Cooling flows and Galaxy Cooling flows and Galaxy formationformation

James BinneyJames BinneyOxford UniversityOxford University

OutlineOutline Phenomenology of CFsPhenomenology of CFs Physics of heatingPhysics of heating Standard galaxy formationStandard galaxy formation Galaxy formation revistedGalaxy formation revisted

collaboratorscollaborators Len CowieLen Cowie Gavin TaborGavin Tabor Henrik OmmaHenrik Omma Fathallah Alouani BibiFathallah Alouani Bibi Carlo NipotiCarlo Nipoti Filippo FraternaliFilippo Fraternali

The phenomenonThe phenomenon Thermal X-rays fromThermal X-rays from Clusters of galaxiesClusters of galaxies Groups of galaxiesGroups of galaxies Individual galaxiesIndividual galaxies

Perseus (Fabian + 03)

Jetha + 07

Cooling timesCooling times shortshort

Usually T(0) < T(Usually T(0) < T(11) by factor ~ 3) by factor ~ 3Jetha + 07

In absence of heatingIn absence of heating Field (1965): Cooling causes runaway Field (1965): Cooling causes runaway

growth of T differencesgrowth of T differences T will drop fastest where entropy is T will drop fastest where entropy is

lowestlowest Malagoli et al (1987): This will be @ Malagoli et al (1987): This will be @

centre because away from centre cool centre because away from centre cool (overdense) regions will sink till they (overdense) regions will sink till they reach gas with the same specific entropy reach gas with the same specific entropy (cf Maller & Bullock 04)(cf Maller & Bullock 04)

@ centre expect cooling catastrophe@ centre expect cooling catastrophe

Central accumulation?Central accumulation? Is cold gas streaming into centre? Is cold gas streaming into centre? In general no because:In general no because: Absence of young stars, of whatever Absence of young stars, of whatever

mass mass (Prestwich et al 97)(Prestwich et al 97) X-ray SB profile insufficiently peakedX-ray SB profile insufficiently peaked X-ray spectrum shows little gas at X-ray spectrum shows little gas at

T<1/3 TT<1/3 T11 (Boehringer + 02, Peterson + 03) (Boehringer + 02, Peterson + 03)

1.44-2 keV

Boehringer + 02

Peterson + 03

@ the centre of Perseus@ the centre of Perseus Molecular gas detectedMolecular gas detected By J=0,1,2.. Transitions of CO By J=0,1,2.. Transitions of CO

(Edge + 01, Salome + 06)(Edge + 01, Salome + 06) By rotation-vibration transitions of HBy rotation-vibration transitions of H2 2

(Hatch + 05)(Hatch + 05) Atomic gas detected in HAtomic gas detected in H etc etc Gas extends out in filamentsGas extends out in filaments Soft X-ray emission from around filaments Soft X-ray emission from around filaments

(Fabian + 03)(Fabian + 03) Not rotatingNot rotating Less gas (~4Less gas (~4££10101010MM¯̄) than expected if ) than expected if

catastrophic cooling for Gyrscatastrophic cooling for Gyrs

Salome + 06

HeatingHeating Invariably a massive elliptical @ centreInvariably a massive elliptical @ centre Such objects host central BHsSuch objects host central BHs And central non-thermal radio sourcesAnd central non-thermal radio sources The Bondi accretion rate onto BH is The Bondi accretion rate onto BH is

temperature-dependenttemperature-dependent

So accretion rate rises steeply with falling So accretion rate rises steeply with falling TT

Evidence for mechanical Evidence for mechanical heatingheating

First cavity seen in 1993 (Boehringer et al)First cavity seen in 1993 (Boehringer et al) Chandra sees many cavities (1999--)Chandra sees many cavities (1999--)

Cavities often coincide with non-thermal Cavities often coincide with non-thermal radio emissionradio emission

In M87In M87 Chandra resolves rChandra resolves rBondiBondi (Di Matteo et al 03)(Di Matteo et al 03) So L = 5So L = 5££10104444 erg/s if 0.1mc erg/s if 0.1mc22 released released LLXX(<20kpc) = 10(<20kpc) = 104343 erg/s erg/s (Nulsen & Boehringer)(Nulsen & Boehringer) LLXX(AGN) < 5x10(AGN) < 5x104040 erg/s erg/s LLMechMech(jet) = 10(jet) = 104343 – 10 – 104444 erg/s erg/s

(Reynolds et al 96; Owen et al 00)(Reynolds et al 96; Owen et al 00) So BH accreting at fraction MSo BH accreting at fraction MBondiBondi & &

heating on kpc scales with high efficiency heating on kpc scales with high efficiency (Binney & Tabor 95) (Binney & Tabor 95)

SimulationsSimulations Adaptive grid 3d hydro simulationsAdaptive grid 3d hydro simulations Extended heat injection Extended heat injection !! realistic entropy profiles realistic entropy profiles (Omma & Binney 05)(Omma & Binney 05) Stress irreversibility of cavity creation Stress irreversibility of cavity creation

