Relations between the observed quantities for a beamed radio jet , apparent transverse speed and apparent luminosity ( \beta _ { \mathrm { app } } , L ) , and the intrinsic quantities , Lorentz factor and intrinsic luminosity ( \gamma , L _ { o } ) , are investigated .
The inversion from measured to intrinsic values is not unique , but approximate limits to \gamma and L _ { o } can be found using probability arguments .
Roughly half the sources in a flux density–limited , beamed sample have a value of \gamma close to the measured \beta _ { \mathrm { app } } .
The methods are applied to observations of 119 AGN jets made with the VLBA at 15 GHz during 1994–2002 .
The results strongly support the common relativistic beam model for an extragalactic radio jet .
The ( \beta _ { \mathrm { app } } , L ) data are closely bounded by a theoretical envelope , an aspect curve for \gamma = 32 , L _ { o } = 10 ^ { 25 } W Hz ^ { -1 } .
This gives limits to the maximum values of \gamma and L _ { o } in the sample : \gamma _ { \mathrm { max } } \approx 32 , and L _ { o, \mathrm { max } } \sim 10 ^ { 26 } W Hz ^ { -1 } .
No sources with both high \beta _ { \mathrm { app } } and low L are observed .
This is not the result of selection effects due to the observing limits , which are flux density S > 0.5 Jy , and angular velocity \mu < 4 mas yr ^ { -1 } .
Many of the fastest quasars have a pattern Lorentz factor \gamma _ { p } close to that of the beam , \gamma _ { b } , but some of the slow quasars must have \gamma _ { p } \ll \gamma _ { b } .
Three of the 10 galaxies in the sample have a superluminal feature , with speeds up to \beta _ { \mathrm { app } } \approx 6 .
The others are at most mildly relativistic .
The galaxies are not off–axis versions of the powerful quasars , but ( catalog Cygnus~A ) might be an exception .