Post on 13-Jan-2016
description
The chemical enrichment of clusters of galaxies
Jelle S. KaastraCollaborators:
Norbert Werner, Jelle de Plaa, Aurora Simionescu, Yan Grange
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Outline
1. Importance clusters
2. Observational challenges
3. Enrichment by supernovae
4. Enrichment by winds
5. Conclusions
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1. Importance clusters for abundance studies
• Largest bound structures
• Deep potential wells, retains most of the gas
• Hot gas: no significant “hiding” of metals in dust
• Spatial extent allows mapping
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2. Observational challenges
1. Fe bias
2. Non-thermal components
3. Complex temperature structure
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The Fe bias
• 1T models sometimes too simple: e.g. in cool cores
• Using 1T gives biased abundances (“Fe-bias, Buote 2000)
• Example: core M87 (Molendi & Gastaldello 2001)
Multi-T 1T
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Non-thermal components
• Example: Sérsic 159-03
• Strong soft excess, modeled by non-thermal component
• Implications on abundances (De Plaa et al. 2006)
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Complex temperature structure I(de Plaa et al. 2006)
• Sérsic 159-3, central 4 arcmin
• Better fits 1Twdemgdem
• Implication for Fe: 0.360.350.24
• Implication for O: 0.360.300.19
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Inverse iron bias: how does it work?
• Simulation: 2 comp, T=2 & T=4 keV, equal emission measure
• Best fit 1-T gives T=2.68 keV
• Fitted Fe abundance 11 % too high
• Due to different emissivity for Fe-L, Fe-K
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Temperature maps(Hydra A, Simionescu et al. 2008)
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Complex temperature structure II(Simionescu et al. 2008)
• Example: Hydra A• Central 3 arcmin:• Full spectrum: Gaussian
in log T (σ=0.2)• 1T fits individual regions:
also Gaussian• Confirmed by DEM
analysis (blue & purple)
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Implications for Fe abundance(Simionescu et al. 2008)
Central 3 arcmin Hydra A, 1T models:
(errors on Fe 0.01 to 0.02)
Band (keV) kT (keV) Fe
Full (0.35-10) 3.4 0.50
Low (Fe-L) 0.35-2 2.8 0.37
High (Fe-K) 2-7 3.9 0.41
Gdem 3.4, σ=0.2 0.45
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Fitting bias: continua ok?(Werner et al. 2006)
• Some features subtle• Example:
2A0335+096, 130 ks XMM-Newton
• To determine Cr abundance (0.5±0.2 solar) needs carefull analysis local continuum
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Fitting bias: calibration uncertainties(de Plaa et al. 2007)
• Some lines (Si) weaker than calibration uncertainty instruments
• Important to estimate systematic uncertainties (no “blind” χ2 fitting) Diffference pn data & best-fit
MOS model Sérsic 159-03
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Quantifying systematics(de Plaa et al. 2007)
• Correction: fudge MOS area to match pn and vice versa (spline)
• Remaining difference systematic:
Mg: too uncertain Si: 11 % Ni: 19 %
Example: Sérsic 159-03
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3. Enrichment by supernovae
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Type Ia, Type II and Solar abundances
O
O
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Supernova yields: core collapse
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Supernova yields: Ia
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Decomposing abundances into SN types
(De Plaa et al. 2006)• Deep exposure XMM-
Newton Sérsic 159-3• Data include RGS• ~50 % SN Ia by
number• Ca problem
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Another case: 2A 0335+096(Werner et al. 2006)
• Use here WDD model• Central 3 arcmin:• Sn Ia: 25 %• Increases to 37 % in
3-9 arcmin annulus• Ni: W7 model predicts
more• Also here Ca problem
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Analysis of a large sample (De Plaa et al. 2007)
• 22 clusters, 685 ks net exposure
• Taken from HIFLUGCS sample (Reiprich & Böhringer 2002)
• All spectra extracted from within 0.2 R500
• Use wdem model
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Solution to the Ca problem(De Plaa et al. 2007)
• Also sample shows Ca excess
• Problem solved by adopting SN Ia yields based on Tycho SNR (Badenes et al. 2006)
• Best fit Ia/(Ia+cc) number ratio: 0.44±0.05
WDD
Tycho
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Sample: mean abundance ratios(De Plaa et al. 2007)
RatioWeighted mean
(Lodders scale)σint
Si/Fe 0.66 ± 0.13 0.17 ± 0.05
S/Fe 0.60 ± 0.06 0.18 ± 0.06
Ar/Fe 0.40 ± 0.03 0.11 ± 0.05
Ca/Fe 1.03 ± 0.04 0.12 ± 0.08
Ni/Fe 1.41 ± 0.31 0.2 ± 0.2
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A 2052(Grange et al. 2008)
• 90 ks exposure (2001, 2007)
• Analysis in progress
• Abundances O to Fe all consistent with sample De Plaa et al. (2007)
• Only Ca more overabundant: Ca/Fe = 1.51±0.10 (compared to 1.03, σ=0.12)
• Needs further confirmation
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Comparison between clusters(Simionescu et al. 2008)
• 6 clusters with deep exposures, taken from literature
• Most have 30-40 % contribution Ia
• Hard to discriminate between Ia models, but see extremes Hydra A / M87
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Radial profiles: example 2A 0335+096(Werner et al. 2006)
Si
FeAr
S
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Comparison between clusters: radial profiles
(Simionescu et al. 2008)• All elements have
decreasing abundances
• Also valid for O (contrary to earlier suggestions of flat O profile, Tamura et al. 2004)
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Abundance ratios constant? (Simionescu et al. 2008)
• Si/Fe flat within 0.1 R200, maybe break at 0.05R200
• O/Fe increases, but only slightly: per dex in radius, O/Fe increases by 0.25±0.09 (Fe decreases by 0.72)
O/Fe
Si/Fe
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Consequences of “flat” oxygen profiles
(Simionescu et al. 2008)
• Flattish O profiles: not only Ia contribute to core enrichment
• Ram pressure stripping works already at Mpc scale (compare to 130 kpc core Hydra A)
• Continued cc SN activity over past 1010 year?
• Early central enrichment cc SN?
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4. Enrichment by winds
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XMM-Newton RGS results
• RGS optimal for point sources
• But still the best for moderately extended sources:
• Δλ (Å) = 0.138 Δθ (arcmin)
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RGS results: M 87(Werner et al. 2006)
• Exposure time: 169 ks• Lines from O, N, & C• C/Fe: 0.74±0.13• N/Fe: 1.62±0.21• O/Fe: 0.59±0.04• Ne/Fe: 1.25±0.12• Mg/Fe: 0.60±0.06• Fe: 1.06±0.03 AGB winds for CN!
Continuum-subtracted RGS spectrum
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Nitrogen with RGS: other cases
• M87: N/Fe = 1.62±0.21
• 2A 0335+096 (Werner et al. 2006): 1.3±0.4
• Sérsic 159-3 (De Plaa et al. 2006): 0.0±0.5
• Centaurus (Sanders et al. 2008): 1.5-3
• Need for more deep exposures with RGS
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Other case: Centaurus(Sanders et al. 2008)
N/Fe=1.5-3
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Future: SXC(and of course XEUS etc)
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5. Conclusions
• XMM-Newton observations of clusters of galaxies can disentangle contributions different SN types and winds
• Need take care of systematics, in particular temperature distribution for reliable results
• Best done using deep exposures