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- 1. Open issues
- 2. Current searches in XXL
- 3. X-ray versus MIR correlations ?
- 4. Further open questions
Marguerite PIERRE CEA Saclay High redshift clusters Paris October - - PowerPoint PPT Presentation
Marguerite PIERRE CEA Saclay High redshift clusters Paris October - - PowerPoint PPT Presentation
Marguerite PIERRE CEA Saclay High redshift clusters Paris October 2016 1. Open issues 2. Current searches in XXL 3. X-ray versus MIR correlations ? 4. Further open questions The existence of massive high redshift clusters is very
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The existence of massive high redshift
clusters is very sensitive to the cosmology => rare event statistics
Why the z>1.2 limit? Is there any solid census of the cluster
density at 1.2<z<2 ?
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Not only a matter of sensitivity Wide and shallow is better than deep and
narrow
A well-defined selection function is
mandatory
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The x-ray properties can be modelled
rather easily :
- Ab initio analytical modelling
- Hydrodynamical simulations
CAVEAT:
X-ray selection is not flux limited
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~ surface brightness limited
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Flux (cts/s) Core radius (arsec)
Not a flux limit ! Class 1 sample
Pacaud et al 2006
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XMM VLP (2010) following XMM-LSS
(2000-2010) :
- 2 x 25 deg2 area
- Total time > 6Ms
An international consortium gathering ~
100 scientists.
The ~ 540 XMM observations were
completed in 2013
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August 2016: first 14 papers out A&A special issue.
- 100 brightest clusters (/450) XXL paper II, Pacaud et al
- 1 000 brightest AGN (/20 000) XXL paper VI, Fotopoulou et al
- Most distant cluster of XXL-100-GC is at z=1.05
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EXPO map
XXL-N 25 deg2
In CFHTLS-W1 2h23 -5d00 (extension of the XMM-LSS field)
Moon
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EXPO map
XXL-S 25 deg2
23h30 -55d00 within the SPT 100 deg2 Deep Field
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XLSSC 001 @ z=0.61
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Working with these data : difficult ! : misleading (Poisson) : ambitious … but feasible and exciting !
XLSSC 008 @ z=0.30
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z = 0.053 z = 1.22
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I
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I 3.6 µm 4.5 µm
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Willis et al 2013
- 22 clusters at z>0.8 in XMM-LSS
Mantz et al 2014
- CARMA detection of an XXL cluster
- The highest redshift cluster ever detected in S-Z
zphot ~ 1.9 ±0.2
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A way to clean samples from
contamination ?
Or a nightmare to tune the correlation
procedure ?
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80% of the RM are found to be coincident with some X-ray emission Blind cross-matching is dangerous !
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9 deg2 XMM-LSS 18 clusters SpARCS (R-3.6 µm) 92 clusters
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EmX ≈ n2 √T
- either there is no gas
- or, the gas is not dense enough
So maybe, after all, the X-ray criterion is
the most reliable ?
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Expected to be stronger than at z<1 Affects the selection function
- either masks the cluster emission
- or boosts it
We have an on-going programme with
Chandra to estimate the AGN contamination rate (B. Maughan)
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Difficult (impossible?) task X-ray
- Few photons – no hints about HE – hard to remove AGN
contamination with XMM alone.
K and IR bands
- Galaxy luminosity – uncertainties about photo-z and cluster
membership
Velocity dispersion
- Strangely: most of the IR-detected clusters have very large σv.
- è are they really virialised ?
- è filaments seen in projection ?
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7’x7’ image centred on a z = 0.95 cluster M500 = 3.5 1014M – the black squares are the in-situ simulated AGN X-ray emissivity 10 ks XMM image
Cosmo-OWLS simulations, Le Brun et al 2014 AGN X-ray contribution, Koulouridis et al, to be submitted
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C1 clusters C2 clusters detected in 10ks
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