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Related papers: Variability and parsec-scale radio structure of ca…

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Observations of young stellar objects (YSOs) in centimeter bands can probe the continuum emission from growing dust grains, ionized winds, and magnetospheric activity, which are intimately connected to the evolution of protoplanetary disks…

We present a three epoch survey for transient and variables in the extended Chandra Deep Field South at 5.5 GHz with the Australia Telescope Compact Array. A region covering $\sim$0.3 deg$^{2}$ was observed on timescales of 2.5 months and…

Astrophysics of Galaxies · Physics 2015-06-17 M. E. Bell , M. T. Huynh , P. Hancock , Tara Murphy , B. M. Gaensler , D. Burlon , C. Trott , K. Bannister

We observed the thirteen extragalactic radio sources of the complete S5 polar cap sample at 15.4 GHz with the Very Long Baseline Array, on 27 July 1999 (1999.57) and 15 June 2000 (2000.46). We present the maps from those two epochs, along…

Astrophysics · Physics 2007-05-23 M. A. Perez-Torres , J. M. Marcaide , J. C. Guirado , E. Ros

Using three epochs of VLA observations of the Galactic Plane in the first quadrant taken ~15 years apart, we have conducted a search for a population of variable Galactic radio emitters in the flux density range 1-100 mJy at 6 cm. We find…

Astrophysics of Galaxies · Physics 2015-05-18 Robert H. Becker , David J. Helfand , Richard L. White , Deanne D. Proctor

We present results from a large 86GHz global VLBI survey of compact radio sources. The main goal of the survey is to increase by factors of 3--5 the total number of objects accessible for future 3-mm VLBI imaging. The survey observations…

We obtained optical spectra of four objects identified with variable radio sources. Three objects (0029+0554, 0400+0550, 2245+0500) were found to be quasars with redshifts of 1.314, 0.761, and 1.091. One object (2349+0534) has a continuum…

Astrophysics · Physics 2009-11-07 V. Chavushyan , R. Mujica , A. G. Gorshkov , V. K. Konnikova , M. G. Mingaliev

We present first results of a four-epoch VLBA survey for nonthermal emission toward all 556 compact radio sources previously identified in a deep VLA survey of the Orion Nebula Cluster (ONC). We identify VLBA counterparts toward an…

Solar and Stellar Astrophysics · Physics 2021-01-13 Jan Forbrich , Sergio A. Dzib , Mark J. Reid , Karl M. Menten

We have used the Very Long Baseline Array (VLBA) to image five radio-quiet quasars (RQQs) at milliarcsecond resolution, at frequencies between 1.4 and 5 GHz. These quasars have typical total flux densities of a few millijansky at gigahertz…

Astrophysics · Physics 2009-11-10 James S. Ulvestad , Robert R. J. Antonucci , Richard Barvainis

According to hierarchical structure formation models, merging galaxies are expected to be seen in different stages of their coalescence. However, currently there are no straightforward observational methods neither to select nor to confirm…

Astrophysics of Galaxies · Physics 2016-07-29 K. É. Gabányi , T. An , S. Frey , S. Komossa , Z. Paragi , X. -Y. Hong , Z. -Q. Shen

We have observed 28 sources selected from the 1Jy sample of BL Lac objects (Stickel et al. 1991) with the Very Large Array (VLA) in A, B and D configurations at 1.36, 1.66 and 4.85 GHz, and/or with the Westerbork Synthesis Radio Telescope…

Astrophysics · Physics 2009-10-31 P. Cassaro , C. Stanghellini , M. Bondi , D. Dallacasa , R. Della Ceca , R. A. Zappala`

We present a study of the radio variability of bright, $S_{1.4}\geq100$ mJy, high-redshift quasars at $z\geq3$ on timescales up to 30-40 years. The study involved simultaneous RATAN-600 measurements at frequencies of 2.3, 4.7, 8.2, 11.2,…

We present the pc-scale radio spectra of a representative sample of 13 Palomar-Green radio-quiet quasars, based on our new Very Long Baseline Array (VLBA) observations at 8.4 and 23.6 GHz and our earlier VLBA studies at 1.5 and 5.0 GHz. The…

Astrophysics of Galaxies · Physics 2024-12-19 Sina Chen , Ari Laor , Ehud Behar , Ranieri D. Baldi , Joseph D. Gelfand , Amy E. Kimball

Compact Symmetric Objects (CSOs) are a distinct category of jetted active galactic nuclei whose high-energy emission is not well understood. We examined the X-ray characteristics of 17 bona fide CSOs using observations from Chandra,…

High Energy Astrophysical Phenomena · Physics 2025-01-22 Subhashree Swain , C. S. Stalin , Vaidehi S. Paliya , D. J. Saikia

Hybrid sources that present FR I - like jet on the one side of the radio core and FR II - like on the other are rare class of objects that may posses key to understanding the origin of FR division. We presents information connected with the…

Astrophysics of Galaxies · Physics 2015-04-03 Maciej Ceglowski , Marcin Gawronski , Magdalena Kunert-Bajraszewska

We present the results of EVN+MERLIN VLBI polarization observations of 8 Broad Absorption Line (BAL) quasars at 1.6 GHz, including 4 LoBALs and 4 HiBALs with either steep or flat spectra on VLA scales. Only one steep-spectrum source,…

Astrophysics · Physics 2009-11-13 Y. Liu , D. R. Jiang , T. G. Wang , F. G. Xie

The Very Large Array (VLA) has been used in C-configuration to map an area \~0.3 square degrees at 1.4 GHz with 5sigma sensitivities of 0.305, 0.325, 0.380 and 0.450 mJy/beam over four equal subareas. Radio properties are presented for 62…

We present Very Long Baseline Array (VLBA) images of 20 TeV blazars (HBLs) not previously well-studied on the parsec scale. Observations were made between August and December 2013, at a frequency of 8.4 GHz. These observations represent the…

High Energy Astrophysical Phenomena · Physics 2015-06-23 B. Glenn Piner , Philip G. Edwards

This paper presents accurate absolute positions from a 24 GHz Very Long Baseline Array (VLBA) search for compact extragalactic sources in an area where the density of known calibrators with precise coordinates is low. The goals were to…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 L. Petrov , Y. Y. Kovalev , E. B. Fomalont , D. Gordon

Kinematic and spectral studies are improving our knowledge of the age distribution in compact radio sources, providing evidence that small sources are generally very young. The properties of jets in objects spanning the size range from a…

Astrophysics · Physics 2007-07-25 M. Giroletti

We have built a sample of 74 radio-selected broad absorption line quasars from the Sloan Digital Sky Survey Data Release 5 (SDSS DR5) and Faint Images of the Radio Sky at Twenty Centimeters (FIRST), along with a well matched sample of 74…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Michael A. DiPompeo , Michael S. Brotherton , Carlos De Breuck , Sally Laurent-Muehleisen