ON THE SOURCE OF FARADAY ROTATION IN THE JET OF THE RADIO GALAXY 3C 120

The source of Faraday rotation in the jet of the radio galaxy 3C 120 is analyzed through Very Long Baseline Array observations carried out between 1999 and 2007 at 86, 43, 22, 15, 12, 8, 5, 2, and 1.7 GHz. Comparison of observations from 1999 to 2001 reveals uncorrelated changes in the linear polarization of the underlying jet emission and the Faraday rotation screen: while the rotation measure (RM) remains constant between approximately 2 and 5 mas from the core, the RM-corrected electric vector position angles (EVPAs) of two superluminal components are rotated by almost 90° when compared to other components moving through similar jet locations. On the other hand, the innermost 2 mas experiences a significant change in RM—including a sign reversal—but without variations in the RM-corrected EVPAs. Similarly, observations in 2007 reveal a double sign reversal in RM along the jet, while the RM-corrected EVPAs remain perpendicular to the jet axis. Although the observed coherent structure and gradient of the RM along the jet support the idea that the Faraday rotation is produced by a sheath of thermal electrons that surrounds the emitting jet, the uncorrelated changes in the RM and RM-corrected EVPAs indicate that the emitting jet and the source of Faraday rotation are not closely connected physically and have different configurations for the magnetic field and/or kinematical properties. Furthermore, the existence of a region of enhanced RM whose properties remain constant over three years requires a localized source of Faraday rotation, favoring a model in which a significant fraction of the RM originates in foreground clouds.

[1]  Paul S. Smith,et al.  LOCATION OF γ-RAY FLARE EMISSION IN THE JET OF THE BL LACERTAE OBJECT OJ287 MORE THAN 14 pc FROM THE CENTRAL ENGINE , 2010, 1011.6454.

[2]  R. Zavala,et al.  ARE THERE ROTATION MEASURE GRADIENTS ACROSS ACTIVE GALACTIC NUCLEI JETS? , 2010, 1009.3465.

[3]  M. Inoue,et al.  MULTI-FREQUENCY POLARIMETRY TOWARD S5 0836+710: A POSSIBLE SPINE–SHEATH STRUCTURE FOR THE JET , 2010 .

[4]  A. Broderick,et al.  PARSEC-SCALE FARADAY ROTATION MEASURES FROM GENERAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATIONS OF ACTIVE GALACTIC NUCLEUS JETS , 2010, 1006.5015.

[5]  Paul S. Smith,et al.  FLARING BEHAVIOR OF THE QUASAR 3C 454.3 ACROSS THE ELECTROMAGNETIC SPECTRUM , 2010, 1003.4293.

[6]  Understanding BL Lac objects Structural & kinematic mode changes in the BL Lac object PKS 0735+178 , 2010, 1002.3531.

[7]  R. Laing,et al.  Structure of the magnetoionic medium around the Fanaroff-Riley Class I radio galaxy 3C 449 , 2010, 1002.0811.

[8]  Paul S. Smith,et al.  PROBING THE INNER JET OF THE QUASAR PKS 1510−089 WITH MULTI-WAVEBAND MONITORING DURING STRONG GAMMA-RAY ACTIVITY , 2010, 1001.2574.

[9]  A. Marscher,et al.  UNEXPECTED HIGH BRIGHTNESS TEMPERATURE 140 PC FROM THE CORE IN THE JET OF 3C 120 , 2009, 0912.2192.

[10]  R. Dodson,et al.  VLBA Scientific Memorandum 31: ASTRONOMICAL CALIBRATION OF mm-VLBI USING SOURCE FREQUENCY PHASE REFERENCED OBSERVATIONS , 2009 .

[11]  J. Stil,et al.  A ROTATION MEASURE IMAGE OF THE SKY , 2009 .

[12]  Taylor S. Chonis,et al.  DISK–JET CONNECTION IN THE RADIO GALAXY 3C 120 , 2009, 0909.2051.

[13]  D. Kazanas,et al.  THE INVARIANT TWIST OF MAGNETIC FIELDS IN THE RELATIVISTIC JETS OF ACTIVE GALACTIC NUCLEI , 2009, 0907.3619.

[14]  D. Gabuzda,et al.  Surprising evolution of the parsec-scale Faraday Rotation gradients in the jet of the BL Lac object B1803+784 , 2009, 0905.2368.

[15]  U. Michigan,et al.  ACCEPTED FOR PUBLICATION IN THE ASTROPHYSICAL JOURNAL Preprint typeset using LATEX style emulateapj v. 10/09/06 FULL POLARIZATION SPECTRA OF 3C 279 , 2022 .

[16]  K. Tsinganos,et al.  SYNTHETIC SYNCHROTRON EMISSION MAPS FROM MHD MODELS FOR THE JET OF M87 , 2009, 0901.2634.

[17]  S. Baum,et al.  ROTATION MEASURES ACROSS PARSEC-SCALE JETS OF FANAROFF-RILEY TYPE I RADIO GALAXIES , 2009, 0901.0913.

