Feedback, Models and Feedback, Models and the effect of Environmentthe effect of Environment

Richard BowerRichard Bower& the GALFORM team& the GALFORM team

Andrew Benson, Andreea Font, Ian McCarthy, Rowena Malbon, John Helly, Carlos Frenk, Carlton Baugh, Shaun

Cole, Cedric Lacey….

What I want to say!What I want to say!

Old stuff!Old stuff!

Quick overview of the Quick overview of the “new” Durham models - “new” Durham models - AGN feedback and what AGN feedback and what it does for you.it does for you.

New stuff!New stuff!

Galaxy Ecology - Galaxy Ecology - modeling how galaxies modeling how galaxies interact with their interact with their environmentenvironment

The flip-side of galaxy The flip-side of galaxy formation - the thermal formation - the thermal history of the IGM/ICMhistory of the IGM/ICM

1.1. The bright end of the luminosity functionThe bright end of the luminosity function What sets the break in the galaxy luminosity function?What sets the break in the galaxy luminosity function?

2.2. The “cooling flow” problemThe “cooling flow” problem Why don’t cooling flows result in bright blue galaxies at the Why don’t cooling flows result in bright blue galaxies at the

centres of clusters?centres of clusters?

3.3. The “hierarchy” problemThe “hierarchy” problem Why are the brightest galaxies old and red?Why are the brightest galaxies old and red?

These problems are closely interconnected: do AGN These problems are closely interconnected: do AGN provide the solution?provide the solution?

The three problems of The three problems of galaxy formationgalaxy formation

4. Only 10% of the baryons form into stars!!! Where are the other baryons? what are their properties?

What cooling+feedback What cooling+feedback need to do!need to do!

dark matter massfunction (fixed M/L)

feedback has successfully depressed galaxy formation in small haloes

but cooling is now too effective in high mass haloes (there's more gas left over)

The same problem is seen in simulations: Balogh et al., 2001; Springel & Hernquist 2003

NB: exacerbated by the high value of WMAP Ωb

Benson et al 2003

AGN the new ingredientAGN the new ingredient

The Power of AGNThe Power of AGN

Comparison of energies:Comparison of energies:Total thermal energy of a 10Total thermal energy of a 101313 M Moo halo … 10 halo … 106161 erg ergAccretion energy of a 10Accretion energy of a 1099 M Moo black hole black hole

… … 2 x 102 x 106262 ergerg

It seems unlikely that AGN are It seems unlikely that AGN are unimportant!unimportant!

The two forms of AGN The two forms of AGN feedbackfeedback

“Quasar” mode

(eg. Granato et al., 2004, Springel et al

2005)

Uplifting matterial?

Radio X-rays Temperature

M87: Forman et al 2006; Perseus: Fabian et al 2000, 2006

Shock heating

Mixed plasma and ICM?

Springel et al 2005

“Radio” mode feedback

(eg. Croton et al 2006, Bower et al 2006 Okamoto et al 2007)

The AGN feedback loopThe AGN feedback loop

CoolingAGN

fuelling

Hydrostatic ?

tcool>tfree-fall

Keres et al 2005; Dekel & Birnboim 2003; Binney 2004

“radio” mode

Present-day GalaxiesPresent-day Galaxies Bj and K luminosity Bj and K luminosity

functionsfunctions Switching “radio” Switching “radio”

feedback off leads feedback off leads to a population of to a population of very bright galaxies very bright galaxies formed in cooling formed in cooling flowsflows

But position of the But position of the LF break is set by LF break is set by the division the division between rapid and between rapid and hydrostatic cooling hydrostatic cooling haloes.haloes.

dustNo dust

K-band

Bj band

No AGN

No AGN

Evolution of the Stellar Evolution of the Stellar Mass FunctionMass Function

The evolution The evolution of the stellar of the stellar mass function mass function from Drory et from Drory et al 2005.al 2005.

More recent More recent tests now tests now possible possible (eg Van (eg Van Dokkum et al 2007, Dokkum et al 2007, Bundy/Stringer 2008)Bundy/Stringer 2008)

z=0

AGN model

McClure et al 2006

Integrated SMD agrees with Stark et al 2006

Evolution of coloursEvolution of colours Evolution of red

sequence tracks passive evolution

…but the blue sequence also get bluer – matches the increase in SFR density

Bower et al 2006 & De Lucia et al 2006 galaxy catalogues are public!Bower et al 2006 & De Lucia et al 2006 galaxy catalogues are public!www.mpa-garching.mpg.de and and www.icc.dur.ac.uk

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Summary (of part I)Summary (of part I)

AGN + semi-analytic galaxy formation provides AGN + semi-analytic galaxy formation provides a frame work for understanding the “anti-a frame work for understanding the “anti-hierarchical” universehierarchical” universe

B06 is by no means the only model to use AGN: eg., Hatton et al 2003, B06 is by no means the only model to use AGN: eg., Hatton et al 2003, Granato et al ‘04, Croton et al. ‘06, De Lucia et al ‘07, Menci et al ‘07, Granato et al ‘04, Croton et al. ‘06, De Lucia et al ‘07, Menci et al ‘07, Cattaneo ‘07, Summerville ‘08 - but be aware of the different flavours.Cattaneo ‘07, Summerville ‘08 - but be aware of the different flavours.

The model seems to do reasonably well …. The model seems to do reasonably well …. (I’m (I’m sure someone will contradict me!)sure someone will contradict me!)

