1. Raffaella Morganti (Astron, NL) C. Tadhunter,T. Oosterloo, B. Emonts, J. Holt and many others ATNF – July 2004 The interplay between radio-activity and the ISM in radio galaxies

2. ATNF – July 2004  Radio galaxies typically hosted by an early-type galaxy: why to look for neutral hydrogen in these objects? HI on the large scale HI on the nuclear scale  AGN triggered by mergers?  HI tracer of the origin and evolution of the galaxy  allows to put the AGN activity in the evolutionary sequence (together with the stellar population)  star formation induced by the interaction between the radio jet and the HI?  structure and physical conditions in circumnuclear tori  nuclear outflows and feedback

3. ATNF – July 2004 NGC 7252an elliptical forming now light profile is r 1/4 shallow, deeper and deep images  NGC 7252 is elliptical formed by gas-rich merger Schweizer 1982 H I (Hibbard et al.) deep images reveal irregular features in outer regions

4. ATNF – July 2004 Formation of early-type galaxies from a major merger: HI can trace the different phases in the evolution of the system (e.g. presence of tidal tails, disks) HI as tracer of the origin and evolution of the galaxy : results for normal early-type galaxies 80kpc long-lived HI structures NGC 5266 ATCA H I (Hibbard et al.)

5. ATNF – July 2004 Large amount of HI (in 5-10% early-type) M HI > 10 9 M sun Often, very regular kinematics  disks Very extended structures (~ hundred kpc) Long-lived gas structures, no diffuse starformation Major mergers BUT OLD! (well over 5x10 9 years, provided the environment is not too hostile) not related to recent accretion HI and early-type galaxies Results from ATCA +VLA + from HIPASS (and follow-up ATCA): statistical study of the occurrence and characteristics of HI in normal early-type galaxies. 200 kpc Sadler, Oosterloo & Morganti (ATCA data) HI total intensity + optical Oosterloo et al. 2001

6. ATNF – July 2004 Large amount of HI (in 5-10% early-type) M HI > 10 9 M sun Often, very regular kinematics  disks Very extended structures (~ hundred kpc) Long-lived gas structures, no diffuse starformation Major mergers BUT OLD! (well over 5x10 9 years, provided the environment is not too hostile) not related to recent accretion HI and early-type galaxies Results from ATCA + from HIPASS (and follow-up ATCA): statistical study of the occurrence and characteristics of HI in normal early-type galaxies. 80kpc

7. ATNF – July 2004 Large amount of HI (in 5-10% early-type) M HI > 10 9 M sun Often, very regular kinematics  disks Very extended structures (~ hundred kpc) Long-lived gas structures, no diffuse starformation Major mergers BUT OLD! (well over 5x10 9 years, provided the environment is not too hostile) not related to recent accretion HI and early-type galaxies Results from ATCA + from HIPASS (and follow-up ATCA): statistical study of the occurrence and characteristics of HI in normal early-type galaxies. 200 kpc Sadler, Oosterloo & Morganti (ATCA data) HI total intensity + optical

8. ATNF – July 2004 180kpc ATCA 80kpc 230kpc HI observation of early-type galaxies: The great majority of the detections are large, regular disks ( Oosterloo et al. in prep) 190kpc

9. ATNF – July 2004 SAURON + WSRT (stellar+gas - neutral and ionized - kinematics) 9 of Sauron sample observed in H I (so far….), with high sensitivity (12 hr of WSRT, 4x12h for NGC4278) H I detection limit (few times) 10 7 M  (i.e. factor 50-75 better than HIPASS) 7 galaxies detected, 5 have HI ‘disks’ some of very low column density (few times 10 19 cm -2 ) detection rate 77%!!! ‘complicated kinematics’ These are mainly radio quiet galaxies: any connection to radio loud galaxies? NGC 4278 NGC 3414 Morganti, Oosterloo, de Zeeuw et al. HI very often detected in early-type (and sometimes in large amount) tracing origin  external, (major) mergers

