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The interplay between radio-activity and the ISM in radio galaxies Raffaella Morganti (Astron, NL) C. Tadhunter ,T. Oosterloo, B. Emonts, J. Holt and many others 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 structure and physical conditions in circumnuclear tori nuclear outflows and feedback (together with the stellar population) star formation induced by the interaction between the radio jet and the HI? ATNF – July 2004 NGC 7252 an elliptical forming now light profile is r1/4 shallow, deeper and deep images Schweizer 1982 deep images reveal irregular features in outer regions NGC 7252 is elliptical formed by gas-rich merger H I (Hibbard et al.) ATNF – July 2004 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. HI total intensity + optical (ATCA data) Large amount of HI (in 5-10% early-type) MHI > 109 Msun Oosterloo et al. 2001 Often, very regular kinematics disks Very extended structures (~ hundred kpc) Long-lived gas structures, no diffuse starformation Sadler, Oosterloo & Morganti Major mergers BUT OLD! (well over 5x109 years, provided the environment is not too hostile) not related to recent accretion ATNF – July 2004 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. Large amount of HI (in 5-10% early-type) MHI > 109 Msun Often, very regular kinematics disks Very extended structures (~ hundred kpc) Long-lived gas structures, no diffuse starformation 80kpc Major mergers BUT OLD! (well over 5x109 years, provided the environment is not too hostile) not related to recent accretion ATNF – July 2004 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. HI total intensity + optical (ATCA data) Large amount of HI (in 5-10% early-type) MHI > 109 Msun Often, very regular kinematics disks Very extended structures (~ hundred kpc) Long-lived gas structures, no diffuse starformation Sadler, Oosterloo & Morganti Major mergers BUT OLD! (well over 5x109 years, provided the environment is not too hostile) not related to recent accretion ATNF – July 2004 HI observation of early-type galaxies: The great majority of the detections are large, regular disks (Oosterloo et al. in prep) ATCA 180kpc 80kpc 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) 107 M (i.e. factor 50-75 better than HIPASS) • 7 galaxies detected, 5 have HI ‘disks’ • some of very low column density (few times 1019 cm-2) • detection rate 77%!!! NGC 4278 NGC 3414 ‘complicated kinematics’ Morganti, Oosterloo, de Zeeuw et al. HI very often detected in early-type (and sometimes in large amount) tracing origin external, (major) mergers These are mainly radio quiet galaxies: any connection to radio loud galaxies? ATNF – July 2004 Are radio galaxies the results of major mergers? (Merger as a way to bring the gas to the central regions) 3C 293 Morphological features: double nuclei, arcs, tails and bridges Molecular gas (CO) Radio cont. (5 GHz) also emission line kinematics consistent with accretion origin (Tadhunter et al. 1989; Baum et al. 1990) 4C 12.50 ~ 5 kpc (5’’) Nuclear concentration of molecular gas Heckman et al. 1986 (Evans et al. 1999,2004) HST image+ CO contours presence of a starburst phase rich ISM in the central regions (at least in the initial phase of the AGN) ATNF – July 2004 HI in radio galaxies: Do we see similar structures as in “normal” early-type? ATCA Total HI intensity Southern radio galaxy PKS B1718-649 Very extended disk with more than 1010 M of HI 100 kpc <10pc Veron-Cetty et al. 1995 VLBI continuum (Tingay et al. 1997) Survey of radio galaxies in HI to look for similar extended structures (Emonts PhD thesis) 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 NGC 612 ATCA (Emonts et al. in prep.) How about the large HI disks? so far large, HI-rich disks (~1010 Msun of HI) have been found only in compact radio galaxies ATNF – July 2004 Emonts et al. in prep. Very extended HI disks in radio galaxies ~1kpc Morganti et al. 2003 WSRT ~1kpc Both compact radio galaxies young (<<107 yr) 125 kpc more than 1010 M of HI! ~160 kpc HI total intensity remarkably regular distribution and kinematics ATNF – July 2004 HI to define an evolutionary sequence? Hibbard et al. AGN phase : Many free parameters: every major merger produces AGN ? effect of environment effect of the radio plasma and/or AGN on the neutral gas >109 yr long-lived HI structures few x 108 yr ? The age of the merger derived (to first order) from the HI will need to be compared with the stellar population analysis. 