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.

Context. We present results of long-term (1987-2010) optical spectral monitoring of the broad-line radio galaxy Arp 102B, a prototype of an active galactic nucleus with double-peaked broad emission lines that are commonly assumed to be emitted from an accretion disk. Aims. To explore the structure of the broad-line region (BLR), we analyze the light-curves of the broad Hα and Hβ lines and the continuum flux. We aim to estimate the dimensions of the broad-line emitting regions and the mass of the central black hole. Methods. We used the cross correlation function to find lags between the lines and continuum variations. We investigated the correlation between line and continuum fluxes in more detail and explored periodical variations of the red-to-blue line flux ratio using Lomb-Scargle periodograms. Results. The line and continuum light-curves show several flare-like events. The fluxes in lines and in the continuum show no significant change (around 20%) during the monitored period. We found a weak correlation between the line and continuum flux variation that may indicate that the line variation is weakly connected with the variation of the central photoionization source. In spite of this weak line-continuum correlation, we estimated a time lag for Hβ of about 20 days using various methods. The correlation between the Hβ and Hα flux variation is significantly higher than that between the lines and continuum. During the monitored period, the Hβ and Hα lines show double-peaked profiles, and we found an indication for a periodical oscillation in the red-to-blue flux ratio of the Hα line. The estimated mass of the central black hole is ∼1.1 × 10 8 M , which agrees with the mass estimated from the M-σ * relation.

We report the results of the first long-term optical spectrophotometric monitoring of a binary black hole candidate QSO E1821+643, a low-redshift high-luminosity radio-quiet quasar. In the monitored period the continua and Hγ fluxes changed for around two times, while the Hβ flux changed around 1.4 times. We found the periodical variations in the photometric flux with the periods of 1200, 1850 and 4000 days, and 4500 days periodicity in the spectroscopic variations. However, the periodicity of 4000-4500 days covers only one cycle of variation and should be confirmed with a longer monitoring campaign. There is an indication of the period around 1300 days in the spectroscopic light curves, but with small significance level, while the 1850 days period could not be clearly identified in the spectroscopic light curves.The line profiles have not significantly changed, showing an important red asymmetry and broad line peak redshifted around +1000 km s −1 . However, Hβ shows broader mean profile and has a larger time-lag (τ ∼ 120 days) than Hγ (τ ∼ 60 days). We estimate that the mass of the black hole is ∼ 2.6 × 10 9 M ⊙ .The obtained results are discussed in the frame of the binary black hole hypothesis. To explain the periodicity in the flux variability and high redshift of broad lines we discuss a scenario where dense gas-rich cloudy-like structures are orbiting around a recoiling black hole.is cooled with liquid nitrogen (Amirkhanian et al. 2000). The pixel scale at the CCD is 0.45 ′′ /pixel, that correspons to 7.5×8.5 arcmin field of view. Both bias and dark current frames were taken, while for the flat-filed frames we adopted the morning and evening sky exposures. The software developed at SAO RAS by Vlasyuk (1993) was used for the data reduction. The photometry is done by integrating the signal in the concentric circular apertures of increasing size, that are centered at the baricenter of the measured object.The photometric system of this instrument resemble those of Johnson in B and V filter, and of Cousins in R filter (Cousins 1976). For local photometric standards we used stars of Penston et al. (1971) that are close to the position of E1821+643 on our CCD images, which results with the negligible effects of differential air mass. In Table 1 (available electronically only) the photometric BVR-magnitude for the aperture of 15 ′′ are presented and in Fig. 1 we plotted the light curve in the R-band. Spectral observationsSpectra of E1821+643 (∼140 nights) were acquired with two telescopes (6 m and 1 m) of the SAO RAS, Russia (during 1998Russia (during -2014, one telescope (INAOE's 2.1 m) of the Guillermo Haro Observatory (GHO) Cananea, Sonora, México (during 1998-2007, and two telescopes (3.5 m and 2.2 m) of Calar Alto Observatory (CAO), Spain (during 1990-1994). All spectra were acquired with long-slit spectrographs with CCDs.The representative wavelength interval was from 4000Å to 7500Å, with the spectral resolution between 4.5Å and 15Å, and the S/N ratio >50 in the continuum close to the Hβ line. Every night t...

Aims. We use a sample of 83 core-dominated active galactic nuclei (AGN) selected from the MOJAVE (Monitoring of Jets in AGN with VLBA Experiments) radio-flux-limited sample and detected with the Fermi Large Area Telescope (LAT) to study the relations between non-simultaneous radio, optical, and γ-ray measurements. Methods. We perform a multi-band statistical analysis to investigate the relations between the emissions in different bands and reproduce these relations by modeling of the spectral energy distributions of blazars.Results. There is a significant correlation between the γ-ray luminosity and the optical nuclear and radio (15 GHz) luminosities of blazars. We report a well defined positive correlation between the γ-ray luminosity and the radio-optical loudness for quasars and BL Lacertae type objects (BL Lacs). A strong positive correlation is found between the radio luminosity and the γ-ray-optical loudness for quasars, while a negative correlation between the optical luminosity and the γ-ray-radio loudness is present for BL Lacs. Modeling of these correlations with a simple leptonic jet model for blazars indicates that variations of the accretion disk luminosity (and hence the jet power) is able to reproduce the trends observed in most of the correlations. To reproduce all observed correlations, variations of several parameters, such as the accretion power, jet viewing angle, Lorentz factor, and magnetic field of the jet, are required.

