Astrophysical Goal of SAMURAI

Astrophysical Goal: Understand how supermassive black holes (SMBHs) generate ultra-relativistic jets and powerful gamma ray emission.

• How are ultra-relativistic jets generated by SMBHs?
• Use VSOP-2 plus the VLBA to image (in full polarization at 43 GHz) a sample of 15-20 of the most highly variable AGNs with bright jets, each observed approximately once per month over an eight-month period, to determine the maximum values for apparent jet speeds, the stability of the jet nozzles, and the magnetic field structures in the jet-launching regions.
• Measure physical sizes and timescales of flux decline of emission knots in the sub-milliarcsecond jet regions at 43 GHz where they are optically thin. From these values, we will derive separately the true jet speed and viewing angle using the method of Jorstad et al. (2005, AJ, 130, 1418).
• Measure the degree of ordering and mean direction of the magnetic field, both with distance from the SMBH and between the flow axis and jet boundary.
• Apply the newly measured jet properties, including their evolution over time, to test extant models of relativistic jet generation near their parent SMBHs.

• Where and how are high-energy gamma rays produced in jets near SMBHs?
• Match events in the multi-epoch full-polarization SAMURAI images of AGN jets, such as the emergence of a new superluminal knot, with gamma-ray flares observed by Fermi to determine unambiguously the site of the gamma-ray emission within ultra-relativistic AGN jets.
• Use the physical properties of the jet knots derived from SAMURAI imaging, including sizes, energy content, and magnetic fields, to compute the expected gamma-ray flux from each AGN for various models, and compare with the time-variable gamma-ray fluxes measured by Fermi.

• How are ultra-relativistic jets confined and shaped as they propagate away from SMBHs?
• Probe for the first time the transverse magnetic field structure on the smallest scales in SMBH jets.
• Map the Faraday rotation in the jet to probe the magnetic field geometry inside the jet and in its surroundings.
• Measure apparent shift of the jet core with frequency and consequently determine for the jet its magnetic field strength, total intrinsic luminosity, and absolute geometry as well as the SMBH mass.

Hosted by NRAO on behalf of the US VSOP-2 Science Team.