VLA observations of unidentified Leiden-Berkeley Deep-Survey sources - Luminosity and redshift dependence of spectral properties
- JPL, Pasadena, CA (USA) Tata Institute of Fundamental Research, Poona (India)
VLA observations of a complete subset of the Leiden-Berkeley Deep Survey sources that have S(1.4 GHz) greater than 10 mJy and are not optically identified down to F=22 mag are reported. By comparing the spectral and structural properties of the sources with samples from the literature, an attempt was made to disentangle the luminosity and redshift dependence of the spectral indices of extended emission in radio galaxies and of the incidence of compact steep-spectrum sources. It is found that the fraction of compact sources among those with a steep spectrum is related primarily to redshift, being much larger at high redshifts for sources of similar radio luminosity. Only a weak and marginally significant dependence of spectral indices of the extended sources on luminosity and redshift is found in samples selected at 1.4 and 2.7 GHz. It is pointed out that the much stronger correlation of spectral indices with luminosity may be arising partly from spectral curvature, and partly due to the preferential inclusion of very steep-spectrum sources from high redshift in low-frequency surveys. 54 refs.
- OSTI ID:
- 6710817
- Journal Information:
- Astronomical Journal; (USA), Vol. 99; ISSN 0004-6256
- Country of Publication:
- United States
- Language:
- English
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GENERAL PHYSICS
COSMIC RADIO SOURCES
LUMINOSITY
RED SHIFT
CATALOGS
COMPARATIVE EVALUATIONS
MORPHOLOGY
QUASARS
RADIANT FLUX DENSITY
RADIO GALAXIES
RADIOWAVE RADIATION
SPECTRA
SURVEYS
DOCUMENT TYPES
ELECTROMAGNETIC RADIATION
FLUX DENSITY
GALAXIES
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources
640105 - Astrophysics & Cosmology- Galaxies