Details

Autor(en) / Beteiligte

• Dagkesamanskii, R.D.

Titel

Spectral Index - Redshift Relation for Radio Galaxies and Quasars

Ist Teil von

• Symposium - International Astronomical Union, 1996, Vol.175, p.569-570

Erscheinungsjahr

1996

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Cosmological evolution of synchrotron spectra of the powerful extragalactic radio sources was studied by many authors. Some indications of such an evolution had been found firstly by analysis of ‘spectral index - flux density’ (α – S ) relation for the sample of relatively strong radio sources. Later Gopal-Krishna and Steppe extended the analysis to weaker sources and found that the slope of α med ( S ) curve changes dramatically at intermediate flux densities. Gopal-Krishna and Steppe pointed out that the maxima of the α med ( S ) curve and of differential source counts are at almost the same flux density ranges (see, Fig. 2). It has to be noticed that the all mentioned results were obtained using the low-frequency spectral indices and on the basis of low frequency samples.