| Optical polarimetry of the jets of nearby radio galaxies: I. The data (2006) | |||||||||||||
Abstract | |||||||||||||
| Optical Polarimetry the Jets Nearby Radio Galaxies The Data Eric Perlman Padgett Markos Georganopoulos William Sparks John Biretta Christopher Dea Stefi Baum Mark Birkinshaw Worrall Fred Dulwich Sebastian Jester Andr Martel Alessandro Capetti Patrick Leahy arXiv astro Jun ABSTRACT this paper the first series present overview new Hubble Space Telescope HST imaging polarimetry six nearby radio galaxies C and with optical jets These observations triple the number extragalactic jets with subarcsecond resolution optical polarimetry discuss the polarization characteristics each jet and our Stokes images also represent far the deepest optical images yet obtained each these Department Physics Joint Center for Astrophysics University Maryland Baltimore County Hilltop Circle Baltimore USA mail perlman apadgett markos jca umbc edu Department Physics and Astronomy Johns Hopkins University North Charles Street Baltimore USA Laboratory for High Energy Astrophysics NASA Goddard Space Flight Center Code Greenbelt Space Telescope Science Institute San Martin Drive Baltimore USA mail sparks biretta jca umbc edu Current Address Department Physics Rochester Institute Technology Lomb Memorial Drive Rochester USA mail odea cis rit edu Current Address Center for Imaging Science Rochester Institute Technology Lomb Memorial Drive Rochester USA mail baum cis rit edu Wills Physics Laboratory University Bristol Tyndall Avenue Bristol mail Mark Birkinshaw worrall Fred Dulwich bristol Fermilab Box Batavia. In this paper, the first in a series, we present an overview of new Hubble Space Telescope (HST) imaging polarimetry of six nearby radio galaxies (3C 15, 3C 66B, 3C 78, 3C 264, 3C 346, and 3C 371) with optical jets. These observations triple the number of extragalactic jets with subarcsecond-resolution optical polarimetry. We discuss the polarization characteristics of each jet and, as our Stokes I images also represent by far the deepest optical images yet obtained of each of these jets, we also discuss the morphology in total flux of each jet in detail. We find evidence of high optical polarization, averaging 20%, but reaching upwards of 50% in some objects, confirming that the optical emission is synchrotron, and that the components of the magnetic fields perpendicular to the line of sight are well ordered. We find a wide range of polarization morphologies, with each jet having a somewhat different relationship between total intensity and polarized flux and the polarization position angle. We find two trends in all of these jets. First, jet “edges” are very often associated with high fractional optical polarizations, as also found in earlier radio observations of these and other radio jets. In these regions, the magnetic field vectors appear to track the jet direction, even at bends, where we see particularly high fractional polarizations. This indicates a strong link between the local magnetic field and jet dynamics. Second, optical flux maximum regions are usually well separated from maxima in fractional polarization and often are associated with polarization minima. This trend is not found in radio data and was found in our optical polarimetry of M87 with HST. However, unlike in M87, we do not find a general trend for near-90◦ rotations in the optical polarization vectors near flux maxima. We discuss possibilities for interpreting these trends, as well as implications for jet dynamics, magnetic field structure and particle acceleration. (Refer to PDF file for exact formulas). | |||||||||||||
Publication details | |||||||||||||
| |||||||||||||