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! selection effects? Tadhunter et al. 2000 the gas is ionized? (see Coma A) different type of merger? environment? 30 kpc Complex morphology of the ionized gas and neutral hydrogen (with similar kinematics) HI absorption Morganti et al. 2002 Radio lobes expanding into gas disk ATNF – July 2004 Origin of radio galaxies: the study of the stellar population ATNF – July 2004 Recent results from the study of the stellar population Tadhunter et al., Wills et al. 2002, 2003 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 3C321 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 old stellar pop. young stellar pop. power law Tadhunter et al. 1996 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) Assuming instantaneous burst model (BC96) ULIG typical ages of the YSP between 0.5 and 2.5 Gyr massive YSP: 109 <MYSP < 5x 1010 Msun (comparable to the mass of molecular gas) that makes up a large proportion of the total stellar mass (~ 1 to 50%) LIG LBOL 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 3C305 3C293 Age (Gyr) ATNF – July 2004 How about the radio galaxies with no YSP? 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 Wills et al. 2002 Also from the study of the stellar population, different type of mergers at the origin of radio galaxies ATNF – July 2004 The nuclear regions ATNF – July 2004 The nuclear regions extra-gas surrounding the AGN, e.g. left over from the merger that triggered the AGN Gas outflows often detected. Relevance for the evolution of the AGN. HI absorption from the torus/circumnuclear disk Study of these phenomena using HI (in absorption) 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. Extended HI absorption (against the Ly ) • Outflows in high z radio galaxies • Outflows in Seyferts: optical and UV Blue-shifted absorption lines in many species of several hundred to over 1000 km/s. Kriss et al. van Ojik et1995 al. Possible origin of outflows in AGNs Starburst winds AGN (radiation) driven outflow Jet driven outflows Hutchings et al. 1998 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 ATNF – July 2004 Broad HI absorption in 3C293 broad, shallow absorption by neutral gas 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 (2003) ATNF – July 2004 Broad HI absorption in 4C12.50 WSRT observations, 20 MHz band Broad HI absorption: full width of ~2000 km/s mostly blueshifted Broad absorption ~ 0.2% NH~1020 cm-2 for TSPIN=100K 100pc ADD FIGURA????? HST image in [OIII] (Axon et al.) VLBI (Stanghellini et al.) ATNF – July 2004 Broad HI absorption in 3C236 ~1500 km/s Optical depth of the broad absorption ~0.15% Schilizzi et al. 2001 O’Dea et al. 2001 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 1500 km/s WSRT (Guainazzi et al. 2004) ~10 pc Stanghellini et al. 1993 Optical depth of the peak absorption ~0.5% NH~8x1020 cm-2 for TSPIN=100K ATNF – July 2004 What we find so far: 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 In these objects the broad HI is mostly blueshifted (compared to the systemic velocity) outflows …but not always…… ATNF – July 2004 …..just to make everything more complicated…… 4C37.11 VLBA ~ 1500 km/s WSRT Taylor et al. (2004) Optical depth of the peak absorption ~0.3% Redshifted component detected also by the VLBI Blueshifted component detected only by low resolution observationsATNF (WSRT) – July 2004 What we find so far: 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 In these objects the broad HI is mostly blueshifted (compared to the systemic velocity) outflows Next - Location of the absorption - Relation with the ionized gas ATNF – July 2004 • H I disk rotating aligned with the dust lane • broad, blue-shifted (~700km/s) H I absorption IC 5063 Seyfert H I Position-velocity slice along major axis (PA 120) Triple radio structure aligned along dust lane ATCA (8 GHz) + HST WFPC2 [O III]5007 image Morganti et al. 1997; Oosterloo et al. 1999 VLBI: absorption against lobe ATNF – July 2004 The case of the radio-loud Seyfert IC 5063 H+[NII] ATCA – 17 GHz Vel ~4arcsec circa 1.3kpc radio core ATCA & NTT Morganti, Saripalli, Subrahmanyan, Oosterloo ATNF – July 2004 Eastern radio hot-spot [SII] Fast