the physics of galaxy formation institute for computational cosmology university of durham michael...

The Physics of Galaxy The Physics of Galaxy FormationFormation

Institute for Computational CosmologyUniversity of Durham

Michael Balogh

M31 “Andromeda” galaxy

Hubble Deep Field/HST

In the beginning …In the beginning …

WMAP(Bennett et al. 2003)

In the beginning…In the beginning…

z ~ 1000

Perturbation GrowthPerturbation Growth

Growth oflinear perturbationsa function of M and

WMAP

In the beginning …In the beginning …

Spergel et al. 2003

Mean and 68% confidence errors

Amplitude of fluctuations A=0.83 0.08Spectral index at k=0.05 Mpc-1 ns=0.93 0.03Derivative of spectral index dns/dlnk=-0.031

0.017Hubble constant h=0.71 0.03Total density/critical density tot=1.02 0.04Matter density/critical density m=0.27 0.04Baryon density/critical density b=0.044 0.004Age of the Universe to=13.7 0.2 GyrReionization Redshift zr=17 4Matter power spectrum normalization

8=0.84 0.04

Decoupling redshift zdec=1089 1Age of the universe at decoupling tdec=379 7 kyrThickness of surface of last scatter zdec=195 2Redshift of matter-radiation equality zeq=3233 200

Fit to the WMAP, CBI, ACBAR, 2dFGRS, SN1a and Lyman forest data

Spergel et al. 2003

Mean and 68% confidence errors

Amplitude of fluctuations A=0.83 0.08Spectral index at k=0.05 Mpc-1 ns=0.93 0.03Derivative of spectral index dns/dlnk=-0.031

0.017Hubble constant h=0.71 0.03Total density/critical density tot=1.02 0.04Matter density/critical density m=0.27 0.04Baryon density/critical density b=0.044 0.004Age of the Universe to=13.7 0.2 GyrReionization Redshift zr=17 4Matter power spectrum normalization

8=0.84 0.04

Decoupling redshift zdec=1089 1Age of the universe at decoupling tdec=379 7 kyrThickness of surface of last scatter zdec=195 2Redshift of matter-radiation equality zeq=3233 200

Fit to the WMAP, CBI, ACBAR, 2dFGRS, SN1a and Lyman forest data

Spergel et al. 2003

Mean and 68% confidence errors

Amplitude of fluctuations A=0.83 0.08Spectral index at k=0.05 Mpc-1 ns=0.93 0.03Derivative of spectral index dns/dlnk=-0.031

0.017Hubble constant h=0.71 0.03Total density/critical density tot=1.02 0.04Matter density/critical density m=0.27 0.04Baryon density/critical density b=0.044 0.004Age of the Universe to=13.7 0.2 GyrReionization Redshift zr=17 4Matter power spectrum normalization

8=0.84 0.04

Decoupling redshift zdec=1089 1Age of the universe at decoupling tdec=379 7 kyrThickness of surface of last scatter zdec=195 2Redshift of matter-radiation equality zeq=3233 200

Fit to the WMAP, CBI, ACBAR, 2dFGRS, SN1a and Lyman forest data

Spergel et al. 2003

Mean and 68% confidence errors

Amplitude of fluctuations A=0.83 0.08Spectral index at k=0.05 Mpc-1 ns=0.93 0.03Derivative of spectral index dns/dlnk=-0.031

0.017Hubble constant h=0.71 0.03Total density/critical density tot=1.02 0.04Matter density/critical density m=0.27 0.04Baryon density/critical density b=0.044 0.004Age of the Universe to=13.7 0.2 GyrReionization Redshift zr=17 4Matter power spectrum normalization

8=0.84 0.04

Decoupling redshift zdec=1089 1Age of the universe at decoupling tdec=379 7 kyrThickness of surface of last scatter zdec=195 2Redshift of matter-radiation equality zeq=3233 200

