Abstract. We present an investigation of the structure of the emission line region in a sample of 12 single-peaked Active Galactic Nuclei (AGNs). Using the high resolution Hβ and Hα line profiles observed with the Isaac Newton Telescope (La Palma) we study the substructure in the lines (such as shoulders or bumps) which can indicate a disk or disk-like emission in Broad Line Regions (BLRs). Applying Gaussian analysis we found that both kinds of emission regions, BLR and NLR, are complex. In this sample the narrow [OIII] lines are composites of two components; NLR1 which have random velocities from ∼200 to 500 km s −1 and systematic velocities toward the blue from 20 to 350 km s −1 , and NLR2 with smaller random velocities (∼100−200 km s −1 ) and a redshift corresponding to the cosmological one. The BLR also have complex structure and we apply a two-component model assuming that the line wings originate in a very broad line region (VBLR) and the line core in an intermediate line region (ILR). The VBLR is assumed to be an accretion disk and the ILR a spherical emission region. The model fits very well the Hα and Hβ line profiles of the AGNs.

We present the results of a long-term (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) spectral optical monitoring campaign of the active galactic nucleus (AGN) Ark 564, which shows a strong Fe II line emission in the optical. This AGN is a narrow line Seyfert 1 (NLS1) galaxies, a group of AGNs with specific spectral characteristics. We analyze the light curves of the permitted Hα, Hβ, optical Fe II line fluxes, and the continuum flux in order to search for a time lag between them. Additionally, in order to estimate the contribution of iron lines from different multiplets, we fit the Hβ and Fe II lines with a sum of Gaussian components. We found that during the monitoring period the spectral variation (F max /F min ) of Ark 564 was between 1.5 for Hα to 1.8 for the Fe II lines. The correlation between the Fe II and Hβ flux variations is of higher significance than that of Hα and Hβ (whose correlation is almost absent). The permitted-line profiles are Lorentzian-like, and did not change shape during the monitoring period. We investigated, in detail, the optical Fe II emission and found different degrees of correlation between the Fe II emission arising from different spectral multiplets and the continuum flux. The relatively weak and different degrees of correlations between permitted lines and continuum fluxes indicate a rather complex source of ionization of the broad line emission region.

Aims. We present the results of a long-term monitoring (11 years, between 1996 and 2006) of Hα and Hβ line variations of the active galactic nucleus of NGC 4151. Methods. High quality spectra (S /N > 50 and R ≈ 8 Å) of Hα and Hβ were investigated. During monitoring period, we analyzed line profile variations. Comparing the line profiles of Hα and Hβ, we studied different details (bumps, absorbtion features) in the line profiles. The variations in the different Hα and Hβ line profile segments were investigated. We also analyzed the Balmer decrement for entire lines and for line segments. Results. We found that the line profiles varied strongly during the monitoring period, and exhibited blue and red asymmetries. This is indicative of a complex BLR geometry inside NGC 4151 with, at least, three kinematically distinct regions: one that contributes to the blue line wing, one to the line core and one to the red line wing. The variation may be caused by an accelerating outflow originating very close to the black hole, where the red part may come from a region closer to the black hole than the blue part, which originates in the region with the highest outflow velocities. Conclusions. Taking into account that the BLR of NGC 4151 has a complex geometry (probably affected by an outflow) and that a portion of the broad line emission does not seem to be produced entirely by photoionization, one may ask whether the study of the BLR using reverberation mapping would be worthwhile for this galaxy.

Here we present the long-term optical spectral monitoring of a changing-look active galactic nuclei (AGN) NGC 3516 that covers 22 years (from 1996 to 2018). We explore a variability in the broad lines and continuum, finding that the continuum is changing by more than a factor of 2, while the broad lines are varying by more than a factor of 10. The minimum of activity is observed in 2014, when the broad lines almost disappeared. We confirm that NGC 3516 is a changing-look AGN, and the absorption seen in the UV and X-ray may indicate that there is an obscuring region which is responsible for this.The line profiles are also changing. The mean profiles of the broad Hα and Hβ lines show shoulder-like structure in the wings, and enhanced peak, that may indicate a complex BLR. The rms-profiles of both lines seem to have the same shape and width of around 4200 km s −1 , indicating practically the same kinematics in the Hα and Hβ emitting regions.Measured time-lags between the continuum and Hα and Hβ broad-line variability are ∼ 15 and 17 days, respectively, that in combination with the broad lines width allows us to estimate the NGC 3516 central black hole mass. We find that the black hole mass is (4.73±1.40)×10 7 M ⊙ which is in agreement with previous estimates.

