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Parsec-Scale Jet-Environment Interactions in AGN

Parsec-Scale Jet-Environment Interactions in AGN. Matthew Lister Purdue University. Extragalactic Jets, May 2007 Girdwood, AK. Review Outline. Evolutionary theories for young radio jets - Gigahertz-peaked spectrum galaxies (CSOs) Numerical jet-cloud simulations

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Parsec-Scale Jet-Environment Interactions in AGN

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  1. Parsec-Scale Jet-Environment Interactions in AGN Matthew Lister Purdue University Extragalactic Jets, May 2007 Girdwood, AK

  2. Review Outline • Evolutionary theories for young radio jets - Gigahertz-peaked spectrum galaxies (CSOs) • Numerical jet-cloud simulations • VLBA studies of young jets and blazars

  3. CSO 0710+439 Self-similar expansion models • Begelman 96, Kaiser and Alexander 97, Bicknell et al. 97 • Hotspots in ram pressure equilibrium • evolution depends on radial profile of ISM density • correlation between hotspot size and overall jet length (Jeyakumar & Saikia 00) Perucho & Marti 02

  4. Self-similar expansion models CSO 0710+439 • Contemporary view : • forward hotspot motion >> side-to-side not a “dentist’s drill” • advancing bow shock interacts with clumpy ISM, creating line emission via shock ionization • hotspot advance unimpeded • fast advance speeds of 0.1 - 0.4 c Perucho & Marti 02

  5. (years) Young jet evolution Kinematic age distribution of CSO jets • Evolution models suggest rapid dimming once jet reaches ~ 1 kpc (e.g., Snellen et al. 00) • CSOs overrepresented in AGN jet population • cutoff in kinematic age distribution • ISM interaction to blame? • change in jet polarization properties past 2-3 kpc (Cotton et al. 03) • first encounter with clumpy medium? tidal effects? shaded = lower limits Gugliucci et al. 05

  6. GPS Galaxies: Young and not so frustrated • Strong observational evidence for dense environments, but dense enough? • huge gas masses (1010 Msun) required to halt medium power jets • HI and X-ray column densities too low • (e.g.,Vermeulen et al. 03, Guaianazzi et al. 06, Vink et al. 06) • Other evidence against frustration: • ‘burst and stall’ can’t apply  in majority of cases advance speeds are measurable (Polatidis & Conway 92) • kinematic expansion ages ≈ spectral ages (< 104 y; Murgia et al. 99) • no IR excess (Fanti et al. 2000)

  7. 180 kpc J1835+620 Intermittent Jet Activity • 5-10% of GPS galaxies show kpc-scale emission • X-ray shells around radio galaxies: (e.g. M87, NGC 1275, 3C 317) • Ultra steep spectrum (fossil) radio galaxies • “Double-double” radio galaxies • only ~dozen known, all large radio galaxies • a few to tens of Myr between jet episodes • symmetric inner doubles imply stoppage at AGN nucleus, not from cloud collisions (Kaiser et al. 00) Saikia et al. 06

  8. Numerical Simulationsof Jet-Cloud Interactions

  9. Jet simulations with clumpy medium False color = density • 3D pure hydro sims: • extends work of Saxton et al. 05 • light hypersonic jet, η = 10-3 • Mach 26, Γ = 5 • External medium: • hot (107 K) ISM plus 104 K turbulent, clumpy disk (1010 Msun) • Main findings: • jet forms channels through weak points in ISM • spherical energy-driven bubble • jet eventually breaks free and recollimates, forming classical bow shock Sutherland & Bicknell, ApJ submitted

  10. Comparisons with CSO 4C 31.04 • Western lobe emission not backflow • flat-spectrum region extended perpendicular to western hotspot • high velocity filaments in simulations: particle acceleration sites • jet near end of breakout phase? • Eastern lobe perhaps at earlier evolutionary phase 50 pc VLBA 5 GHz: Giroletti et al. 03

