Related papers: Interpreting the Variability of Double-Peaked Emis…
Emission lines indicative of active accretion have been seen on a handful of low-mass companions (M < 30 MJup) to stars. Line variability is ubiquitous on stellar accretors but has never been characterized in detail on low-mass companions…
We use data from a two-year intensive RXTE monitoring campaign of the broad-line radio galaxy 3C 390.3 to investigate its stationarity. In order to exploit the potential information contained in a time series more efficiently, we use a…
Spectra taken with HST reveal that NGC 4450 emits Balmer emission lines with displaced double peaks and extremely high-velocity wings. This characteristic line profile, previously seen in a few nearby LINERs and in a small fraction of…
Continuum and emission-line variability of active galactic nuclei provides a powerful probe of microarcsecond scale structures in the central regions of these sources. In this contribution, we review basic concepts and methodologies used in…
We discuss the long-term evolution of the broad double-peaked H alpha profile of the LINER/Seyfert 1 nucleus of NGC 1097. Besides the previously known variation of the relative intensities of the blue and red peaks, the profile has recently…
The variability of the Fe K alpha line near 6.5 keV seems to be reduced compared to the variability of the hard X-rays which presumably drive the line emission. This is observed both in active galactic nuclei and galactic black hole…
Dual epoch spectroscopy of the lenticular galaxy, NGC 4203, obtained with the Hubble Space Telescope (HST) has revealed that the double-peaked component of the broad H{\alpha} emission line profile is time variable, increasing by a factor…
Accretion disks around supermassive black holes in active galactic nuclei produce continuum radiation at ultraviolet and optical wavelengths. Physical processes in the accretion flow lead to stochastic variability of this emission on a wide…
We used the Z-transformed Discrete Correlation Function (ZDCF) and the Stochastic Process Estimation for AGN Reverberation (SPEAR) methods for the time series analysis of the continuum and the H${\alpha}$ and H${\beta}$ line fluxes of a…
[abridged] Extending the work of Czerny et al. (2004), we model the fractional variability amplitude due to distributions of hot spots co-orbiting on the accretion disk around a supermassive black hole. From defined radial distributions,…
A detailed multi-wavelength study of the properties of the triple-peaked AGN Mrk\,622 showing different aspects of the nuclear emission region is presented. Radio, near- and mid-infrared, optical and X-ray data has been considered for the…
We discuss a model of X-ray variability of active galactic nuclei (AGN). We consider multiple spots which originate on the surface of an accretion disk following intense irradiation by coronal flares. The spots move with the disk around the…
We present a sample of 167 type 2 AGNs with double-peaked [O III] 4959,5007 narrow emission lines, selected from the Seventh Data Release of the Sloan Digital Sky Survey. The double-peaked profiles can be well modeled by two velocity…
Double-peaked (DP) broad emission line profiles in active galactic nuclei (AGNs) are often interpreted as signatures of rotating disk-like structures in the broad-line region (BLR) and are commonly observed in low-luminosity AGNs using…
We propose the study of long-term variations in the Fe Kalpha line profile as a discriminator for binary black hole (BH) systems. The existence of a binary BH in the center of an active galaxy will produce a particular signature in the…
Results of the analysis of the variability of the H$\beta$ and H$\alpha$ broad emission-line profiles and the He II $\lambda4686$A emission-line fluxes in the 3C 390.3 nucleus during 1992-2014 are present. The observed velocity-dependent…
Context. Plaskett's star (HD47129) is a very massive O-star binary in a post Roche-lobe overflow stage. CoRoT observations of this system revealed photometric variability with a number of frequencies. Aims. The aim of this paper is to…
Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-95 are presented. The broad-band fluxes (B, V, R, and I), the spectrophotometric optical continuum flux F(5177) and the integrated emission-line fluxes of Ha, Hb, Hg,…
About 3-10\% of Type I active galactic nuclei (AGN) have double-peaked broad Balmer lines in their optical spectra originating from the motion of gas in their accretion disk. Double-peaked profiles arise not only in AGN, but occasionally…
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…