fluorescent processes research school of astronomy & astrophysics fluorescent processes feeding...

Fluorescent Processes

Research School of Astronomy & Astrophysics

Feeding The Beast: Infall, Mergers or Starbursts?

Mike Dopita (ANU)



Topics to be Covered:

What is the nature of “cooling flow Elliptical Galaxies”?

How do Luminous IR galaxies (LIRGS) evolve and feed their Black Holes?

What can we learn from IR spectroscopy of LIRGS?

How do AGNs feed back on their hosts in the hi-Z Universe? (the revenge of the AGNs!)

How do starbursts blow winds? (the revenge of the massive stars!)



1. “Cooling Flow” Elliptical Galaxies

collaborators

Catherine Farage ANU (Thesis Project),

Peter McGregor ANU



“Cooling flows”

According to the Fabian/Nulsen model, the hot X-ray emitting plasma in Elliptical Galaxies cools and falls into the galactic core, feeding the supermassive Black Hole.

Is this model correct?

Consider first the southern “poster child” of cooling flows, NGC 4696...



NGC4696 (Crawford 2005)




Note close correlation of X-ray and H-

alpha





alpha

Radio emission

morphology is determined by gas, not vice-

versa.





alpha

Radio emission

morphology is determined by gas, not vice-

versa.

Where would dust come from in a

cooling flow?



..so, make WiFeS Observations of NGC 4696

Farage, Dopita & McGregor

B 7000

R 7000



[N II] Brightness Distribution

(note strong central concentration)



[N II] Velocity Dispersion

(note low velocity dispersion)

[N II] Velocity Centroid

(note evidence for rotation)



LINER spectrum. Strong [NII] and [N I] and weak [O III]] imply low shock velocities ~ 80km/s

Compare with the Herbig-Haro

spectrum of DG Tau



Conclusion on NGC 4696

The presence of dust implies we see matter from a minor merger, not a cooling flow. This is supported by:

Rotational support rather than infall

Low velocity dispersion in filaments

“Liner” Spectrum characteristic of low velocity (<100km/s) shocks.



A much larger and more luminous source: Abell 2204



..again, a LINER spectrum. Strong [NII] very strong [N I] and weak [O III]] again

imply low shock velocities, despite a much larger total velocity dispersion.



If either shocks or cooling flows, the X-ray is too strong for the observed H-alpha in

emission line radio E galaxies

T = 5E5 K T =2.5E6 K



A Dynamical Model:Fragments of merger orbit through hot halo gas,

and are shocked as a result.

T ; c0

1 T

0

n0

Vorb Vs

nc



Implications of this “Heating Flow” model:

Orbital Motion is transonic (weak shocks):

Ram pressure drives cloud shock:

Some likely parameters of the problem:

Therefore we have:



2. Luminous IR Galaxy MergerscollaboratorsJeff Rich IFA, Hawaii (Thesis Project), Lisa Kewley & Dave

Sanders IFA, HawaiiLee Armus Spitzer Science Center

and the GOALS team



GOALS: Merging IR-Luminous Galaxies in the local Universe



IRAS 18293-3413

He I + Na I [S II]

H-alpha + [N II]



Galaxy Image

Velocity Field

H-Alpha Image

Line Ratio Map



The Merger ScenarioSanders & Mirabel (1996); Banes & Hernquist (1996) etc.

Starburst Phase

First Passage: Formation of Tidal Tails





Second Passage & Merging Phase

AGN Phase

Starburst Phase





Second Passage & Merging Phase

Abundance GradientsNormal

Abundance GradientsDisrupted



Abundance Gradients Mixed, gas flows lower nuclear abundance



Gas flows from Abundance Measurements:Kewley Geller & Barton 2006, AJ, 131,2004

Nuclear Abundance Lower in Merging Galaxies:Implies Gas flows to nucleus



Gas flows from Abundance Measurements:Kewley Geller & Barton 2006, AJ, 131,2004

..and Abundance Gradientis disrupted

Nuclear Abundance Lower in Merging Galaxies:Implies Gas flows to nucleus

(Keck LRIS Spectroscopy)



Amount of Gas Inflow to Nucleus in Mergers

Assuming gas inflow ~7 M_sun/yr

and an initially normal metallicity gradient

We need 50-60% dilution in nucleus

c.f. Merger models, which predict 60%

and we need an infall timescale of 10-100 Myr

c.f. merger models, which predict 100 Myr.

Fluorescent ProcessesResearch School of Astronomy & Astrophysics

Excitation Conditions



Spectral Classification: Yuan, Kewley & Sanders (2009)

IRGs

LIRGs

ULIRGs

logL>8

logL >12

10.5<logL <12



Old Classifications:

Veilleux et al. (2005)

Sy 2

Sy 1

LINER

HII



New Classifications:

HII

Sy 2

Sy 1

Comp

Amb

Yuan, Kewley & Sanders (2009)

Note how Seyfert activity is at first hidden, then becomes dominant both at late phases and in ULIRGs



What is the Nature of Transition Objects?

Do all (or any of) the transition objects contain an AGN?

For: Their line ratios are shifted in the direction of AGN.

Against: No radio point sources are detected in these objects.

Could this be the result of high free-free optical depth in the radio?

