Bibcode
López-Corredoira, M.; Perucho, M.
Bibliographical reference
Astronomy and Astrophysics, Volume 544, id.A56
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8
2012
Journal
Citations
8
Refereed citations
7
Description
Aims: The MOJAVE (MOnitoring of Jets in AGN with VLBA
Experiments) survey contains 101 quasars with a total of 354 observed
radio components that are different from the radio cores, among which
95% move with apparent projected superluminal velocities with respect to
the core, and 45% have projected velocities larger than 10c (with a
maximum velocity 60c). We try to determine whether this distribution is
statistically probable, and we make an independent measure of the
kinetic power required in the quasars to produce such powerful
ejections. Methods: Doppler boosting effects are analyzed to
determine the statistics of the superluminal motions. We integrate over
all possible values of the Lorentz factor, the values of the kinetic
energy corresponding to each component. The calculation of the mass in
the ejection is carried out by assuming the minimum energy state, i.e.,
that the magnetic field and particle energy distributions are arranged
in the most efficient way to produce the observed synchrotron emission.
This kinetic energy is multiplied by the frequency at which the portions
of the jet fluid identified as "blobs" are produced. Hence, we estimate
the average total power released by the quasars in the form of kinetic
energy in the long term on pc-scales. Results: A selection effect
in which both the core and the blobs of the quasar are affected by huge
Doppler-boosting enhancement increases the probability of finding a jet
ejected within 10 degrees of the line of sight ≳ 40 times above
what one would expect for a random distribution of ejection, which
explains the ratios of the very high projected velocities given above.
The average total kinetic power of each MOJAVE quasar should be very
high to obtain this distribution: ~ 7 × 1047 erg/s.
This amount is much higher than previous estimates of kinetic power on
kpc-scales based on the analysis of cavities in X-ray gas or radio lobes
in samples of objects of much lower radio luminosity but similar black
hole masses. The kinetic power is a significant portion of the Eddington
luminosity, on the order of the bolometric luminosity, and proportional
on average to L0.5rad standing for radio
luminosity, although this correlation might be induced by Malmquist-like
bias.
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