By taking into account relativistic corrections to the magnetic dipole operator, the theoretical [OIII] 5006.843/4958.511 line intensity ratio of 2.98 is obtained. In order to check this new value using AGN spectra we present the measurements of the flux ratio of the [OIII] λλ4959, 5007 emission lines for a sample of 62 AGN, obtained from the Sloan Digital Sky Survey (SDSS) Database and from published observations. We select only high signal-to-noise ratio spectra for which the line shapes of the [OIII] λλ4959,5007 lines are the same. We obtained an averaged flux ratio of 2.993 ± 0.014, which is in a good agreement with the theoretical one.

Context. We present the results of the long-term (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) spectral monitoring of the broad-line radio galaxy 3C 390.3, a well known AGN with double-peaked broad emission lines, usually assumed to be emitted from an accretion disk. Aims. To explore dimensions and structure of the BLR, we analyze the light curves of the broad Hα and Hβ line fluxes and the continuum flux. To detect variations in the BLR, we analyze the Hα and Hβ line profiles, as well as the change in the line profiles during the monitoring period. Methods. We attempt first to find a periodicity in the continuum and Hβ light curves, finding that there is a high probability of measuring quasi-periodical oscillations. Using the line shapes and their characteristics (such as e.g., peak separation and their intensity ratio, or FWHM) of broad Hβ and Hα lines, we discuss the structure of the BLR. We also cross-correlate the continuum flux with Hβ and Hα lines to determine the dimensions of the BLR. Results. During the monitoring period, we found that the broad emission component of the Hα and Hβ lines, and the continuum flux varied by a factor of ≈4−5. We also detected different structure in the line profiles of Hα and Hβ. An additional central component appears to be present and superimposed on the disk emission. In the period of high activity (after 2002), Hβ became broader than Hα and red wing of Hβ was higher than that of Hα. We detected time lags of ∼95 days between the continuum and Hβ flux, and about 120 days between the continuum and Hα flux. Conclusions. Variations in the line profiles, as well as correlation between the line and continuum flux during the monitoring period, are consistent with a disk origin of the broad lines and the possible contribution of some additional region and/or some kind of perturbation in the disk.

In order to contribute to the general effort aiming at the improvement of our knowledge about the physical conditions within the broad-line regions ( BLRs) of active galactic nuclei (AGNs), here we present the results achieved by our analysis of the spectral properties of a sample of 90 broad-line-emitting sources, collected from the Sloan Digital Sky Survey database. By focusing our attention mainly on the Balmer series of hydrogen emission lines, which is the dominant feature in the optical wavelength range of many BLR spectra, we extracted several flux and profile measurements, which we related to other source properties, such as optical continuum luminosity, inferred black hole mass, and accretion rate. Using the Boltzmann plot method to investigate the Balmer-line flux ratios as a function of the line profiles, we found that AGNs that emit broader lines typically have larger H/H and smaller H/H and H/H line ratios. With the help of some recent investigations, we model the structure of the BLR, and we study the influence of the accretion process on the properties of BLR plasma.

Here we present an analysis of spectro-polarimetric observations of type 1.5 AGN Mrk 6, performed with 6m telescope SAO RAN in 12 epochs (2010-2013. Additionally, the interstellar mater (ISM) polarization has been observed and its contribution to the AGN spectral polarization is taken into account.We measured Stokes parameters and determined the polarization parameters in 12 spectra with and without correction for the ISM polarization. We estimated the time lag between the unpolarized and polarized continuum flux variation of about ∼ 2 days, that indicates a compact scattering region which contributes to the polarized continuum variability. The polarization in Hα is complex, showing three prominent components in the BLR, one redshifted around +3000 kms −1 that corresponds to the red shoulder in Hα, and two blue-shifted around -2000 kms −1 and -6000 kms −1 .We found that the ISM polarization has a very significant influence on the measured AGN polarization parameters. After correcting the observations for the ISM polarization we were able to detect the Keplerian motion in the BLR.We give a new method for the black hole mass estimation using spectro-polarimetric observation in the line profile, finding the black hole mass in Mrk 6 of M BH ∼ 1.53 · 10 8 M ⊙ , that is in a good agreement with reverberation estimates.