The VLBA Imaging and Polarimetry Survey at 5 GHz
We present the first results of the VLBA Imaging and Polarimetry Survey (VIPS), a 5 GHz VLBI survey of 1127 sources with flat radio spectra. Through automated data reduction and imaging routines, we have produced publicly available I, Q, and U images and have detected polarized flux density from 37% of the sources. We have also developed an algorithm to use each source's I image to automatically classify it as a pointlike source, a core jet, a compact symmetric object (CSO) candidate, or a complex source. Using data from the Sloan Digital Sky Survey (SDSS), we have found no significant trend between optical flux and 5 GHz flux density for any of the source categories. Using the velocity width of the Hβ emission line and the monochromatic luminosity at 5100 Å to estimate the central black hole mass, M_(BH), we have found a weak trend between M_(BH) and 5 GHz luminosity density for objects with SDSS spectra. The mean ratio of the polarized to total 5 GHz flux density for VIPS sources with detected polarized flux density ranges from 1% to 20% with a median value of about 5%. We have also found significant evidence that the directions of the jets in core-jet systems tend to be perpendicular to the electric vector position angles (EVPAs). The data are consistent with a scenario in which ~24% of the polarized core jets have EVPAs that are antialigned with the directions of their jet components and that have a substantial amount of Faraday rotation. In addition to these initial results, plans for future follow-up observations are discussed.
Additional Information© 2007 The American Astronomical Society. Received 2006 October 17; accepted 2006 November 14. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. Information regarding SCHED can be found at http://www.aoc.nrao.edu/_cwalker/sched/sched/sched.html. The Web site for the 5GHzVLA/VLBA Polarization Calibration database is http://www.vla.nrao.edu/astro/calib/polar/. The authors would like to thank the University of New Mexico and Stanford University for the purchase of Mk 5 disks for the VLBA, which was instrumental in achieving a larger data rate, making this survey possible. Funding for the Sloan Digital Sky Survey (SDSS) and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web site is http://www.sdss.org/. The SDSS is managed by the Astrophysical Research Consortium (ARC) for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, the Astrophysical Institute Potsdam, the University of Basel, the University of Cambridge, Case Western Reserve University, the University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), the Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, the University of Pittsburgh, the University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.
Published - Helmboldt_2007_ApJ_658_203.pdf
Accepted Version - 0611459.pdf