(Binney et al 07)(Binney et al 07)

Explain how heating statistically matched Explain how heating statistically matched to cooling to cooling (Omma & Binney 05)(Omma & Binney 05)

VVjetjet= 10,000 km/s = 10,000 km/s Entr2kpc.movEntr2kpc.mov VVjetjet=20,000 km/s =20,000 km/s \u\henrik\20kv\entr.mov\u\henrik\20kv\entr.mov

Omma thesis 05

Donahue + 05

SummarySummary

Deep potential wells filled with gas at TDeep potential wells filled with gas at Tvirvir Gas doesn’t cool: thermostated by AGNGas doesn’t cool: thermostated by AGN Probably regulated by Bondi accretion of Probably regulated by Bondi accretion of

gas at Tgas at Tvirvir Heating mechanicalHeating mechanical Bubbles dynamical & only tips of icebergsBubbles dynamical & only tips of icebergs

Galaxy formationGalaxy formation Dark matter clusters from zDark matter clusters from z''30003000 Baryons cluster with DM from zBaryons cluster with DM from z''10001000 At z~20 small regions start At z~20 small regions start

collapsingcollapsing On collapse gas shockedOn collapse gas shocked In absence of cooling In absence of cooling

TT!! T Tvirvir

White & Rees (1978) ffWhite & Rees (1978) ff CDM spectrum has much power on small CDM spectrum has much power on small

scalesscales So large fraction of baryons quickly collapse So large fraction of baryons quickly collapse

into small-scale halosinto small-scale halos CDM halos are cuspy, so survive on falling in CDM halos are cuspy, so survive on falling in

to much larger halosto much larger halos So expect bulk of baryons to be in myriads of So expect bulk of baryons to be in myriads of

small galaxiessmall galaxies In reality ~1/4 of baryons in galaxies, and In reality ~1/4 of baryons in galaxies, and

most in L*most in L*'' 10 101212MM¯̄ halos halos Conclude: star formation suppressed in small Conclude: star formation suppressed in small

haloshalos

Suppression of SFSuppression of SF On smallest scales: On smallest scales:

photoionization, evaporation photoionization, evaporation (Efstathiou 92; Dekel 04) (Efstathiou 92; Dekel 04)

On larger scales: On larger scales: SN feedbackSN feedback (Dekel & Silk 86) (Dekel & Silk 86)

Trapped gas Trapped gas (Binney 2004)(Binney 2004) With standard IMF, SNe yield With standard IMF, SNe yield

~keV/particle ~keV/particle !! T TSNSN~10~1077KK If TIf Tvirvir<T<TSNSN heated gas flows out heated gas flows out Once TOnce Tvirvir>T>TSNSN it accumulates it accumulates In classic semi-analytic models of GF In classic semi-analytic models of GF !!

“overcooling” and formation of many “overcooling” and formation of many luminous blue galaxies luminous blue galaxies (Benson et al 03)(Benson et al 03)

Actually most luminous galaxies Actually most luminous galaxies belong to red sequence: no recent SFbelong to red sequence: no recent SF

Baldry + 04

GD II

M/L=220

GF by cooling?GF by cooling? Galaxies of red sequence either have gas Galaxies of red sequence either have gas

trapped @ Ttrapped @ Tvirvir (X-rays) or are subhalos of (X-rays) or are subhalos of halos with gas @ Thalos with gas @ Tvirvir

White & Rees (78), White & Frenk (91) White & Rees (78), White & Frenk (91) assumed gas shock-heated to Tassumed gas shock-heated to Tvirvir on infall on infall & GF occurred on cooling& GF occurred on cooling

But CF data show trapped gas doesn’t But CF data show trapped gas doesn’t cool!cool!

So how do galaxies form?So how do galaxies form?

Cold infall Cold infall (Binney 2004)(Binney 2004)

In simulations, higher resolution In simulations, higher resolution !! higher higher density density !! faster cooling faster cooling

Dekel & Birnboim (03, 06) argued gas only Dekel & Birnboim (03, 06) argued gas only heated when M>10heated when M>101212MM¯̄

Corroborates results from clustering Corroborates results from clustering simulations (Keres + 05)simulations (Keres + 05)

So blue-cloud galaxies can form from cold So blue-cloud galaxies can form from cold gasgas

Inefficiently because TInefficiently because TSNSN>T>Tvirvir so so M(eject)~M(SF)M(eject)~M(SF)

Role of AGNRole of AGN Does AGN blast ISM away during a Does AGN blast ISM away during a

merger?merger? Easiest at low MEasiest at low M So if ever possible, all galaxies would So if ever possible, all galaxies would

be redbe red AGN thermostats trapped gas to TAGN thermostats trapped gas to Tvirvir

