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