AAS 200th meeting, Albuquerque, NM, June 2002
Session 45. The New Radio Universe
Display, Tuesday, June 4, 2002, 10:00am-6:30pm, SW Exhibit Hall

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[45.03] Probing the central parsecs of AGN using Faraday Rotation

R.T. Zavala (New Mexico State University, NRAO), G.B. Taylor (NRAO)

A broad frequency range and low instrumental polarization makes the Very Long Baseline Array (VLBA) an ideal instrument for studying polarimetry at sub-milliarcsecond resolution. To take advantage of these unique capabilities we have conducted a multi-frequency polarization survey of 40 radio-loud AGN (Quasars, BL Lacs, and radio galaxies). Our aim is to use Faraday Rotation Measures (RMs) as a probe of the central 1-50 parsecs of these objects. The RM is produced by the line of sight magnetic field weighted by the electron density. Using the electron density established through spectral line diagnostics a magnetic field strength and topology can be estimated within a few parsecs of the central engines of these AGN.

The observations for the survey are complete, and we present the first results for 8 quasars, 5 BL Lacs, and 4 radio galaxies. The magnitudes for the RMs range from several thousand rad m-2 in the quasars and radio galaxies to a few hundred rad m-2 in the BL Lac objects. These values are in agreement with the basic ideas of the unified model for AGN. We also observe variations in the RM on small spatial (\lesssim 1 pc) in radio galaxies and quasars; and short time scales (~ 6 months) in the quasars 3C 273 and 3C 279.

R.T.Z. gratefully acknowledges support from a pre-doctoral research appointment at NRAO and from the New Mexico Alliance for Graduate Education and the Professiorate through NSF grant HRD-0086701.

The author(s) of this abstract have provided an email address for comments about the abstract: rzavala@nrao.edu

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.