scholarly journals The Radio Properties of a Complete Sample of Bright Galaxies

1982 ◽  
Vol 35 (3) ◽  
pp. 321 ◽  
Author(s):  
JI Harnett
Keyword(s):  
Radio Emission ◽  
Radio Telescope ◽  
Spiral Galaxies ◽  
Radio Continuum ◽  
Spectral Indices ◽  
Radio Luminosity ◽  
Complete Sample ◽  
Luminosity Functions ◽  
The Mean

Results are given for the radio continuum properties of an optically complete sample of 294 bright galaxies, 147 of which have been detected. Data were obtained with the 408 MHz Molonglo Radio Telescope. The radio luminosity functions for all galaxies and for spiral galaxies alone are derived and the radio emission for different galaxy types is investigated. Spectral indices of 73 galaxies which had been detected at other frequencies were derived; the mean index of a reliable subsample is <ex) = -0,71.

scholarly journals Low frequency radio counterparts of HESS J1731−347 a.k.a SNR G353.6−0.7

2017 ◽  
Vol 12 (S331) ◽  
pp. 201-205
Author(s):  
A. J. Nayana ◽  
Poonam Chandra
Keyword(s):  
Radio Emission ◽  
Radio Telescope ◽  
Supernova Remnants ◽  
Low Frequency ◽  
High Energy ◽  
Spectral Indices ◽  
Thermal Radio Emission ◽  
Very High Energy ◽  
Γ Rays ◽  
Very High

AbstractHESS J1731−347 a.k.a. SNR G353.6−0.7 is one of the five known very high energy (VHE, Energy > 0.1 TeV) shell-type supernova remnants. We carried out Giant Metrewave Radio Telescope (GMRT) observations of this TeV SNR in 1390, 610 and 325 MHz bands. We detected the 325 and 610 MHz radio counterparts of the SNR G353.6−0.7 (Nayana et al. 2017). We also determined the spectral indices of individual filaments and our values are consistent with the non-thermal radio emission. We compared the radio morphology with that of VHE emission. The peak in radio emission corresponds to the faintest feature in the VHE emission. We explain this anti-correlated emission in a possible leptonic origin of the VHE γ-rays.

scholarly journals Radio Continuum Spectra of Planetary Nebulae

Galaxies ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 6
Author(s):  
Marcin Hajduk ◽  
Peter van Hoof ◽  
Karolina Sniadkowska ◽  
Andrzej Krankowski ◽  
Leszek Błaszkiewicz ◽  
...  
Keyword(s):  
Radio Emission ◽  
Planetary Nebulae ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Physical Parameters ◽  
Spectral Indices ◽  
Homogeneous Sphere ◽  
Spherical Morphology ◽  
Competing Models ◽  
Source Of Information

Radio continuum emission of planetary nebulae is a rich source of information about their structure and physical parameters. Although radio emission is well studied, planetary nebulae show higher spectral indices than expected for homogeneous sphere. A few competing models exist in the literature to explain this discrepancy. We propose that it is related to non-spherical morphology of most of planetary nebulae.

scholarly journals The Radio Emission of Interacting Galaxies

1982 ◽  
Vol 97 ◽  
pp. 93-94
Author(s):  
E. Hummel ◽  
J. M. van der Hulst ◽  
J. H. van Gorkom ◽  
C. G. Kotanyi
Keyword(s):  
Spiral Galaxies ◽  
Gravitational Interaction ◽  
The Other ◽  
Radio Continuum ◽  
Interacting Galaxies ◽  
Continuum Emission ◽  
Radio Sources ◽  
Complete Sample ◽  
Extended Emission ◽  
Straightforward Interpretation

Gravitational interaction is a straightforward interpretation of some of the peculiar optical morphologies shown by galaxies. There have also been attempts to study the effects of a gravitational interaction on the radio continuum emission. Statistically, the central radio sources (inner 1 kpc) in interacting spiral galaxies are about three times stronger than in isolated spirals; on the other hand, the intensity of the extended emission does not seem to be affected (Stocke, 1978; Hummel, 1981). Peculiar radio morphologies are not a general property of interacting galaxies, since in the complete sample studied by Hummel (1981) of spirals with a probability ≥0.8 of being physically related to their companion, less than 5% have a peculiar radio morphology.

scholarly journals ATCA Radio Polarization Observations of NGC 1566 and NGC 1672

1994 ◽  
Vol 158 ◽  
pp. 358-360
Author(s):  
R. Beck ◽  
M. Ehle ◽  
R. F. Haynes ◽  
J. I. Harnett
Keyword(s):  
Radio Emission ◽  
Southern Hemisphere ◽  
Spiral Galaxies ◽  
Radio Continuum ◽  
Linearly Polarized ◽  
First Time ◽  
Compact Array

NGC 1566 and NGC 1672 have successfully been observed in radio continuum at 6 cm (26″ HPBW) with the Australia Telescope Compact Array (ATCA) using a 375-m array. We have detected for the first time with this telescope linearly polarized radio emission from two southern hemisphere spiral galaxies, NGC 1566 and NGC 1672.

scholarly journals Australian Journal of Physics Astrophysical Supplements Number 22, May 1972

1972 ◽  
Vol 25 (3) ◽  
pp. 339
Author(s):  
REB Munro
Keyword(s):  
Radio Telescope ◽  
Australian Journal ◽  
Radio Sources ◽  
Spectral Indices ◽  
The Mean

Observations at 408 MHz of radio sources from the 4C catalogue. IV. Declination range 20� to 0�. By R. E. B. Munro Abstract. Radio positions and flux densities measured at 408 MHz with the Molonglo radio telescope are given for 1392 sources from the Fourth Cambridge catalogue in the declination range 20� to 0�. The mean spectral indices between 178 and 408 MHz are also considered in the light of these improved flux densities.

