The Arcsecond Morphology of Compact Radio Sources

1982 ◽  
Vol 97 ◽  
pp. 175-176
Author(s):  
R. A. Perley
Keyword(s):  
Preliminary Analysis ◽  
Angular Size ◽  
Radio Sources ◽  
Use Of Self ◽  
Extended Structure ◽  
Self Calibration ◽  
Calibration Program ◽  
Calibration Techniques

As part of the VLA calibration program, 404 small angular size sources have been observed in the “A” array at both 6 and 20 cm with resulting resolutions of 0.4′ and 1.2′ respectively. Use of self-calibration techniques has allowed a search for associated extended structure to a level of ∼0.3% of the peak. Here we report preliminary analysis of the results.

COMMENT ON "ANGULAR SIZE TEST ON THE EXPANSION OF THE UNIVERSE," BY M. LÓPEZ-CORREDOIRA

2011 ◽  
Vol 20 (06) ◽  
pp. 1167-1169 ◽  
Author(s):  
D. L. KHOKHLOV
Keyword(s):  
Angular Size ◽  
Radio Sources ◽  
Expansion Of The Universe ◽  
The Difference ◽  
The Universe

The results of the angular size test in the paper under comment are at variance with those for compact radio sources. The possible reason for the difference between the two results is discussed.

scholarly journals 12. The measurement of the distance of the radio sources

1957 ◽  
Vol 4 ◽  
pp. 71-79 ◽  
Author(s):  
R. D. Davies ◽  
D. R. W. Williams
Keyword(s):  
Radio Emission ◽  
Surface Area ◽  
Radio Astronomy ◽  
Angular Size ◽  
Radio Sources ◽  
Absolute Luminosity

In radio astronomy it is becoming increasingly important to know the distance of the radio sources. An identification with astronomical objects observed optically is then more readily obtained and this in turn may allow further investigation of the mechanism of radio emission. A measurement of the distance of sources will also resolve the problem of their distribution in space, showing which are galactic and which are extra-galactic. Furthermore the surface area and absolute luminosity can be estimated from a knowledge of the distance and angular size of a source.

80 MHz Observations of the Coronal Broadening of the Crab Nebula

1970 ◽  
Vol 1 (7) ◽  
pp. 319-320 ◽  
Author(s):  
J. R. Harries ◽  
R. G. Blesing ◽  
P. A. Dennison
Keyword(s):  
Interplanetary Medium ◽  
Crab Nebula ◽  
Angular Size ◽  
Space Vehicles ◽  
Radio Sources ◽  
The Sun ◽  
Amplitude Scintillation ◽  
Interplanetary Plasma ◽  
The Crab Nebula

Regions of the interplanetary medium currently inaccessible to space vehicles may conveniently be studied using the radio scattering properties of the interplanetary plasma. These effects may give rise to angular broadening of radio sources sufficiently close to the Sun, or to amplitude scintillation of sources of small angular size.

scholarly journals Extended Structure in High-Redshift Radio Sources

1982 ◽  
Vol 97 ◽  
pp. 59-60
Author(s):  
P. J. Duffett-Smith ◽  
A. Purvis
Keyword(s):  
Radio Source ◽  
High Redshift ◽  
Radio Sources ◽  
List Type ◽  
Type Number ◽  
Extended Structure ◽  
Structure Changes ◽  
Lower Luminosity ◽  
Source Structure

We have compared measurements of several hundred 3C and 4C radio sources at large redshifts to investigate how radio-source structure changes over a factor of 5–10 in luminosity. Our results show that for z ≳ 0.6: (i)most sources (both 3C and 4C) have hotspots about 3.5 kpc in size (Ho = 50 km s−1 Mpc−1, Ω = 1);(ii)lower-luminosity sources (bottom of 4C) have less-extended outer lobes.

MASS INHOMOGENEITIES AND THE ANGULAR SIZE-REDSHIFT RELATION

2004 ◽  
Vol 13 (07) ◽  
pp. 1309-1313 ◽  
Author(s):  
JAILSON S. ALCANIZ ◽  
JOSÉ A. S. LIMA ◽  
RAIMUNDO SILVA
Keyword(s):  
Dark Energy ◽  
Angular Size ◽  
Matter Density ◽  
Radio Sources ◽  
Density Parameter ◽  
Energy Component ◽  
Dark Energy Component ◽  
Smoothness Parameter ◽  
Best Fit ◽  
Size Data

We investigate the influence of mass inhomogeneities on the angular size-redshift test through a statistical analysis of angular size data for a large sample of milliarcsecond radio sources. The results are based on flat models driven by nonrelativistic matter plus a dark energy component in the form of a relic cosmological constant. To model the mass inhomogeneities we use the Zeldovich–Kantowski distance formula (also known as Dyer–Roeder distance redshift relation) which is characterized by the smoothness parameter α. Marginalizing over the characteristic angular size l and assuming a Gaussian prior on the matter density parameter, i.e., Ωm=0.35±0.07, the best fit model occurs at Ωm=0.35 and α=0.8. For an analysis without priors and minimizing χ2 for the parameters l, Ωm and α we find that a conventional homogeneous scenario (α=1) with Ωm=0.2 and D=22.6h-1 pc constitutes the best fit model for the present angular size data.

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