  11. Comparisons with CSO 4C 31.04 • Western lobe emission not backflow • flat-spectrum region extended perpendicular to western hotspot • high velocity filaments in simulations: particle acceleration sites? • jet near end of breakout phase? • Eastern lobe likely at an earlier evolutionary phase 65 kyr 50 pc VLBA 5 GHz: Giroletti et al. 03

  12. Relativistic 3-D Hydro simulations • Choi & Wiita, ApJ ‘07 • Oblique shocks deflect the beam • no jet deceleration or decollimation • bend is transient • Highest deflections expected for low-Mach jets hitting denser clouds Density Pressure cloud/ISM density ratio = 10 Jet Lorentz factor = 2.3 Mach number = 6.4

  13. Model B: thicker cloud: • less encompassed by bow shock, so Mach disk interacts sooner • perpendicular structure similar to 4C 31.04 Density Pressure • Clouds can survive impact without fragmentation • may be important star formation sites cloud/ISM density ratio = 100 Jet Lorentz factor = 2.3 Mach number = 6.4

  14. VLBA Studies of Jet-Environment Interactions: I. Seyferts

  15. Jets in Seyfert galaxies • VLBA resolution: < 104 A.U. at typical Seyfert distances (15-20 Mpc) • Much lower jet power and speed • more subject to entrainment and disruption (Bicknell et al. 98, de Young 06) • accretion may be sporadic, leading to random jet axis directions (King & Pringle 07)

  16. Seyfert NGC 4151: Mundell et al. 03 red: radio jet green: molecular hydrogen torus central black region: ionized gas 200 pc • Seyfert 1.5 (nearly face on), 13.3 Mpc • Possible deflection at site of eastern HI absorption: flat radio spectrum

  17. NGC 4151 • Numerous [O III] emission clouds near radio jet • some are high velocity • NLR geometry suggests radiative excitation from AGN HST image (Winge et al. 97)+ jet overlay (Mundell et al. 03) • Some clouds are high velocity (> 1000 km/s) • cocoon may shock ionize NLR clouds close to the jet

  18. NGC 3079: Middelberg et al. 07 • Seyfert 2 at 15 Mpc • Powerful water maser disk, indicative of thick molecular torus 5 GHz VLBA image • Multi-epoch VLBA monitoring: • A and B: compact, SSA/FFA radio spectra • A is moving at 0.1 c away from B • recently slowed and increased in flux density • cpts E and F may represent earlier (branching?) outflow

  19. 1345+125: A young precessing AGN Jet • Host galaxy: gas rich ULIRG at z = 0.12 • Tidal tails, young stellar pop., double nucleus  recent merger Stanghellini et al. 2005

  20. PKS 1345+125: Young radio jet at z = 0.1 • Jet follows a conical helix: • intrinsic speed 0.8 c • cone axis inclined 82 degrees from line of sight • 280 pc helix wavelength AGN • northern jet truncated at site of dense HI absorption (>1022 cm-2; Morganti et al. 05) VLBA 2 cm image (Lister et al. 2003

  21. fpol = 10% fpol > 40% • High polarization at bend and jet terminus • shocked regions • Mach disk implies active hotspot: jet not stifled in this very gas rich galaxy • Outer (kpc-scale) structure likely remnant of earlier activity cycle Lister et al. 03

  22. VLBA Studies of Jet-Enviroment InteractionsII. Blazars

  23. Using blazars to probe jet-ISM interactions • Small jet viewing angles: • small jet bends exaggerated by projection • less obscured view through hole in torus • trace gas via Faraday rotation of polarization • Superluminal blobs effectively trace jet flow • century of jet evolution in a few years

  24. 3C279: Homan et al. 2003 50 pc (projected) Feature C4 moved steadily on linear path for over a decade at 8 c • sudden acceleration to 13 c and change by 26° • intrinsic change in direction only ~1° • Event occurred a few kpc from nucleus: • reconfinement following flaring of initially overpressured jet? • deflection by oblique density gradient? MOJAVE / 2 cm Survey (Lister & Homan 05) more movies at: www.physics.purdue.edu/MOJAVE

