scholarly journals A sample of 669 ultra steep spectrum radio sources to find high redshift radio galaxies

2000 ◽  
Vol 143 (2) ◽  
pp. 303-333 ◽  
Author(s):  
C. De Breuck ◽  
W. van Breugel ◽  
H. J.A. Röttgering ◽  
G. Miley
Keyword(s):  
High Redshift ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Spectrum Radio

scholarly journals Spatially resolved studies of extragalactic jets in high redshift radio galaxies

2014 ◽  
Vol 10 (S313) ◽  
pp. 231-235
Author(s):  
Leah K. Morabito ◽  
Adam Deller ◽  
J. B. R. Oonk ◽  
Huub Röttgering ◽  
George Miley
Keyword(s):  
High Redshift ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Spatially Resolved ◽  
Long Baseline ◽  
Early Results ◽  
Spectrum Radio ◽  
Extragalactic Jets ◽  
Frequency Survey

AbstractThe correlation between radio spectral steepness and redshift has been successfully used to find high redshift (z ⩾ 2) radio galaxies, but the origin of this relation is unknown. The ultra-steep spectra of high-z radio sources make them ideally suited for studies with the Low Band Antenna of the new Low Frequency Array, which covers 10–80 MHz and has baselines up to about 1300 km. As part of an ongoing survey, we use the longest baselines to map the low-frequency (< 70 MHz) spatial distributions along the jets of 5 bright extended steep spectrum high-z radio sources. From this, we will determine whether the spectra change over these spatially resolved sources, thereby constraining particle acceleration processes. We present early results from our low-frequency survey of ultra-steep spectrum radio galaxies. The first low frequency long baseline images of these objects are presented.

scholarly journals Radio-optical Identification of Very-Steep Spectrum Radio Sources from the UTR-2 Catalogue

2002 ◽  
Vol 199 ◽  
pp. 217-218 ◽  
Author(s):  
H. Andernach ◽  
O.V. Verkhodanov ◽  
N.V. Verkhodanova
Keyword(s):  
Radio Source ◽  
High Redshift ◽  
Radio Galaxies ◽  
Image Databases ◽  
Radio Continuum ◽  
Radio Sources ◽  
Optical Identification ◽  
X Ray ◽  
Spectrum Radio

We used radio source catalogues accessible from the CATS database to establish radio continuum spectra for decametric radio sources in the UTR-2 catalogue. In an attempt to find further candidates for high-redshift radio galaxies, we searched the FIRST and NVSS surveys for counterparts of a sample of UTR sources with ultra-steep radio spectra (USS, α ≤ −1.2, S ∼ vα). We derived accurate positions and sizes for 23 of these USS sources. The search for optical counterparts from the APM (object) and DSS (image) databases, as well as infrared and X—ray identifications of these UTR sources are in progress.

scholarly journals Multiwavelength characterization of faint ultra steep spectrum radio sources: A search for high-redshift radio galaxies

2014 ◽  
Vol 569 ◽  
pp. A52 ◽  
Author(s):  
V. Singh ◽  
A. Beelen ◽  
Y. Wadadekar ◽  
S. Sirothia ◽  
C. H. Ishwara-Chandra ◽  
...  
Keyword(s):  
High Redshift ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Spectrum Radio

scholarly journals VLBI Morphology of GHz-Peaked Spectrum Radio Galaxies

1994 ◽  
Vol 159 ◽  
pp. 425-425
Author(s):  
D. Dallacasa ◽  
C. Fanti ◽  
R. Fanti
Keyword(s):  
Radio Galaxies ◽  
Radio Sources ◽  
Complete Sample ◽  
Spectrum Radio ◽  
5 Ghz

GHz-Peaked Spectrum (GPS) radio sources are intrinsically small (< 1 kpc) and unbeamed objects. The galaxies considered here (0316+161, 0404+768, 0428+205, 1323+321, 1358+624, 1819+39, 1829+29) have been selected from the Peacock and Wall (1981) catalogue, and belong to a complete sample of Compact Steep-Spectrum (CSS) radio sources (Fanti et al., 1990). Their radio spectra show a turnover which could be explained in terms of synchrotron self-absorption. It occurs at frequencies ranging from about 100 MHz to 5 GHz and for this reason they do not appear in the 3CR catalogue.

