Cluster Lensing Cluster Lensing Modeling, Physics & Cosmology Modeling, Physics & Cosmology Jean-Paul KNEIB Laboratoire d’Astrophysique de Marseille, France
Dec 19, 2015
Cluster LensingCluster Lensing
Modeling, Physics & CosmologyModeling, Physics & Cosmology
Jean-Paul KNEIBLaboratoire d’Astrophysique de Marseille, France
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Outline
• Cluster Lens Modeling
• Recent results– Mass distribution - small to large scales
– Scaling relations
– Cosmology
– [Cosmic Telescope: Hi-z, SN]
• Prospects
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More than 2 decades ago: 1st arc in cluster
• 1987 the first giant luminous arc discovered• “Cluster are massive and dense enough to
produce strong lensing - they must be filled with dark matter”
• Every massive cluster is a lens !!!
Abell 370Abell 370CFHT - 1985CFHT - 1985 WFPC2- 1996WFPC2- 1996
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Lensing Back to Basics• Basics of lensing:
– Large mass over-densities locally deform the Space-Time
– A pure geometrical effect, no dependence with photon energy - depends on TOTAL MASS
• Lensing by (massive) clusters– Deflection of ~10-50 arcsec– strongly lens many background
sources => allow detailed mass reconstruction at different scales: cluster core, substructures, large scales
– ~1 SL cluster-lens per ~10 sq. deg: potentially ~2000 to study, Probably only ~200 identified today, nearly 20 with “a good” (SL) mass model
Ned Wright
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Halo Mass FunctionCluster mass function evolves strongly with redshift => cosmological probe (growth factor)
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2DSL+WL
1DWL
1DWL Stacking
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X-ray Luminosity
t~2Gyr t~2Gyr t~2Gyr
z=0 z=0.2 z=0.5 z~1
Massive X-ray selected Cluster
LoCuss
Hamilton-Morristalk
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• ~130 MACS clusters (z>0.3), HST, Subaru, Chandra, ground-based spectroscopy follow-up– Find many strong lensing clusters (>50% show SL)– Constrain cluster masses individually and in a statistical way with ultimately
possible cosmological implications
HST MACS survey
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MACSJ1149.5+2233MACSJ1149.5+2233
A
B
C
[OII] @ Z=1.48MACSJ1206.2-0847MACSJ1206.2-0847
Ebeling et al 2009
Smith et al 2009
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Optically Selected Strong lensing ClustersRCS-1 (Rz survey ~90 deg2), 5 arcs (Gladders et al 2003) found by visual inspection
CFHT-LS wide (150 deg2 provides a few arcs in clusters): Cabanac et al 2007
RCS-2 ~830 deg2 provide better stat a few tens
SDSS Altogether more than 200 clusters identified with bright arcs (Gladders et al 2009, Oguri et al 2009)
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Mass Distribution Measurement
• How do we measure mass ?• Central mass profile ? => learn about DM and
baryon interactions• Large scale mass profile and substructures ?
=> structure formation paradigm, halo models• Case of mergers => probe nature of DM• Comparison of the distribution of the different
components => scaling relations, cluster thermodynamics
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SL Cluster Modeling and Errors Constraints:– Multiple images (position, redshift, flux, shape)– Single images with known redshift– Light/X-ray gas distributionModel parameterization– Need to include small scales: galaxy halos
(parametric form scaled with light)– Large scale: DM/X-ray gas (parametric form or
multi-scale grid)Model optimization – e.g. Bayesian approach (robust errors)– Not a unique solution: “most likely model and
errors”– Predict amplification value and errors => cluster as
telescopes
Jullo et al 2007, Jullo & Kneib 2009 LENSTOOL public software http://www.oamp.fr/cosmology/lenstool
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Where is the Matter in A2218?
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BAD FIT GOOD FIT
MATTER vs GAL. LIGHT MATTER vs. X-Ray Gas
Strong Lensing constraints in Abell 2218: Mass distribution proportional to the stellar mass produce a BAD FIT to the lensing dataRequire large scale mass distribution (cluster DM)Important difference between DM , Galaxy distribution and X-ray gas (different physics)But, scaling relation should exists
Eliasdottir et al. 2009
Mass scales with stellar mass
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Deep = Many
Qu
ickTim
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and
a d
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ture
.
Deep HST/ACS multi-band imaging of massive clusters provides MANY multiple images:A1689 ~40 systemsA1703 ~20 systemsStandard parametric modeling have the RMS image position fit proportional to number of constraints = model too rigid!
Need a change of paradigm in strong lensing mass modelingGrid approach: Jullo & Kneib 2009LensPerfect approach: Coe et al 2008
Limousin et al 2008. Richard et al 2009Limousin et al 2008. Richard et al 2009
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X KECK/LRIS
X VLT/FORS
X CFHT/MOS
X MAGELLAN
/LDSS2
X Littérature
• Mass models form different groups w. or w/o weak lensing• Massive spectroscopic surveys (2003-2006) • 41 multiple image systems, 24 with spectro-z with 1.1 < z < 4.9
Broadhurst et al 2005Halkola et al 2007Limousin, et al. 2007 Richard et al. 2007Frye et al 2007Leonard et al 2007Jullo & Kneib 2009 …
The most massive cluster: Abell 1689
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Multi-Scale Grid Based Modeling
More flexible ”multi-scale” model:• hexagonal/triangle padding- to match
the natural shape of clusters• Multi-scale: split triangles according to
a mass density threshold • Circular mass clump at each grid point:
– Truncated isothermal profile with a core– size of the mass clump depends on the
grid: r_core =grid-size– Truncation also depends on the grid:
r_cut/r_core = 3– one free parameter for each clump
• Add galaxy-scale mass clumps• MCMC optimized• Easy extension to WL regime
ACS field of A1689
Jullo & Kneib 2009Jullo & Kneib 2009
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Application to Abell 1689
Mass map similar to Limousin et al 2007 mean RMS = 0.22” RMS min = 0.09” max = 0.48” (sys6)
Mass distribution and S/N map (300,200,100,10)
Jullo & Kneib 2009Jullo & Kneib 2009
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LensPerfect - not yet perfect !