Fit to the WMAP, CBI, ACBAR, 2dFGRS, SN1a and Lyman forest data

stars= 0.0014 ± 0.00013

>95% of baryons are dark

The matter budget: The matter budget: starsstars

Cole et. al 2002

The baryon budget: starsThe baryon budget: stars

Coma: XMM-Newton ObservatoryComa cluster

The baryon budget: hot gasThe baryon budget: hot gas

Remaining dark matter (~84%)

Stars in galaxies (~1%)

Hot gas between galaxies (~15%)

The matter budget: The matter budget: clustersclusters

M ≈ 0.23

b ≈ 0.04

* ≈ 0.003

The baryon budgetThe baryon budget

Too cool to emit observable

X-ray radiation.

We know it exists, but can’t

directly measure how much

there is

?

?

Stars in Galaxies (~5%) Gas in Galaxies (~2%)

Gas in Clusters (~7%)

Gas in Groups

InterclusterGas

Ignore the lights…Ignore the lights…

• Most of the baryons are invisible• Most of the matter is non-

baryonic, dark, and weakly interacting

• Most of the energy is not matter

Ignore the lights…Ignore the lights…

• Most of the baryons are invisible• Most of the matter is non-

baryonic, dark, and weakly interacting

• Most of the energy is not matter

The easy part: Dark The easy part: Dark mattermatter

University of Durham

Institute for Computational Cosmology

150 Mpc/h

dalla Vechia, Jenkins & Frenk

University of Durham

Institute for Computational Cosmology

3 Mpc/h

dalla Vechia, Jenkins & Frenk

The hard part: baryonsThe hard part: baryons

Baryonic PhysicsBaryonic Physics

Radiativecooling

Radiativecooling

Invisible baryons: ~106 K

MergersMergers

Barnes (1992)

MergersMergers

Barnes (1992)

Baryonic PhysicsBaryonic Physics

Radiativecooling

Radiativecooling

The cooling catastropheThe cooling catastrophe

Cooling occurs primarily throughbremsstrahlung radiation, so tcool T1/2-

1

The typical density of haloes is higher at early times: (1+z)3

Thus, gas cools very efficiently in small haloes at high redshift.

•White & Frenk (1991)•Balogh et al. (2001)

Why so few stars?Why so few stars?

Balogh et al. (2001)

Observations imply */b 0.05

f co

ol

0.1

0.6

0.5

0.4

0.3

0.2

Fraction of condensed gas in simulations is much larger, depending on numerical resolution

Pearce et al. (2000)

Lewis et al. (2000)

Katz & White (1993)

kT (keV)1 10

Galaxy Luminosity Galaxy Luminosity FunctionFunction

Benson et al. 2003

Overcooling leads to the formation of hundreds more small galaxies than are observed.

Supernova feedback?Supernova feedback?

M82/Subaru Telescope M82/Chandra Observatory

Baryonic PhysicsBaryonic Physics

Radiativecooling

Radiativecooling

Feedback

Feedback

DetailsDetails

z > 1: Feedback z < 1: Environment

z > 1: Feedbackz > 1: Feedback

Why are groups Why are groups underluminous?underluminous?

If cluster structure were self-similar, then we would expect L T2

Observations disagree, but why?

Preheating by supernovae & AGNs?

10

1

kT

(keV

)

40 41 42 43 44 45 46

log10Lx (ergs s-1)

L

T2

K0=400 keV cm2

Isothermal modelM=1015 M0

Preheated gas has a minimum entropy thatis preserved in clusters(Kaiser 1991; Balogh et al. 1999)

Definition of S: S = (heat) / T Equation of state: P = K5/3

Relationship to S: S = N ln K3/2 + const.

