Related papers: Broad-line region in active galactic nuclei: Dusty…
We analyze the broad H$\beta$ line profile variability of the "changing look" active galactic nucleus (CL-AGN) NGC 3516 over a long period of 25 years. The observed change in the broad line profile may indicate a change in the geometry of…
The most characteristic property of active galaxies, including quasars, are prominent broad emission lines. I will discuss an interesting possibility that dust is responsible for this phenomenon. The dust is known to be present in quasars…
Broad emission lines are the most characteristic features in the spectra of active galaxies. They mostly show either a single-peaked or double-peaked profiles; and originate from a complex dynamics of the likely discrete clouds moving in a…
The origin of the Broad Line Region (BLR) in active galaxies remains unknown. It seems to be related to the underlying accretion disk but an efficient mechanism is required to rise the material from the disk surface without giving too…
We use the Balmer decrements of the broad-line regions (BLRs) and narrow-line regions (NLRs) of active galactic nuclei (AGNs) as reddening indicators to investigate the location of the dust for four samples of AGNs with reliable estimates…
Archival Hubble Space Telescope (HST) observations of the Seyfert 1 nucleus of NGC 3227 obtained with the Space Telescope Imaging Spectrograph (STIS) are re-examined in order to constrain a viable photoionization model for the broad-line…
Most results of the reverberation monitoring of active galaxies showed a universal scaling of the time delay of the Hbeta emission region with the monochromatic flux at 5100 A, with very small dipersion. Such a scaling favored the…
The spectra of active galactic nuclei exhibit broad-emission lines that presumably originate in the Broad-Line Region (BLR) with gaseous-dusty clouds in a predominantly Keplerian motion around the central black hole. Signatures of both…
Strong broad emission lines are the most important signatures of active galactic nuclei. These lines allowed to discover the cosmological nature of quasars, and at present these lines allow for convenient method of weighting the black holes…
We have recently initiated the first spectroscopic dust reverberation programme on active galactic nuclei (AGN) in the near-infrared. Spectroscopy enables measurement of dust properties, such as flux, temperature and covering factor, with…
Broad Emission Lines are the most characteristic features of Active Galaxies, but the mechanism of creating a medium able to emit these intense lines is not quite clear. Observations clearly indicate that the motion of the material is…
We present a new scheme for modeling the broad line region in active galactic nuclei. It involves photoionization calculations applied to a number of variable emission lines at {\it all times}. We demonstrate how fitting all lines…
The formation processes and the exact appearance of the dust torus and broad line region (BLR) of active galactic nuclei (AGN) are under debate. Theoretical studies show a possible connection between the dust torus and BLR through a common…
The profiles of the broad emission lines of active galactic nuclei (AGNs) and the time delays in their response to changes in the ionizing continuum ("lags") give information about the structure and kinematics of the inner regions of AGNs.…
Since many years we know that dust in the form of the dusty-molecular torus is responsible for the obscuration in active galactic nuclei (AGN) at large viewing angles and thus for the classification of AGN. Recently, we gained some…
How do active galactic nuclei with low optical luminosities produce powerful radio emission? Recent studies of active galactic nuclei with moderate radio and low optical luminosities (Fanaroff & Riley class I, FR I) searching for broad…
In the standard AGN reverberation-mapping model, variations in broad-line region (BLR) fluxes are predicted from optical continuum variability (taken as a proxy for the ionizing continuum) convolved with a response function that depends on…
NGC 5548 is the best-observed reverberation-mapped active galactic nucleus with long-term, intensive monitoring. Here we report results from a new observational campaign between January and July, 2015. We measure the centroid time lag of…
The broad-line region (BLR) of active galactic nuclei (AGN) is an essential component, yet its small size keeps its origin, structure, and kinematics uncertain. Infrared interferometry with VLTI/GRAVITY is now resolving BLR-scale emission,…
Type 1 active galactic nuclei display broad emission lines, regarded as arising from photoionized gas moving in the gravitational potential of a supermassive black hole. The origin of this broad-line region gas is unresolved so far,…