Answer: Only if surface rate of SF is rather extreme, or if the AGN has a very strong ionized wind.

If so, why are the ULIRGS more LINER-like than Seyfert II -like?

Could this indicate a role for distributed shock emission?

Could the IMF in these objects be unusually flat?


3. Infrared Modelling of LIRGS



Analytic Modelling (Dopita et al. 2004-8)

Use STARBURST 99 to provide the intrinsic stellar SEDs.

Use MAPPINGS IIIq to compute HII region temperature, ionisation, emission line spectrum, dust and PAH absorption, dust re-emission in the mid- and far-IR.

Dust model includes grain shattering size spectrum, quantum fluctuations of the dust temperature & PAH photodissociation.

Ensure that any cluster of a given age is placed in its self-consistent evolving HII region.

Add the contribution of the old (10-100Myr) stars.

Put the whole lot behind a dusty turbulent foreground screen.



Our Model Starburst: HII Regions of all ages and many cluster masses evolve in an ISM of a given pressure & chemical abundance


Fits to SEDs of “template” starburst galaxies.


Fits to SEDs of “template” starburst galaxies...Pretty good!


GOALS IRS Sample (Armus et al.)

log C = 5.5A(v) = 8 mag

A(v) = 19 mag A(v) = 31 mag log C = 5.5log C = 5.5

A(v) = 0 mag log C = 5.5


AGN +SB in GOALS Sample (Armus et al.)

PAH Class C emission?see Tielens 2008, ARAA

NLR dominated


..curiously enough, only 15-20% have AGN!

PAH Class C emission?see Tielens 2008, ARAA

NLR dominated


GOALS Sample - Silicate Absorption

A(v) = 60 mag; SFR = 60

A(v) = 56 mag; SFR = 65

Draine “Astronomical” Silicate Opacity does not give a good fit

to the 10 and 18 µm Si absorption.The 18 µm Si absorption is too weak,

and the central wavelength of the 10 µm feature is too short.


24 µm

18.4 µm

10.0 µm

9.3 µm

18.0 µm


...due to larger grain size (~1.5 µm) in the starburst region



4. Radio Galaxy AGN Feedback(the revenge of the AGN)

- Expelling the Interstellar Gas

- The Transition to “red-and-dead”



QuickTime™ and aGraphics decompressor

are needed to see this picture.

The Evolution of a Radio Galaxy(Model by Sutherland)



ACS Observations,Box: 2x2 arc sec. ~ 16x16 kpc

Scale 0.05 arc sec/ pixel ~ 400 pc

CIII] 1937Å

CIII] 1937ÅCIII] 1937Å

1513Å 1513Å

1513Å

[O III] Galaxies around Radio Galaxy MRC 0316-257 (z=3.13)

Maschietto et al. 2008 MNRAS



Example: 4C 41.17Universe: 1.6 Gyr old

Data By: van Breugel et al 2002

low freq.radio jet

Feedback by AGNJet Interaction



..forming stars at the rate of 5000 solar masses per year!



..with shock excited jet emission



Ly−α and H−α 1138-262in PKS( , , , & , 2003)Kurk Pentericci Röttgering Miley Heckman

Jet Hot-spot

Colour: Ly−αContours: H−α

Nucleus



Ly-Alpha Halos associated with Hi-z Radio Galaxies are:

Luminous: F = 10-15 erg s-1 cm-2 or L = 1044 erg sec-1 &

Large: up to 200 kpc across or ~ 20 arc sec in diameter!

Over 400 candidates remain unstudied.

These Galaxies both represent truly galaxy-wide starbursts with chemical enrichment and “maximal” star formation extending over some 10-100 kpc2.

Such galaxies (and their radio-quiet counterparts) probably represent the dominant mode of star formation in the Universe at 4 > z > 2, forming typically 300-3000 solar masses per year.



The Expanding Shell of 4C 60.07:Evidence for AGN Feedback

Reuland et al. 2006 AJ


4. Galactic Winds and Fountains (the

revenge of the stars)


The Prototypical Superwind - M82 Chandra, HST, Spitzerhttp://chandra.harvard.edu/photo/2006/m82/m82_comp.jpg



Condition to drive a Galactic WindWe need (at least) that the kinetic energy injection per unit area into a fraction of the disk gas will exceed its binding energy:

Star formation follows the Kennicutt (1998) Law:

So a wind becomes possible when:

Therefore, a wind is driven when:

Escape Velocity is Low (i.e. galaxy is small)Lifetime of Starburst is longGas surface density is high



Structure of a Superwind

Cooper, Bicknell & Sutherland, RSAA: astro-ph 0710.5437



The Movie of a Superwind

QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

Cooper, Bicknell & Sutherland, 2008



Conclusions: Winds & Fountains

Galactic winds can be driven when the collective effects of disk star formation become important, i.e. when hot bubbles can collide & merge in the halo.

Starburst winds are driven when the star formation is of high concentration, long continued, and when the depth of the galaxian potential is sufficiently shallow.

These conditions may be mutually exclusive, but are generally favoured in merging starburst galaxies.



That’s All Folks!!

fluorescent processes research school of astronomy & astrophysics fluorescent processes feeding...

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