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We present a study of a sample of 223 radio-loud quasars (up to redshift $<$0.3) in order to investigate their spectral properties. Twenty-six of these radio-loud quasars are identified as Flat Spectrum Radio Quasars (FSRQs) and fifty-four…

High Energy Astrophysical Phenomena · Physics 2019-10-23 Haritma Gaur , Minfeng Gu , S. Ramya , Hengxiao Guo

Flat-spectrum radio-loud Narrow-Line Seyfert 1 galaxies (NLS1s) are a recently discovered class of $\gamma$-ray emitting Active Galactic Nuclei (AGN), that exhibit some blazar-like properties which are explained with the presence of a…

High-energy {\gamma}-rays, which are produced by powerful relativistic jets, are usually associated with blazars and radio galaxies. In the current active galactic nuclei (AGN) paradigm, such jets are almost exclusively launched from…

Astrophysics of Galaxies · Physics 2014-12-24 Emilia Järvelä , Anne Lähteenmäki , Jonathan León-Tavares

High redshift quasars ($z>5$) that also shine brightly at radio wavelengths are unique signposts of supermassive black hole activity in the early universe. However, bright radio sources at $z\ge5$ are extremely rare and therefore we have…

We have exploited LOFAR deep observations of the Lockman Hole field at 150 MHz to investigate the relation between the radio luminosity of star-forming galaxies (SFGs) and their star formation rates (SFRs), as well as its dependence on…

The Very Large Array Sky Survey (VLASS) is observing the entire sky north of $-40^{\circ}$ in the S-band ($2<\nu<4\,$GHz), with the highest angular resolution ($2''.5$) of any all-sky radio continuum survey to date. VLASS will cover its…

The origin of the radio emission in active galactic nuclei (AGN) is still debated. Multiple physical mechanisms can contribute to the spectrum at these frequencies, including relativistic jets, the jet base, outflows, star formation, and…

High Energy Astrophysical Phenomena · Physics 2026-04-01 M. Berton , E. Järvelä , S. Chen , L. Crepaldi , I. Varglund , M. Coloma Puga , A. Jimenez-Gallardo , A. Lähteenmäki , S. Panda , C. Piscitelli , A. Tortosa

Narrow-line Seyfert 1 galaxies (NLS1s) is one of the few classes of active galactic nuclei (AGN) harboring powerful relativistic jets and detected in $\gamma$ rays. NLS1s are well-known X-ray sources. While in non-jetted sources the origin…

Astrophysics of Galaxies · Physics 2019-12-18 M. Berton , V. Braito , S. Mathur , L. Foschini , E. Piconcelli , S. Chen , R. W. Pogge

We present the first wide area (19 deg$^2$), deep ($\approx120-150$ {\mu}Jy beam$^{-1}$), high resolution ($5.6 \times 7.4$ arcsec) LOFAR High Band Antenna image of the Bo\"otes field made at 130-169 MHz. This image is at least an order of…

We present AGN from the Sloan Digital Sky Survey (SDSS) having double-peaked profiles of [OIII] 5007,4959 and other narrow emission-lines, motivated by the prospect of finding candidate binary AGN. These objects were identified by means of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Krista L. Smith , G. A. Shields , E. W. Bonning , C. C. McMullen , D. J. Rosario , S. Salviander

At redshift larger than 3 there is a disagreement between the number of blazars (whose jet is pointing at us) and the number of expected parents (whose jet is pointing elsewhere). Now we strengthen this claim because (i) the number of…

High Energy Astrophysical Phenomena · Physics 2016-07-13 Gabriele Ghisellini , Tullia Sbarrato

To better constrain the hypotheses proposed to explain why only a few quasars are radio loud (RL), we compare the characteristics of 1958 nearby $(z\le 0.3)$ SDSS quasars, covered by the FIRST and NVSS radio surveys. Only 22\% are RL with…

A Faraday rotation measure (RM) catalogue, or RM Grid, is a valuable resource for the study of cosmic magnetism. Using the second data release (DR2) from the LOFAR Two-metre Sky Survey (LoTSS), we have produced a catalogue of 2461…

We analyze radio continuum emission of early-type galaxies with dynamical measurements of central super-massive black hole (SMBH) masses, and well-characterized large-scale environments, but regardless on the exact level of the nuclear…

