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Gas outflows in radio galaxies

Gas outflows in radio galaxies

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Gas outflows in radio galaxies

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  1. Gas outflows in radio galaxies Raffaella Morganti (ASTRON) and Tom Oosterloo (ASTRON) Bjorn Emonts (Kapteyn Inst., Groningen) Clive Tadhunter, Joanna Holt (Sheffield Univ.)

  2. Why should we expect gas outflows in radio galaxies? • Starburst winds • AGN (radiation) driven outflow • Jet driven outflows All activity-inducing processes (e.g. mergers) involve the injection of substantial amounts of gas/dust into the nuclear regions : gas outflows important in the early-stageof radio source evolution Results on gas outflows from ionized and neutral gas

  3. Gas outflow in PKS 1549-79 Core Jet Δz ~ 600 km s-1 6 [O III]4959,5007Å z = 0.1501 ± 0.0002 FWHM ~ 1350 km s-1 200 pc 4 Relative flux [O III] [O II] 3727Å z = 0.1526 ± 0.0002 FWHM ~ 650 km s-1 2 H [O II] [Ne III] [Ne V] Wavelength (Å) (Tadhunter et al 2001)

  4. HI and low ionization emission lines same redshift! HI in the nuclear regions Detected HI absorption ( = 0.02, NH = 2x1018cm-2 for TSPIN=100K) [OIII] I [OII] I Critical the combination with the ionized gas Tadhunter et al. 2001

  5. A possible scenario for PKS 1549-79 Young source surrounded by a cocoon of material left over from the even that trigger the radio source [OIII] Tadhunter et al. 2001

  6. Far-IR bright, LIR~2x1012 Lsun Large amount of CO, ~ 1010 Msun 4C12.50 Best example of link between radio galaxies and ULIRGs (Evans et al. 1999) Compact and powerful radio galaxy (P5GHz = 1026 W Hz-1) 100pc Very rich ISM VLBI (Stanghellini et al.) HST image in [OIII] (Axon et al.) Ionized gas: new WHT data (Holt et al. 2003) HI absorption detected with Arecibo but more found using the new broad band system at the WSRT

  7. Optical data for PKS 1345+12 Extended [O II] emission (WHT data, Holt et al. 2003) +500 0 -500 Velocity shift (km s-1) -1000 -1500 -2000 -2500 3 components of [O III] in the nucleus 0 0 -20 -15 -10 -5 5 10 15 20 Position (kpc) Blue-shifted material outflow

  8. “Stratified” outflow quiescent halo emitting narrow component narrow component intermediate component Far side of galaxy, completely obscured from view broad component Observer’s L.O.S. bi-polar radio jets bi-polar radio jets obscured quasar The broadest components are the most highly reddened & higher density (> 5000 cm-3)

  9. The broad HI absorption 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

  10. Ionized gas & HI [OIII]4959,5007 fit with 3 components

  11. The radio galaxy 3C293 Radio continuum WSRT VLBI +CO Akujor et al. 1999 Evans et al. 1999

  12. 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 in press

  13. HI OII The ionized gas in 3C293 Systemic velocity

  14. More common? Broad HI absorption components could be common in starburst radio galaxies 800 km/s A recent candidate: 3C305 3C459: An other possible candidate • - Far-IR bright • - Young stellarpopulation

  15. 0.5< tys <0.9Gyr What produces the HI outflows? Despite the highly energetic phenomena involved, gas remains (or becomes again) neutral Insight in the physical conditions of the medium around the AGN • Starburst winds: about 30% of radio galaxies show a young stellar population component (in addition to the old stellar population) All objects with fast outflows show this component. consistent with the merger • hypothesis for the triggering • of the radio activity BUT typical ages between 0.5 and 2 Gyr 3C305

  16. What produces the HI outflows? Despite the highly energetic phenomena involved, gas remains (or becomes again) neutral Insight in the physical conditions of the medium around the AGN Dopita et al. 2002 • Radiation pressure in dusty narrow line regions (Dopita et al. 2002) BUT but very different ionization in the objects detected

  17. What produces the HI outflows? Mellema et al. 2002 • Interaction between the radio jet and ISM Evolution of clouds in radio galaxy cocoons shock runs over a cloud compression phase (overpressured cocoon) fragmentation & cooling formation of dense, cool & fragmented structures looks promising BUT can the fragmented clouds be accelerated to such high velocities?

  18. [OIII] 4959, 5007 Å H+[NII] 400 km/s ~4arcsec circa 1.3kpc radio core The case of the Seyfert galaxy IC 5063 ATCA & NTT

  19. Cooled & fragmented clouds: HI outflow? A possible scenario Young source surrounded by a cocoon of material left over from the even that trigger the radio source

  20. Conclusions Outflows in radio galaxies of ionized and neutral gas Ionized gas: stratified outflows, emission originates from kinematically distinct components HI outflows: very broad HI absorption observed now in some radio galaxies. Difficult to detect due to technical limitations We now need complete statistics Radio jets strongly interacting with the rich medium SO FAR: very broad HI absorption only 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?