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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