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High Resolution X-ray Spectroscopic Constraints on Cooling-Flow Models. John Peterson, Steven Kahn, Frits Paerels (Columbia); Jelle Kaastra, Takayuki Tamura, Johan Bleeker, Carlo Ferrigno (SRON); Garrett Jernigan (Berkeley). Cooling Flows.

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high resolution x ray spectroscopic constraints on cooling flow models

High ResolutionX-ray Spectroscopic Constraintson Cooling-Flow Models

John Peterson,

Steven Kahn, Frits Paerels (Columbia);

Jelle Kaastra,

Takayuki Tamura, Johan Bleeker, Carlo Ferrigno (SRON);

Garrett Jernigan (Berkeley)

cooling flows
Cooling Flows
  • Long-standing prediction that cores of clusters should cool by emitting X-rays in less than a Gyr =>Range of Temperatures
  • Differential Luminosity predicted to be:dLx=5/2 (Mass Deposition Rate) k/(mp) dT
  • Predicts a unique X-ray spectrum; Free parameters: Tmax, Abundances, Mass Deposition Rate
slide3

Assumptions

X-ray Luminosity is

heat loss

No heating

Steady-state

Extra assumptions: atomic physics determines L and T,

Locally maxwellian, no absorption, metal distribution,

Exact prediction for mdot depends on grav. potential

slide4

Measuring a differential luminosity at keV temperatures

=> Need Fe L ions (temperature sensitive)

=> Need to resolve each ion separately (i.e. / ~ 100)

Very difficult to do in detail with CCD instrument

(ASCA, XMM-Newton EPIC, Chandra ACIS)

Works with XMM-Newton RGS (for subtle reasons)

slide5

RGS (dispersive spectrometer) :

High dispersion angles (3 degrees) for XMM PSF

/ ~ 3 degrees / ang. size ~ 100 for arcminute size

Soft X-ray band from Si K to C K; 5 to 38 angstroms

FOV: 5 arcminutes by 1 degree

Analysis not simple: dispersive, background, few counts

failure of the model
Failure of the Model

8 keV  3 keV  ?

Peterson et al. 2001

slide8

Warm Clusters (2-4 keV):

No Fe XVII,

Very weak Fe XVIII-XX

slide9

Cool Clusters/Groups

(1 to 2 keV):

Some Fe XVII,

Fe XVII not any stronger

Than Fe XVIII,

No O VII

slide10

Decompose

into temperature

bins

Put multiphase

region in a

3-d envelope

Adjust

the normalization

of each bin

to get a

limit on Mdot

16 free

parameters

slide11

Data

Model

slide15

Differential Luminosity vs.

Fractional Temperature

Differential Luminosity vs. Temperature

slide16

Differential Luminosity ~ T

 ~ 1 to 2

Observational Results

1. Sub Tmax plasma always there

2. Model fails at a fraction of Tmax rather than fixed T~1keV

3. Model fails in shape as well as normalization;

Tilted toward higher temperatures

slide17

Overall normalization

difficult to interpret w/o model

5. Some scatter in both slope and normalization (unknown if this is a real difference)

6. Unclear if relation continues to low temperature for all

clusters or not

Limits as strong as a factor of 10

T cutoff is oversimplified;

small mdot is oversimplified too

slide18

Theoretical Intepretation: Essentially Three Fine-tuning Problems

RADIATIVE COOLING+???

Can find ways to add heat or subtract heat (through

additional non x-ray luminosity), but…

1. Energetics: Need average heating or cooling power ~ Lx

Coolants: Dust (IR), Cold clouds (UV), particles

Heating: AGN mech. energy+particles, mergers,

outer regions via conduction

Affects the normalization of the diff. luminosity plot

slide19

Dynamics: Either need energy source to work at low temperatures or at t ~ tcool (before complete cooling would occur)

Cooling time ~ T2 / (cooling function)

If at 1/3 Tmax then why cool for 8/9 of the cooling time?

or why at low temperatures?

Affects the fractional temperature where problem occurs

slide20

Get Energetic and Dynamics right at all spatial positions

Observational situation is not fully worked out

Soft X-rays missing throughout entire cflow volume

Steep differential luminosity distribution difficult

partly spatially stratified/partly intrinsic steep distribution

  • (See Kaastra’s talk)
slide22

Perseus

at 5

different

cross-

dispersion

locations

slide23

Perseus:

Differential luminosity of the inner 3.5 arcminutes

slide24

4 actual cooling flows:

Mukai, Kinkhabwala, Peterson, Kahn, Paerels 2003

conclusions
Conclusions

Cooling flow model fails to reproduce X-ray spectrum; Several strong observational constraints

Much more theoretical work needed for fine-tuning challenges

Much more observational work is needed to constrain the spatial distribution and to connect to other wavelengths

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