Insights on Jet Physics & High-Energy Emission Processes from Optical Polarimetry

1. Insights on Jet Physics & High-Energy Emission Processes from Optical Polarimetry Eric S. Perlman Florida Institute of Technology Collaborators: C. A. Padgett, M. Georganopoulos (UMBC), F. Dulwich, D. M. Worrall, M. Birkinshaw (Bristol), A. S. Wilson (UMCP), W. B. Sparks, J. A. Biretta (STScI), C. O’Dea, S. Baum (RIT) + several others…

2. Radiation Processes in Jets e- B Jet “beam” Inverse-Compton – scattering interaction between photon and a relativistic particle that results in a higher-energy photon. Synchrotron radiation emitted by relativistic particles in magnetic field Radiation from jets emitted by two processes: synchrotron and inverse-Compton. For inverse-Compton, the ‘scattered’ photon can be either from within the jet (often called synchrotron self-Compton) or some external source (e.g, the cosmic microwave background or emission line regions). Important questions: What does the magnetic field configuration look like? Does it change as one goes up in energy? What clues can the magnetic field configuration and ordering give us to radiation and physical mechanisms involved in producing high-energy emissions?

3. Perlman et al. 1999

4. Comparing jet width in Radio, optical, X-rays… X-ray jet is narrowest Optical jet is next Radio jet is widest

5. Perlman & Wilson 2005

7. Stratified jet… High energy particles nearer jet axis Low energy particles evenly distributed B gets compressed, becomes  to jet in shocks inside jet Shocks accelerate particles, so they brighten optical emission but not radio Further development of magnetic field depends on two scale lengths: Magnetic field coherence length lB Synchrotron cooling length lcool Perlman et al. 1999 lB = lcool Perlman, Georganopoulos & Kazanas, in progress lB=2lcool

8. 3C15 Optical and radio jet roughly similar but optical jet narrower 2 knots in X-ray, one coincident with knot C, the other not coincident with radio/opt (A’) Knot A’ X-ray max corresponds to a feature seen in UV but not in any other r/o band

11. 3C 15 • Polarimetry differences more subtle than M87 • In all X-ray maxima, there are interesting radio-optical polzn differences in the neighborhood • Resolution marginal • Optical spectrum hardens too • But still indicate stratification • 2-component plasma, relativistic spine, slower sheath • Knot C is a torsional compression of the jet where X-ray emission is triggered

12. 3C 264 • Wide-angle tail type source. • Bend about 4” from nucleus • Optical emission dims markedly after 1” • X-ray emission both from inner jet as well as optically fainter outer jet

15. 3C 264 • Resolution of Chandra data too low to firmly associate inner jet X-ray emission with optical feature • But polarization anomalies at 0.8” from nuclueus, just up-stream of “ring” • Outer jet emission -- optically faint, hard to tell

16. 3C 346 • Kinked jet seen in both radio and optical • Major bend may be the result of the passage of a companion galaxy • X-ray emission from ~0.3” before kink • Major change in polarization characteristics near kink

18. 3C 346 • Increase in polarization near X-ray maximum. • Small rotation in position angles, only in optical, at that point. • Hardening of optical spectrum at X-ray max. • Synchrotron X-ray emission with associated compression?

19. 3C 371

21. 3C 371 • Optical shows low polarization in 2 X-ray maxima, high polarization in one. • Significant rotations seen in optical also • Neither is seen in radio

22. Summary • In all cases, *something* happens in polarimetry at loci of X-ray emission • What happens appears different in each jet and each component • Usually associated with an increase in radio-optical polarimetry differences • Optical spectrum seems to harden at X-ray flux max • X-ray emission from only a small part of jet “cross-section” • Optical Polarimetry can serve as a diagnostic for X-ray emission mechanism • This is crying out to be done for higher-power jets!