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The MOJAVE AGN Program

The MOJAVE AGN Program. Fermi. Matthew Lister. Chandra. Dept. of Physics Purdue University (currently on sabbatical at Univ. College Cork, Ireland). VLBA. UMRAO. OVRO. MOJAVE Collaborators. M onitoring O f J ets in A ctive Galaxies with V LBA E xperiments.

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The MOJAVE AGN Program

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  1. The MOJAVE AGNProgram • Fermi Matthew Lister Chandra Dept. of Physics Purdue University (currently on sabbatical at Univ. College Cork, Ireland) • VLBA • UMRAO • OVRO

  2. MOJAVE Collaborators Monitoring Of Jets in Active Galaxies with VLBA Experiments • M. Lister (P.I.), N. Cooper, B. Hogan, S. Kuchibhotla, T. Hovatta(Purdue) • T. Arshakian, C.S. Chang, L. Fuhrmann, Y. Kovalev, A. Lobanov, A. Pushkarev, T. Savolainen, J. A. Zensus(Max Planck Inst. for Radioastronomy, Germany) • M. and H. Aller(Michigan) • M. Cohen, A. Readhead(Caltech) • D. Homan (Denison) • M. Kadler, M. Boeck (U. Erlangen-Bamberg, Germany) • K. Kellermann(NRAO) • Y. Kovalev(ASC Lebedev, Russia) • E. Ros(Valencia, Spain) • N. Gehrels, J. McEnery, J. Tueller(NASAGSFC) Very Long Baseline Array Fermi The MOJAVE Program is supported under NASA Fermi Grant NNX08AV67G and NSF grant 0807860-AST.

  3. Outline • The MOJAVE program: present and future • Kinematics of highly beamed AGN jets • parsec-scale radio imaging • connections with gamma-ray emission • Case study: Impact of 8 antenna VLBA array on jet studies

  4. The MOJAVE Program Monitoring Of Jets in Active Galaxies with VLBA Experiments • Regularly taking VLBA images of the ~300 brightest jets in the northern sky • Jet kinematics on decadal timescales • full polarization images provide additional information on jet magnetic fields • Concurrent multiwavelength studies of the sample • Currently funded by the National Science Foundation and NASA http://www.physics.purdue.edu/MOJAVE Lister et al., 2009, AJ, 137, 3718

  5. Scientific Highlights: Jet Kinematics • Motions of superluminal bright features are related to true flow speed • some near-stationary features are seen (6%), more common in lower power BL Lac jets • Most AGN jets are only mildly relativistic (Γ ~ few) • extended tail to speed distribution • some exceedingly rare jets (blazars) have Γ ~ 50 • Fastest jets all have very high synchrotron and gamma-ray luminosity (not likely a beaming effect) Lister et al., 2009, AJ, 138, 1874 Lister et al., 2009, ApJ 696, L22

  6. Scientific Highlights: Accelerations • Accelerations of features are common (at least 50%) in both speed and direction • sudden events: collimation of 3C279 jet • continuous: curved motions around stationary bends • unpredictable: different accelerations/non-accelerations seen in the same jet Homan et al., 2003, ApJ, 589, L9 • Positive (speeding up) accelerations more prevalent close to the base of the jet  jet flows are still becoming organized on parsec scales Homan et al., 2009, ApJ, 706, 1253

  7. 1308+326 Image from March 1996 Recent image: June 2009 Jet Activity States • At any given time, only the energized portion of a broader jet is visible • Activity states of jets evolve over time • long quiescent periods of no jet ejections are seen • new features ejected at new position angles (precession?) • Fermi is preferentially detecting currently active jets (brighter than their historical average radio level) (Kovalev et al. 2009, ApJL 696, L17) Stacked image: 1995-2009 Lister et al., 2009, AJ, 137, 3718

  8. What makes a jet gamma–ray bright? Complex combination of: • Light output peaked at high energy(more important at fainter gamma-ray levels) • Preferred viewing angle (aimed toward us) • Fast intrinsic jet speed (highly beamed) • High current activity state • Blazar gamma-ray emission is directly related to pc-scale radio jet properties

  9. Preliminary • more Doppler boosting in gamma-rays than radio (Lister et al. in prep) • Gamma-ray emission may be intrinsically anisotropic (Savolainen et al. 2010)

