The cold component of cluster accretion

Yuval BirnboimJerusalem 2011

Clusters should be simple!

Abell 1689Composite: X-ray(Chandra) + Optical (HST)

The cooling flow Problem in Cool Core Clusters

1. No cool (<1keV) gas2. Star formation in brightest central galaxy lower

by 10-100 than expected from cooling3. BCG smaller by a factor or a few than expected

(“failure to thrive”)

Allen & Ebeling

Cool Core Cluster properties

Cavagnolo et al. 2009

Leccardi & Molendi 2008

Reiprich 2003

M(BCG) ≤ 10 12MSFR≤20 M/yrLx~10 44-10 45erg/sec

Score~20KeV cm 2

Overcooling. Mvir=3X1014Mʘ

Immediate suspect: AGNs

M87 – HST image

Artist’s impression for supermassive black hole, NASA/JPL-Caltech

Criteria for cluster heat source

1) Enough energy2) Smooth in time (toff<tcool)3) Smooth in space (<10kpc)4) No explosions, please

Accretion and Gravitational heating in Clusters

virnpenetratioclumpgasbar

clump

gas

RRz

ZZ

fff

f

f

1.00

3.005.0

05.0

Dekel & Birnboim 2008

Dekel et al. 2009

Courtesy of Volker Springel

Clusters are not smooth!

Clump physics

Heating by baryonic cold (10^4K) clumps

1. Hydrodynamic drag: 22

21

shearclumphaloddrag vrCF

Clump physics

Heating by baryonic cold (10^4K) clumps

1. Hydrodynamic drag2. Jeans mass (Bonnor-Ebert)3. K-H/R-T instabilities and clump fragmentation4. DF5. Conduction/evaporation (Gnat et al. 2010)

1gr/cm^3

10-3gr/cm^3

Heating

Gravitational heating by clumps

Murray & Lin 2004 Dekel & Birnboim 2008

Cold gas in Perseus

Conselice et al. 2001

Mass of structures: 106-108M⊙ (Fabian et al. 2008)

HVCs in MW

Dynamic response

Problems with static calculations:• Cold mass is dumped near center• Energy injection is not self regulated• Timescale of clumps: many GyrsProblems with full 3D hydro:• ResolutionSubgrid 1D model:• clump shells interact with gas• At clump destruction – cold mass added in situ

No clump simulation – OvercoolingMvir=3X1014Mʘ

5% of baryons in clumps of 108M⊙

Convection

5.05.12

:heating

)(:cooling

T :mequilibriu chydrostati

CHT

const

Stability

• Maximal convection (vbubbles=cs)• Mixing length theory (implicit scheme)

5% of baryons in clumps of 108M⊙Clumps + Convection

5% of baryons in clumps of 108M⊙Clumps + Convection

Birnboim and Dekel. 2011

Summary

• Gravitational infall is a powerful engine• Clumps interact with gaseous haloes– and heat them

• The inherit instability drives convection

Thank you