10. ATNF – July 2004 Heckman et al. 1986 also emission line kinematics consistent with accretion origin (Tadhunter et al. 1989; Baum et al. 1990) Morphological features: double nuclei, arcs, tails and bridges Are radio galaxies the results of major mergers? (Merger as a way to bring the gas to the central regions) ~ 5 kpc (5’’) 3C 293 Molecular gas (CO) Radio cont. (5 GHz) 4C 12.50 HST image+ CO contours Nuclear concentration of molecular gas (Evans et al. 1999,2004)  presence of a starburst phase  rich ISM in the central regions (at least in the initial phase of the AGN)

11. ATNF – July 2004 Veron-Cetty et al. 1995 100 kpc Survey of radio galaxies in HI to look for similar extended structures (Emonts PhD thesis) HI in radio galaxies: Do we see similar structures as in “normal” early-type? Southern radio galaxy PKS B1718-649 Very extended disk with more than 10 10 M  of HI Total HI intensity VLBI continuum (Tingay et al. 1997) <10pc ATCA

12. ATNF – July 2004 Preliminary results from a statistical study (Emonts PhD thesis) Sample of radio galaxies (up to ~12000 km/s): looking for HI emission (and absorption) Some interesting cases  also in radio galaxies a number of HI disk-like structures are seen next: relation with stellar population ATCA (Emonts et al. in prep.) NGC 612 How about the large HI disks? so far large, HI-rich disks (~10 10 M sun of HI) have been found only in compact radio galaxies ~40 kpc

13. ATNF – July 2004 Very extended HI disks in radio galaxies 125 kpc ~1kpc Both compact radio galaxies  young (<<10 7 yr) WSRT more than 10 10 M  of HI! ~1kpc remarkably regular distribution and kinematics ~160 kpc HI total intensity Morganti et al. 2003 Emonts et al. in prep.

14. ATNF – July 2004 : long-lived HI structures HI to define an evolutionary sequence? AGN phase >10 9 yr Many free parameters: every major merger produces AGN ? effect of environment effect of the radio plasma and/or AGN on the neutral gas few x 10 8 yr ? Hibbard et al. The age of the merger derived (to first order) from the HI will need to be compared with the stellar population analysis.

15. ATNF – July 2004 Some preliminary results from the statistical study Major merger is the possible scenario for some BUT……. so far large, HI-rich disks only in compact radio galaxies: no idea why! Complex morphology of the ionized gas and neutral hydrogen (with similar kinematics) 30 kpc Morganti et al. 2002 HI absorption Tadhunter et al. 2000 Radio lobes expanding into gas disk  selection effects?  the gas is ionized? (see Coma A)  different type of merger?  environment?

16. ATNF – July 2004 Origin of radio galaxies: the study of the stellar population

17. ATNF – July 2004 young stellar populations (YSP) make a significant contribution to the optical/UV continua in 25 to 40% of radio galaxies at low and intermediate redshifts and of different radio powers Consistent with the idea of (major?) mergers triggering the activity  these mergers are known to produce circum-nuclear starburst as the material is driven toward the central regions connection with UV excess and IR luminosity  tendency for the galaxies with YSP to be detected by IRAS Tadhunter et al., Wills et al. 2002, 2003 Recent results from the study of the stellar population Tadhunter et al. 1996 3C321 old stellar pop. young stellar pop. power law

18. ATNF – July 2004 Evolution of the host galaxy from the YSP Results on 3C293, 3C305 and 4C12.50 (Tadhunter, Robinson, Gonzalez-Delgado et al. 2004)  typical ages of the YSP between 0.5 and 2.5 Gyr  massive YSP: 10 9 <M YSP < 5x 10 10 M sun (comparable to the mass of molecular gas) that makes up a large proportion of the total stellar mass (~ 1 to 50%)  link between radio galaxies and luminous- and ultra luminous infrared galaxies  consistent with AGN activity (in some radio galaxies) triggered by major merger  AGN appears late after the merger ULIG LIG 3C293 3C305 Assuming instantaneous burst model (BC96) Age (Gyr) L BOL

