High resolution x ray spectroscopic constraints on cooling flow models
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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


High resolution x ray spectroscopic constraints on cooling flow models

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


High resolution x ray spectroscopic constraints on cooling flow models

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)


High resolution x ray spectroscopic constraints on cooling flow models

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



High resolution x ray spectroscopic constraints on cooling flow models

Warm Clusters (2-4 keV):

No Fe XVII,

Very weak Fe XVIII-XX


High resolution x ray spectroscopic constraints on cooling flow models

Cool Clusters/Groups

(1 to 2 keV):

Some Fe XVII,

Fe XVII not any stronger

Than Fe XVIII,

No O VII


High resolution x ray spectroscopic constraints on cooling flow models

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


High resolution x ray spectroscopic constraints on cooling flow models

Data

Model





High resolution x ray spectroscopic constraints on cooling flow models

Differential Luminosity vs.

Fractional Temperature

Differential Luminosity vs. Temperature


High resolution x ray spectroscopic constraints on cooling flow models

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


High resolution x ray spectroscopic constraints on cooling flow models

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


High resolution x ray spectroscopic constraints on cooling flow models

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


High resolution x ray spectroscopic constraints on cooling flow models

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


High resolution x ray spectroscopic constraints on cooling flow models

  • Get Energetic and Dynamics right at all spatial positions temperatures or at t ~ t

    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)


High resolution x ray spectroscopic constraints on cooling flow models

Perseus Cluster temperatures or at t ~ t


High resolution x ray spectroscopic constraints on cooling flow models

Perseus temperatures or at t ~ t

at 5

different

cross-

dispersion

locations


High resolution x ray spectroscopic constraints on cooling flow models

Perseus: temperatures or at t ~ t

Differential luminosity of the inner 3.5 arcminutes


High resolution x ray spectroscopic constraints on cooling flow models

4 actual cooling flows: temperatures or at t ~ t

Mukai, Kinkhabwala, Peterson, Kahn, Paerels 2003


Conclusions
Conclusions temperatures or at t ~ t

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