scholarly journals Radio Emission from High Redshift Galaxies: VLA Observations of the Hubble Deep Field

1998 ◽  
Vol 179 ◽  
pp. 356-357
Author(s):  
E.A. Richards
Keyword(s):  
Radio Emission ◽  
Small Area ◽  
High Redshift ◽  
Radio Galaxies ◽  
Radio Sources ◽  
High Redshift Galaxies ◽  
Area 5 ◽  
Moderate Power ◽  
Galaxy Populations ◽  
Hubble Deep Field

To study galaxy populations and their evolution at the highest possible redshifts, a small area of the sky, the Hubble Deep Field (HDF) was imaged to an unprecedented sensitivity of R = 29.5 (Williams et al. 1996). As a complement to the HST observations, we have used the VLA at 8 GHz to image an area 5.′4 in diameter (FWHM) centered on the HDF to an rms sensitivity of 2 μJy. With a radio resolution of about 3″, we have 33 sources above 9.5 μJy, seven in the 4 arcmin2 HDF field of which six have clear optical IDs. There are an additional 12 IDs in the HST flanking fields. The optical counterparts of the radio sources are a mixture of ellipticals, spirals, and irregulars, consistent with earlier surveys of comparable depth (Windhorst et al. 1995). With a median redshift <z> ∼ 1, the radio galaxies we are sampling are somewhat more distant than the classical starbursting galaxies which dominate less sensitive radio surveys. Our HDF identifications are predominately with post-starburst galaxies, moderate power AGN, and blue irregulars (Fomalont et al. 1996).

scholarly journals A search for high-redshift quasars among GB/FIRST flat-spectrum radio sources

1998 ◽  
Vol 297 (4) ◽  
pp. 1115-1122 ◽  
Author(s):  
I. M. Hook ◽  
R. H. Becker ◽  
R. G. McMahon ◽  
R. L. White
Keyword(s):  
High Redshift ◽  
Radio Sources ◽  
Spectrum Radio

Steep-Spectrum Radio Sources in Clusters of Galaxies—The Southern Sample

1984 ◽  
Vol 5 (4) ◽  
pp. 516-529 ◽  
Author(s):  
O. B. Slee ◽  
J. E. Reynolds
Keyword(s):  
Radio Galaxies ◽  
High Energy ◽  
Radio Spectrum ◽  
Radio Sources ◽  
Clusters Of Galaxies ◽  
Detailed Review ◽  
X Ray ◽  
High Energy Electrons ◽  
Spectrum Radio ◽  
Inverse Compton

It is well established (e.g. Slee et al. 1983) that radio galaxies near the centres of rich clusters of galaxies tend to have steeper radio spectra than field radio galaxies. The fact that the sources with the steepest spectra occur in clusters that are highly luminous X-ray emitters has generally been interpreted in terms of the confining influence of a hot (~108 K), relatively dense (10-2 to 10-3 electrons cm-3) intra-cluster gas; the confined relativistic plasma then preferentially loses its high-energy electrons through synchrotron and inverse Compton losses, resulting in a steepening of the radio spectrum. A more detailed review of the evidence for this process is given by Robertson (1983).

scholarly journals A Population Study of Faint Compact Steep Spectrum Radio Sources: Self-Similar Growth

2003 ◽  
Vol 20 (1) ◽  
pp. 75-78 ◽  
Author(s):  
Wolfgang Tschager ◽  
Richard Schilizzi ◽  
Huub Röttgering ◽  
Ignas Snellen ◽  
George Miley ◽  
...  
Keyword(s):  
Population Study ◽  
Growth Process ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Self Similarity ◽  
Spectrum Radio ◽  
Wide Range ◽  
Self Similar ◽  
Similar Growth ◽  
Intrinsic Characteristic

AbstractThe main topic of this contribution is the investigation of the morphological self-similarity of the growth process during the gigahertz peaked spectrum (GPS) and compact steep spectrum (CSS) phase of evolving radio galaxies. By investigating a new sample of faint CSS radio sources we establish that self-similar evolution must hold for peaked spectrum sources over a wide range of luminosities as well as physical sizes. Thus, we argue that self-similarity should be regarded as an essential, intrinsic characteristic of the growth process of young radio sources, and be treated as such, and not merely as a supplementary constraint for evolution models.

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