Aims. We study the correlations between the VLBA (Very Long Baseline Array) radio emission at 15 GHz, extended emission at 151 MHz, and optical nuclear emission at 5100 Å for a complete sample of 135 compact jets. Methods. We use the partial Kendall's tau correlation analysis to check the link between radio properties of parsec-scale jets and optical nuclear luminosities of host active galactic nuclei (AGN). Results. We find a significant positive correlation for 99 quasars between optical nuclear luminosities and total radio (VLBA) luminosities of unresolved cores at 15 GHz originated at milliarcseconds scales. For 18 BL Lacs, the optical continuum emission correlates with the radio emission of the jet at 15 GHz. We suggest that the radio and optical emission are beamed and originate in the innermost part of the sub-parsec-scale jet in quasars. Analysis of the relation between the apparent speed of the jet and the optical nuclear luminosity at 5100 Å supports the relativistic beaming model for the optical emission generated in the jet, and allows the peak values of the intrinsic optical luminosity of the jet and its Lorentz factor to be estimated for the populations of quasars (2 × 10 20 W Hz −1 and γ = 52), BL Lacs (9 × 10 21 W Hz −1 and γ = 20), and radio galaxies (1.5 × 10 21 W Hz −1 and γ = 9). The radio-loudness of quasars (the ratio of 15 GHz flux density and optical nuclear flux at 5100 Å) is found to increase at high redshifts, which is interpreted as progressively higher Doppler factors in radio regime compared to those in optical. A strong positive correlation is found between the intrinsic kinetic power of the jet (measured from the flux density at 151 MHz) and the apparent luminosities of the total and the unresolved core emission of the jet at 15 GHz. This correlation is interpreted in terms of an intrinsically more luminous parsec-scale jet producing more luminous extended structure, which is detectable at low radio frequencies, 151 MHz. A possibility that the low frequency radio emission is relativistically beamed in superluminal sources and therefore correlates with radio luminosity of the jet at 15 GHz cannot be ruled out. Monitoring of superluminal AGN in a wide range of frequencies is required to check the contribution of each effect.

Context. We investigate the 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 in the period from 1987 to 2011, and a new set of observations performed in 2012-2013. Aims. We explore variations in the Hα and Hβ line parameters during the monitored period to explore the broad-line region (BLR) geometry and to clarify some contradictions about the nature of the BLR in Arp102B. Methods. We fit the broad lines with three broad Gaussian functions finding the positions and intensities of the blue and red peaks in Hα and Hβ. Additionally, we fit averaged line profiles with the disk model. Results. 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 Hα line. The positions of the blue and red peaks have not changed significantly during the monitored period. The Hβ line is broader than Hα line in the monitored period. The disk model is able to reproduce the Hβ and Hα broad line profiles, however, observed variability in the line parameters are not in good agreement with the emission disk hypothesis. Conclusions. It seems that the BLR of Arp 102B has a disk-like geometry, but the role of an outflow can also play an important role in observed variation of the broad line properties.

We study the Baldwin Effect (BE) in 96 core-jet blazars with optical and ultraviolet spectroscopic data from a radio-loud AGN sample obtained from the MOJAVE 2 cm survey. A statistical analysis is presented of the equivalent widths (W λ ) of emission lines Hβ λ4861, Mg II λ2798, C IV λ1549, and continuum luminosities at 5100Å, 3000Å, and 1350Å. The BE is found statistically significant (with confidence level c.l. ≥ 95%) in Hβ and C IV emission lines, while for Mg II the trend is slightly less significant (c.l. = 94.5%). The slopes of the BE in the studied samples for Hβ and Mg II are found steeper and with statistically significant difference than those of a comparison radio-quiet sample. We present simulations of the expected BE slopes produced by the contribution to the total continuum of the non-thermal boosted emission from the relativistic jet, and by variability of the continuum components. We find that the slopes of the BE between radio-quiet and radio-loud AGN should not be different, under the assumption that the broad line is only being emitted by the canonical broad line region around the black hole. We discuss that the BE slope steepening in radio AGN is due to a jet associated broad-line region.

A significant minority of high redshift radio galaxy (HzRG) candidates show extremely red broad band colours and remain undetected in emission lines after optical 'discovery' spectroscopy. In this paper we present deep GTC optical imaging and spectroscopy of one such radio galaxy, 5C 7.245, with the aim of better understanding the nature of these enigmatic objects. Our g-band image shows no significant emission coincident with the stellar emission of the host galaxy, but does reveal faint emission offset by ∼3 ′′ (26 kpc) therefrom along a similar position angle to that of the radio jets, reminiscent of the 'alignment effect' often seen in the optically luminous HzRGs. This offset g-band source is also detected in several UV emission lines, giving it a redshift of 1.609, with emission line flux ratios inconsistent with photoionization by young stars or an AGN, but consistent with ionization by fast shocks. Based on its unusual gas geometry, we argue that in 5C 7.245 we are witnessing a rare (or rarely observed) phase in the evolution of quasar hosts when stellar mass assembly, accretion onto the back hole, and powerful feedback activity has eradicated its cold gas from the central ∼20 kpc, but is still in the process of cleansing cold gas from its extended halo.