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相关论文: On the Unified View of Extragalactic Sources based…

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The concept of the evolutionary sequence of jetted active galactic nuclei (AGNs) has been challenged in the last few decades since AGN subclasses are considered to be different due to their viewing angle. In this paper, we collected a…

星系天体物理 · 物理学 2022-01-26 Evaristus U. Iyida , Christian I. Eze , Finbarr C. Odo

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…

高能天体物理现象 · 物理学 2021-12-08 E. U. Iyida , I. O. Eya , F. C. Odo

We use the distributions of spectral indices of a large homogenous sample of Fermi-detected blazars to re-investigate the relationship between flat spectrum radio quasars (FSRQs) and subclasses of BL Lac objects (BL Lacs). We compute the…

高能天体物理现象 · 物理学 2020-07-20 E. U. Iyida , F. C. Odo , A. E. Chukwude , A. A. Ubachukwu

Based on the classical unification, blazars, namely BL Lacertae objects (BL Lacs) and flat-spectrum radio quasars (FSRQs), are believed to correspond with radio galaxies when observed at small jet viewing angles. In this paper, we aim to…

A radio study of a carefully selected sample of 20 Seyfert galaxies that are matched in orientation-independent parameters, which are measures of intrinsic active galactic nuclei (AGN) power and host galaxy properties is presented to test…

宇宙学与河外天体物理 · 物理学 2015-05-27 Dharam V. Lal , Prajval Shastri , Denise Gabuzda

(abridged) We present a comprehensive study of a sample of 23 genuine radio-loud NLS1 galaxies which have the radio-loudness parameters greater than 100. The radio sources of the sample are ubiquitously compact. A significant fraction of…

天体物理学 · 物理学 2009-11-13 W. Yuan , H. Y. Zhou , S. Komossa , X. B. Dong , T. G. Wang , H. L. Lu , J. M. Bai

Blazar subclasses ranging from flat-spectrum radio quasars (FSRQs) through low-frequency-peaked BL Lac objects (LBLs) to high-frequency-peaked BL Lac objects (HBLs) exhibit a sequence of increasing spectral hardness with decreasing…

天体物理学 · 物理学 2009-11-06 M. Boettcher , C. D. Dermer

(abridged) We performed a homogeneous and systematic analysis of simultaneous X-ray and optical/UV properties of a group of 15 gamma-ray loud AGN, using observations performed with XMM-Newton. The sample is composed of 13 blazars (6 BL Lac…

Narrow-line Seyfert 1 (NLS1) galaxies are a type of active galactic nuclei (AGN) that were originally classified as sources with little to no radio emission. Although the class is rather unified from an optical perspective, their radio…

星系天体物理 · 物理学 2025-11-26 I. Varglund , E. Järvelä , M. J. Hardcastle , S. Varglund , A. Lähteenmäki

We report on a multiwavelength survey of a sample of 42 flat-spectrum radio-loud narrow-line Seyfert 1 galaxies (RLNLS1s). This is the largest known sample of this type of active galactic nucleus (AGN) to date. We found that 17% of sources…

Narrow-line Seyfert 1 galaxies (NLS1s) are active galactic nuclei (AGN) recently identified as a new class of $\gamma$-ray sources. The high energy emission is explained by the presence of a relativistic jet observed at small angles, just…

We present a new accurate sample of narrow-line Seyfert 1 galaxies (NLS1s) in the southern hemisphere from the Six-degree Field Galaxy Survey (6dFGS). Based on the optical spectral features, 167 sources were classified as NLS1s. We derived…

星系天体物理 · 物理学 2018-09-19 S. Chen , M. Berton , G. La Mura , E. Congiu , V. Cracco , L. Foschini , J. H. Fan , S. Ciroi , P. Rafanelli , D. Bastieri

We have carried out an analysis of the radio and optical properties of a statistical sample of 45 Seyfert galaxies from the Palomar spectroscopic survey of nearby galaxies. We find that the space density of bright galaxies (-22 mag <=…

天体物理学 · 物理学 2009-11-06 James S. Ulvestad , Luis C. Ho

We have conducted a multiwavelength survey of 42 radio loud narrow-1ine Seyfert 1 galaxies (RLNLS1s), selected by searching among all the known sources of this type and omitting those with steep radio spectra. We analyse data from radio…

We construct samples of jetted active galactic nuclei (AGNs) with low-frequency radio data from the recent released TGSS AD1 catalog at 150 MHz. With these samples, we compare the properties of jet power for blazars, radio-loud narrow-line…

宇宙学与河外天体物理 · 物理学 2019-07-17 Xu-Liang Fan , Qingwen Wu

In this paper we investigate the properties of a sample of six BL Lacs by fitting their spectra using our inhomogeneous jet model with an accelerating, magnetically dominated, parabolic base, which transitions to a slowly decelerating…

高能天体物理现象 · 物理学 2015-06-17 William J. Potter , Garret Cotter

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…

Aims. We present low-frequency radio imaging and spectral properties of a well defined sample of Seyfert galaxies using GMRT 240/610 MHz dual frequency observations. Radio spectra of Seyfert galaxies over 240 MHz to 5.0 GHz are investigated…

宇宙学与河外天体物理 · 物理学 2013-04-23 Veeresh Singh , Prajval Shastri , Ishwara-Chandra C. H. , Ramana Athreya

We present 8.4 GHz VLA A-configuration observations of 87 sources from the mid-infrared-selected AGN sample of Rush et al (1993). These 0.25 arcsec resolution observations allow elongated radio structures tens of parsecs in size to be…

天体物理学 · 物理学 2009-10-31 Andy Thean , Alan Pedlar , Marek J. Kukula , Stefi A. Baum , Christopher P. O'Dea

The phenomenology of gamma-ray bright blazars can be accounted for by a sequence in the source power and intensity of the diffuse radiation field surrounding the relativistic jet. Correspondingly, the equilibrium particle distribution peaks…

天体物理学 · 物理学 2009-10-30 G. Ghisellini , A. Celotti , G. Fossati , L. Maraschi , A. Comastri
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