The Relationship Between Beam Power and Radio Power for Classical Double
  Radio Sources
  Beam power is a fundamental parameter that describes, in part, the state of a
supermassive black hole system. Determining the beam powers of powerful
classical double radio sources requires substantial observing time, so it would
be useful to determine the relationship between beam power and radio power so
that radio power could be used as a proxy for beam power. A sample of 31
powerful classical double radio sources with previously determined beam and
radio powers are studied; the sources have redshifts between about 0.056 and
1.8. It is found that the relationship between beam power, Lj, and radio power,
P, is well described by Log(Lj) = 0.84 Log(P) + 2.15, where both L_j and P are
in units of 10^(44) erg/s. This indicates that beam power is converted to radio
power with an efficiency of about 0.7%. The ratio of beam power to radio power
is studied as a function of redshift; there is no significant evidence for
redshift evolution of this ratio over the redshift range studied. The
relationship is consistent with empirical results obtained by Cavagnolo et al.
(2010) for radio sources in gas rich environments, which are primarily FRI
sources, and with the theoretical predictions of Willott et al. (1999).
