Related papers: Parameter Correlations and Cosmological Properties…
The recent BeppoSAX observations of the BL Lac objects Mkn 501 and 1ES 2344+514 have shown that the synchrotron spectrum of these objects peaks, in a v-vF(v) representation, at energies at or above 100 keV. One can wonder if these are the…
Blazars are characterized by rapid variability at virtually all wavelengths from radio through TeV gamma-rays. The challenge since their discovery has been to understand the origin of their luminous, apparently nonthermal, nuclear emission.…
Since 2002, the number of detected blazars at E_\gamma > 100 GeV has more than doubled. I study all currently known BL Lac-type objects with published energy spectra. Their intrinsic energy spectra are reconstructed by removing…
Historically, the blazar population has been poorly understood at low frequencies because survey sensitivity and angular resolution limitations have made it difficult to identify megahertz counterparts. We used the LOFAR Two-Metre Sky…
We present two BeppoSAX observations of BL Lacertae as part of a multiwavelength radio-to-TeV campaign. During the first observation we observe a faint Compton spectrum, while during the second, we detect a synchrotron spectrum with the…
Eight optical and four radio observatories have been intensively monitoring the BL Lac object 0716+714 in the last years: 4854 data points have been collected in the UBVRI bands since 1994, while radio light curves extend back to 1978. Many…
The assessment of the relationship between radio continuum luminosity and star formation rate (SFR) is of crucial importance to make reliable predictions for the forthcoming ultra-deep radio surveys and to allow a full exploitation of their…
We are presenting a detailed parameter study of the time-dependent electron injection and kinematics and the self-consistent radiation transport in jets of intermediate and low-frequency peaked BL Lac objects. Using a time-dependent,…
HESS J1943+213 is an unidentified TeV source that is likely a high-frequency-peaked BL Lac (HBL) object but also compatible with a pulsar wind nebula (PWN) nature. Each of these enormously different astronomical interpretations is supported…
The "blazar sequence" posits that the most powerful BL Lacertae objects and flat-spectrum radio quasars should have relatively small synchrotron peak frequencies, nu_peak, and that the least powerful such objects should have the highest…
BL Lacertae objects (BL Lacs) is the dominant population of TeV emitting blazars. In this work, we investigate whether there is any special observational properties for TeV sources. To do so, we will compare the observational properties of…
Blazars have traditionally been separated into two broad categories based upon their optical emission characteristics; BL Lacs, with faint or no emission lines, and flat spectrum radio quasars (FSRQs) with prominent, broad emission lines.…
We present the results of a series of radio, optical, X-ray and gamma-ray observations of the BL Lac object S50716+714 carried out between April 2007 and January 2011. The multi-frequency observations were obtained using several ground and…
BL Lac objects can be extreme in two ways: with their synchrotron emission, peaking beyond 1 keV in their spectral energy distribution, or with their gamma-ray emission, peaking at multi-TeV energies up to and beyond 10-20 TeV, like 1ES…
We have obtained high dynamic range, good natural seeing i' images of BL Lacertae objects (BL Lacs) to search for the AGN host and thus constrain the source redshift. These objects are drawn from a sample of bright flat-spectrum radio…
Average Spectral Energy Distributions (SED) for different subgroups of blazars are derived from available homogeneous (but small) data sets, including the gamma-ray band. Comparing Flat Spectrum Radio Quasars (FSRQ) with BL Lacs extracted…
Statistical analyses are invaluable methods used to understand intrinsic emission processes and the unification of extragalactic radio sources. In this paper, we collected radio, X-ray and {\gamma}-ray data of blazars from the Fermi-LAT and…
A sample of 103 quasars from the Large Bright Quasar Survey (LBQS) has been observed with the VLA at 8.4 GHz to study the evolution of the radio luminosity distribution and its dependence on absolute magnitude. Radio data from pointed…
We investigate the luminosity evolution of the host galaxies of radio-loud AGN through Hubble Space Telescope imaging of 72 BL Lac objects, including new STIS imaging of nine z > 0.6 BL Lacs. With their intrinsically low accretion rates and…
We investigate the spectral properties of blazars detected with the Fermi-Large Area Telescope (LAT) in the high energy regime 100 MeV - 100 GeV. We find that over long timescales a log-parabola provides an adequate description of the…