19. ATNF – July 2004 How about the radio galaxies with no YSP? Wills et al. 2002 Mass of the YSP is relatively minor  minor merger Sources observed long after the merger Reddened starburst (but none of the undetected are luminous in far-IR) Radio galaxies without YSP are triggered by a small merger, or are seen very late after the merger Also from the study of the stellar population, different type of mergers at the origin of radio galaxies

20. ATNF – July 2004 The nuclear regions

21. ATNF – July 2004 radio jet The nuclear regions radiation shocks Gas outflows often detected. Relevance for the evolution of the AGN. extra-gas surrounding the AGN, e.g. left over from the merger that triggered the AGN Study of these phenomena using HI (in absorption) HI absorption from the torus/circumnuclear disk

22. ATNF – July 2004 Issues related to AGN Outflows They can affect the evolution of the host galaxy and its ISM They influence the ionization of the medium What structure they have, or how much mass and energy they carry. Outflows in high z radio galaxies Outflows in Seyferts: optical and UV Extended HI absorption (against the Ly  ) van Ojik et al. Blue-shifted absorption lines in many species of several hundred to over 1000 km/s. Kriss et al. 1995 Hutchings et al. 1998 Starburst winds AGN (radiation) driven outflow Jet driven outflows Possible origin of outflows in AGNs

23. ATNF – July 2004 How about nearby radio galaxies?  Evidence of outflows in ionized gas  Clear cases of radio galaxies embedded in very rich ISM (far-IR bright, CO etc.)  They possibly represent the radio galaxies originating from major mergers (e.g. young stellar population observed) Study in HI of these cases  HI associated with outflows and disturbed kinematics

24. ATNF – July 2004 WSRT Deep absorption: Haschick & Baan (1985) Beswick et al. (2002) broad, shallow absorption by neutral gas Morganti et al. ApJL (2003) Broad absorption  ~0.15% N H ~2 x 10 20 cm -2 for T SPIN =100K Broad HI absorption in 3C293

25. ATNF – July 2004 Broad HI absorption in 4C12.50 Broad absorption  ~ 0.2% N H ~10 20 cm -2 for T SPIN =100K WSRT observations, 20 MHz band Broad HI absorption: full width of ~2000 km/s mostly blueshifted ADD FIGURA????? HST image in [OIII] (Axon et al.) VLBI (Stanghellini et al.) 100pc

26. ATNF – July 2004 Schilizzi et al. 2001 O’Dea et al. 2001 Optical depth of the broad absorption  ~0.15% ~1500 km/s Broad HI absorption in 3C236

27. ATNF – July 2004 A recent new case: OQ208  known to have fast outflow in the broad emission lines (Marziani et al.)  particularly rich medium from X-ray absorption: radio jets possibly piercing their way through a Compton-thick medium pervading the nuclear environment (Guainazzi et al. 2004) ~10 pc Stanghellini et al. 1993 Optical depth of the peak absorption  ~0.5% WSRT 1500 km/s N H ~8x10 20 cm -2 for T SPIN =100K

28. ATNF – July 2004  Relatively high number of objects with broad HI absorption in radio galaxies with: - young stellar population - compact (young) or restarted activity biased result?  Very low optical depth (<0.005)  need very strong radio continuum What we find so far: mostly  In these objects the broad HI is mostly blueshifted (compared to the systemic velocity)  outflows …but not always……

29. ATNF – July 2004 …..just to make everything more complicated…… Taylor et al. (2004) 4C37.11 Optical depth of the peak absorption  ~0.3% ~ 1500 km/s WSRT Redshifted component  detected also by the VLBI Blueshifted component  detected only by low resolution observations (WSRT) VLBA

