XMM-Newton XMM-Newton and and

Galaxy Clusters:Galaxy Clusters:from from

Cooling FlowsCooling Flowsto to

Cool Cores Cool Cores Silvano Molendi (IASF-MI)Silvano Molendi (IASF-MI)

XMM-Newton XMM-Newton and and

Galaxy Clusters Galaxy Clusters

Silvano Molendi (IASF-MI)Silvano Molendi (IASF-MI)

IntroductionIntroduction This is a rapidly evolving research field.This is a rapidly evolving research field.

The new satellites are allowing us to make much The new satellites are allowing us to make much progress. You may view this session as a sampler of progress. You may view this session as a sampler of

the science we are now doing.the science we are now doing.

Radial characterization of individual systems temperature (Pratt) mass (Pointecouteau), implications for cosmology (Arnaud).Study objects at unconcievable redshifts (Jones, Vauclair)Approach physical phenomena with an unprecedented combination of spectral and spatial capabilities (A. Finoguenov), mergers (J.L Sauvageot, Sakelliou).

ConclusionsConclusions

This is a very exciting time This is a very exciting time to be working on Clusters!to be working on Clusters!

From Cooling-Flows From Cooling-Flows toto

Cool Cores Cool Cores

Silvano Molendi (IASF-MI)Silvano Molendi (IASF-MI)

Cooling FlowsCooling Flowstcool ≈ Tg

1/2 np

-1

• For large radii np is small tcool »tHubble

• In the core np is large Э rcool tcool ~ tHubble

The gas within The gas within rrcoolcool will cool will cool and flow inwardsand flow inwards

Key IssueKey Issue

This has been explained in the context of multi-phase models (Nulsen 1986)

Different phases T,ρ coexist at every rMulti-phase models require gas with T down to 0.1 keV

The surface brightness is not as peaked as would be expected if all the cooling gas were to reach the

center M≠const Mr (Fabian, Nulsen & Canizares 1984)

Most of the gas drops out the flow before reaching the center

..

The The ((XMMXMM))-Newton-Newtonianian

RevolutionRevolution

A1795 Tamura et al. (2001a); A1835 Peterson etA1795 Tamura et al. (2001a); A1835 Peterson et al. (2001); AS1101 Kaastra et al. (2001); A496 al. (2001); AS1101 Kaastra et al. (2001); A496 Tamura et al. (2001b); sample of 14 objects Tamura et al. (2001b); sample of 14 objects Peterson et al. (2003)Peterson et al. (2003)

There is a remarkable lack of emission lines expected from gas with temperatures smaller

than 1-3 keV.The most straightforward interpretation is that

there is no gas with temperatures smaller than 1-3 keV.

Standard CF model predicts gas with T down to at least 0.1 keV!

The RGS ResultThe RGS Result

EPIC has a spectral resolution ~ 10 EPIC has a spectral resolution ~ 10 times worse than RGS.times worse than RGS.

It cannot resolve individual lines. It cannot resolve individual lines.

However it can discriminate between However it can discriminate between models with and without a minimum models with and without a minimum temperaturetemperature

The major discriminant is the Fe L The major discriminant is the Fe L Shell blend profileShell blend profile

The EPIC ResultThe EPIC Result

Spectra above ~1.3 keV are similar.

Below we observe a prominent line-like

feature: Fe-L shell line complex.

In the spectrum with Tmin=0.1 keV we see a

shoulder down to ~ 0.8, this is due to low

ionization lines from gas colder than 0.9 keV.In the spectrum with

Tmin=0.9 keV the shoulder is absent because the

low ionization lines are missing

Molendi & Pizzolato (2001)

Tmin=0.9 keV

Tmin=0.1 keV

Model spectra degraded to the EPIC resolution

Comparison between Comparison between multi-temperature modelsmulti-temperature models

EPIC minimum temperatures are in EPIC minimum temperatures are in good agreement with RGS minimum good agreement with RGS minimum temperatures.temperatures.

The result on TThe result on Tminmin is a solid one! is a solid one!

All cluster cores observed so far All cluster cores observed so far show a Tshow a Tminmin

Values range between ~1 and ~3 keV Values range between ~1 and ~3 keV

Minimum TemperatureMinimum Temperature

Spatially resolved Spatially resolved spectroscopy of Cluster spectroscopy of Cluster

cores with EPICcores with EPIC

Molendi (2002)

M87 Temperature mapM87 Temperature map1. In most of the core

the gas is single temperature

2. The only regions where we find evidence of more than 1 temperature are the SW and E radio arms which are cospatial with the radio emission

3. No evidence of gas cooler than 1 keV

•Gas is NOT multiphase, at least not in the sense Gas is NOT multiphase, at least not in the sense required by required by .the standard multi-phase CF modelthe standard multi-phase CF model•Multiphaseness is or was a fundamental ingredient of Multiphaseness is or was a fundamental ingredient of the CF the CF .model, without it the model falls!model, without it the model falls!

