Astron. Astrophys. 345, 769-777 (1999)

5. Conclusions

The high-frequency integrated spectrum of CSS sources shows a break with a moderate spectral steepening (), well fitted by the continuous injection model spectrum with constant magnetic field. Spectral fits with synchrotron models with decreasing magnetic field are definitely poorer. There is no evidence of sharp cut-offs as would be expected if the supply of relativistic electrons had stopped more than years ago.

In lobe dominated CSS sources the radiative ages are likely to represent the source ages. Assuming equipartition magnetic field strengths the source ages are in the range of up to years, in agreement with the recent results on expansion velocities of small size CSOs by Owsianik et al. (1998) and Owsianik & Conway (1998) derived from VLBI observations. Therefore, assuming the CSS sources to be young, the magnetic field has been deduced to be equal to the equipartition value within a factor .

In jet or hot spot dominated CSS sources, the radiative life times are much shorter and very likely represent the permanence time of the electrons in those components.

© European Southern Observatory (ESO) 1999

Online publication: April 28, 1999
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