30. ATNF – July 2004  Relatively high number of objects with broad HI absorption in radio galaxies with: - young stellar population - compact (young) or restarted activity biased result?  Very low optical depth (<0.005)  need very strong radio continuum What we find so far: mostly  In these objects the broad HI is mostly blueshifted (compared to the systemic velocity)  outflows - Location of the absorption - Relation with the ionized gas Next

31. ATNF – July 2004 H I disk rotating aligned with the dust lane broad, blue-shifted (~700km/s) H I absorption H I Position-velocity slice along major axis (PA 120) ATCA (8 GHz) + HST WFPC2 [O III ]5007 image Triple radio structure aligned along dust lane IC 5063 Seyfert Morganti et al. 1997; Oosterloo et al. 1999 VLBI: absorption against lobe

32. ATNF – July 2004 The case of the radio-loud Seyfert IC 5063 H  +[NII] ~4arcsec circa 1.3kpc ATCA & NTT radio core Vel ATCA – 17 GHz Morganti, Saripalli, Subrahmanyan, Oosterloo

33. ATNF – July 2004 [SII] flux Eastern radio hot-spot Fast outflow of ionized gas! FWHM = ~1000 km/s Blueshifted by ~500 km/s Densities: Narrow: ~10 2 cm -3 Broad: ~10 3 cm -3 Also seen in other lines, e.g. [OII] [SII]

34. ATNF – July 2004  Relatively high number of objects with broad HI absorption in radio galaxies with: - young stellar population - compact (young) or restarted activity biased result?  Very low optical depth (<0.005)  need very strong radio continuum What we find so far: mostly  In these objects the broad HI is mostly blueshifted (compared to the systemic velocity)  outflows  Indication that at least in some cases the HI absorption (and the broad optical lines) happens off-nucleus (~ 1 kpc  case of IC 5063)  Similarities with the ionized gas (a blueshifted component is always seen in neutral and ionized): are the two outflows due to the same mechanism?

35. ATNF – July 2004  Starburst wind  Post-starburst galaxies (typical ages between 0.5 and 2 Gyr )  Radiation pressure+dust (Dopita et al.) Despite the very energetic phenomena involved, gas remains - or becomes again - neutral Insight on the physical conditions of the medium around the AGN What produces the HI outflows  Interaction between the radio jet and ISM  Adiabatically expanded broad emission line clouds (Elvis 2002)  located in the nuclear regions

36. ATNF – July 2004 Energy flux estimate: case of 4C12.50 and OQ208 log Energy flux ~ 40.4 – 41.1 erg/s from the HI outflows big uncertainties: size of the HI and shock area Energy flux from the radio jets log F E ~ 42 – 42.4 erg/s  efficiency between 0.01 and 0.1 From X-ray luminosity: acceleration of the gas due to radiation if coupled with dust (van Bemmel et al., Dopita et al.) The acceleration of the gas should start on the pc scale

37. ATNF – July 2004 Energy flux estimate: case of 4C12.50 and OQ208 log Energy flux ~ 40.4 – 41.1 erg/s from the HI outflows big uncertainties: size of the HI and shock area Energy flux from the radio jets log F E ~ 42 – 42.4 erg/s  efficiency between 0.01 and 0.1 From X-ray luminosity: acceleration of the gas due to radiation if coupled with dust (van Bemmel et al., Dopita et al.) The acceleration of the gas should start on the pc scale

38. ATNF – July 2004 van Bemmel et al. Energy flux estimate: case of 4C12.50 and OQ208 log Energy flux ~ 40.4 – 41.1 erg/s from the HI outflows big uncertainties: size of the HI and shock area Energy flux from the radio jets log F E ~ 42 – 42.4 erg/s  efficiency between 0.01 and 0.1 From X-ray luminosity: acceleration of the gas due to radiation if coupled with dust (van Bemmel et al., Dopita et al.) The acceleration of the gas should start on the pc scale  Broad Line regions? Galaxies like 3C293: very low ionization

