Gas and stars in compact (young) radio sources

Transcription

1 Gas and stars in compact (young) radio sources ASTRON, Dwingeloo Kapteyn Inst. Groningen B. Emonts, J. Holt, C. Tadhunter, T. Oosterloo C. Struve

2 Motivations Learn more about the formation and evolution of the host galaxy of CSS/GPS Characteristics of the stellar population in the host galaxy Even if CSS/GPS are not frustrated, there are indications of strong interaction between the radio plasma and their galactic environment can we quantify this? All relevant in order to quantify the importance (if any) of the radio-loud phase of AGN for the feedback

3 Very nearby (z<0.04) cases of CSS - presence of neutral hydrogen Field galaxies Presence of neutral hydrogen in radioquiet and radio-loud early-type galaxies. Use HI to understand the origin of the host galaxy Radio quiet Radio loud major mergers vs small merger vs cold accretion HI mass and radio power -> comparison with nearby radio-quiet early-type sample: first order similarity BUT radio galaxies with large amounts of extended HI disk (MHI >109 Msun over many tens of kpc up to 200 kpc!) all have a compact radio source (BUT not all compact sources have large-scale HI) Emonts et al A&A Emonts, Struve, Morganti & Oosterloo in prep.

4 Very nearby (z<0.04) cases of CSS - presence of neutral hydrogen Field galaxies Presence of neutral hydrogen in radioquiet and radio-loud early-type galaxies. Use HI to understand the origin of the host galaxy Radio quiet Radio loud major mergers vs small merger vs cold accretion HI mass and radio power -> comparison with nearby radio-quiet early-type sample: first order similarity BUT radio galaxies with large amounts of extended HI disk (MHI >109 Msun over many tens of kpc up to 200 kpc!) all have a compact radio source (BUT not all compact sources have large-scale HI) Emonts et al A&A Emonts, Struve, Morganti & Oosterloo in prep.

5 Very nearby (z<0.04) cases of CSS - presence of neutral hydrogen Field galaxies Presence of neutral hydrogen in radioquiet and radio-loud early-type galaxies. Use HI to understand the origin of the host galaxy Radio quiet Radio loud major mergers vs small merger vs cold accretion FRI HI mass and radio power -> comparison with nearby radio-quiet early-type sample: first order similarity BUT radio galaxies with large amounts of extended HI disk (MHI >109 Msun over many tens of kpc up to 200 kpc!) all have a compact radio source (BUT not all compact sources have large-scale HI) Emonts et al A&A Emonts, Struve, Morganti & Oosterloo in prep.

6 ~1kpc ~1kpc HI-rich low-power compact radio sources do not grow into extended FRI sources They represent just a short phase in the life of an early-type galaxy? either because NGC 3894 frustrated by the ISM in the central region of the galaxy or because the fuel stops before the source expands (see also Giroletti et al.) Origin of the host galaxy? Study of the stellar population FRI sources not originating via major mergers but via accretion of hot or cold gas Giroletti et al Morganti et al Emonts et al. 2006, astro-ph/

7 A case of major merger B kpc 8.5 x 109 Msun Emonts et al MDM 2.4m Hiltner Optical B+V

8 A case of major merger B WHT 4m La Palma Spectroscopy Dominating 300 Myr young post-starburst stellar pop. 190 kpc 8.5 x 109 Msun MDM 2.4m Hiltner Optical B+V YSP OSP HI 4th CSS/GPS workshop May 2008 Emonts et al.- Riccione, 2006, A&A, 454, 125

9 A case of major merger B kpc 8.5 x 109 Msun WHT 4m La Palma Spectroscopy Dominating 0.3 Gyr young post-starburst stellar pop. Emonts et al (in prep.) MDM 2.4m, optical B+V ~1kpc Past gas-rich merger event Different stages of activity: merger - starburst - radio AGN Gas needs a few galactic orbits to settle Emonts et al. 2006, A&A, 454, 125 Morganti et al Giroletti et al. 2005

10 Stellar ages Flux (10!16 erg s!1 cm!2 Å!1) 4 10!16 Flux 3 10! !16 OSP 1 10! YSP Rest wavelength (Angstroms) Flux (10!16 erg s!1 cm!2 Å!1) 4 10!16 Flux 3 10!16 YSP 2 10!16! Rest wavelength (Angstroms) YSP: age 1.0 Gyr E(B!V) = Rest wavelength (Å) YSP: age 5.0 Gyr E(B!V) = Rest wavelength (Å)

