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Direct imaging of AGN jets and black hole vicinity

Direct imaging of AGN jets and black hole vicinity. Tiziana Venturi tventuri@ira.inaf.it. Active Galactic Nuclei 9 Ferrara, 27.05.2010. Radio VLBI as the most direct way to look into the inner regions of AGNs

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Direct imaging of AGN jets and black hole vicinity

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  1. Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010

  2. Radio VLBI as the mostdirect way to look into the innerregionsofAGNs Knowledgeof the innerjets in AGN even more relevantthesedays due to the currentγ-rayobservatories: truesimultaneous radio/γ-raystudiesofcorrelatedvariability, essentialto locate the γ-rayemission. Currenthot VLBI studiesofAGNs - Simultaneous radio/γ–raymonitoring (radio imaging) offlaringblazars - The veryfaintUniverse: low powernearby AGN (seeGiroletti) & powerfulhigh-zquasars z=0.01 -> 1 mas = 0.2 pc z=0.1 -> 1 mas = 1.8 pc z=2 -> 1 mas = 8 pc

  3. Unified view of Radio Loud AGN High power Low power FR I and BL Lacs FR II and FSRQ Unification models (Orr & Browne 1982; Urry & Padovani 1995) successfully tested in the radio band for the two power ranges : viewing angles and intrinsic relativistic speeds at the jet base

  4. AGNs all very similar from a morphological point of view when looked on the parsec-scale: mostly core-dominated with an asymmetric jet, regardless of the classification (radio galaxies, BL Lacs, FSRQ) Orientation and relativistic velocities at the jet base Mkn 421 3C454.3 BL Lac Markarian 421 – Blue BL BL Lac – Red BL 3C454.3 - FSRQ M87 Cygn A - FRII M87 - FRI Cygnus A Images from MOJAVE at 15GHz

  5. Sample of low/intermediate power radio galaxies (Giovannini et al. 2001) Sample of neraby BLLacs (Giroletti et al. 2004) Consistency in the distribution of Lorentz factors

  6. Sample of nearby BLLacs (Giroletti et al. 2004) Sample of low power radio galaxies(Giovannini et al. 2001) Distribution of viewing angles consistent with the idea that the two classes of radio sources belong to the same population of objects seen under differentangles to the line of sight

  7. The nuclear radio properties of highly beamed sources The Blazar World • When we look at the powerful radio sources aligned at small angles to the line of sight, the most extreme properties are found: • Strong flux density variability • Morphological changes implying superluminal speeds • Instabilities in the radio jet Observer

  8. Expanding cloud of relativistic electrons initially thick at some frequencies and viewed very close to the line of sight Flux density variability Venturi et al. 2001 & 2003

  9. Structuralvariability and superluminalmotion Favourableviewing angle and high intrinsicspeedof the radio emitting plasma, leadto superluminal propermotion 1995 - 2010 1995 - 2010 1995 - 2010 2200+420 BLLac; z=0.0686 βapp= 10.57c 3C454.3 HPRQ; z=0.859 βapp= 14.19c PKS 1510-089 HPRQ; z=0.36 βapp= 23.76c Polarization and total intensity movies from MOJAVE

  10. 3C279 VLBA 43GHz HPRQ, z=0.536 βapp = 20.57c Radio galaxy, z=0.033 βapp = 5.43

  11. Current studies. I. Statistics from the MOJAVE survey The sample & the project - Nearly 300 compact AGN in the Northern Sky, 135ofwhichform a complete flux density limited sample (δ > -20o, S2cm > 1.5 Jy at anyepochbetween 1994 and 2004) - Monitoringcarried out with the VLBA at 2 cm startingfrom 1994 - Statisticalanalysismade on the basisof the original sample: 135 sources 526 separate features in 127 jets (no speedmeasurementsfor8 sources) database consistingof 2424 images Ideal band: high angular resolution, very good image sensitivity and better reliability compared to BU monitoring

  12. Analysis carried out for BL Lacs, FSRQ and radio galaxies separately(Lister et al. 2009) Peak at ~ 10c Fastest component moving at 50.6c and interpreted as the upper end of the AGN jet Lorentz factor distribution Apparent velocity vs redshift: the distribution is not the result of observational limitations

  13. Locus of (βapp,L) for sources with γ=32 and L=1025 W/Hz VLBA observational limit set at S=0.5 Jy and μ=4 mas/yr BL Lacs Quasars Radio galaxies

  14. Currentstudies.II. Simultaneous radio/γ-raymonitoringwith VLBI imaging Before the adventof AGILE, FERMI and ground-basednew VHE observatories,only a handfulofsimultaneousmultibandcampaigncarried out on the best knownblazars (i.e. 3C279, Mrk 421 …) with a varietyofresults(Hartmannet al. 2001; Blazejowskiet al. 2005), or a posteriori correlations(Jorstadet al. 2001) γ-ray radio γ-rayflare Superluminal ejection

