325 datasets found

In this paper, we have searched for the Two Micron All Sky Survey (2MASS, Cat. II/246) counterparts of 1434 BL Lacs. 833 of 1434 BL Lacs (58%) have spatially coincident 2MASS...

By using results from the 2MASS observation, the differences between the X-ray selected BL Lac objects (XBLs) and the radio selected ones (RBLs) in the near infrared are...

The 2MASS observations of known BL Lac objects are presented in this paper. The 2MASS associations for 511 BL Lac objects are identified. From the 2MASS near infrared two-color...

We have collected an up-to-date sample of 123 superluminal sources (84 quasars, 27 BL Lac objects and 12 galaxies) and calculated the apparent velocities ({beta}app) for 224...

Here we present the first optical photometric monitoring results of a sample of twelve newly discovered blazars from the ICRF - Gaia CRF astrometric link. The observations were...

Extreme High-frequency BL Lacs (EHBL) feature their synchrotron peak of the broadband spectral energy distribution (SED) at {nu}s>=10^17^Hz. The BL Lac object 1ES 2344+514...

Observational studies of collimation in jets in active galactic nuclei (AGN) are a key to understanding their formation and acceleration processes. We have performed an...

This paper presents the results of a {gamma}-ray likelihood analysis over all the extreme and high synchrotron peak blazars (EHSP and HSP) from the 3HSP catalogue. We...

The Fermi Large Area Telescope (LAT) has detected more than 5000 gamma-ray sources in its first 8 years of operation. More than 3000 of them are blazars. About 60 per cent of...

Machine learning is an automatic technique that is revolutionizing scientific research, with innovative applications and wide use in astrophysics. The aim of this study was to...

We present the 1-100GeV spectral energy distribution (SED) for a population of 148 high-synchrotron-peaked (HSP) blazars recently detected with Fermi-LAT as part of the First...

It is widely believed that the cool gas clouds traced by MgII absorption, within a velocity offset of 5000km/s relative to the background quasar are mostly associated with the...

In its first four years of operation, the Fermi-Large Area Telescope (LAT) detected 3033 {gamma}-ray emitting sources. In the Fermi-LAT Third Source Catalogue (3FGL) about 50...

Blazars are known to show periods of quiescence followed by outbursts visible throughout the electromagnetic spectrum. We present a novel maximum likelihood approach to...

The Fermi-Large Area Telescope (LAT) is currently the most important facility for investigating the GeV {gamma}-ray sky. With Fermi-LAT, more than three thousand {gamma}-ray...

This work is a summary of the X-ray spectral studies of 29TeV (10^12^eV, tera-electron-volt) {gamma}-ray emitting blazars observed with Swift/XRT, especially focusing on sources...

We study the relationship between jet power and accretion for Fermi and non-Fermi blazars. We also compare the relevant parameter. Our main results are: (i) Fermi and non-Fermi...

Based on a large Fermi blazar sample, the blazar sequence (synchrotron peak frequency {nu}peak versus synchrotron peak luminosity L_peak_) is revisited. It is found that there...

By statistically analysing a large sample that includes Fermi-detected blazars (FBs) and non-Fermi-detected blazars (NFBs), we find that there are significant differences...

We present the colour indices V-R of BL Lacertae object PKS 0537-441 on the basis of the photometric data monitored by the Rapid Eye Mounting (REM) telescope located at the ESO...