny, K. Hryniewicz, G. J. Ferland
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: G1014655825, G1045171642, G11597159, Collaborative Research: Spectral diagnostics of heavy elements at high redshift, Probing Strong Gravity by Black Holes Across the Range of Masses, Gas Flows and Rapid Metal Enrichment in AGN, G3093838504, G3207356259, THE CRAB NEBULA IS THE NEAREST AND BRIGHTEST SUPERNOVA REMNANT. IT IS EXCEPTIONAL BECAUSE IT IS STILL IN THE EARLY STAGES OF ITS EVOLUTION WHERE THE, G393177772, G4088657796, G4104599821, G5069241290, Emission-lines from AGN&Starbursts: new steps to understanding their message, G5702163051, G5803244198, G6124101475, G8134911741, G8169805169, G8469037737
OpenAlex ID: W2419254804