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Related papers: Radio Polarization of BL Lacertae objects

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Blazars are radio-loud Active Galactic Nuclei (AGN) whose jets have a very small angle to our line of sight. Observationally, the radio emission are mostly compact or a compact-core with a 1-sided jet. With 2.5$^{\prime\prime}$ resolution…

We construct a large sample of gamma-ray blazars with low-frequency radio data using the recent released TGSS AD1 catalog at 150 MHz. The radio/gamma connections of blazars are compared from 143 GHz to 150 MHz. The radio flux density at all…

High Energy Astrophysical Phenomena · Physics 2018-12-26 Xu-Liang Fan , Qingwen Wu

We present deep VLA observations of the polarization of radio sources in the GOODS-N field at 1.4 GHz at resolutions of 1.6" and 10". At 1.6", we find that the peak flux cumulative number count distribution is N($>$p) $\sim$ 45 *…

Astrophysics of Galaxies · Physics 2014-03-31 Lawrence Rudnick , Frazer Owen

We obtained optical imaging polarimetry with the ACS/HRC aboard the HST of the 9 closest radio-galaxies in the 3C catalogue with an FR I morphology. The nuclear sources seen in direct HST images in these galaxies are found to be highly…

A sample of 312 low-frequency peaked BL Lacertae objects (LBLs) and 694 flat spectrum radio quasars (FSRQs) with the parameters both redshift and $\gamma$-ray photon spectral index ($\Gamma _\gamma$) is compiled from the active galactic…

High Energy Astrophysical Phenomena · Physics 2025-03-31 S. Liang , W. G. Yang , Y. G. Zheng , S. J. Kang

(Abridged). We report on the linear polarimetric observations in the Johnson I filter of 44 M6-L7.5 ultracool dwarfs (2800-1400 K). Eleven (10 L and 1 M) dwarfs appear to have significant linear polarization (P = 0.2-2.5%). We have compared…

Astrophysics · Physics 2009-11-10 M. R. Zapatero Osorio , J. A. Caballero , V. J. S. Bejar

A deep radio observation of the A2255 cluster of galaxies has been carried out at 1.4 GHz with the Very Large Array synthesis telescope. Thanks to the excellent (u,v) coverage and sensitivity achieved by our observation, the low brightness…

Blazars can be classified on the basis of their overall Spectral Energy Distribution (SED). BL Lac objects are usually divided in LBL or HBL (Low or High energy peaked BL Lacs), according to the peak frequency of the synchrotron emission,…

The parsec-scale radio properties of 232 active galactic nuclei (AGNs), most of which are blazars, detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long…

High Energy Astrophysical Phenomena · Physics 2015-06-11 J. D. Linford , G. B. Taylor , F. K. Schinzel

The polarized and total flux of the BL Lac object PKS 2155-304 were monitored intensively and simultaneously in the optical UBVRI bands with the Turin photopolarimeter at the CASLEO 2.15 m telescope during 4 campaigns in June, August,…

We have measured multi-band optical flux and colour variations for a sample of 12 low energy peaked blazars on short, day-to-month, timescales. Our sample contains six BL Lacertae objects and six flat spectrum radio quasars. These…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Bindu Rani , Alok C. Gupta , A. Strigachev , R. Bachev , Paul J. Wiita , E. Semkov , E. Ovcharov , B. Mihov , S. Boeva , S. Peneva , B. Spassov , S. Tsvetkova , K. Stoyanov , A. Valcheva

The radio polarization properties of the pulsar population are only superficially captured by the conventional picture of pulsar radio emission. We study the broadband polarization of 271 young radio pulsars, focusing particularly on…

High Energy Astrophysical Phenomena · Physics 2023-01-16 L. S. Oswald , S. Johnston , A. Karastergiou , S. Dai , M. Kerr , M. E. Lower , R. N. Manchester , R. M. Shannon , C. Sobey , P. Weltevrede

Fast radio bursts (FRBs) are transient radio bursts of extragalactic origin characterized by millisecond durations and high luminosities. We report on observations of FRB 20240114A conducted with the Robert C. Byrd Green Bank Telescope…

The RoboPol instrument and the relevant program was developed in order to conduct a systematic study of the optical polarisation variability of blazars. Driven by the discovery that long smooth rotations of the optical polarisation plane…

BL Lacertae has been the target of several observing campaigns by the Whole Earth Blazar Telescope (WEBT) collaboration and is one of the best studied blazars at all accessible wavelengths. A recent analysis of the optical and radio…

We report observations of the linear polarization of a sample of 49 nearby bright stars measured to sensitivities of between ~1 and 4 x 10^-6. The majority of stars in the sample show measurable polarization, but most polarizations are…

Solar and Stellar Astrophysics · Physics 2015-05-18 Jeremy Bailey , P. W. Lucas , J. H. Hough

We monitored BL Lacertae for 13 nights in optical B, V, R, and I bands during October and November 2014 including quasi-simultaneous observations in V and R bands using two optical telescopes in India. We have studied multi-band optical…

Astrophysics of Galaxies · Physics 2015-06-02 Aditi Agarwal , Alok C. Gupta

While scattering of light by atoms and molecules yields large amount of polarization at the B-band of both T- and L-dwarfs, scattering by dust grains in cloudy atmosphere of L-dwarfs gives rise to significant polarization at the far-optical…

Solar and Stellar Astrophysics · Physics 2016-10-04 Sujan Sengupta

The parsec-scale radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been investigated using observations with the Very Long Baseline Array (VLBA). Comparisons between LAT…

High Energy Astrophysical Phenomena · Physics 2012-05-04 J. D. Linford , G. B. Taylor , R. W. Romani , J. F. Helmboldt , A. C. S. Readhead , R. Reeves , J. L. Richards

We present multi-frequency observations of a sample of 15 radio-emitting Broad Absorption Line Quasars (BAL QSOs), covering a spectral range between 74 MHz and 43 GHz. They display mostly convex radio spectra which typically peak at about…

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