Periodic Structure in the Megaparsec-Scale Jet of PKS 0637-752
MetadataShow full item record
We present 18 GHz Australia Telescope Compact Array imaging of themegaparsec-scale quasar jet PKS 0637-752with angular resolution ~0.58.We draw attention to a spectacular train of quasi-periodic knots along the inner 11of the jet, with average separation ~1.1 arcsec (7.6 kpc projected). We consider two classes of model to explainthe periodic knots: those that involve a static pattern through which the jet plasma travels (e.g., stationary shocks)and those that involve modulation of the jet engine. Interpreting the knots as re-confinement shocks implies thejet kinetic power Qjet ~ 1046 erg s-1, but the constant knot separation along the jet is not expected in a realisticexternal density profile. For models involving modulation of the jet engine, we find that the required modulationperiod is 2×103 yr < t < 3×105 yr. The lower end of this range is applicable if the jet remains highly relativisticon kiloparsec scales, as implied by the IC/CMB model of jet X-ray emission. We suggest that the periodic jetstructure in PKS 0637-752 may be analogous to the quasi-periodic jet modulation seen in the microquasar GRS1915+105, believed to result from limit cycle behavior in an unstable accretion disk. If variations in the accretionrate are driven by a binary black hole, the predicted orbital radius is 0.7 pc a 30 pc, which corresponds to amaximum angular separation of ~0.1–5 mas.
Showing items related by title, author, creator and subject.
Rushton, A.; Miller-Jones, James; Campana, R.; Evangelista, Y.; Paragi, Z.; Maccarone, T.; Pooley, G.; Tudose, V.; Fender, R.; Spencer, R.; Dhawan, V. (2012)We present evidence for the presence of a weak compact jet during a soft X-ray state of Cygnus X-1. Very-high-resolution radio observations were taken with the VLBA, EVN and MERLIN during a hard-to-soft spectral state ...
Reducing the dimensionality of hyperspectral remotely sensed data with applications for maximum likelihood image classificationSantich, Norman Ty (2007)As well as the many benefits associated with the evolution of multispectral sensors into hyperspectral sensors there is also a considerable increase in storage space and the computational load to process the data. ...
Barton, M.; Calo, Victor (2016)We introduce a new concept for generating optimal quadrature rules for splines. To generate an optimal quadrature rule in a given (target) spline space, we build an associated source space with known optimal quadrature ...