  15. PKS 1510-089 (Marscher et al. 2010) VLBA 43 GHz monitoring & Fermi LAT and AGILE observations Optical and γ-rayflares in goodcoincidence Rotation of the opticalpolarizationvector 2 new superluminal features with speeds of 24±2 c and 21.6±0.6 c Multibandobservationsinterpretedas a single feature (seenas superluminal) movingthrough a helicalmagneticfield in the jet acceleration zone

  16. 3C454.3 (Vercellone et al. 2010) VLBA 15 GHz monitoring & AGILE observations 15 GHz - 7 Aug 2007 Total flux density increase due to the radio core (component C) Flux density of the main jet components stable or decreasing No proper motion along the jet No birth of new components so far From the core variability at 43 GHz it was derived that the source is viewed at θ~1.5° and that Γ~20 Flares in the optical and γ-ray band Slow monotonic flux density increase at radio wavelengths

  17. The case of M87 (Giroletti et al. 2010) Coordinated radio-VHE (VERITAS) observational campaign VHE flares on 9/2/2010 and April 2010 Second radio galaxy, beyond 3C84, detected at high energies

  18. ATel #2431 – VHE flare on 9 Feb 2010 eVLBI monitoring – 2 epochs before the flare and 4 during and after the flare HST-1 Inner jet Evidence for flux density increase at the jet base (~10%) and continued proper motion in HST-1 with vapp~7c

  19. Current studies.III. VLBI Imaging of high-z quasars - Frey et al. High-z radio quasars with available SDSS spectroscopy Sample selection: z>4.5; compact on FIRST with 8.8 mJy < S1.4GHz <28.8 mJy z=5.01 α=-0.58 z=4.92 α=-0.60 z=4.87 α=-0.58 z=4.73 α=-0.55 VLBI results: • EVN detection rate 100% at 1.6 GHz (top row) as well as at 5 GHz (bottom row) (the sample was not selected on flat radio spectrum!) • Compact sources, but 4 out of 5 have steep spectrum (α~-0.6) on this scale

  20. Maincurrentground VLBI facilities VLBA(δ≥ -30o) : 327 MHz - 43 GHz, 512 Mbps www.nrao.edu GMVA (δ≥ -30o ): up to 86 GHz LBA (southernhemisphere): up to 22 GHz European VLBI Network (δ ≥ -10o): 1.4- 22 GHz, 1 Gbps e-EVN, more flexible and more frequentthan EVN www.evlbi.org Major supportprovidedtonewusersby the JIVE staff

  21. Future Space VLBI missions Space Radio Telescope – 2011 327 MHz, 1.6, 4.8, 15-22 GHz www.asc.rssi.ru/radioastron/news/news.html ASTRO-G – 2014 www.vsop.iasa.ac.jp/vsop2 Dual Pol. – 8.4, 22, 43 GHz sub-mas to μas resolutions from 327 MHz to 43 GHz

  22. Final Considerations VLBI is the only way to directly image the central regions in AGNs The present performances and flexibility of VLBI and e-EVN make AGN cores and jets and very faint AGN the most targeted sources these days The new space and ground-based high energy observatories have revived the interest in the study of the inner regions in powerful radio galaxies: monitoring of large samples are the current approach

  23. Current radio programs - I. Imaging Monitoring MOJAVE Imaging + monitoring survey (~200 sources) – VLBA @15 GHz TANAMI southern monitoring of blazars (~80 sources) – LBA @ 8.4 & 22 GHz BU Blazar Group 22 & 43 GHz VLBA imaging monitoring of ~ 20 sources VIPS VLBI Imaging and Polarimetry Survey, VLBA@5 GHz, ~1200sources USNO-RRFID Database of geodetic observations at 2.3/8.4 GHz and 22 GHz DXRBS EVN observations at 5 GHz of ~ 100 sourcesfrom the DXRBS sample

  24. Current radio programs - II. Single dish monitoring UMRAO UMich Radio Observatory, full polarization long term monitoring at 4.8, 8.4, 15 GHz of ~ 50 bright sources Ratan monitoring survey of ~ 700 bright sources Metsahovi long term monitoring (~ 100 sources) @ 22 & 37 GHz OVRO daily monitoring of ~ 1000 sources @ 15 GHz FGamma Eb (11cm to mm)/IRAM (1,2,3 mm) simultaneous monitoring Medicina and Noto Monthly monitoring of ~ 30 sources at 5, 8.4 and 22 GHz

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