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Published 1989 | public
Book Section - Chapter

Statistics of superluminal sources

Abstract

The probability density that a randomly selected beamed source lies at angle θ to the line of sight is shown in Fig. 3. For reasonable values of the Lorentz factor, the Doppler boost exponent and the N(S) exponent, p(θ) peaks at a few degrees, well inside the angle for maximum apparent transverse velocity. Theoretical distributions of the apparent transverse velocity are sharply peaked near the maximum possible value, but the observed distribution is peaked at low velocities. Some of the difference is due to the inhomogeneous nature of the sample. BL Lacs have a lower average velocity than quasars. From a purely statistical point of view this might be due to their being the low-θ tail of the quasar distribution; this also would help to explain the rapid intensity variations and high continuum/line ratios. However this explanation is unlikely, because the redshift distributions are so different.

Additional Information

© Springer-Verlag 1989. I am grateful to the Lick Observatory, where some of this work was done, and to Tim Pearson for helpful comments. This work was supported by NSF Grant AST 85-09822.

Additional details

Created:
August 22, 2023
Modified:
February 10, 2024