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

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
  gt Range of Temperatures
• Differential Luminosity predicted to be dLx5/2
  (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
• gt Need Fe L ions (temperature sensitive)
• gt 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 T1keV
• 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. energyparticles,
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 Kaastras talk)

21
Perseus Cluster
22
Perseus at 5 different cross- dispersion location
s
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