Results of a Radio Continuum Survey of Spiral Galaxies at 10.55 GHz

1996 ◽  
Vol 171 ◽  
pp. 424-425
Author(s):  
S. Niklas ◽  
R. Wielebinski ◽  
U. Klein ◽  
J. Braine
Keyword(s):  
Flux Density ◽  
Radio Telescope ◽  
Literature Search ◽  
Spiral Galaxies ◽  
Radio Continuum ◽  
Total Flux ◽  
Observational Methods ◽  
Radio Flux ◽  
Made In

The Revised Shapley-Ames Catalog (Sandage & Tamman, 1981) contains 335 spiral galaxies brighter than BT = 12. A subsample of these galaxies with δ ≥ –25° and total flux densities at 1.49 GHz (Condon, 1987) above 10 mJy were observed at λ2.8 cm using the 100-m radio telescope of the MPIfR Bonn. Depending on the expected flux density and extent of the source two observational methods were used: cross-scanning and mapping. In total, radio flux densities of 192 galaxies have been derived (Niklas et al., 1995). Additionally, a literature search was made in order to get flux densities at other frequencies.

scholarly journals The Role of Environment in the Origin of Radio Emission from Galaxies

1987 ◽  
Vol 121 ◽  
pp. 411-414
Author(s):  
T.K. Menon
Keyword(s):  
Radio Emission ◽  
Compact Group ◽  
Radio Source ◽  
Spiral Galaxies ◽  
Compact Groups ◽  
Radio Radiation ◽  
Luminosity Functions ◽  
Group Galaxy ◽  
Absolute Luminosity

The influence of the environment on the origin of radio radiation from galaxies is studied by compairing the occurence of radio emission in galaxies in compact high density groups of Hickson (1982) with that in field galaxies of similar types. The study shows that the fractional luminosity functions of elliptical and spiral galaxies in compact groups are similar in shape to that of field galaxies but the probability of a compact group galaxy being a radio source is 5 to 10 times greater than that of an isolated galaxy of the same type. Radio Loud group ellipticals tend to be the optically brightest galaxy in the group independent of their absolute luminosity.

scholarly journals The Large Scale Distribution of Radio Continuum in E and SO Galaxies

1978 ◽  
Vol 77 ◽  
pp. 49-55
Author(s):  
R.D. Ekers
Keyword(s):  
Radio Emission ◽  
Radio Source ◽  
Large Scale ◽  
Spiral Galaxies ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
The Other ◽  
Radio Continuum ◽  
Radio Structure ◽  
Similar Morphology

If we look at the radio properties of the nearby ellipticals we find a situation considerably different from that just described by van der Kruit for the spiral galaxies. For example NGC 5128 (Cen A), the nearest giant elliptical galaxy, is a thousand times more powerful a radio source than the brightest spiral galaxies and furthermore its radio emission comes from a multiple lobed radio structure which bears no resemblance to the optical light distribution (e.g. Ekers, 1975). The other radio emitting elliptical galaxies in our neighbourhood, NGC 1316 (Fornax A), IC 4296 (1333–33), have similar morphology. A question which then arises is whether at lower levels we can detect radio emission coming from the optical image of the elliptical galaxies and which may be more closely related to the kind of emission seen in the spiral galaxies.

scholarly journals Radio Emission of 158 Galaxies

1968 ◽  
Vol 21 (2) ◽  
pp. 193 ◽  
Author(s):  
HM Tovmassian
Keyword(s):  
Radio Emission ◽  
Radio Telescope ◽  
Spiral Galaxies ◽  
Radio Observations ◽  
Central Regions ◽  
The University ◽  
East West

Radio observations of Hi8 mainly spiral galaxies have been made at 21 em and additional observations have been made for some at 11 and 75 em. The observations at 11 and 21 cm were made with the CSIR<z 210 ft radio telescope at Parkes and those at 75 cm with the east-west arm of the Mills Cross at the Molonglo Observatory of the University of Sydney. Radio emission was detected from central regions of 20 of the galaxies.

scholarly journals Radio Emission Of The Nuclei Of Barred Spiral Galaxies

1966 ◽  
Vol 19 (6) ◽  
pp. 883 ◽  
Keyword(s):  
Radio Emission ◽  
Radio Telescope ◽  
Radio Astronomy ◽  
Spiral Galaxies ◽  
Astronomy Observatory ◽  
Radio Observations ◽  
Barred Galaxies ◽  
Radio Astronomy Observatory ◽  
Barred Spiral Galaxies

The results of radio observations of 98 barred galaxies at 11, 21, and 75 cm are presented. The observations were carried out with the 210 ft radio telescope of the Australian National Radio Astronomy Observatory and with the Mills Cross of the Sydney Uni

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