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Central Regions of AGNs probed by the Neutral Hydrogen

Central Regions of AGNs probed by the Neutral Hydrogen. Raffaella Morganti ASTRON Netherlands Foundation for Research in Astronomy, Dwingeloo. in collaboration with Tom Oosterloo, Clive Tadhunter and many others. The gas in the central regions.

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Central Regions of AGNs probed by the Neutral Hydrogen

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  1. Central Regions of AGNs probed by the Neutral Hydrogen Raffaella Morganti ASTRON Netherlands Foundation for Research in Astronomy, Dwingeloo in collaboration with Tom Oosterloo, Clive Tadhunter and many others Joint Discussion 18: Quasar cores & jets

  2. The gas in the central regions • HI detected in absorption against the nuclear regions: • Gas settled: circumnuclear disks/tori • relevant for unified schemes • Gas unsettled: • infalling gas (feeding the AGN) cocoon of gas surrounding the central regions • gas outflows (feedback effects) Joint Discussion 18: Quasar cores & jets

  3. Low luminosity radio galaxies: thin nuclear disks? Low detection rate (~10%) of HI absorption: supporting the idea of thin disks in FRI. NGC 4261 HI detections presence of HST dust disks absence of optical core. (van Langevelde et al. 2000) Joint Discussion 18: Quasar cores & jets

  4. High detection rate of HI absorption in compact radiogalaxies (Conway 1996) ideal background to detected nuclei tori? Cygnus A (Conway 1996) HI and X-ray in the Compact Steep Spectrum 1946+708 Peck, Taylor & Conway 1999 Risaliti, Woltjer & Salvati 2003 -40 km/s Atomic torus r>15pc +40 km/s Tracer of a particular stage in the evolution of the galaxy? or a particular merger that trigger the radio source? Powerful radio galaxies: atomic obscuring tori? Constrains on the properties of the obscuring gas Also radio galaxies with young stellar population show an high detection rate of HI absorption. HI tracing unsettled gas: the most interesting part of the story? Joint Discussion 18: Quasar cores & jets

  5. The gas in the central regions • HI detected in absorption against the nuclear regions: • Gas settled: circumnuclear disks/tori • relevant for unified schemes • Gas unsettled: • infalling gas (feeding the AGN) cocoon of gas surrounding the central regions • gas outflows (feedback effects) Joint Discussion 18: Quasar cores & jets

  6. Infalling gas: no evidence from recent HI observations Sample of compact sources Vermeulen et al. 2003 NGC 315 redshifted narrow HI absorption: extended, tidal debris at large distance from the nucleus? (Peck 1999, Morganti et al. 2002) Joint Discussion 18: Quasar cores & jets

  7. The gas in the central regions • HI detected in absorption against the nuclear regions: • Gas settled: circumnuclear disks/tori • relevant for unified schemes • Gas unsettled: • infalling gas (feeding the AGN) cocoon of gas surrounding the central regions • gas outflows (feedback effects) Joint Discussion 18: Quasar cores & jets

  8. A possible scenario for young (or restarted) radio galaxies Young radio sources surrounded by a cocoon of material left over from the even that trigger the activity Outflows of ionized gas observed : how about the HI? Joint Discussion 18: Quasar cores & jets

  9. Broad HI absorption in 4C12.50 WSRT observations, 20 MHz band • Broad HI absorption: • full width of ~2000 km/s • mostly blueshifted "Deep" Absorption  only 1%, NH~2x1020cm-2for TSPIN=100K (already known from Mirabel 1989) Broad absorption  ~0.2% NH~1020 cm-2 for TSPIN=100K Correspondence with ionized gas Joint Discussion 18: Quasar cores & jets

  10. HI OII Broad HI absorption in 3C293 New broad, shallow absorption WSRT Broad absorption ~0.15% NH~2 x 1020 cm-2 for TSPIN=100K Deep absorption: Haschick & Baan (1985) Beswick et al. (2002) Morganti et al. ApJL (astro-ph/0307241) Joint Discussion 18: Quasar cores & jets

  11. A recent candidate: 3C305 800 km/s Broad HI absorption more common? Correspondence with ionized gas [OIII] 4959,5007Å ESO-NTT PKS 1814-63 ATCA data 3C459 an other candidate? Joint Discussion 18: Quasar cores & jets

  12. What is the origin of the gas outflows? Where is the HI located? the VLBI follow up Joint Discussion 18: Quasar cores & jets

  13. Starburst wind Radiation pressure(Dopita et al.) but very different ionization in the objects detected Interaction between the radio jet and ISM shock runs over a cloud compression phase (overpressured cocoon) fragmentation & cooling formation of dense, cool & fragmented structures Mellema et al. 2002 What produces the HI outflows? Despite the highly energetic phenomena involved, gas remains (or become again) neutral Insight on the physical conditions of the medium around the AGN Evolution of clouds in radio galaxy cocoons Can they reach the high velocities observed? Joint Discussion 18: Quasar cores & jets

  14. The case of the Seyfert galaxy IC 5063 Oosterloo et al. 2000 • VLBI • absorption against brightest lobe! • OUTFLOW! Joint Discussion 18: Quasar cores & jets

  15. [OIII] 4959, 5007 Å H+[NII] 400 km/s ~4arcsec circa 1.3kpc radio core Optical and HI data for the Seyfert galaxy IC 5063 ATCA & NTT Joint Discussion 18: Quasar cores & jets

  16. 4C12.50: High resolution follow up 5 GHz (Stanghellini et al.) core ~250 pc Continuum image (~ 20x4 mas beam) 4C12.50: new global VLBI experiment Joint Discussion 18: Quasar cores & jets

  17. Where is the HI? 100 pc Integrated HI profile ~30%, NH~3x1021 for TSPIN=100K black=WSRT red = VLBI Mass of the HI cloud ~105-6 Msun Joint Discussion 18: Quasar cores & jets

  18. 2D simulations Bicknell et al. Joint Discussion 18: Quasar cores & jets

  19. Conclusions • Not all the HI in the central region of radio galaxies is in circumnuclear disk/tori. But no strong evidence for HI infall. • HI outflows: very broad HI absorption observed in some radio galaxies. We now need complete statistics. • Difficult to detect due to technical limitations • Possibly resulting from radio jets strongly interacting with the rich medium • SO FAR: very broad HI absorption in objects with rich ISM & young stellar population • Tracer of a particular stage in the evolution of the galaxy? or a particular merger that trigger the radio source? • The location of the HI can be a “surprise”: • follow up at higher resolution are important! Joint Discussion 18: Quasar cores & jets

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