  25. 3C 120 • Broad-line Sy 1 galaxy at 145 Mpc (z = 0.033) • Signs of merger activity • One-sided pc-scale jet, speeds ~6 c, viewing angle < 20 deg. (Jorstad et al. 05) • High velocity emission line components suggest jet interaction with gas clouds (Axon et al. 89) HST archive image: Cheung and Harris Rosat contours + radio greyscale (Harris)

  26. Multiepoch, multifrequency VLBA polarimetry of inner jet (Gomez et al. 2000, 2001, 2006, Jorstad et al. 2005) • Spatial resolution of ~0.1 pc allows resolution across the jet 22 GHz

  27. Jet features brighten and rotate in polarization as they move along southern half of the jet • changes occur after they have left the nucleus, and no kinematic accelerations seen • suggestive of medium interaction Gomez et al. 01

  28. Dynamics of 3C 120’s Jet • Cloud interaction? • occurs at 8 pc (deprojected) from the nucleus • jet remains well collimated • strong and variable RM indicates dynamic interaction Gómez et al. in prep.

  29. Future research avenues • Finding the youngest AGN jets: • only ~ 40 currently identified CSOs • large area radio surveys above 15 GHz: ATCA 20 GHz, 9th Cambridge, Planck • large VLBA surveys: VIPS, VCS • Studies of low-power CSOs: • intermediate stage before classical FR II? • very few currently known, especially at scales > 1 kpc: (e.g., Giroletti et al. 06, Augusto et al. 06) • identification a challenge for VLBA: science driver for space VLBI • Can we identify the beamed CSOs? • how relativistic are young radio jets? similarities with blazars?

  30. Summary • VLBI studies indicate clumpy, asymmetric ISM • jet evolution likely affected, but not stifled on pc-scale • Drop-off in jet population at ~1 kpc size: • jet disruption, or central engine turn off? • Variety of powerful tools available: • x-ray and radio absorption measures • high resolution optical emission line imaging • VLBA polarimetry • numerical simulations • The VLBA offers unparalleled means of probing dynamics of jet-cloud interactions on sub-decade timescales

  31. Future research avenues • Finding the youngest AGN jets: • only ~ 40 currently identified CSOs • large area radio surveys above 15 GHz: ATCA 20 GHz, 9th Cambridge, Planck • large VLBA surveys: VIPS, VCS • Studies of low-power CSOs: • intermediate stage before classical FR II? • very few currently known, especially at scales > 1 kpc: (e.g., Giroletti et al. 06, Augusto et al. 06) • identification a challenge for VLBA: science driver for space VLBI • Can we identify the beamed CSOs? • how relativistic are young radio jets? similarities with blazars?

  32. Nagging Questions For Discussion • Is the ~kpc size cutoff related to merger activity/fueling, or jet stifling? • Where does deceleration of GPS lobes occur? • classical radio galaxies have much slower hotspot advance speeds • Could more powerful jets be evolving in less clumpy environments? • role of Roche tidal radius?

  33. X = 10 Γ = 7.1 M = 11.6

  34. Seyfert 2: NGC 1068 (Das et al. 06) • Seyfert 2

  35. Jet precession and interaction • well established phenomenon in microquasars (eg. SS 433, GRO J 1655-40) • jets constantly encountering new material • S-shaped morphologies more common in CSOs than blazars • causes: • KH instability • current driven instability • pressure-driven instability • precession of jet nozzle • merger • binary BH • accretion disk warp (Lai 03, Quillen 01, Pringle 96) • Lu 1990: offset accretion disk exerts torque • Peck and Taylor 01 find offset torus needed to explain HI absorption distribution in CSO 1946+708

  36. Precession and interaction • Jet precession periods too short to be from warped accretion disks (Bardeen-Peterson effect; Lodato & Pringle 06) • Binary BH have been proposed in several AGN: • OJ 287 (Valtonen XXX) • 3C 345 (Lobanov and Roland 05) • 0402+379 (Rodriguez et al. 06)

  37. Entrainment • Entrainment of external material excites K-H surface instabilities that can penetrate jet and disrupt lower Mach flows (Perucho et al. 05, de Young 06) • Slower speed, turbulent surface mixing layer forms (Aloy et al. 99, Laing & Bridle 02,06, Attridge et al. 99) • Difficult to study observationally de Young 2006 Brown & Roshko 74