11 Why interesting? A few nearby, low radio-power compact sources with a lot of HI -> what are they? Result of major mergers? a case of recent major merger - while the other are hosted in older merger remnants Similar to what found in many early-type, radio quiet galaxies Different to FRI -> they will not evolve in large FRI gas Direct merger Retrograde merger: greater star formation efficiency Di Matteo, Combes et al. 2007

12 Powerful CSS/GPS: HI and ionised gas Evidence for a kinematically complex ISM (e.g. Gelderman & Whittle 1994, Axon et al. 2000, O Dea et al just to mention a few!) detailed/systematic study needed Global VLBI 4C12.50 Long slit spectra for a sample of 14 CSS/GPS (and steep spectrum cores) from 3C/4C-2Jy samples -> see talk of Jo In parallel, study of the HI absorption Core ~50pc Key part: to define the systemic velocity Morganti, Oosterloo, Vermeulen et al C pc black=wsrt red = VLBI Integrated HI profile HST image in [OIII] (Axon et al.) VLBI (Stanghellini et al.) Holt et al. 2002

13 Identify gas components and compare with HI systemic velocity accurately measured HI absorption detected in most of them Two cases of HI redshifted (something that was supposed to be *very* common but it is not) km/s

14 Identify gas components and compare with HI systemic velocity accurately measured HI absorption detected in most of them Two cases of HI redshifted (something that was supposed to be *very* common but it is not) km/s

15 Identify gas components and compare with HI systemic velocity accurately measured HI absorption detected in most of them Two cases of HI redshifted (something that was supposed to be *very* common but it is not) Two cases HI component only at the systemic velocity km/s

16 1.2GHz ~200 pc core PKS LBA observations [OII] [OII] Tzioumis et al. Not enough sensitivity to detect broad HI, but the HI at the systemic velocity represents the cocoon around the radio source

17 Identify gas components and compare with HI systemic velocity accurately measured HI absorption detected in most of them Two cases of HI redshifted (something that was supposed to be *very* common but it is not) Two cases HI component only at the systemic velocity km/s

18 Identify gas components and compare with HI systemic velocity accurately measured HI absorption detected in most of them Two cases of HI redshifted (something that was supposed to be *very* common but it is not) Two cases HI component only at the systemic velocity Often blueshifted both ionised and HI gas Confirmed similarity between HI and ionised gas kinematics km/s

19 4C12.50 (PKS ) Extended [O II]3727 emission Deep HI 21cm absorption (Mirabel 89, Morganti et al 04) Global VLBI 4C12.50 Core [O III] emission in the nucleus ~50pc Morganti, Oosterloo, Vermeulen et al (Holt et al 03a,b)

20 4C12.50 (PKS ) Extended [O II]3727 emission Deep HI 21cm absorption (Mirabel 89, Morganti et al 04) Global VLBI 4C12.50 kn ell ~50pc et al rad jet io hig de h clo nsity ud Core Bic [O III] emission in the nucleus Morganti, Oosterloo, Vermeulen et al (Holt et al 03a,b)

21 ~1500 km/s ~1400 km/s ~1000 km/s a few cases of fast HI outflows revealed by broad & blueshifted HI absorption τ ~0.003 τ ~0.004 τ ~ all resulting from jet/ cloud interaction? perhaps not! Mass outflow rate derived: between a few and ~50 M /yr higher for the cold component compored to the warm ~2000 km/s ~800 km/s ~2000 km/s Radio sources with fast HI outflows are either compact/young or objects with restarted radio activity (3C293 and 3C236) τ ~ τ ~0.006 τ ~0.002 All with rich ISM (CO, farir...) Up to 2000 km/s width, optical depth <<1% Column density few times cm -2 (for T spin = 1000 K) and higher Mostly blueshifted HI outflows - Morganti, Oosterloo, Tadhunter A&A 2005

22 The case of 3C305 The broad HI absorption is found off-nucleus at the location of the radio lobe (about 1.6kpc from the nucleus) column density 2x1021 cm-2 (for Tspin=1000K) Mass outflowing gas ~106 Msun 1 kpc from Krause (2006) WSRT VLA Effect of jet/ism interaction important for the evolution of the galaxy? VLA HI core 500 km/s Krause 2006 Morganti, Oosterloo, Tadhunter, van Moorsel & Emonts 2005 A&A

23 Main results Nearby low radio power CSS B A few nearby, low radio-power compact sources with a lot of HI -> what are they? result of major mergers? a case of recent major merger - while the other are hosted in older merger remnants similar to radio-quiet galaxies they will not evolve in large FRI Powerful CSS/GPS Evidence for interaction 190 kpc 8.5 x 10 9 M sun Global VLBI 4C12.50 Core ~50pc Presence of massive outflows of cold gas (HI) Similarity HI - ionised High mass outflow rate in HI