  10. Other MOJAVE Studies • Intraday variability (Kuchibhotla, Ph.D. Thesis 2010) • rapid flux variations common in quasars, rare in BL Lacs • origin is likely galactic ISM scattering, but requires compact, highly beamed emitting regions • Chandra survey (Hogan et al. 2010, ApJ in press) • X-ray jets are ubiquitous in blazars with extended radio emission • IC-CMB model requires relativisic jet speeds on kpc-scales • Deep VLA imaging survey (Cooper, Ph.D. Thesis 2010, Kharb et al. 2010, ApJ) • low-energy peaked BL Lacs can have FR I or II jet morphologies

  11. MOJAVE: What’s in store • Kinematics of complete set of gamma-ray blazars • Circular and linear polarization jet evolution • SED and optical spectroscopy analysis • Extension of sample down to 1.5 Jy and dec > -30º • Extended Chandra and EVLA surveys

  12. Case Study: Science Impact of Dropping Two Inner VLBA Antennas • Image quality • total intensity and linear polarization • Model fitting • positions and flux densities of Gaussian fits

  13. Observational Dataset • BL149CP: MOJAVE Program • 24 hour run on Sept 17, 2010 • 15 GHz, 512 Mbps, continuum, dual pol. • 30 compact AGN jets, 0.2 to 16 Jy • scans interleaved to optimize u,v coverage • ~35 min total integration time per source • excellent weather at all 10 sites, minimal downtime • Data were reduced twice: 1. with all antennas 2. with two inner antennas (KP and LA) completely flagged

  14. Image comparison: compact jets 8 antennas 8 antennas 8 antennas 10 antennas 10 antennas 10 antennas

  15. Image comparison: extended jets 8 antennas 8 antennas 8 antennas 10 antennas 10 antennas 10 antennas

  16. Image rms noise slightly higher than theoretical 2 antenna loss • Extended jets suffer higher image rms loss than compact jets Most of extended jet emission lost

  17. Gaussian model fitting • Evolutionary changes in jets are most simply tracked by modeling emission as discrete Gaussians • Positional accuracy: typically ~1/5 beamwidth (0.2 mas)

  18. Comparison: Gaussian component flux densities • Negligible difference for strongest components (> 300 mJy) • Strong difference between 8 and 10 ants. for weaker components

  19. Comparison: Astrometry (con’t) • Typical offset from 10 antenna-fitted position is 0.1 mas • Positional error strongly dependent on flux density of feature Nominal positional accuracy

  20. Recording sensitivity versus u,vcoverage • What would 2X improved VLBA sensitivity look like for AGN jets? • Image using all 10 antennas, flagging 3/4 of all the IFs (10 antennas ¼ of IFs) Full array, low recording bandwidth Colorscale = fractional linear polarization

  21. Recording sensitivity versus u,vcoverage • What would 2X improved VLBA sensitivity look like for AGN jets? • Image using all 10 antennas, flagging no IFs 10 antennas all IFs Full array, high recording bandwidth Colorscale = fractional linear polarization

  22. Recording sensitivity versus u,vcoverage • What would 2X improved VLBA sensitivity look like for AGN jets? • Image using all 8 antennas, flagging no IFs (8 antennas all IFs) Reduced array, high recording bandwidth Colorscale = fractional linear polarization

  23. Summary: • Loss of 2 inner VLBA antennas = 38% loss in available baselines • but higher rise in image noise • 10 antenna VLBA is already a ‘minimum array’ for imaging • Improving recording bandwidth cannot make up for loss of short interferometric baselines • emission on scales > 3 mas becomes invisible to the VLBA (at 15 GHz) • flux and positional measurements significantly degraded for 45% of jet features in MOJAVE survey • strongly affects imaging science capabilities, and will affect astrometry of weaker, less compact features • MOJAVE is a comprehensive program aiming to understand the physics of highly relativistic jets from black holes • - Lorentz factors up to at least 50 • - sudden/smooth, parallel and perpendicular accelerations • MOJAVE+Fermi combination is a providing a huge leap forward in our understanding of AGN outflows, emission and particle acceleration • MOJAVE project webpage and data archive: www.physics.purdue.edu/MOJAVE

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