Observing galaxy cluster simulations with an X-ray telescope

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Observing galaxy cluster simulations with an
X-ray telescope

• Elena Rasia
• Department of Physics,
• University of Michigan
• Chandra Fellows Symposium
• Harvard-Smithsonian Center for AstrophysicsOctobe
  r 13, 2006

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COSMOLOGY
From WMAP (3rd year)
From WMAP(1st year) SDSS 2dF weak lensing SNe
Ia Ly-? forest Age of G.C.

• H073 /- 3 km/s/Mpc
• ?80.74 /- 0.05
• n 0.951 0.01/-0.02

• H071 /- 2 km/s/Mpc
• ?80.9 /- 0.03
• n 0.98 /- 0.02

• ?? 0.72 /-0.02
• ?B 0.024 /-0.003
• ?DM h20.115/-0.013

• ?B h20.0223 /-0.0008
• ?DM h20.127 0.007/-0.013
• ? 0.09 /- 0.03

(Spergel et al. 2006)
(Seljak et al. 2005)
DUNE (Dark Universe Explorer) DES (Dark Energy
Survey) XEUS (X-ray Evolving Universe
Spectroscopy mission) Constellation-X
SNAP
Plank
clusters
(Haiman et al 2005)
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X-MASX-ray MapSimulator (Gardini et al 2004,
Rasia et al. 2006)
SIMULATIONS GADGET/GADGET2 Tree SPH (Springel
et al .01 Springel 05) ?CMD (?M ? 0.27, ? ? ?
0.7, ?8 0.8/0.9, h0.70) Explicit entropy
conservation (Springel Hernquist 02) Radiative
cooling uniform evolving UV background Multiphas
e model for star-formation galactic winds
(Springel Hernquist 03) Thermal conduction
(Jubelgas et al. 04 Dolag et al. 04) ?Chemical
enrichment from Sn-Ia and II (Tornatore et al.
04, 06) Reduced-viscosity SPH scheme (Dolag et
al. 05)
First part Selection of los projection into
the sky, is quite general computation of the
spectral emissivity
Second part Depend on the characteristics of the
X-ray telescope and detector (Chandra ACIS-S,
Chandra ACIS-I, XMM-Newton EPIC-MOS12 XMM-Newton
EPIC-PN)
X-RAY EVENT FILES which can be analyzed using the
X-ray tools
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X-ray MapSimulator
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Main Results
Contrast between temperature definitions in
simulations and observations TEW is not a good
description of the X-ray spectroscopic
temperature (Gardini et al. 2004) Temperature to
use in simulations TSL -gtcosmological consequence
for M-T (Mazzotta et al 2004, Rasia et al.
2005) Study of systematics bias of mass
measurement (Rasia et al. 2006) and metallicity
measurement (Rasia et al. in prep.)
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TEMPERATURES
simulation
X-ray observation
The different degree of thermal homogeneity has
strong implications on the temperature profiles
for the perturbed systems the spectral and
emission-weighted temperature profiles are not
in good agreement (Gardini et al. 2004)
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TEMPERATURES
Spectroscopic-Like
Emission-Weighted
Shock front
No Shock front
beside being biased toward densest regions the
spectroscopic temperature is also biased toward
the coolest regions (Mazzotta et al. 2004)
Mazzotta et al. 2004, see also Vikhlinin 2006
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COSMOLOGICAL IMPLICATIONS
Simple theoretical arguments supported by hydro
N-body simulations suggest the existence for
virialized gravitational systems of a tight
relation between M-T M500M0(kT500/1keV)?
TSL(0.700.01)TEW(0.290.05)
Rasia et al .2005, Kawahara et al. in prep
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MASS-TEMPERATURE RELATION
M0 is higher using Tsl instead of Tew
T_EW (Borgani et al.2004)
T_SL (Rasia et al. 2005)
M?,?
Msim
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MASS-TEMPERATURE RELATION
Scatter reduced from 30 to 16
M?,?
Msim
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MASS BIAS

• Hydrostatic equilibrium equation
• Hydro(dynamic?) equilibrium equation
• (Rasia et al. 2004, see also Kay et al. 2004,
  Faltenbacher et al. 2005, Lau et al. 2006, Nagai
  et al. 2006)

Gap explained by the velocity motions of the gas
the is not completely at rest even in the center
of the cluster
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MASS BIAS
The mass recovered through the HE equation are
underestimated by 20, half or more of which
solved by including the kinetic pressure term
(Rasia et al. 2006, see also Nagai et al.
2006). The mass measurements reconstructed via
the ?-model show a systematic underestimate, with
typical deviation of about 40 at R2500 and R500.
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SUMMARY

• Clusters are good probe to extract cosmological
  parameters
• To study systematics bias, to verify models and
  hypothesis and to test (X-ray, but not only)
  methods we need SIMULATIONS
• We built X-MAS that allow us to make proper
  comparison between simulations and observations
• TEW is not a good description of Tspec -gt we
  propose another formulation TSL -gt this has
  relevant cosmological consequence for M-T
• X-ray mass estimates present systematic bias due
  to different reasons -gt this has to be taken into
  account in comparing different M-T relation
  present in literature