[18]  R. Blandford,et al.  Stability of relativistic jets from rotating, accreting black holes via fully three-dimensional magnetohydrodynamic simulations , 2008, 0812.1060.

[19]  S. O’Sullivan,et al.  Three-dimensional magnetic field structure of six parsec-scale active galactic nuclei jets , 2008, 0811.4426.

[20]  M. Inoue,et al.  Multifrequency Polarimetry of the NRAO 140 Jet: Possible Detection of a Helical Magnetic Field and Constraints on Its Pitch Angle , 2008, 0806.4233.

[21]  A. Marscher,et al.  Faraday Rotation and Polarization Gradients in the Jet of 3C 120: Interaction with the External Medium and a Helical Magnetic Field? , 2008, 0805.4797.

[22]  S. Croke,et al.  Aligning VLBI images of active galactic nuclei at different frequencies , 2008, 0809.3313.

[23]  Paul S. Smith,et al.  The inner jet of an active galactic nucleus as revealed by a radio-to-γ-ray outburst , 2008, Nature.

[24]  M. Inoue,et al.  Time Variation of the Rotation Measure Gradient in the 3C 273 Jet , 2008, 0806.4231.

[25]  A. Lobanov,et al.  Opacity in compact extragalactic radio sources and its effect on astrophysical and astrometric studies , 2008, 0802.2970.

[26]  M. Bremer,et al.  Superluminal non-ballistic jet swing in the quasar NRAO 150 revealed by mm-VLBI , 2007, 0710.5435.

[27]  T. Krichbaum,et al.  Search for Electron-Positron Annihilation Radiation from the Jet in 3C 120 , 2007 .

[28]  Paul S. Smith,et al.  Multiwaveband Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Correlated Polarization Behavior , 2007, 0705.4273.

[29]  T. Krichbaum,et al.  Jet–cloud collisions in the jet of the Seyfert galaxy NGC 3079 , 2007, astro-ph/0702481.

[30]  Bonn,et al.  The milliarcsecond-scale jet of PKS 0735+178 during quiescence , 2006, astro-ph/0604543.

[31]  J. McKinney.  General relativistic magnetohydrodynamic simulations of the jet formation and large-scale propagation from black hole accretion systems , 2006, astro-ph/0603045.

[32]  J. Krolik,et al.  Magnetically Driven Jets in the Kerr Metric , 2005, astro-ph/0512227.

[33]  J. Wardle,et al.  Concurrent 43 and 86 GHz Very Long Baseline Polarimetry of 3C 273 , 2005, astro-ph/0506243.

[34]  Cosmology,et al.  Faraday Rotation Measure Gradients from a Helical Magnetic Field in 3C 273 , 2005, astro-ph/0505357.

[35]  Paul S. Smith,et al.  Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Jet Kinematics from Bimonthly Monitoring with the Very Long Baseline Array , 2005, astro-ph/0502501.

[36]  K. Tsinganos,et al.  Magnetic collimation of the relativistic jet in M 87 , 2005, astro-ph/0509064.

[37]  Research School of AstronomyAstrophysics,et al.  Interactions of jets with inhomogeneous cloudy media , 2005, astro-ph/0502367.

[38]  K. Hirotani.  Kinetic Luminosity and Composition of Active Galactic Nuclei Jets , 2004, astro-ph/0411087.

[39]  R. Walker,et al.  Modeling the 3C 120 Radio Jet from 1 to 30 Milliarcseconds , 2004, astro-ph/0410720.

[40]  L. Christensen,et al.  Clean Optical Spectrum of the Radio Jet of 3C 120 , 2004, astro-ph/0407128.

[41]  J. Krolik,et al.  Magnetically Driven Accretion in the Kerr Metric. III. Unbound Outflows , 2004, astro-ph/0407092.

[42]  M. Lyutikov,et al.  Polarization and structure of relativistic parsec-scale AGN jets , 2004, astro-ph/0406144.

[43]  D. Gabuzda,et al.  Helical magnetic fields associated with the relativistic jets of four BL Lac objects , 2004, astro-ph/0405394.

[44]  A. Abraham,et al.  Can long-term periodic variability and jet helicity in 3C 120 be explained by jet precession? , 2003, astro-ph/0312407.

[45]  N. Vlahakis,et al.  Magnetic Driving of Relativistic Outflows in Active Galactic Nuclei. I. Interpretation of Parsec-Scale Accelerations , 2003, astro-ph/0310747.

[46]  National Radio Astronomy Observatory,et al.  A View through Faraday’s Fog. II. Parsec-Scale Rotation Measures in 40 Active Galactic Nuclei , 2003, astro-ph/0405534.

[47]  D. Gabuzda,et al.  Parsec-scale Faraday rotation distribution in the BL Lac object 1803+784 , 2003 .

