Variability at frequencies 3.9 and 7.5 GHz: Radio sources from the Zelenchukskii survey with fluxes >~ 200 mJy

Details Variability at frequencies 3.9 and 7.5 GHz: Radio sources from the Zelenchukskii survey with fluxes >~ 200 mJy Variability at frequencies 3.9 and 7.5 GHz: Radio sources from the Zelenchukskii survey with fluxes >~ 200 mJy

May 1995

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995arep...39..257g&link_type=abstract

Astronomy Reports, Volume 39, Issue 3, May 1995, pp.257-267

Astronomy and Astrophysics

Astronomy

1

Scientific paper

Studies of the statistical character of variability for a complete sample of radio sources from the Zelenchukskii survey have been conducted. One hundred and eighty radio sources with fluxes S_3.9_ > 200 mJy with declination 4^deg^ - 6^deg^ were observed over the course of seven years. Among the sample sources, 46% were identified with optical objects to 21"', and 51% are located in empty fields in the Palomar Survey maps. Thirty percent of the sample sources have variable fluxes with relative amplitudes V = {DELTA}S/ greater than 0.12. The variability of objects having different types of optical identification is considered, The ratio of relative variability amplitudes at 3.9 and 7.5 GHz is 1.2 +/- 0.1, which corresponds to a frequency dependence in the degree of variability V ~ v^0.3^. There is no statistically significant dependence of the relative variability amplitude on flux or visible stellar magnitude. We find that the degree of variability decreases with an increase in absolute radio luminosity and red shift. Such a dependence may be caused either by cosmological "time dilation" or by an actual decrease in the relative variation with an increase in absolute luminosity. Observations over a longer period will permit discrimination between these alternatives.