Sydney, 23 July 2003 Joint Discussion 18: Quasar cores & jets Central Regions of AGNs probed by the...

Sydney, 23 July 2003 Joint Discussion 18: Quasar cores & jets

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


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)

The gas in the central regions


HI detections

presence of HST dust disks absence of optical core.

Low detection rate (~10%) of HI absorption: supporting the ideaof thin disks in FRI.

Low luminosity radio galaxies: thin nuclear disks?

(van Langevelde et al. 2000)

NGC 4261


Powerful radio galaxies: atomic obscuring tori?

Constrains on the properties of the obscuring gas

HI and X-ray in the Compact Steep Spectrum 1946+708

Peck, Taylor & Conway 1999Risaliti, Woltjer & Salvati 2003

High detection rate of HI absorption in compact radiogalaxies (Conway 1996) ideal background to detected nuclei tori?

Also radio galaxies with young stellar population show an high detection rate of HI absorption.

Tracer of a particular stage in the evolution of the galaxy?or a particular merger that trigger the radio source?

HI tracing unsettled gas: the most interesting part of the story?

(Conway 1996)

-40 km/s

+40 km/s

Cygnus A

Atomic torusr>15pc




Gas unsettled:




Infalling gas: no evidence from recent HI observations

NGC 315 redshifted narrow HI absorption:extended, tidal debris at large distance from the nucleus?

(Peck 1999, Morganti et al. 2002)

Vermeulen et al. 2003

Sample of compact sources




Gas unsettled:




Young radio sources surrounded by a cocoon of material left over from the even that trigger the activity

A possible scenario for young (or restarted) radio galaxies

Outflows of ionized gas observed :

how about the HI?


Broad HI absorption in 4C12.50

"Deep" Absorption only 1%, NH~2x1020 cm-2 for TSPIN=100K

Broad absorption ~0.2% NH~1020 cm-2 for TSPIN=100K

WSRT observations, 20 MHz bandBroad HI absorption: full width of ~2000 km/s mostly blueshifted

(already known from Mirabel 1989)

Correspondence with ionized gas


Broad HI absorption in 3C293

WSRT

Deep absorption: Haschick & Baan (1985) Beswick et al. (2002)

New broad, shallow absorption

Morganti et al. ApJL (astro-ph/0307241)

Broad absorption ~0.15% NH~2 x 1020 cm-

2 for TSPIN=100K

HI

OII


Broad HI absorption more common?

A recent candidate: 3C305

800 km/s

Correspondence with ionized gas

PKS 1814-63ATCA data

[OIII] 4959,5007ÅESO-NTT

3C459 an other candidate?


Where is the HI located? the VLBI follow up

What is the origin of the gas outflows?


What produces the HI outflows?

Despite the highly energetic phenomena involved, gas remains (or become again) neutralInsight on the physical conditions of the medium around the AGN

Mellema et al. 2002Evolution of clouds in radio galaxy cocoons

shock runs over a cloud compression phase (overpressured cocoon)

fragmentation & cooling

formation of dense, cool & fragmented structures

Can they reach the high velocities observed?

Starburst wind

Radiation pressure (Dopita et al.)

but very different ionization in the objects detected

Interaction between the radio jet and ISM


• VLBIabsorption against

brightest lobe! OUTFLOW!

Oosterloo et al. 2000

The case of the Seyfert galaxy IC 5063


Optical and HI data for the Seyfert galaxy IC 5063

[OIII] 4959, 5007 ÅH+[NII]

~4arcseccirca 1.3kpc

radio core

400 km/s

ATCA & NTT


4C12.50: High resolution follow up

4C12.50: new global VLBI experiment

5 GHz (Stanghellini et al.)

core

~250 pc

Continuum image (~ 20x4 mas beam)


Where is the HI?

100 pc

~30%,

NH~3x1021 for TSPIN=100K

black=WSRTred = VLBI

Integrated HI profile

Mass of the HI cloud ~105-6 Msun


2D simulationsBicknell et al.


Conclusions

The location of the HI can be a “surprise”:follow up at higher resolution are important!

HI outflows: very broad HI absorption observed in some radio galaxies. We now need complete statistics.Difficult to detect due to technical limitations

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?

Possibly resulting from radio jets strongly interacting with the rich medium

Not all the HI in the central region of radio galaxies is in circumnuclear disk/tori. But no strong evidence for HI infall.

Sydney, 23 July 2003 Joint Discussion 18: Quasar cores & jets Central Regions of AGNs probed by the...

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