The 2009 Fermi Symposium

Probing the Inner Jet of the Quasar PKS 1510-089 with Multi-waveband Monitoring

Alan Marscher, Boston University

Abstract:

Our multiwaveband (microwave, optical, X-ray, and gamma-ray) monitoring allows us to infer the physical origin of the gamma-ray emission of 1510-089. Multiple flares occur as a superluminal knot (imaged by the VLBA) propagates down the relativistic jet. The knot first follows a spiral path through a toroidal magnetic field in the acceleration zone of the jet, causing the position angle of the optical linear polarization to rotate by as much as 720 degrees. Gamma-ray flares observed by Fermi occurred as the knot encounters local sources of seed photons from either the spine or sheath of the jet. The most spectacular combined gamma/optical flare occurred as a knot passed through the core seen on VLBA images in May 2009. The gamma-ray emission continues as the knot moves downstream of the core. The X-ray emission monitored by RXTE correlates most closely with the microwave variability, leading us to conclude that it arises from Compton scattering of photons from out! side the jet by electrons with energies ∼ 20 mc².