Onset of sterilityOnset of sterility Star-forming galaxies consume gas in Star-forming galaxies consume gas in

less than tless than tHubbleHubble E.g. MW: 2ME.g. MW: 2M ¯̄yryr-1-1

of SF consumes 4of SF consumes 4££101099MM¯̄ in 2 Gyr in 2 Gyr Galaxies rejuvenated by infall of cold Galaxies rejuvenated by infall of cold

gas (NGC 4550)gas (NGC 4550) Gas continuously replenished (HVCs; gas Gas continuously replenished (HVCs; gas

from Sgr dwarf, Magellanic Clouds etc)from Sgr dwarf, Magellanic Clouds etc)

Peek + 07

Putman + 03

Stopping ReplenishmentStopping Replenishment Atmosphere of trapped gas at TAtmosphere of trapped gas at Tvirvir

affects replenishment in 2 ways:affects replenishment in 2 ways: 1. Drag on infalling clouds1. Drag on infalling clouds 2. Evaporation of cold gas2. Evaporation of cold gas

DragDrag mmccdv/dt=-Adv/dt=-Acchh v v22 !! v(t)=v v(t)=v00/(1+t//(1+t/) )

=v=v00mmcc/A/Acchh With RWith Rcc<100 pc, v<100 pc, v00=100 km s=100 km s-1-1 and and

nnhh=10=10-3-3cmcm-3-3, , ''300 Myr300 Myr So clouds can’t move fast through So clouds can’t move fast through

halohalo

NGC 5746NGC 5746 (Rasmussen + 07)(Rasmussen + 07)

Key transition object; vKey transition object; vcc=310 km s=310 km s-1-1

Spherical halo unconnected to SFing Spherical halo unconnected to SFing diskdisk

Extraplanar HIExtraplanar HI SF cycles gas through halo SF cycles gas through halo

(HVCs; NGC 891; Fraternali & B 06)(HVCs; NGC 891; Fraternali & B 06) Extraplanar HI still rapidly rotatingExtraplanar HI still rapidly rotating Not consistent with existence of Not consistent with existence of

n=10n=10-3-3cmcm-3-3 non-rotating halo non-rotating halo (Fraternali + B 07)(Fraternali + B 07) Fraternali + 05

Cored & Power-law EsCored & Power-law Es Dichotomy in Es: Dichotomy in Es:

(Faber + 1997, Ferrarese + 06)(Faber + 1997, Ferrarese + 06) Central SB slope Central SB slope

<0.3 (CGs) or <0.3 (CGs) or >0.5 (PLGs)>0.5 (PLGs) PLGs: PLGs:

disky, Mdisky, MVV>-20.5, large (v/>-20.5, large (v/))**, low L, low LXX/L/LBB PLGs younger centresPLGs younger centres What’s the connection between X-ray What’s the connection between X-ray

gas and stellar distribution?gas and stellar distribution?Ferrarese + 06

Nipoti + B 07

Nipoti & B 07Nipoti & B 07 N-bodies consistent with conjecture: N-bodies consistent with conjecture:

when galaxies with BHs merge, when galaxies with BHs merge, remnant has core with Mremnant has core with Mdefdef'' M MBHBH by by upscattering (Milosavljevic & Merritt)upscattering (Milosavljevic & Merritt)

Will be filled in by SF only if tWill be filled in by SF only if tevapevap>t>tdyndyn ttevapevap/t/tdyndyn smaller by 10 smaller by 1033 in X-ray in X-ray

luminous CG compared to PLGluminous CG compared to PLG So in PLG central SF possible after So in PLG central SF possible after

last mergerlast merger

SummarySummary Central BHs thermostat trapped gas at TCentral BHs thermostat trapped gas at Tvirvir Contradicts premise of White-Rees theoryContradicts premise of White-Rees theory Gas falls into low-M halos coldGas falls into low-M halos cold SF drive outflow when TSF drive outflow when TSNSN>T>Tvirvir At M~10At M~101212MM¯̄ (a) (a)

TTvirvir~T~TSNSN and (b) and (b) infall gravitationally heated to Tinfall gravitationally heated to Tvirvir

So for M>10So for M>101212MM¯̄ halos trap SN-heated gas halos trap SN-heated gas

Summary (2)Summary (2) Galaxies in blue cloud while cold infall Galaxies in blue cloud while cold infall

continuescontinues Galaxies transfer to red sequence Galaxies transfer to red sequence

when either when either (a) T (a) Tvirvir>T>TSNSN or or (b) fall in to halo with T (b) fall in to halo with Tvirvir>T>TSNSN

Because hot atmosphere kills cold Because hot atmosphere kills cold infall by (a) drag on clouds infall by (a) drag on clouds (b) evaporation of clouds (b) evaporation of clouds

Summary (3)Summary (3) Trapped gas almost non-rotatingTrapped gas almost non-rotating So drag prevents infall feeding diskSo drag prevents infall feeding disk After merger SF at centre of lower-L After merger SF at centre of lower-L

E possibleE possible Explains correlation of LExplains correlation of LXX with optical with optical

properties properties