outflow of ionized gas! FWHM = ~1000 km/s Blueshifted by ~500 km/s flux Also seen in other lines, e.g. [OII] Densities: Narrow: ~102 cm-3 Broad: ~103 cm-3 l [SII] ATNF – July 2004 What we find so far: 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 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? ATNF – July 2004 What produces the HI outflows Despite the very energetic phenomena involved, gas remains - or becomes again - neutral Insight on the physical conditions of the medium around the AGN Starburst wind Post-starburst galaxies (typical ages between 0.5 and 2 Gyr) Adiabatically expanded broad emission line clouds (Elvis 2002) located in the nuclear regions Radiation pressure+dust (Dopita et al.) Interaction between the radio jet and ISM 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 FE ~ 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 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 FE ~ 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 ATNF – July 2004 Energy flux estimate: case of 4C12.50 and OQ208 van Bemmel et al. • 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 FE ~ 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 ATNF – July 2004 A possible scenario from the ionized gas Young source surrounded by a cocoon of material left over from the even that trigger the radio source Undisturbed gas [OIII] Tadhunter et al. 2001 ATNF – July 2004 A possible scenario from the neutral hydrogen Young source surrounded by a cocoon of material left over from the even that trigger the radio source molecular cloud Undisturbed HI? Cooled & fragmented clouds: HI outflow? ATNF – July 2004 “Fighting” its way out Rich ISM against which the jet has to fight against in order to expand out of the galaxy VLBI 4C12.50 Core High column density (NH~1022 cm-2) HI absorption ~50 pc Mass of the HI cloud ~105-6 Msun black=WSRT red = VLBI Integrated HIdense profile cloud radio jet Morganti et al. 2004 A&A in press 2D simulations Bicknell et al. 2003 ATNF – July 2004 What jet/cloud interaction can do for us? Mellema et al. 2002 Simulations show that cooled fragmented clouds do form as result of the interaction Mellema et al. 2002, Fragile et al. 2003 Evolution of clouds in radio galaxy cocoons: shock runs over a cloud fragmentation & cooling compression phase (overpressured cocoon) formation of dense, cool & fragmented structures looks promising also to explain the broad HI BUT can the fragmented clouds be accelerated to such high velocities? ATNF – July 2004 Jet-induced starformation ATNF – July 2004 Jet induced star formation (observations) Considered to be very important for high-z radio galaxies, Nearby examples: Centaurus A Minkowsky object (van Breugel et al. 1985) What do we learn from the HI? NGC 541 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 H Outer filaments Inner filaments interaction? photo-ionized by nucleus? • Jet and filaments interrelated – Induced star formation – ISM heating by shocks Radio /bulk motions CO Morganti et al. Charmandaris et al. HI Schiminovich et al. 1994 ATNF – July 2004 Filaments contain young stars (10 Myr) H I cloud Graham 1998 outer filament H I ring at large radius, regular rotation One H I cloud near outer filament & jet Jet-induced star formation? Rejkuba et al. 2002 ATNF – July 2004 Outer filament: FUV + H • UV emission from: blue: FUV from GALEX – young blueet stars (Neff al. AAS 2004) gas in the ESO-2.2m filaments red– :ionized H from WFI FUV HI H jet flow • Far-UV “leads” optical continuum and line emission –> shocks? shocks? ~1kpc jet flow young stars Jet hitting HI cloud near the outer filament? ATNF – July 2004 Kinematical signature of interaction in the HI? New ATCA data higher spatial (20’’) and velocity resolution (6 km/s) Kinematics of H I ring smooth except at the southern tip! velocity range of ionized gas jet ~1 kpc Kinematical signature of interaction? Oosterloo & Morganti 2004 ATNF – July 2004 Recent results on the Minkowski object Region of star formation: numerical simulations from Fragile, van Breugel et al. (2003) ATNF – July 2004 Recent results on the Minkowski object Detected (VLA observations) a cloud of about 5 x 108 M of HI close to the location of the starformation region Morganti, van Breugel, van Gorkom, Oosterloo 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 ATNF – July 2004