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Using a self-similar model for the expansion of cocoons surrounding the jets in powerful extragalactic radio sources (type FRII), we investigate the influence of the properties of the gas surrounding these objects on their evolution. The…

Astrophysics · Physics 2007-05-23 Christian R. Kaiser , Paul Alexander

In observations with the Australia Telescope Compact Array we have resolved the radio counterpart of the unusual X-ray binary Cir X-1 into an asymmetric extended structure on arcsecond scales. In order to quantify the asymmetry we have…

Central compact objects (CCOs) constitute a population of radio-quiet, slowly-spinning ($\ge$100 ms) young neutron stars with anomalously high thermal X-ray luminosities. Their spin-down properties imply weak dipole magnetic fields…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Slavko Bogdanov , C. -Y. Ng , Victoria M. Kaspi

We consider evolution properties of galaxies and quasars with steep radio spectrum at the decametre band from the UTR-2 catalogue. The ratios of source's monochromatic luminosities at the decametre and high-frequency bands display the…

Astrophysics of Galaxies · Physics 2016-10-19 Alla Miroshnichenko

Densely time sampled multi-frequency flux measurements of the extreme BL Lac object S5 0716+714 over the past three years allow us to study its broad-band variability, and the detailed underlying physics, with emphasis on the location and…

High Energy Astrophysical Phenomena · Physics 2019-08-16 B. Rani , T. P. Krichbaum , L. Fuhrmann , B. Lott , M. Boettcher , J. A. Zensus

We present radio observations of 19 candidate compact steep-spectrum (CSS) objects selected from a well-defined, complete sample of 52 B2 radio sources of intermediate strength. These observations were made with the VLA A-array at 4.835…

Astrophysics · Physics 2009-11-07 D. J. Saikia , P. Thomasson , R. E. Spencer , F. Mantovani , C. J. Salter , S. Jeyakumar

A small number of double-lobed radio galaxies (17 from our own census of the literature) show an additional pair of low surface brightness `wings', thus forming an overall `X'-shaped appearance. The origin of the wings in these radio…

Astrophysics · Physics 2008-11-26 C. C. Cheung

Many of the compact extragalactic radio sources that are used as fiducial points to define the celestial reference frame are known to have proper motions detectable with long-term geodetic/astrometric Very Long Baseline Interferometry…

Cosmology and Nongalactic Astrophysics · Physics 2013-04-16 A. Moór , S. Frey , S. B. Lambert , O. Titov , J. Bakos

Radio sources of low power are the most common in the universe. Their jets typically move at nonrelativistic velocity and show plume-like morphologies that in many instances appear distorted and bent. We investigate the role of magnetic…

High Energy Astrophysical Phenomena · Physics 2019-01-23 S. Massaglia , G. Bodo , P. Rossi , S. Capetti , A. Mignone

Powerful radio galaxies exist as either compact or extended sources, with the extended sources traditionally classified by their radio morphologies as Fanaroff--Riley (FR) type I and II sources. FRI/II and compact radio galaxies have also…

Astrophysics of Galaxies · Physics 2017-04-26 H. Miraghaei , P. N. Best

Radio galaxies can be seen out to very high redshifts, where in principle they can serve as probes of the early evolution of the Universe. Here we show that for any model of radio-galaxy evolution in which the luminosity decreases with time…

Astrophysics · Physics 2009-10-31 Katherine M. Blundell , Steve Rawlings

The properties of a sample of 31 very powerful classical double radio galaxies with redshifts between zero and 1.8 are studied. The source velocities, beam powers, ambient gas densities, total lifetimes, and total outflow energies are…

Astrophysics · Physics 2007-08-09 Ruth Daly , C. O'Dea , P. Kharb , S. Baum , Kenneth Freeman , Matthew Mory

We have investigated the correlations between optical and radio isophotal position angles for 14302 SDSS galaxies with r magnitudes brighter than 18. All the galaxies are identified with extended FIRST radio sources. For passive early-type…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-12 I. W. A. Browne , R. A. Battye

In conjunction with a previous southern-hemisphere work, we present the largest radio survey of jets from massive protostars to date with high-resolution, ($\sim 0.04^{\prime\prime}$) VLA observations towards two subsamples of massive…

Astrophysics of Galaxies · Physics 2021-03-17 S. J. D. Purser , S. L. Lumsden , M. G. Hoare , S. Kurtz

In order to find a law characterising the decrease of velocity along a jet, five analytical methods are suggested. The first two simple models examine the variation of velocity in the presence of Newton's or Stoke's resistance. The equation…

Astrophysics · Physics 2011-09-20 Lorenzo Zaninetti

Intrinsic emission and absorption lines of QSOs provide several independent probes of the metal abundances in QSO environments. They indicate that the metallicities are typically solar or higher out to redshifts z > 4. These results support…

Astrophysics · Physics 2007-05-23 Fred Hamann

I briefly review our current knowledge of the cosmological evolution of radio sources, and show that the redshift distributions of new complete samples of radio sources confirm the existence of the high-redshift decline in comoving number…

Astrophysics · Physics 2007-05-23 James Dunlop

We present the first systematic search for UV signatures from radio source-driven AGN feedback in Compact Steep Spectrum (CSS) radio galaxies. Owing to their characteristic sub-galactic jets (1-20 kpc projected linear sizes), CSS hosts are…

The simple unification scheme of powerful radio galaxies and quasars, based entirely on the orientation dependent effects, has been confronted with the observed radio structures for 152 radio galaxies and 173 steep spectrum quasars.…

Astrophysics · Physics 2008-02-03 Krzysztof T. Chyzy , Stanislaw Zieba

QSOs and radio-galaxies, together with the CMB, ``normal'' galaxies and clusters, represent the main source of information about the origin and evolution of the Large Scale Structure. They can be used either directly, as tracers of the…

Astrophysics · Physics 2007-05-23 S. Cristiani