  38. Limb brightening in resolved jets: • Centaurus A (Kataoka et al. 06) • 3C 353 (Swain et al. 98) • M87 (Ly et al. 07, Kovalev et al. in prep) • Possible major sites of particle acceleration (Stawarz & Ostrowski 02) • implications for beaming models of high energy emission Centaurus A M87 VLBA 7 mm: Ly et al. 07 Chandra X-ray: Kataoka et al. 06

  39. Jet-medium interactions in Seyfert galaxies • Much lower jet power and speed • more subject to entrainment and disruption • accretion may be sporadic, leading to random jet axis directions (King & Pringle 07) • VLBA resolution: < 104 A.U. at typical Seyfert distances (15-20 Mpc).

  40. Density Pressure Γ Relativistic 3-D Hydro simulations • Choi & Wiita 07 • Off-axis collision • X = cloud/ISM density ratio • Γ = jet Lorentz factor • M = Mach number X = 10 Γ = 2.3 M = 6.4

  41. Density Pressure Γ • Model B: thick cloud: • less encompassed by bow shock • Mach disk interacts sooner • stronger oblique shocks deflect the beam • perpendicular structure similar to 4C 31.04 X = 100 Γ = 2.3 M = 6.4

  42. Density Pressure Γ • Model C: faster jet • Mach disk further offset from bow shock • thinner backflow cocoon • Beam deflected in all models • oblique shocks form, but do not decelerate or decollimate the jet, unlike non-relativistic sims (Wang et al. 00, Higgins et al. 99) • bends appear to be transient • Deflection angle more dependent on cloud density than jet Mach number • highest deflection expected for low-Mach jets hitting denser clouds • Clouds can survive impact without fragmentation • large cloud/jet density contrast suppresses K-H instabilities • may be important star formation sites X = 100 Γ = 7.1 M = 11.6

  43. Compact Steep-Spectrum Sources (CSS) • Sizes up to a few kpc • Spectral turnovers < 100 MHz • Strong evidence for jet/ISM interaction: • asymmetric jets (Saikia et al. 02, 03) • high rotation measures and depolarization • high-velocity emission line systems and jet alignments (Gelderman & Whittle 94, Labiano et al. 05, de Vries et al. 99)

  44. Radio galaxy B1450+333 Schoenmakers et al. 00

  45. Important issues addressed via pc-scale jet-medium interaction studies • How is AGN jet activity triggered? • What is the nature of the ISM in AGN hosts, and how does it affect jet evolution? • Which young jets evolve into classical radio galaxies? (And how?)

  46. Model B: thicker cloud: • less encompassed by bow shock, so Mach disk interacts sooner • perpendicular structure similar to 4C 31.04 Density Pressure • Clouds can survive impact without fragmentation • may be important star formation sites cloud/ISM density ratio = 100 Jet Lorentz factor = 2.3 Mach number = 6.4

  47. Double-double radio galaxies • No hotspots in inner double expected if jets propagating through previous cocoon material • would be difficult to observe (Marecki et al. 06, Clarke et al. 92) • restarted jet may encounter warm, dense clouds from previous cocoon backflow (Kaiser et al. 00)

  48. Is CSO growth affected by dense gas? • Gupta et al. 06 find no dependence of jet morphology on HI properties • HI in obscuring torus, not interacting with jet? • NGC 1052: nearly identical jet&counterjet, yet significant absorption (Vermeulen et al. 03) • 1345+125: well collimated jet in very dense environment (Lister et al. 03) Gupta et al. 06

  49. The youngest AGN Jets • Gigahertz-Peaked Spectrum (GPS) galaxies: • 5% of AGN selected at 5 GHz • large intrinsic radio luminosities (not beamed) • many host galaxies have distorted morphologies / close companions (O’Dea et al. 96) • Compact Symmetric Objects (CSOs): • misnomer? jet asymmetries are common • miniature versions of two-sided radio galaxies (1000x smaller) • jets oriented near sky plane Gugliucci et al. 2005

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