Spectral optical monitoring of 3C390.3 in 1995-2007: I. Light curves and flux variation of the continuum and broad lines

Here we present the results of the long-term (1995-2007) spectral monitoring of the broad line radio galaxy \object{3C~390.3}, a well known AGN with the double peaked broad emission lines, usually assumed to be emitted from an accretion disk. To explore dimensions and structure of the BLR, we analyze the light curves of the broad H$\alpha$ and H$\beta$ line fluxes and the continuum flux. In order to find changes in the BLR, we analyze the H$\alpha$ and H$\beta$ line profiles, as well as the change in the line profiles during the monitoring period. First we try to find a periodicity in the continuum and H$\beta$ light curves, finding that there is a good chance for quasi-periodical oscillations. Using the line shapes and their characteristics (as e.g. peaks separation and their intensity ratio, or FWHM) of broad H$\beta$ and H$\alpha$ lines, we discuss the structure of the BLR. Also, we cross-correlate the continuum flux with H$\beta$ and H$\alpha$ lines to find dimensions of the BLR. We found that during the monitoring period the broad emission component of the H$\alpha$ and H$\beta$ lines, and the continuum flux varied by a factor of $\approx$4-5. Also, we detected different structure in the line profiles of H$\alpha$ and H$\beta$. It seems that an additional central component is present and superposed to the disk emission. In the period of high activity (after 2002), H$\beta$ became broader than H$\alpha$ and red wing of H$\beta$ was higher than the one of H$\alpha$. We found time lags of $\sim$95 days between the continuum and H$\beta$ flux, and about 120 days between the continuum and H$\alpha$ flux. Variation in the line profiles, as well as correlation between the line and continuum flux during the monitoring period is in the favor of the disk origin of the broad lines with the possible contribution of some additional region and/or some kind of perturbation in the disk.Comment: 32 pages, accepted to A&A, typos correcte

Spectral monitoring of AGNs: Preliminary results for Ark 564 and Arp 102B

We present preliminary results of the long term spectral monitoring of two active galactic nuclei with different broad line shapes: Ark 564 and Arp 102B. Ark 564 is a bright nearby narrow line Syfert 1 (NLS1) galaxy with relatively narrow permitted optical emission lines and a high FeII/H${\beta}$ ratio, while Arp 102B is a nearby broad-line radio galaxy with broad double-peaked Balmer emission lines. The spectra of Ark 564 were observed during 11-year period (1999-2009) and the spectra of Arp 102B in the 12-year period (1998-2009), with SAO 6-m and 1-m telescopes (Russia) and the GHAO 2.1-m telescope (Cananea, Mexico).Comment: Presented on "8th Serbian Conference on Spectral Line Shapes in Astrophysics". In revised version minor changes in the tex

Long-term variability of the optical spectra of NGC 4151: II. Evolution of the broad Ha and Hb emission-line profiles

Results of the long-term (11 years, from 1996 to 2006) H$\alpha$ and H$\beta$ line variations of the active galactic nucleus of NGC 4151 are presented. High quality spectra (S/N>50 and R~8A) of H$\alpha$ and H$\beta$ were investigated. We analyzed line profile variations during monitoring period. Comparing the line profiles of H$\alpha$ and H$\beta$, we studied different details (bumps, absorption features) in the line profiles. The variations of the different H$\alpha$ and H$\beta$ line profile segments have been investigated. Also, we analyzed the Balmer decrement for whole line and for line segments. We found that the line profiles were strongly changing during the monitoring period, showing blue and red asymmetries. This indicates a complex BLR geometry of 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. Such variation can be caused by an accelerating outflow starting very close to the black hole, where the red part may come from the region {closer to the black hole than the blue part, which is coming} from the region having the highest outflow velocities. Taking into account the fact that the BLR of NGC 4151 has a complex geometry (probably affected by an outflow) and that a portion of the broad line emission seems to have not a pure photoionization origin, one can ask the question whether the study of the BLR by reverberation mapping may be valid in the case of this galaxy.Comment: 24 pages, 18 figures, accepted for publications in A&

The First Spectroscopically Resolved Sub-parsec Orbit of a Supermassive Binary Black Hole

One of the most intriguing scenarios proposed to explain how active galactic nuclei are triggered involves the existence of a supermassive binary black hole system in their cores. Here we present an observational evidence for the first spectroscopically resolved sub-parsec orbit of a such system in the core of Seyfert galaxy NGC 4151. Using a method similar to those typically applied for spectroscopic binary stars we obtained radial velocity curves of the supermassive binary system, from which we calculated orbital elements and made estimates about the masses of components. Our analysis shows that periodic variations in the light and radial velocity curves can be accounted for an eccentric, sub-parsec Keplerian orbit of a 15.9-year period. The flux maximum in the lightcurve correspond to the approaching phase of a secondary component towards the observer. According to the obtained results we speculate that the periodic variations in the observed H{\alpha} line shape and flux are due to shock waves generated by the supersonic motion of the components through the surrounding medium. Given the large observational effort needed to reveal this spectroscopically resolved binary orbital motion we suggest that many such systems may exist in similar objects even if they are hard to find. Detecting more of them will provide us with insight into black hole mass growth process.Comment: 29 pages, 10 figures, published in ApJ, 759, 11

Long-term variability of the optical spectra of NGC 4151: I. Light curves and flux correlations