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•IDEA: Solve lensing equation perfectly using curl-free basis of function
•However for a multiple image system, there is an infinity of solution depending on the source position
•What is the most likely “perfect model” ???
•Perfect model only converge if an infinity of constraints …
Coe et al 2008, Coe 2009
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Mass Profile of Clusters (SL+Dynamics)
Sand, et al. 2007
•DM simulation predicts a universal profile; what is observed in the inner core?
•Combination of strong lensing (radial and tangential arcs) + dynamical estimates from the cD galaxies
•Some degeneracies, but indication of a flatter profile than canonical NFW: -0.5<beta<-1•“Flat” core found in other clusters (RCS0224, Cl0024)
•Possibly probe DM & Baryon coupling?
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Abell 383
MS2137
New detailed modeling
Kneib JENAM-09 19Log(radius)
Log
(she
ar)
HST/WFPC2 mosaic
SUBARU
CFHT
Mass Profile of Clusters (SL+WL)
Limousin, et al. 2007, Dahle et al 2009
•background source selection is critical to accurately measure WL
•Improved lensing constraints, revised concentration from c~15 to c~8
•Better agreement.•See also: Smith/Hoekstra talks
Abell 1689
« Bullet Cluster » unusually strong mergers
1E06571E0657
•Encounter of 2 massive clusters•Significant offset between X-ray gas and lensing mass peaks probably best evidence for « collision-less dark matter » put constraints on DM/baryon interactions
Clowe et al 2006,Clowe et al 2006,
Bradac et al 2006Bradac et al 2006
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Combining the Chandra data with lensing mass maps -> place an upper bound on the dark matter self-interaction cross section:
Baby bullet:σ/m < 4 cm2g−1 = 8
barn/GeV.Bullet cluster:σ/m < 0.7 cm2g−1 =
1.3barn/GeV (Randall et al.2008)
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Other « Baby Bullet» and Nature of DM
MACSJ0025-1222Bradac et al 2008
Kneib JENAM-09 23WL mass calibration for X-ray clusters
23
Massey et al. 2007
Cluster/groups in COSMOS
~200 XMM cluster candidates:64 clusters: 0.5<z<1.0 50 clusters: z> 1(Finoguenov et al 2007, 2008)
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Photo-z concentration
X-ray clusters
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• Weak Lensing in COSMOS not only allows tomography (Massey 3D map) but makes possible a direct measurement of mass of structures down to galaxy sizes
Clusters/Groups in COSMOS probed by WL
Leauthaud et al 2009
mas
s p
rofi
le
radius
0.4 keV 0.8 keV 1.6 keV
X-ray Luminosity vs Lensing Mass
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• M ~ L 0.6 over 3 decades in X-ray luminosity! (slope inconsistent with self-similar prediction)• But redshift evolution: consistent with self-similar model
Results: Lensing mass as a function of X-ray luminosity
Possibility to use other mass proxy like richness (used for SDSS measurement)
Leauthaud et al 2009
Cosmography with SL clusters
Golse et al 2002, Soucail et al 2004Golse et al 2002, Soucail et al 2004
Abell 2218Abell 2218
•Lensing depends on cosmology via the angular distance. Probing different source planes, one probes different distances!=> Clusters with many (>>3) multiple image systems at different redshift can constrain cosmology
•Early work on A2218: with 4 multiple image systems at z=0.7, 1.03, 2.55, 5.56 favors Lambda-CDM• Need of deep imaging and deep spectroscopy …
Omega_matter
Om
ega_
lam
bd
a
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Cosmography with Abell 1689Mass model with 12 multiple image systems with
spectroscopic redshifts.
Optimizing cosmography (M , wX ) for a flat Universe
Jullo et al 2009Jullo et al 2009
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Cosmography with Abell 1689Mass model with 12 multiple image systems with
spectroscopic redshifts.
Optimizing cosmography (M , wX ) for a flat Universe
Jullo et al 2009Jullo et al 2009
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Combination with other cosmological probes (WMAP5, SDSS-BAO, SNLS) => mild improvement
Evidence for a non Lambda cosmology ??
More cluster cosmography constraints needed!Easier than Cosmic shear?
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Future Prospects• Lensing images better from space => true for cluster
lensing too (both SL and WL), multicolor very helpful• Mass reconstruction techniques are limited by
quality/quantity of data => results will improve with better, larger dataset … and faster computers!
• Slope of DM and substructure are measurable quantities => need to improve datasets
• Cluster cosmography is a promising new (geometrical) cosmological probe - Simple? Competitive?
• New serviced HST and JWST, as well as wide-field/spectroscopy ground-based 8-10m telescope are unique tools to conduct cluster lensing science.