Implications for Cooling-Flow Implications for Cooling-Flow modelsmodels

•Little evidence of gas cooler than 1-Little evidence of gas cooler than 1-33 keV keV anywhereanywhere•If gas does not cool below 1-If gas does not cool below 1-33 keV it will not be keV it will not be deposited as cold gasdeposited as cold gas•Mass deposition, if there is any, must be much Mass deposition, if there is any, must be much smaller than smaller than previously thoughtpreviously thought

MultiphaseneMultiphasenessss

Mass Mass depositiondeposition

Implications for Cooling-Flow Implications for Cooling-Flow modelsmodels

The name itself is missleading as it The name itself is missleading as it describes a phemoneon of little or describes a phemoneon of little or

no impact no impact

Cooling Flow Cool coreCooling Flow Cool core

Now that we have Now that we have brought the house brought the house

down it is time to think down it is time to think about rebuilding!about rebuilding!

Cool CoresCool CoresWhat happens to the gas which should be

cooling on very short timescales?Two classes of solutions have been

proposed:

The cooler gas is there but it is

somehow hidden (Fabian et al. 2001)

The gas is prevented from cooling below a certain temperature by

some form of heating. Heating must be widespread as we do not observe accumulation of gas at a particular

radius or temperature. Various mechanisms have been considered:

thermal conduction (Narayan & Medvedev 2001, Fabian et al. 2002) Heating from the central AGN (e.g.

Begelman 2002, Churazov et al. 2002)

✘✘

Heating MechanismsHeating Mechanisms:: ConductionConduction

• Determine the conduction coef. Determine the conduction coef. necessary to balance cooling and necessary to balance cooling and compare it to the Spitzer coefficent compare it to the Spitzer coefficent (Voigt et al. 2003, Ghizzardi et al. (Voigt et al. 2003, Ghizzardi et al. 2003)2003)

• Heating from conduction is insufficent Heating from conduction is insufficent within the very core.within the very core.

• Extra heating is required to balance Extra heating is required to balance coolingcooling

Heating from the AGN

Chandra finds what appear to be holes

“cavities”.Radio lobes are

conicident with X-ray cavities

Radio lobes inflated by jets appear to be

making their way pushing aside the X-ray emitting plasma

Hydra A

McNamara et al. (2001)

Heating from the AGNHeating from the AGNAbell 2052 Blanton et al. (2001)

Radio lobes fill X-ray Radio lobes fill X-ray cavities cavities

Cavities are Cavities are surrounded by denser surrounded by denser

& cooler gas.& cooler gas. If the lobes are If the lobes are

responsible for heating responsible for heating the flow why are they the flow why are they surrounded by cool surrounded by cool

gas?gas?

Heating from the Heating from the AGN AGN

Fabian et al. (2002)

The total energy required to quench a flow can be

consider-able.

Take total cooling energy, determined from L(<

rcool )•tHubble for a set of clusters and compare it with the total energy emitted by

an AGN over tHubble.

The more luminous cores imply very large black-hole

masses

From outside:From outside:The gas outside rThe gas outside rcool cool is a huge heat reservoir, look for is a huge heat reservoir, look for

meachansim that tap this source (thermal meachansim that tap this source (thermal conduction).conduction).

From the AGN:From the AGN:1)1) Interaction with Radio structures is localizedInteraction with Radio structures is localized2)2) No evidence of heating at the site of the No evidence of heating at the site of the

interaction (quite the contrary)interaction (quite the contrary)3)3) Heating could be episodic through outbursts of Heating could be episodic through outbursts of

AGN activity, however we have various indicators AGN activity, however we have various indicators that point to a gentle and non sporadic form of that point to a gentle and non sporadic form of heating (e.g. Mathews & Brighenti 2003).heating (e.g. Mathews & Brighenti 2003).

4)4) The overall energy available from the AGN may not The overall energy available from the AGN may not be sufficent for the most massive systems.be sufficent for the most massive systems.

Do we have a credible Do we have a credible mechanism?mechanism?

Probably Probably notnot

Do we have a credible Do we have a credible mechanism?mechanism?

The hunt is still on!The hunt is still on!

We need a form of widespread gentle We need a form of widespread gentle heating.heating.Something connected with subsonic gas Something connected with subsonic gas motions would be nice. motions would be nice. We do have evidence of widespread gas We do have evidence of widespread gas motions in the core of Perseus through the motions in the core of Perseus through the lack of Resonant Scattering (Gastaldello & lack of Resonant Scattering (Gastaldello & Molendi 2003, Churazov et al. 2003) and Molendi 2003, Churazov et al. 2003) and detection of pressure waves (Fabian et al. detection of pressure waves (Fabian et al. 2003). 2003).

Looking for something Looking for something betterbetter

SummarySummaryClusters are extremely interesting astrophys. Clusters are extremely interesting astrophys.

objects. objects. Amongst the most demanding from an Amongst the most demanding from an

instrumental point of view, it’s no wonder that instrumental point of view, it’s no wonder that innovative new satellites like Chandra and XMM-innovative new satellites like Chandra and XMM-Newton are providing us with great new resultsNewton are providing us with great new results

Cooling Flows as we understood Cooling Flows as we understood them in pre XMM-Newton them in pre XMM-Newton

days are dead!days are dead!Currently we do not have a solid Currently we do not have a solid

understanding of what keeps the gas from understanding of what keeps the gas from cooling, the answer may come in a week in a cooling, the answer may come in a week in a

year or maybe 10 years from now year or maybe 10 years from now