Study Systematics on the ICM metallicity measurements Elena Rasia Chandra Fellow Physics Department,...
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Study Systematics on the ICM metallicity measurements
Elena RasiaChandra Fellow
Physics Department,
University of Michigan,
Ann Arbor
Columbus, Great Lakes Cosmology, June, 1st 2007
In collaboration with
Mazzotta P., Moscardini L., Borgani S., Dolag K., Ettori S., Tornatore L., Bourdin H. (submitted ApJ)
CLUSTERS OF GALAXIES
VIEWPOINT OF COSMIC WEB
LABORATORIES OF THE ICM PHYSICS
Dolag, Meneghetti, Moscardini, Rasia, Bonaldi, 06
http://www.astro.unipd.it/~cosmo/
Abell 1689
Abell 2390 & MS2137.3-2353
Key quantity:MASS
Key quantities:Hydro-propertiesGas densityTemperaturePressuremetals
X-MASRasia et al. 07 Gardini et al. 04
See also:Mazzotta, et al 05, Rasia et al. 05, Rasia et al.06
MILLENIUM SIMULATION WITH GAS
Non-cooling simulation (Pearce, Gazzola et al., in prep) Preheating simulation
4000 Mpc/hX
62.5 Mpc/h
In collaboration with R. Stanek (PI), Gus Evrard and Brian Nord - see talk by Gus Evrard.
Scaling relations and Covariance betweenM - Tx, fICM, YSZ, Lx …
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Color: Temperature
Courtesy of Klaus Dolag
Borgani et al. 04
275 Mpc
SIMULATIONS
Metalicity treatment: Tornatore et al.07
Galaxy Clusters as
Laboratories for Stellar
Evolution and
History
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Sun like star Massive star
CLUSTERS AS LABORATORIES FOR THE STELLAR EVOLUTION AND HISTORY
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Chandra Comparison of Type Ia Supernova Remnants
http://chandra.harvard.edu/photo/2006/crab/index.html http://imagine.gsfc.nasa.gov/Images/icons/adv_snr.gif
CRAB NEBULAESN II
1987ASN II irr
http://chandra.harvard.edu/photo/2007/kepler/index.html
CLUSTERS AS LABORATORIES FOR THE STELLAR EVOLUTION AND HISTORY
SNe IA
PROGENITORS:white dwarf accreting matter from a nearby companion star
Iron (major contributor), Silicon
SNe II
PROGENITORS:massive stars (with mass greater than 8 Msun )
-elements,as Oxygen, Magnesium, Silicon
[/Fe] gives indication of (SN Ia/ SN II)[Si/Fe] gives indication of yields of SN Ia
Silicon Profiles6-9 keV
1-2 keV
2-3 keV
Silicon profiles are well recovered for all the clusters in the sample
freefrozen
Oxygen & Magnesium Profile
8-12 keV 6-9 keV
For systems with T < 5 keV, we perfectly recover Oxygen. Magnesium is difficult to detect at all temperatures.Large and hot systems show a systematic overestimate of Oxygen and Magnesium lines.
freefrozen
Interpretation: Oxygen and Magnesium
At high temperatures, Oxygen and Magnesium are very weak. For both elements, slight changes in the continuum produce large deviation on the lines’ emissivity measurements.
Multi temperature nature of the plasma
Plasma @ 8 keV
Iron profile8-12 keV
1-2 keV
2-3 keV
Overestimate of Iron only for the cluster at temperature of 2-3 keV. Good agreement for hotter and colder systems.
freefrozen
1keV
4keV
A 2-3 keV object is a combination of temperature: those larger than 2.5/3 give a large contribution to the Fe-K lines; those smaller, to the Fe-L lines => both groups of lines are pumped up by different-temperature plasmas
Interpretation: Iron profile
Baumgartner et al. 05
• The systematic overestimate of Fe for systems of 2-3 keV can reduce the significance of the bump of Baumgartner et al. plot
• Attention has to be paid to different [/Fe] ratios…• and to their interpretation
Consequences
KEY POINTS
• Clusters are fantastic laboratories both for studying cosmology and for understanding the physics of the Intra Cluster Medium
•Necessity of X-MAS to compare Simulations and Observations 1:1
•Simulations are now very powerful: large cosmological boxes are simulated with sophisticated physics.
SUMMARY ON METALLICITY
Due to the multi-temperature nature of plasma in clusters, the measurement of elements that have weak emission compared to the continuum IS NOT A SOLID AND ROBUST ESTIMATE
Iron estimate for systems of 2-3 keV can likely be biased towards higher values since this is a critical temperature range where we mix together plasma presenting either strong Fe-L or strong Fe-K lines.
i) Silicon, ii) Oxygen for clusters cooler than 6 keV, iii) Iron for both cold systems (T < 2 keV) and hot systems (T > 4 keV) ARE WELL RECOVERED