Results of a long-term spectral monitoring of the active galactic nucleus of NGC 4151 are presented (11 years, from 1996 to 2006). High quality spectra (S/N>50 in the continuum near Halpha and Hbeta) were obtained in the spectral range ~4000 to 7500 \AA, with a resolution between 5 and 15 A, using the 6-m and the 1-m SAO's telescopes (Russia), the GHAO's 2.1-m telescope (Cananea, Mexico), and the OAN-SPM's 2.1-m telescope (San-Pedro, Mexico). The observed fluxes of the Halpha, Hbeta, Hgamma and HeII emission lines and of the continuum at the observed wavelength 5117 A, were corrected for the position angle, the seeing and the aperture effects. We found that the continuum and line fluxes varied strongly (up to a factor 6) during the monitoring period. The emission was maximum in 1996-1998, and there were two minima, in 2001 and in 2005. The Halpha, Hgamma and He II fluxes were well correlated with the Hbeta flux. We considered three characteristic periods during which the Hbeta and Halpha profiles were similar: 1996-1999, 2000-2001 and 2002-2006. The line to continuum flux ratios were different; in particular during the first period, the lines were not correlated with the continuum and saturated at high fluxes. In the second and third period, where the continuum flux was small, the Halpha and Hbeta fluxes were well correlated to the continuum flux, meaning that the ionizing continuum was a good extrapolation of the optical continuum. The CCFs are often asymmetrical and the time lags between the lines and the continuum are badly defined indicating the presence of a complex BLR, with dimensions from 1 to 50 light-days.Comment: A&A, accepte

Spectral optical monitoring of the double peaked emission line AGN Arp 102B: II. Variability of the broad line properties

We investigate a long-term (26 years, from 1987 to 2013) variability in the broad spectral line properties of the radio galaxy Arp 102B, an active galaxy with broad double-peaked emission lines. We use observations presented in Paper I (Shapovalova et al. 2013) in the period from 1987 to 2011, and a new set of observations performed in 2012--2013. To explore the BLR geometry, and clarify some contradictions about the nature of the BLR in Arp 102B we explore variations in the H$\alpha$ and H$\beta$ line parameters during the monitored period. We fit the broad lines with three broad Gaussian functions finding the positions and intensities of the blue and red peaks in H$\alpha$ and H$\beta$. Additionally we fit averaged line profiles with the disc model. We find that the broad line profiles are double-peaked and have not been changed significantly in shapes, beside an additional small peak that, from time to time can be seen in the blue part of the H$\alpha$ line. The positions of the blue and red peaks { have not changed significantly during the monitored period. The H$\beta$ line is broader than H$\alpha$ line in the monitored period. The disc model is able to reproduce the H$\beta$ and H$\alpha$ broad line profiles, however, observed variability in the line parameters are not in a good agreement with the emission disc hypothesis. It seems that the BLR of Arp 102B has a disc-like geometry, but the role of an outflow can also play an important role in observed variation of the broad line properties.Comment: 17 pages, Accepted for publication in A&

The line parameters and ratios as the physical probe of the line emitting regions in AGN

Here we discuss the physical conditions in the emission line regions (ELR) of active galactic nuclei (AGN), with the special emphasize on the unresolved problems, e.g. the stratification of the Broad Line Region (BLR) or the failure of the photoionization to explain the strong observed optical Fe II emission. We use here different line fluxes in order to probe the properties of the ELR, such as the hydrogen Balmer lines (Ha to He), the helium lines from two subsequent ionization levels (He II 4686 and He I 5876) and the strongest Fe II lines in the wavelength interval 4400-5400 \AA. We found that the hydrogen Balmer and helium lines can be used for the estimates of the physical parameters of the BLR, and we show that the Fe II emission is mostly emitted from an intermediate line region (ILR), that is located further away from the central continuum source than the BLR.Comment: 8 pages, 9 figures, 2 tables, New Astronomy Reviews (Proceeding of 7th SCSLSA), in pres

Spectral optical monitoring of 3C 390.3 in 1995-2007: II. Variability of the spectral line parameters

A study of the variability of the broad emission-line parameters of 3C390.3, an active galaxy with the double-peaked emission-line profiles, is presented. We give a detail analysis of variation in the broad Ha and Hb profiles, the ratios, and the Balmer decrement of different line segments. Studying the variability of the line profiles we explore the disk structure, that is assumed to emit the broad double-peaked Ha and Hb emission lines. We divided the observed spectra in two periods (before and after the outburst in 2002) and analyzed separately the variation in these two periods. First we analyzed the spectral emission-line profiles of Ha and Hb, measuring the peak positions. Then, we divided lines into several segments, and we measured the line-segment fluxes. The Balmer decrement variation for total Ha and Hb fluxes, as well as for the line segments has been investigated and discussed. We modeled the line parameters variation using an accretion disk model. We compared the variability in the observed line parameters with the disk model predictions and found that the variation in line profiles and in line segments corresponds to the emission of a disk-like BLR. But, also there is probably one additional emission component that contributes to the Ha and Hb line center. We found that the variation in the line profiles is caused by the variation in the parameters of the disk-like BLR, first of all in the inner (outer) radius which can well explain the line parameter variations in the Period I. The Balmer decrement across the line profile has a bell-like shape, and it is affected not only by physical processes in the disk, but also by different emitting disk dimension of the Ha and Hb line. The geometry of the BLR of 3C390.3 seems to be very complex, and inflows/outflows might be present, but it is evident that the broad line region with disk-like geometry has dominant emission.Comment: Accepted for publication by A&