Related papers: Four New BL Lac Surveys: Sampling New Populations
BL Lac Objects (BL Lacs) and Flat Spectrum Radio Quasars (FSRQs) are radio-loud active galaxies (AGNs) whose jets are seen at a small viewing angle (blazars), while Misaligned Active Galactic Nuclei (MAGNs) are mainly radiogalaxies of type…
Observations of blazar jets are shrouded in relativistic effects, thus hindering our understanding of their intrinsic properties and dominant physical processes responsible for their generation, evolution,radiation and particle emission. In…
The most elusive and extreme sub-class of active galactic nuclei (AGNs), known as BL Lac objects, shows features that can only be explained as the result of relativistic effects occurring in jets pointing at a small angle with respect to…
The infrared properties of blazars can be studied from the statistical point of view with the help of sky surveys, like that provided by the Wide-field Infrared Survey Explorer (WISE) and the Two Micron All Sky Survey (2MASS). However,…
We present the analysis of archival data from ROSAT and ASCA of a serendipitous source PKS 2316-423. According to its featureless non-thermal radio/optical continuum, the object has been assumed as a BL Lac candidate in the literature. It…
We study the X-ray spectra of 114 flat-spectrum radio quasars (FSRQ) using the hardness ratios as given in the WGA catalogue of ROSAT sources. This sample includes all WGA FSRQ with high-quality data and comprises about 20 per cent of…
The origin of broad-absorption-line quasars (BAL QSOs) is still an open issue. Accounting for ~20% of the QSO population, these objects present broad absorption lines in their optical spectra generated from outflows with velocities up to…
The observed population of young radio pulsars has grown substantially in recent years due to a combination of large-scale surveys and deep targeted searches. Many of the pulsars are associated with supernova remnants and/or unidentified…
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 put forward a scenario where blazars are classified as flat-spectrum radio quasars, BL Lacs, low synchrotron, or high synchrotron peaked objects according to a varying combination of Doppler boosted radiation from the jet, emission from…
We collected a sample of 661 confirmed and 361 possible BL Lac candidates from the recent catalog of BL Lac objects (Veron-Cetty & Veron 2006). We searched these sources in the recent data release DR5 of the Sloan Digital Sky Survey (SDSS)…
We have collected a large amount of multifrequency data for the objects in the Metsahovi Radio Observatory BL Lacertae sample and computed their spectral energy distributions (SED). This is the first time the SEDs of BL Lacs have been…
The Green Bank Telescope (GBT) is the largest fully steerable radio telescope in the world and is one of our greatest tools for discovering and studying radio pulsars. Over the last decade, the GBT has successfully found over 100 new…
Using three complete, radio flux limited, blazar samples we compare the LogN-LogS and the preliminary radio luminosity function of the general population of BL Lacs to those of the subclass of high energy synchrotron peaked (HBL) BL Lacs.…
We investigate the environments of galaxies around BL Lac objects and FR I radiogalaxies, the alleged parent populations of misaligned sources. We compare the environment of a sample of 50 BL Lac objects at 0.1<z<0.33 with that of a sample…
The first three months of sky-survey operation with the Fermi Gamma Ray Space Telescope (Fermi) Large Area Telescope (LAT) reveals 132 bright sources at |b|>10 deg with test statistic greater than 100 (corresponding to about 10 sigma). Two…
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…
Diffuse radio emission from galaxy clusters in the form of radio halos and relics are tracers of the shocks and turbulence in the intra-cluster medium. The imprints of the physical processes that govern their origin and evolution can be…
Previous analyses of the space densities of extragalactic radio sources have proceeded on the assumption of two populations: flat-spectrum and steep-spectrum objects, compact and extended in radio structure respectively. It is now generally…
The present status of the blazar spectral sequence is discussed, including new findings about blazars selected with different criteria than the original complete radio-samples. Despite extensive searches of blazars "breaking" the sequence,…