Astrophysics of Galaxies · Physics 2023-03-08 Anna Wójtowicz , Łukasz Stawarz , C. C. Cheung , Norbert Werner , Dominik Rudka

We conducted an extensive identification and analysis of various morphological classes and subclasses of radio galaxies using the latest high-resolution data from the second data release of the LOFAR Two-Metre Sky Survey (LoTSS DR2). This…

Astrophysics of Galaxies · Physics 2026-04-29 Soumen Kumar Bera , Taotao Fang , Tapan K. Sasmal , M. Kunert-Bajraszewska , Xuelei Chen , Soumen Mondal

In this Letter, the properties of the extended radio emission form SDSS DR7 quasars with $0.4<z<0.8$ is studied. This low redshift sample is useful since any corresponding FIRST radio observations are sensitive enough to detect extended…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Brian Punsly , Shaohua Zhang

Radio-loud high-redshift quasars (RHRQs) provide crucial insights into the evolution of relativistic jets and their connection to the growth of supermassive black holes. Beyond the extensively studied population at $z \ge 5$, the cosmic…

Astrophysics of Galaxies · Physics 2025-12-08 Yingkang Zhang , Ruqiu Lin , Krisztina Perger , Sándor Frey , Tao An , Xiang Ji , Qiqi Wu , Shilong Liao

We have optically identified a sample of 56 featureless continuum objects without significant proper motion from the 2dF QSO Redshift Survey (2QZ). The steep number--magnitude relation of the sample, $n(\bj) \propto 10^{0.7\bj}$, is similar…

The low frequency array (LOFAR), is the first radio telescope designed with the capability to measure radio emission from cosmic-ray induced air showers in parallel with interferometric observations. In the first $\sim 2\,\mathrm{years}$ of…

Instrumentation and Methods for Astrophysics · Physics 2014-06-27 P. Schellart , A. Nelles , S. Buitink , A. Corstanje , J. E. Enriquez , H. Falcke , W. Frieswijk , J. R. Hörandel , A. Horneffer , C. W. James , M. Krause , M. Mevius , O. Scholten , S. ter Veen , S. Thoudam , M. van den Akker , A. Alexov , J. Anderson , I. M. Avruch , L. Bähren , R. Beck , M. E. Bell , P. Bennema , M. J. Bentum , G. Bernardi , P. Best , J. Bregman , F. Breitling , M. Brentjens , J. Broderick , M. Brüggen , B. Ciardi , A. Coolen , F. de Gasperin , E. de Geus , A. de Jong , M. de Vos , S. Duscha , J. Eislöffel , R. A. Fallows , C. Ferrari , M. A. Garrett , J. Grießmeier , T. Grit , J. P. Hamaker , T. E. Hassall , G. Heald , J. W. T. Hessels , M. Hoeft , H. A. Holties , M. Iacobelli , E. Juette , A. Karastergiou , W. Klijn , J. Kohler , V. I. Kondratiev , M. Kramer , M. Kuniyoshi , G. Kuper , P. Maat , G. Macario , G. Mann , S. Markoff , D. McKay-Bukowski , J. P. McKean , J. C. A. Miller-Jones , J. D. Mol , D. D. Mulcahy , H. Munk , R. Nijboer , M. J. Norden , E. Orru , R. Overeem , H. Paas , M. Pandey-Pommier , R. Pizzo , A. G. Polatidis , A. Renting , J. W. Romein , H. Röttgering , A. Schoenmakers , D. Schwarz , J. Sluman , O. Smirnov , C. Sobey , B. W. Stappers , M. Steinmetz , J. Swinbank , Y. Tang , C. Tasse , C. Toribio , J. van Leeuwen , R. van Nieuwpoort , R. J. van Weeren , N. Vermaas , R. Vermeulen , C. Vocks , C. Vogt , R. A. M. J. Wijers , S. J. Wijnholds , M. W. Wise , O. Wucknitz , S. Yatawatta , P. Zarka , A. Zensus

We present near-infrared spectra of young radio quasars [P(1.4GHz) ~ 26-27 W/Hz] selected from the Wide-Field Infrared Survey Explorer. The detected objects have typical redshifts of z ~ 1.6-2.5 and bolometric luminosities ~ 10^47 erg/s.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Minjin Kim , Luis C. Ho , Carol J. Lonsdale , Mark Lacy , Andrew W. Blain , Amy E. Kimball