Astrophys. J., 658, 232-244 (2007/March-3)
Relativistic beaming and the intrinsic properties of extragalactic radio jets.
COHEN M.H., LISTER M.L., HOMAN D.C., KADLER M., KELLERMANN K.I., KOVALEV Y.Y. and VERMEULEN R.C.
Abstract (from CDS):
Relations between the observed quantities for a beamed radio jet, which are the apparent transverse speed and the apparent luminosity (βapp, L), and the intrinsic quantities, which are the Lorentz factor and the intrinsic luminosity (γ, L0), are investigated. The inversion from measured to intrinsic values is not unique, but approximate limits to γ and L0can be found using probability arguments. Roughly half the sources in a flux density-limited, beamed sample have a value of γ close to the measured value of βapp. 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 (βapp, L) data are closely bounded by a theoretical envelope, an ``aspect'' curve for γ=32 and L0=1025 W/Hz. This gives limits to the maximum values of γ and L0in the sample: γmax~32, and L0,max∼1026 W/Hz. No sources with both high values of βapp and low values of L are observed. This is not the result of selection effects due to the observing limits, which are a flux density of S>0.5 Jy and an angular velocity of µ<4 mas/yr. Many of the fastest quasars have a pattern Lorentz factor, γp, that is close to that of the beam, γb, but some of the slow quasars must have γp≪γb. Three of the 10 galaxies in the sample have a superluminal feature, with speeds up to βapp~6. The others are at most mildly relativistic. The galaxies are not off-axis versions of the powerful quasars, but Cygnus A might be an exception.
Galaxies: BL Lacertae Objects: General - Galaxies: Active - Galaxies: Individual: Name: Cygnus A - Galaxies: Jets - Galaxies: Statistics - Galaxies: Quasars: General
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