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High Resolution X-ray Spectroscopic Constraints on Cooling-Flow Models

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

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  1. 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)

  2. 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

  3. 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

  4. 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)

  5. 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

  6. Failure of the Model 8 keV  3 keV  ? Peterson et al. 2001

  7. Hot Clusters (4-10 keV): No Fe XVII through Fe XX

  8. Warm Clusters (2-4 keV): No Fe XVII, Very weak Fe XVIII-XX

  9. Cool Clusters/Groups (1 to 2 keV): Some Fe XVII, Fe XVII not any stronger Than Fe XVIII, No O VII

  10. 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

  11. Data Model

  12. Hot clusters

  13. Warm Clusters

  14. Cool clusters/groups

  15. Differential Luminosity vs. Fractional Temperature Differential Luminosity vs. Temperature

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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)

  21. Perseus Cluster

  22. Perseus at 5 different cross- dispersion locations

  23. Perseus: Differential luminosity of the inner 3.5 arcminutes

  24. 4 actual cooling flows: Mukai, Kinkhabwala, Peterson, Kahn, Paerels 2003

  25. 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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