Transcript Study Systematics on the ICM metallicity measurements

Study Systematics on the ICM
metallicity measurements
Elena Rasia
Chandra Fellow
Physics Department,
University of Michigan,
Ann Arbor
In collaboration with
Mazzotta P., Moscardini L., Borgani S., Dolag K., Ettori S., Tornatore L.,
Bourdin H. (submitted ApJ)
Columbus, Great Lakes Cosmology, June, 1st 2007
CLUSTERS OF
GALAXIES
Abell 2390 & MS2137.3-2353
Abell 1689
VIEWPOINT OF
COSMIC WEB
Key quantity:
MASS
http:
//www.astro.unipd.it/~cosmo/
LABORATORIES OF THE
ICM PHYSICS
Key quantities:
Hydro-properties
Gas density
Temperature
Pressure
metals
Dolag, Meneghetti, Moscardini,
Rasia, Bonaldi, 06
X-MAS
Rasia 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
4000 Mpc/h
X
62.5 Mpc/h
Non-cooling simulation
(Pearce, Gazzola et al., in prep) Preheating simulation
In collaboration with R. Stanek (PI), Gus Evrard
and Brian Nord - see talk by Gus Evrard.
Scaling relations and Covariance between
M - Tx, fICM, YSZ, Lx …
SIMULATIONS
275 Mpc
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Courtesy of
Klaus
Dolag
Metalicity treatment: Tornatore et al.07
Color:
Temperature
Borgani et al. 04
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Sun like star
Galaxy
Clusters as
Laboratories
for Stellar
Evolution
and History
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Massive star
CLUSTERS AS LABORATORIES FOR THE STELLAR
EVOLUTION AND HISTORY
http://chandra.harvard.edu/photo/2006/crab/index.html
CRAB NEBULAE
SN II
http://chandra.harvard.edu/photo
/2007/kepler/index.html
http://imagine.gsfc.nasa.gov/Images/icons/adv_snr.gif
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1987A
SN II irr
Chandra
Comparison of
Type Ia
Supernova
Remnants
CLUSTERS AS LABORATORIES FOR THE
STELLAR EVOLUTION AND HISTORY
SNe IA
SNe II
PROGENITORS:
white dwarf accreting
matter from a nearby
companion star
PROGENITORS:
massive stars (with
mass greater than 8
Msun )
Iron (major
contributor), Silicon
-elements,as
Oxygen, Magnesium,
Silicon
[/Fe] gives indication of (SN Ia/ SN II)
[Si/Fe] gives indication of yields of SN Ia
Silicon Profiles
6-9 keV
2-3 keV
1-2 keV
Silicon profiles are
well recovered for all
the clusters in the
sample
free
frozen
Oxygen & Magnesium Profile
8-12 keV
6-9 keV
free
frozen
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.
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.
Plasma @ 8 keV
Multi temperature nature
of the plasma
Iron profile
8-12 keV
1-2 keV
2-3 keV
free
frozen
Overestimate of Iron only for the
cluster at temperature of 2-3 keV.
Good agreement for hotter and colder
systems.
Interpretation:
Iron profile
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
Consequences
• 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
Baumgartner et al. 05
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
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
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.