Convective Stability: dS/dr 0

Useful Observable: Tne-2/3 K

Only radiative cooling can reduce Tne-2/3

Only heat input can raise Tne-2/3

Ko=400 keV cm2

300

200

100

Balogh, Babul & Patton 1999Babul, Balogh et al. 2002

log10 LX [ergs s-1]

kT [k

eV

]10

1

0.140 42 44 46

Isothermal model

Preheated modelKo=400 keV cm2

Sunyaev-Zeldovich EffectSunyaev-Zeldovich Effect

Gomez et al. 2003

Decrement: 150 GHz Intermediate: 220 GHz Increment: 275 GHz

35’Abell 3266

(Inverse-Compton scattering of CMB photons off hot electrons in the ICM)

S-y0 relation

y0-TX relation

Constraints on “entropy”floor:

S-y0 K0=540 keV cm2

y0-TX K0=300 keV cm2

McCarthy et al. 2003

Sunyaev-Zeldovich EffectSunyaev-Zeldovich Effect

Does supernova feedback Does supernova feedback work?work?

• Local SN rate ~0.002/yr (Hardin et al. 2000; Cappellaro et al. 1999)

• An average supernova event releases ~1044 J

•Assuming 10% is available for heating the gas over 12.7 Gyr, total energy available is 2.5x1050 J

• This corresponds to a temperature increase of 5x104 K

•To achieve an entropy floor K0 T/2/3:

/avg = 0.28 (K0/100 keV cm2)-3/2

Consider the energetics for 1011Msun of gas:

SN energy too low by at least a factor ~50

What about active What about active galaxies?galaxies?

Perseus Cluster & 3C 84Perseus Cluster / Chandra

10 kpc

Bubbles in the Intracluster MediumBubbles in the Intracluster Medium

Quilis, Bower & Balogh 2001

Bubbles in the Intracluster MediumBubbles in the Intracluster Medium

Quilis, Bower & Balogh 2001

Effective at disruptingcooling in the core,over the ~50 Myrlifetime of the bubble

The AGN solution?The AGN solution?

• There is ~100 times more energy available in AGN than in supernovae

• Proven effective at disrupting cooling flows

• Details of how this energy is coupled to the surrounding gas are still uncertain

z < 1: Galaxy Ecologyz < 1: Galaxy Ecology

B) External? Hierarchical build-up of structure inhibits star formation

A) Internal? i.e. gas consumption and “normal” aging

Steidel et al. 1999

SFR ~ (1+z)1.7

(Wilson, Cowie et al. 2002)

Why Does Star Formation Stop?Why Does Star Formation Stop?

Galaxy clusters: the end of Galaxy clusters: the end of star formation?star formation?

Additional physics?Additional physics?

Ram-pressure stripping (Gunn & Gott 1972)

Collisions / harassment (Moore et al. 1995)

“Strangulation” (Larson et al. 1980; Balogh et al. 2000)

Additional physics?Additional physics?

Ram-pressure stripping (Gunn & Gott 1972)

Collisions / harassment (Moore et al. 1995)

“Strangulation” (Larson et al. 1980; Balogh et al. 2000)

Quilis, Moore & Bower 2000

Additional physics?Additional physics?

Ram-pressure stripping (Gunn & Gott 1972)

Collisions / harassment (Moore et al. 1995)

“Strangulation” (Larson et al. 1980; Balogh et al. 2000)

Additional physics?Additional physics?

Ram-pressure stripping (Gunn & Gott 1972)

Collisions / harassment (Moore et al. 1995)

“Strangulation” (Larson et al. 1980; Balogh et al. 2000)

Abell 2390 (z~0.23)Abell 2390 (z~0.23)3.6 arcmin R image from

CNOC survey(Yee et al. 1996)

HH in Abell 2390 in Abell 23903.6 arcmin

Balogh & Morris 2000

300

200

100

0-1

00-2

00-3

00

-200 -100 0 100 200Dec

RA

AC114 (z=0.31)AC114 (z=0.31)

(Couch, Balogh et al. 2001)

Nod & Shuffle: LDSS++ Nod & Shuffle: LDSS++ (AAT)(AAT)

band-limiting filter +microslit = ~800 galaxies per 7’ field

HH in Rich Clusters at z~0.3 in Rich Clusters at z~0.3

Balogh et al. 2002MNRAS, 335, 110

Couch, Balogh et al. 2001ApJ 549, 820

LDSS++ with nod and shuffle sky subtraction, on AAT

(Field)

TimescalesTimescales

Use numerical model ofinfall to estimate timescalefor disruption of SFR

Radial gradients in CNOCclusters suggest ~2 Gyr

Suppressed star formation within several Mpc of cluster centre! What environment is responsible?

