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Using nearly simultaneous radio, near-infrared, optical, and ultraviolet data collected since 2009, we constructed 106 spectral energy distributions (SEDs) of the blazar OJ 287. These SEDs were well-fitted by a log-parabolic model. By…

We carried a detailed temporal and spectral study of the BL\,Lac by using the long-term \emph{Fermi}-LAT and \emph{Swift}-XRT/UVOT observations, during the period MJD\,59000-59943. The daily-binned $\gamma$-ray light curve displays a…

High Energy Astrophysical Phenomena · Physics 2023-11-16 Zahir Shah

We present new optical and near-IR spectroscopy as well as new high dynamic range, arcsecond-resolution VLA radio maps of BL Lacs from the complete radio-selected "1 Jansky" (1Jy) sample (RBLs) for which such data were not previously…

Astrophysics · Physics 2009-11-06 Travis A. Rector , John T. Stocke

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

The "blazar sequence" posits that the most powerful BL Lacertae objects and flat-spectrum radio quasars should have relatively small synchrotron peak frequencies, nu_peak, and that the least powerful such objects should have the highest…

Astrophysics · Physics 2008-11-26 P. Padovani

A comprehensive statistical analysis of the broadband properties of EGRET blazars is presented. This analysis includes sources identified as blazars in the Sowards-Emmerd publications. Using this sample of 122 sources, we find that there is…

Astrophysics · Physics 2009-11-13 S. D. Bloom

Aims. We aim to determine the redshift (or stringent lower limits) of a number of bright BL Lacs objects. Methods. We secured medium resolution optical and near-infrared spectra of 4 bright BL Lac objects of unknown redshift using the…

Astrophysics of Galaxies · Physics 2014-11-05 Marco Landoni , Renato Falomo , Aldo Treves , Boris Sbarufatti

In this review, recent progress in theoretical models for the broadband (radio through gamma-ray) emission from blazars are summarized. The salient features of both leptonic and hadronic models are reviewed. I present sample modeling…

Cosmology and Nongalactic Astrophysics · Physics 2012-05-03 Markus Boettcher

We have considered all blazars observed in the X-ray band and for which the slope of the X-ray spectrum is available. We have collected 421 spectra of 268 blazars, including 12 archival unpublished ASCA spectra of 7 blazars whose analysisis…

Astrophysics · Physics 2009-11-06 D. Donato , G. Ghisellini , G. Tagliaferri , G. Fossati

We have searched the archived, pointed ROSAT Position Sensitive Proportional Counter data for blazars by correlating the WGACAT X-ray database with several publicly available radio catalogs, restricting our candidate list to serendipitous…

Astrophysics · Physics 2008-11-26 H. Landt , P. Padovani , E. Perlman , P. Giommi , H. Bignall , A. Tzioumis

High synchrotron peak (HSP; $\nu_{sy}^{pk} > 10^{15}$ Hz) BL Lacs are some of the most extreme accelerators in the Universe. Those found at high redshifts ($z>1$) challenge our understanding of blazar evolution models and are crucial for…

High Energy Astrophysical Phenomena · Physics 2020-02-12 M. Rajagopal , L. Marcotulli , M. Ajello , A. Kaur , V. Paliya , D. Hartmann

Single-zone synchrotron self-Compton and external Compton models are widely used to explain broad-band Spectral Energy Distributions (SEDs) of blazars from infrared to gamma-rays. These models bear obvious similarities to the homogeneous…

The spectral properties from radio to optical bands are compared between the 18 optically bright Gamma-ray burst afterglows and well established power-spectrum sequence in Blazars. The comparison shows that the afterglows are well agreement…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 J. Wang , J. Y. Wei

Very high energy (VHE; $E \geq$ 100GeV) $\gamma-$ray from cosmological distances are attenuated by the extragalactic background light (EBL) in the IR to UV band. By contrasting measured versus intrinsic emission, the EBL photon density can…

High Energy Astrophysical Phenomena · Physics 2020-09-01 Longhua Qin , Jiancheng Wang , Quangui Gao , Weiwei Na , Huaizhen Li , Ju Ma , Jianping Yang

We present the soft X-ray (0.1--2.4 keV) properties of a complete sample of 88 southern radio sources derived from the Wall \& Peacock 2-Jy sample. It comprises 68 radio galaxies, 18 quasars and 2 BL Lac objects. Whereas both BL Lac objects…

(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…

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

We present the results of the \textit{Fermi}-LAT 10-years-long light curves (LCs) modeling of selected blazars: six flat spectrum radio quasars (FSRQs) and five BL Lacertae (BL Lacs), examined in 7-, 10-, and 14-day binning. The LCs and…

High Energy Astrophysical Phenomena · Physics 2021-09-24 Mariusz Tarnopolski , Natalia Żywucka , Volodymyr Marchenko , Javier Pascual-Granado

The extragalactic $\gamma$-ray sky is dominated by blazars and their study plays an important role in understanding jet physics, cosmic evolution history and origin of ultra high energy cosmic rays. In this work, we study a large sample of…

High Energy Astrophysical Phenomena · Physics 2022-05-23 Muhammad Shahzad Anjum , Liang Chen , Minfeng Gu

PKS 1424+240 is a distant very high energy gamma-ray BL Lac object with redshift $z=0.601$. It was found that pure synchrotron self-Compton (SSC) process normally need extreme input parameters (e.g., very low magnetic field intensity and…

High Energy Astrophysical Phenomena · Physics 2016-06-15 Shiju Kang , Yong-Gang Zheng , Qingwen Wu , Liang Chen

The spectral energy distribution and variability of several blazars (Mkn 501, 1 ES 2344+51.4, PKS 2155-30.4, 1 ES 1218+30.4, 3C 454.3) along the blazar sequence is investigated using a selfconsistent and timedependent lepto-hadronic hybrid…

High Energy Astrophysical Phenomena · Physics 2011-09-12 Matthias Weidinger , Felix Spanier