Abstract
We discuss acceleration measurements for a large sample of extragalactic
radio jets from the Monitoring Of Jets in Active Galactic Nuclei with
VLBA Experiments (MOJAVE) program, which studies the parsec-scale jet
structure and kinematics of a complete, flux-density-limited sample of
active galactic nuclei (AGNs). Accelerations are measured from the
apparent motion of individual jet features or "components" which may
represent patterns in the jet flow. We find that significant
accelerations are common both parallel and perpendicular to the observed
component velocities. Parallel accelerations, representing changes in
apparent speed, are generally larger than perpendicular acceleration
that represent changes in apparent direction. The trend for larger
parallel accelerations indicates that a significant fraction of these
changes in apparent speed are due to changes in intrinsic speed of the
component rather than changes in direction to the line of sight. We find
an overall tendency for components with increasing apparent speed to be
closer to the base of their jets than components with decreasing
apparent speed. This suggests a link between the observed pattern
motions and the underlying flow which, in some cases, may increase in
speed close to the base and decrease in speed further out; however,
common hydrodynamical processes for propagating shocks may also play a
role. About half of the components show "non-radial" motion, or a
misalignment between the component's structural position angle and its
velocity direction, and these misalignments generally better align the
component motion with the downstream emission. Perpendicular
accelerations are closely linked with non-radial motion. When observed
together, perpendicular accelerations are usually in the correct
direction to have caused the observed misalignment.
Original language | English |
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Pages (from-to) | 1253-1268 |
Journal | The Astrophysical Journal |
Volume | 706 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2009 |
MoE publication type | A1 Journal article-refereed |
Keywords
- BL Lacertae objects: general
- galaxies: active
- galaxies: jets
- quasars: general
- radio continuum: galaxies
- surveys