Related papers: Is BL Lacertae an "orphan" AGN? Multiband and spec…

High energy observations of extreme BL Lac objects, such as 1ES 0229+200 or 1ES 0347-121, recently focused interest both for blazar and jet physics and for the implication on the extragalactic background light and intergalactic magnetic…

We performed optical spectroscopic monitoring of the BL Lac object AO 0235+164 (z=0.94) with the VLT and TNG telescopes from Aug. 2003 to Dec. 2004, during an extended WEBT campaign. The flux of this source is both contaminated and absorbed…

We present an updated and revised analysis of the relationship between the Hbeta broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness…

Six BL Lac objects from the complete 1 Jy radio-selected sample of 34 objects were observed in Cycle 5 with the HST WFPC2 camera to an equivalent limiting flux of mu_I~26 mag/arcsec^2. Here we report results for the second half of this…

Using the sample of radio selected BL Lacertae objects (RBLs) and X-ray selected BL Lacertae objects (XBLs) presented by Sambruna et al. (1996), we calculated the luminosities of radio, optical and X-ray of each source and made the…

We report on a large HST imaging survey of BL Lac objects, at spatial resolution ~10 times better than previous ground-based surveys. We focus on data reduction and analysis, describing the procedures used to model the host galaxy surface…

Recent analysis of the long term radio lightcurve of the extremely variable BL Lacertae object AO 0235+16 by Raiteri et al. (2001) have revealed the presence of recurrent outbursts in this source with a period of ~ 5.7 +/- 0.5 yr.…

Estimating black hole masses of blazars is still a big challenge. Because of the contamination of jets, using the previously suggested size -- continuum luminosity relation can overestimate the broad line region (BLR) size and black hole…

We have measured multi-band optical flux and colour variations for a sample of 12 low energy peaked blazars on short, day-to-month, timescales. Our sample contains six BL Lacertae objects and six flat spectrum radio quasars. These…

In the last two decades, very-high-energy gamma-ray astronomy has reached maturity: over 200 sources have been detected, both Galactic and extragalactic, by ground-based experiments. At present, Active Galactic Nuclei (AGN) make up about…

We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3-m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in…

Several studies indicate that radio-loud (RL) Active Galactic Nuclei (AGN) are produced only by the most massive black holes (BH), $M_{\rm BH} \sim 10^8$-$10^{10} M_\odot$. This idea has been challenged by the discovery of RL Narrow Line…

We present the scientific goals, the strategy and the first results of the REX project, an effort aimed at creating a sizable and statistically complete sample of Radio Emitting X-ray sources (REX) using the available data from a VLA survey…

We present a uniform and systematic analysis of the 0.6-10 keV X-ray spectra of radio-loud active galactic nuclei (AGN) observed by ASCA. The sample 10 BLRGs, 5 QSRs, 9 NLRGs, and 10 RGs. At soft X-rays, about half of the NLRGs and all of…

We present geometric and dynamical modeling of the broad line region for the multi-wavelength reverberation mapping campaign focused on NGC 5548 in 2014. The dataset includes photometric and spectroscopic monitoring in the optical and…

Among active galactic nuclei, BL Lac objects show extreme properties that have been interpreted as the effect of relativistic beaming on the emission from a plasma jet oriented close to the line of sight. The Doppler amplification of the…

We monitored BL Lacertae frequently during 2014 - 2016 when it was generally in a high state. We searched for intra-day variability for 43 nights using quasi-simultaneous measurements in the B, V, R, and I bands (totaling 143 light curves);…

The physical origin of optical changing-look AGNs (CLAGNs), characterized by the appearance or disappearance of broad emission lines, is thought to be mainly driven by the variation of the black-hole (BH) accretion rate. In this work, we…

We investigate the relationship between accretion rates and the spectral energy distributions (SEDs) of BL Lac objects, using a sample of objects for which published information on the host galaxies, emission-line luminosities, and peak…

We present new optical and near-IR spectroscopy as well as new high dynamic range, arcsecond-resolution VLA radio maps of BL Lacs from the complete radio-selected "1 Jansky" (1Jy) sample (RBLs) for which such data were not previously…