[48]  R. Sutherland,et al.  GPS and CSS Sources — Theory and Modelling , 2003, Publications of the Astronomical Society of Australia.

[49]  K. Tsinganos,et al.  Magnetic collimation of relativistic outflows in jets with a high mass flux , 2002 .

[50]  M. Lister,et al.  Observational evidence for the accretion-disk origin for a radio jet in an active galaxy , 2002, Nature.

[51]  S. Iguchi,et al.  A Helical Magnetic Field in the jet of 3C 273(Session 1:Astrophysical Jets,High-Energy Emission from Accreting Compact Objects,Korea-Japan Seminar) , 2002, astro-ph/0205497.

[52]  D. Meier,et al.  Extraction of Black Hole Rotational Energy by a Magnetic Field and the Formation of Relativistic Jets , 2002, Science.

[53]  I. Agudo,et al.  Evidence for parsec-scale absorption from VSOP observations of the BL Lacertae object 0735+178 , 2001 .

[54]  C. Reynolds,et al.  Faraday rotation in the VLBI core of BL Lacertae , 2001 .

[55]  A. Marscher,et al.  Monthly 43 GHz VLBA Polarimetric Monitoring of 3C 120 over 16 Epochs: Evidence for Trailing Shocks in a Relativistic Jet , 2001, astro-ph/0110133.

[56]  Usa,et al.  Changes in the trajectory of the radio jet in 0735+178? , 2001, astro-ph/0109179.

[57]  J. Benson,et al.  The Structure and Motions of the 3C 120 Radio Jet on Scales of 0.6-300 Parsecs , 2001, astro-ph/0103379.

[58]  R. Zavala,et al.  Time-Variable Faraday Rotation Measures of 3C 273 and 3C 279 , 2001, astro-ph/0103180.

[59]  U. Hertfordshire,et al.  The evidence for jet-cloud interactions in a sample of high-redshift radio galaxies , 2001, astro-ph/0101457.

[60]  D. H. Roberts,et al.  Parsec-Scale Blazar Monitoring: Proper Motions , 2000, astro-ph/0009301.

[61]  Jorstad,et al.  Flashing superluminal components in the jet of the radio galaxy 3C120 , 2000, Science.

[62]  P. Wiita,et al.  Radio Jet Interactions with Massive Clouds , 2000 .

[63]  P. McCulloch,et al.  A Strong Jet-Cloud Interaction in the Seyfert Galaxy IC 5063: VLBI Observations , 2000, astro-ph/0002140.

[64]  G. Taylor.  Magnetic Fields in Quasar Cores. II. , 1999, astro-ph/9911414.

[65]  M. Aloy,et al.  High-Resolution Three-dimensional Simulations of Relativistic Jets , 1999, astro-ph/9906428.

[66]  A. Marscher,et al.  The Twisted Parsec-Scale Structure of 0735+178 , 1999, astro-ph/9901379.

[67]  G. Taylor.  Magnetic Fields in Quasar Cores , 1998 .

[68]  D. Kazanas,et al.  A Cosmic Battery , 1998, astro-ph/9808223.

[69]  A. Marscher,et al.  Subparsec Polarimetric Radio Observations of 3C 120: A Close-up Look at Superluminal Motion , 1998 .

[70]  A. Raga,et al.  Jet-Cloud Interactions and the Brightening of the Narrow-Line Region in Seyfert Galaxies , 1997, astro-ph/9710178.

[71]  D. H. Roberts,et al.  Evidence for Ordered Magnetic Fields in the Quasar Environment , 1997, astro-ph/9704112.

[72]  A. Raga,et al.  Jet Cocoons and the Formation of Narrow Line Clouds in Seyfert Galaxies , 1996, astro-ph/9612051.

[73]  J. Zensus,et al.  Linear Polarization Imaging with Very Long Baseline Interferometry at High Frequencies , 1995 .

[74]  H. Netzer,et al.  Dust in the Narrow-Line Region of Active Galactic Nuclei , 1993 .

[75]  E. Meurs,et al.  The jets of 3C120 , 1989, Nature.

[76]  M. Aller,et al.  Synchrotron emission from shocked relativistic jets. I: The theory of radio-wavelength variability and its relation to superluminal motion , 1989 .

[77]  J. Benson,et al.  Radio morphology of 3C 120 on scales from 0. 5 parsecs to 400 kiloparsecs , 1987 .

[78]  Walter Kieran Gear,et al.  Models for high-frequency radio outbursts in extragalactic sources, with application to the early 1983 millimeter-to-infrared flare of 3C 273. , 1985 .

[79]  R. Laing,et al.  Magnetic fields in extragalactic radio sources. , 1980 .

[80]  D. F. Cioffi,et al.  Internal Faraday rotation effects in transparent synchrotron sources , 1980 .

[81]  Roger D. Blandford,et al.  Relativistic jets as compact radio sources , 1979 .

[82]  B. Burn.  On the Depolarization of Discrete Radio Sources by Faraday Dispersion , 1965 .