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Blazars are active galactic nuclei (AGN) whose relativistic jets point nearly to the line of sight. Their compact radio structure can be imaged with very long baseline interferometry (VLBI) on parsec scales. Blazars at extremely high…

Astrophysics of Galaxies · Physics 2017-02-12 H. -M. Cao , S. Frey , K. É. Gabányi , Z. Paragi , J. Yang , D. Cseh , X. -Y. Hong , T. An

AIMS. We are studying an unbiased sample of 42 nearby (z < 0.2) BL Lacertae objects with a multi-wavelength approach. The results of VLBI observations were presented in the first paper of this series. In this paper, we study the…

High Energy Astrophysical Phenomena · Physics 2018-11-08 F. D'Ammando , M. Giroletti , S. Rainò

We present the results of nine years of the blazar observing programme at the RATAN-600 radio telescope (2005-2014). The data were obtained at six frequency bands (1.1, 2.3, 4.8, 7.7, 11.2, 21.7 GHz) for 290 blazars, mostly BL Lacs. In…

Astrophysics of Galaxies · Physics 2017-07-26 M. Mingaliev , Yu. Sotnikova , T. Mufakharov , E. Nieppola , M. Tornikoski , J. Tammi , A. Lahteenmaki , R. Udovitskiy , A. Erkenov

Context. The gamma-ray emitting source WISE J141046.00+740511.2 has been associated with a Fermi-LAT detection by crossmatching with Swift/XRT data. It has shown all the canonical observational characteristics of a BL Lac source, including…

We examine the clustering properties of low-power radio galaxies at redshift 0.4<z<0.8, using data from the 2SLAQ Luminous Red Galaxy (LRG) survey. We find that radio-detected LRGs (with optical luminosities of 3-5L* and 1.4GHz radio powers…

Astrophysics · Physics 2009-11-13 David A. Wake , Scott M. Croom , Elaine M. Sadler , Helen M. Johnston

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…

High Energy Astrophysical Phenomena · Physics 2021-12-08 E. U. Iyida , I. O. Eya , F. C. Odo

Blazars are the brightest and most abundant persistent sources in the extragalactic gamma-ray sky. Due to their significance, they are often observed across various energy bands to explore potential correlations between emissions at…

High Energy Astrophysical Phenomena · Physics 2024-01-22 P. Giommi , N. Sahakyan , D. Israyelyan , M. Manvelyan

In the framework of the unification scheme of radio-loud active galactic nuclei, BL Lac objects and quasars are the beamed end-on counterparts of low-power (FRI) and high-power (FRII) radio galaxies, respectively. Some BL Lacs have been…

Astrophysics of Galaxies · Physics 2015-06-18 Natalia Zywucka , Arti Goyal , Marek Jamrozy , Michal Ostrowski , Lukasz Stawarz

The classification of the host galaxies of the radio sources in the 25 deg$^2$ ultimate XMM extragalactic survey south field (XXL-S) is presented. XXL-S was surveyed at 2.1 GHz with the Australia Telescope Compact Array (ATCA) and is thus…

The unification of X-ray and radio selected BL Lacs has been an outstanding problem in the blazar research in the past years. Recent investigations have shown that the gap between the two classes can be filled with intermediate objects and…

Astrophysics · Physics 2011-05-23 V. Beckmann , D. Engels , N. Bade , O. Wucknitz

We present a radio/optical study of a sample of BL Lac objects at arcsecond and milliarcsecond resolution. The sample consists of 30 nearby (z<0.2) BL Lacs, mostly X-ray selected. These nearby objects are weak in the radio, yet we have…

Astrophysics · Physics 2007-05-23 M. Giroletti , G. Giovannini , G. B. Taylor , R. Falomo

We present results from four years of twice-weekly 15 GHz radio monitoring of about 1500 blazars with the Owens Valley Radio Observatory 40 m telescope. Using the intrinsic modulation index to measure variability amplitude, we find that,…

High Energy Astrophysical Phenomena · Physics 2014-01-16 Joseph L. Richards , Talvikki Hovatta , Walter Max-Moerbeck , Vasiliki Pavlidou , Timothy J. Pearson , Anthony C. S. Readhead

We present a catalogue of positions and correlated flux densities of 410 flat-spectrum, compact extragalactic radio sources, previously detected in the AT20G survey. The catalogue spans the declination range -90deg, -40deg and was…

Cosmology and Nongalactic Astrophysics · Physics 2011-06-24 Leonid Petrov , Chris Phillips , Alessandra Bertarini , Tara Murphy , Elaine M. Sadler

This paper reports on the X-ray emission from BL Lacertae during its July 1997 outburst as observed with the Rossi X-ray Timing Explorer (RXTE), compares the RXTE data to previous measurements, and interprets the overall electromagnetic…

Astrophysics · Physics 2022-01-26 G. Madejski , M. Sikora , T. Jaffe , M. Blazejowski , K. Jahoda , R. Moderski

We discuss the optical polarization properties of X-ray selected BL Lacertae objects (XSBLs) as determined from three years of monitoring 37 BL Lac objects and candidates. The observed objects include a complete X-ray flux limited sample…

Astrophysics · Physics 2009-10-22 B. T. Jannuzi , P. S. Smith , R. Elston

Our understanding of the unification of jetted AGNs has advanced greatly as the size of extragalactic sources increased. In the present paper, based on the large sample of radio sources, we compiled 680 blazars (279 FSRQs and 401 BL Lacs)…

Astrophysics of Galaxies · Physics 2021-11-17 E. U. Iyida , I. O. Eya , F. C. Odo

We report on a detailed investigation of the gamma-ray emission from 18 broad line radio galaxies (BLRGs) based on two years of Fermi Large Area Telescope (LAT) data. We confirm the previously reported detections of 3C 120 and 3C 111 in the…

We carried out multi-color optical monitoring of a sample of ten blazars from 2005 to 2011. The sample contains 3 LBLs, 2 IBLs, 4 HBLs, and 1 FSRQ. Our monitoring focused on the long-term variability and the sample included nine BL Lac…

Astrophysics of Galaxies · Physics 2018-08-08 Nankun Meng , Xiaoyuan Zhang , Jianghua Wu , Jun Ma , Xu Zhou

Since mid-2007 we have carried out a dedicated long-term monitoring programme at 15 GHz using the Owens Valley Radio Observatory 40 meter telescope. One of the main goals of this programme is to study the relation between the radio and…

High Energy Astrophysical Phenomena · Physics 2015-06-23 W. Max-Moerbeck , J. L. Richards , T. Hovatta , V. Pavlidou , T. J. Pearson , A. C. S. Readhead , O. G. King , R. Reeves

A list of 205 gamma-ray strong objects was reported recently as a result of a 3-month integration with the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. We attempted identification of these objects, cross-correlating…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Y. Y. Kovalev