Balogh, Navarro & Morris 2000Diaferio et al. 2001

The 2dFGRS and SDSSThe 2dFGRS and SDSS

2dF Galaxy redshift survey:– spectra and redshifts for 220 000 nearby

galaxies– only photographic plate photometry

Sloan digital sky survey:– goal is spectra for 1 million galaxies, with

digital photometry (ugriz)– Early data release contained 50 000 galaxies

SFR-Density Relation in the SFR-Density Relation in the 2dFGRS2dFGRS

Lewis, Balogh et al. 2002MNRAS 334, 673

Field

Normalised star formationrate measured from Hin17 nearby clusters

Identified a critical densityof ~1 Mpc-2, where environmental effects become important

This corresponds to lowdensity groups in theinfall regions of clusters

Importance of EnvironmentImportance of Environment

Star formation is inhibited in only moderately overdense (hence common) environments

Likely due to a relatively slow process; not ram pressure stripping

Impact on global evolution is still unknown

What Next?What Next?

Tying star formation to Tying star formation to structure growthstructure growth

Groups Clusters

Local Groups in the Local Groups in the 2dFGRS/SDSS2dFGRS/SDSS

Based on friends-of-friends catalogue (V. Eke)

Mean SFR appears to be suppressed in all galaxy associations at z=0!

CNOC2 Groups at z~0.45CNOC2 Groups at z~0.45Deep spectroscopy with LDSS-2 on Magellan 1 (~30 groups)

Infrared (Ks) images from INGRID

Combined with CNOC2 multicolour photometry and spectroscopy, we can determine group structure, dynamics, stellar mass, and star formation history.

LDSS2 on MagellanLDSS2 on Magellan[OII] [OII]

The CFHLSThe CFHLS

Survey Area Filters DepthTotal (ks)

StrategyTotal nights

Wide Synoptic

1 8x92 7x7

u* 25.5 6

162

g’ 26.5 2.5

r’ 25.7 2 1 early1 3a later

i’ 25.5 4.3

z’ 24.0 7.2

Deep Synoptic

4 1x1 u* 27 118.8

5.25 nights per run,5 runs a year for each field

202

g’ 28.4 118.8

r’ 28 237.6

i’ 27.8 475.2

z’ 26 237.6

The CFHLSThe CFHLS

• identify clusters and groups to z=1. Expect ~50 clusters at 1<z<1.5 in Wide Synoptic Survey

• Overlap with XMM Large Scale Survey allows analysis of X-ray properties

• Requires spectroscopic and NIR follow-up

Galaxy formation Galaxy formation theorytheory

• Need self-consistent feedback model which explains:– galaxy luminosity function– cluster/group X-ray properties– cold fraction of baryons

• This likely requires coupling energy output of AGN to surrounding material. Detailed work is only now beginning.

SummarySummary

• Underlying galaxy formation model is fairly well established

• However, it is dominated by unknown feedback processes. Wealth of data (esp. from Chandra and XMM-Newton) are shedding light on this, now

• Importance of additional physics in dense environments is currently unknown, but will be established with the completion of large surveys at z~1

Benson et al. 2002

Z=5

Benson et al. 2002

Z=3

Benson et al. 2002

Z=2

Benson et al. 2002

Z=1

Benson et al. 2002

Z=0.5

Benson et al. 2002

Z=0