39. ATNF – July 2004 A possible scenario from the ionized gas Tadhunter et al. 2001 [OIII] Young source surrounded by a cocoon of material left over from the even that trigger the radio source Undisturbed gas

40. ATNF – July 2004 Young source surrounded by a cocoon of material left over from the even that trigger the radio source Cooled & fragmented clouds: HI outflow? A possible scenario from the neutral hydrogen Undisturbed HI? molecular cloud

41. ATNF – July 2004 Rich ISM against which the jet has to fight against in order to expand out of the galaxy “Fighting” its way out 4C12.50 Core Mass of the HI cloud ~10 5-6 M sun High column density (N H ~10 22 cm -2 ) HI absorption VLBI Morganti et al. 2004 A&A in press 2D simulations Bicknell et al. 2003 radio jet dense cloud black=WSRT red = VLBI Integrated HI profile ~50 pc

42. ATNF – July 2004 Mellema et al. 2002 looks promising also to explain the broad HI BUT can the fragmented clouds be accelerated to such high velocities? Evolution of clouds in radio galaxy cocoons: shock runs over a cloud compression phase (overpressured cocoon) fragmentation & cooling formation of dense, cool & fragmented structures What jet/cloud interaction can do for us? Simulations show that cooled fragmented clouds do form as result of the interaction Mellema et al. 2002, Fragile et al. 2003

43. ATNF – July 2004 Jet-induced starformation

44. ATNF – July 2004 Considered to be very important for high-z radio galaxies, Nearby examples: Centaurus A Minkowsky object (van Breugel et al. 1985) Jet induced star formation (observations) What do we learn from the HI? NGC 541 15 kpc

45. ATNF – July 2004 Cen-A Orientation: Jet and Filaments Jet/radio lobes extend  40 kpc from nucleus Emission line filaments (high ionization) extend ~20 kpc from nucleus Very turbulent (>200 km/s) over 1 arcsec, jet-cloud interaction? photo-ionized by nucleus? Jet and filaments interrelated –Induced star formation –ISM heating by shocks /bulk motions HH Outer filaments Inner filaments Schiminovich et al. 1994 HICO Charmandaris et al. Radio Morganti et al.

46. ATNF – July 2004 outer filament H I cloud H I ring at large radius, regular rotation One H I cloud near outer filament & jet Jet-induced star formation? Rejkuba et al. 2002 Graham 1998 Filaments contain young stars (10 Myr)

47. ATNF – July 2004 jet flow blue: FUV from GALEX (Neff et al. AAS 2004) red : H  from WFI ESO-2.2m Outer filament: FUV + H  FUV H I H  young stars ~1kpc shocks? jet flow Jet hitting HI cloud near the outer filament? UV emission from: – young blue stars – ionized gas in the filaments Far-UV “leads” optical continuum and line emission –> shocks?

48. ATNF – July 2004 Kinematical signature of interaction? jet Kinematics of H I ring smooth except at the southern tip! velocity range of ionized gas New ATCA data higher spatial (20’’) and velocity resolution (6 km/s) Kinematical signature of interaction in the HI? ~1 kpc Oosterloo & Morganti 2004

49. ATNF – July 2004 Recent results on the Minkowski object Region of star formation: numerical simulations from Fragile, van Breugel et al. (2003)

50. ATNF – July 2004 Recent results on the Minkowski object Morganti, van Breugel, van Gorkom, Oosterloo Detected (VLA observations) a cloud of about 5 x 10 8 M  of HI close to the location of the starformation region

51. ATNF – July 2004 Some conclusions….. Large amount of HI in regular disks observed in compact radio sources: (old) major mergers? However, a variety of possible mergers at the origin of radio galaxies is derived from the study of the stellar population. HI with extreme kinematics observed in the nuclear regions of radio galaxies: mostly outflows Interaction between the radio plasma and the ISM (or radiation pressure in some cases?) The interaction between the radio jet and HI clouds can trigger star formations. Examples so far Centaurus A & Minkowski’s object