Part II:Part II:Improving the modelImproving the model

1)1) A better description of A better description of environmental processesenvironmental processes

2)2) (Pre-) heating the IGM(Pre-) heating the IGM

But models that work are boring…

Problems with the Problems with the standard model…standard model…

Satellites are too red. Satellites are too red. Regardless of halo Regardless of halo mass.mass.

The effect of The effect of “strangulation” is “strangulation” is overestimatedoverestimated

A satellite galaxy A satellite galaxy orbiting within another orbiting within another halo is assume to halo is assume to loose its own hot gas loose its own hot gas reservoir.reservoir. This is far too simplisticThis is far too simplistic

Weinmann et al 2006; Baldry et al 2006.

(one of them)

Environmental Physics is not Environmental Physics is not correctly handledcorrectly handled

All satellites are red!

All GalaxiesSatellite Galaxies

No blue satellites!

Environmental Physics is not Environmental Physics is not correctly handledcorrectly handled

Is this realistic?

•Mass ratio of haloes

•Gas atmosphere of the main halo

Old Strangulation model

•Remove gas reservoir as galaxy orbits larger halo

Hot gas reservoir

SNe winds quickly exhaust disk gas

Larson, Tinsley & Caldwell 1980

Strangulation = suffocation = starvation

McCarthy et al – an improved model for halo stripping – depends on the orbit of the satellite and the gas content of the satellite and main halo.

(Actually, Gunn & Gott’s formulae re-calibrated for halo gas using numerical simulations)

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McCarthy et al. 2007

Controlled SPH and FLASH simulations

Solving the problem by adjusting Solving the problem by adjusting the environment physicsthe environment physics

Dramatic improvement in the environmental dependence of satellite Dramatic improvement in the environmental dependence of satellite properties from reducing the effects of starvation.properties from reducing the effects of starvation.

Font et al 2008

Problem solved?Problem solved?

There are many more tests of the interaction of galaxies with their environment - more work is needed to extract the data and model in comparable ways (Balogh/Font/McGee/IGM/RGB et al 2008)

A closer look at the colour A closer look at the colour distribution of galaxiesdistribution of galaxies

The Field The Clusters

Font, Balogh, McGee et al, in prep.(Distributions shifted to to agree with red-sequence colours)

Too many intermediate colours galaxies, not enoough blue objects

Too many faint red galaxies

What about the ICM?What about the ICM?

The flip-side of galaxy The flip-side of galaxy formationformation

Only 10% of the baryons form into stars!!! - what about the rest of the baryons???

X-ray Emission from X-ray Emission from Groups and ClustersGroups and Clusters

L-T relation : well known L-T relation : well known that the self-similar that the self-similar relation failsrelation fails

AGN: standard model just AGN: standard model just prevents cooling… it prevents cooling… it doesn’t affect the X-ray doesn’t affect the X-ray luminosityluminosity

Data from Horner et al.

B06 Model

Data from Osmond & Ponman

The AGN feedback loop The AGN feedback loop (new version)(new version)

CoolingAGN

fuelling

Hydrostatic ?

Heating

redistribute halo gas Based on the “excess energy”

method (Wu et al 1999), plus the hydrostatic criterion

“radio” mode

P=min(Ledd,Mcool)

A note for pundits:

•This is “in-situ” heating

• there’s no “pre-heating”

•its going to be expensive, but not prohibitively so.

X-ray Emission from X-ray Emission from Groups and ClustersGroups and Clusters

L-T relation : well L-T relation : well known that the self-known that the self-similar relation failssimilar relation fails

AGN: standard model AGN: standard model just prevents coolingjust prevents cooling

Revised model, AGN Revised model, AGN feedback redistributes feedback redistributes halo gas until the halo gas until the cooling rate drops and cooling rate drops and AGN power is cut offAGN power is cut off

AGN redistributes halo gas

Scatter driven by diverse assembly history

Voit & Bryan 2001; Bower et al 2008, MN, in press (astro-ph/0808.2994)

A huge step forward - I’ve been trying to achieve this

for ten years!

The baryon content of haloes - The baryon content of haloes - where are all those baryons?where are all those baryons?

Stars and cold gas

Hot X-ray emitting gas

“Ejected” gas

T (keV)

Conclusions – what you Conclusions – what you should remember!should remember!

AGN regulate the AGN regulate the formation of the brightest formation of the brightest galaxies.galaxies.

The break in the LF is set The break in the LF is set by hydrostatic vs rapid by hydrostatic vs rapid cooling.cooling.

The model describes the The model describes the properties of field properties of field galaxies and their galaxies and their evolution well.evolution well.

Cluster galaxies form Cluster galaxies form earlier than field galaxiesearlier than field galaxies

But…But… Galaxy ecology is a formidable Galaxy ecology is a formidable

testtest Improved treatment of ram-Improved treatment of ram-

pressure stripping of halo gas pressure stripping of halo gas makes a huge improvementmakes a huge improvement

Font et al 2008Font et al 2008 X-ray emission from groups X-ray emission from groups

and clusters and clusters Over estimated in standard Over estimated in standard

modelmodel AGN do more than prevent AGN do more than prevent

coolingcooling Bower et al 2008Bower et al 2008

Thank you!Thank you!

Evolution of the Stellar Evolution of the Stellar Mass FunctionMass Function

The evolution The evolution of the stellar of the stellar mass function mass function from Drory et from Drory et al 2005.al 2005.

z=0

AGN model

McClure et al 2006

Integrated SMD agrees with Stark et al 2006