SKA

P ti f l ti f t Perspectives of solution: future instruments instruments

Françoise CombesEuclid

The greatb t i

E-ELTIn construction observatories

of the future

ALMA inaugurated in 2013Atacama desert

ALMA

JWST2018

In operation

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Large fieldf iof view

and billions of galaxies

Construction 2018-22

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Euclid, 20201 billion $

BAO: baryonic oscillationsStandard ruler

Test

cz/H

Test Can also test the bias b

Or = m0.6/b

ObserverD

Eisenstein et al. (2005)50 000 galaxies SDSS

cz/H = D

D 50 000 galaxies SDSS

determine H(z)

Recent BAO results with spectro-z

Excellent agreementwith CDM (grey)

DV (z=2.34) = 4628 Mpc

Slosar et al 2013Delubac et al 2014

5Anderson et al 2012

BAO in the Ly forest at z=2.3137 000 BOSS quasars2 1 < z < 3 5(cos 2.1 z 3.5Blue Ly autocorrelationRed: Quasar-Ly cross-correl(Font-Ribera et al 2013)( )Black: combined

Delubac et al 2015Red points : obs compared with simulationsof quasars(grey)rd sound horizon

DA angular dist, DH= c /HT i ith Pl k à 2 5

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Tension with Planck à 2.5

RSD « Redshift space distortions »p

Di t ti d tDistortions due topeculiar velocitieson the line of sight(Fingers of God)

Kaiser effect in clustersSystematic infall

These velocity flowsThese velocity flowsallow to determine

= 0.6/b = m /bbias δgalaxies = b (δmass)and gal

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Status of RSD measures

te

of s

ight

Various galaxy surveysVIPERS, de la Torre et al 2013

on th

e lin

e

Separation on the skyarat

ion

o

f 8 (growth rate)

Thick line: GR gravity

Separation on the sky

Sep

a

Thick line: GR gravity

Dahed or dotted linesM difi d itModified gravityDGP (Dvali et al 2010f(R) models, etc..

8z

Tension on H0 between Planck, Cepheids, BAO …0 , p ,

BAO at 68 and 95% confidence level (blue)( )Ho (Cepheids) = 74km/s/Mpc, while Planck favors 67 km/s/Mpc

Planck

9Delubac et al 2014

Growth rateas a test of gravityas a test of gravity

Growth rate f= dlog () /dlog (a) ~m

This growth produces peculiar velocities RSDThis growth produces peculiar velocities RSD

The growth rate will be measured byThe growth rate will be measured by1- Weak Lensing (WL) Tomography2- Redshift-space distortion in galaxy clusters (RSD)

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2 Redshift space distortion in galaxy clusters (RSD)

« Square Kilometre Array »

Project (~2020-30) for a giant radiotelescope

q y

Project ( 2020-30) for a giant radiotelescopein the centimetre-metre range

• one square kilometre collecting surface• one square kilometre collecting surface50-100 x more sensitive than present radio telescopes

for spectral line observations1000 iti th t di t l1000 x more sensitive than present radio telescopesfor continuum observations

• frequencies: 70MHz – 25 GHz ( 1.2cm – 4m)• field of view: 1 ( 100?) square degrees at 21 cm / 1.4 GHz

8 independent fields of viewp• angular resolution: 0.01 arcsec at 21 cm / 1.4 GHz baselines up to ~ 3000 km

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In Australia and in South Africa

Multi-beam observation

EMBRACEPrototypeat Nancay

SKA: Square km ArraySurface: one million m2

World wide project in m/cm

will observe HI-21cm redshiftedfrom galaxies up to z=5(i t d f 0 3 t d )(instead of z=0.3 today)

Follow the DM content of galaxiesIn all the history of the Universe

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HI mass detectable as a function of z in 360 hz          Time     Mass HI   # Detections

(Gyr)          (Mo)HI mass function

0.5‐1.0    4.2‐6.2      1.7 108 6.6 1051.0‐1.5    6.2‐7.3      4.7 108 2.3 1051.5‐2.0 7.3‐8.0 1.1 109 1.0 1051.5 2.0    7.3 8.0      1.1 10 1.0 102.0‐2.5    8.0‐8.5      2.2 109 4.4 1042.5‐3.0    8.5‐8.9      4.1 109 3.0 1043 0 3 5 8 9 9 1 6 7 109 1 0 1043.0‐3.5    8.9‐9.1      6.7 10 1.0 103.5‐4.0    9.1‐9.2      1.2 1010 9.5 103

4.0‐4.5    9.2 9.3      1.6 1010 7.0 103

14Star Formation vs z

Maximum redshift pour une intégration de 360 h avec SKA

2000 galaxies/ degg g

M 101100 000

Rotation curvesRotation curvesAs a function of time

M 5130 000

SMC

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Search of dark dwarfs in HISearch of dark dwarfs in HIALFALFA: Arecibo (300m)

Red: opticalS h i th id

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Blue HIGreen: both

Search in the voids: Negative until now

ALFALFA: High velocity HI cloudsSearch of stars in optical: Always a signal foundDiscovery of normal dwarfsy

No dark dwarfs

M(HI) 106 MM(HI) ~ 106 M

17Haynes 2008

Always some stars low Always some stars, low

18M(HI) < 107.2 MHaynes 2008

Images SDSS

Discovery of 2 candidates?Discovery of 2 candidates?0.4% of systemsAl d kAlmost dark

19Janowiecki et al 2015

Kinematics of HI cloudsKinematics of HI cloudsJust outside of the Virgo cluster

One of the systems is composedof 2 clumps

Is the DV between them relevant?

Difficult to identify anyDifficult to identify anyrotation, or interpret thevelocity profiles

Inclination?May be face-on

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Baryon Fraction (stars)y ( )

Halob dabundance

matching

And for 8000selectedgalaxies

21Papastergis et al 2012

Baryon Fraction (stars+gas)y ( g )reio fraction of baryons predicted by hydrodynamical simulations Including the reionization Okamoto et al 2008Including the reionization Okamoto et al 2008

Baldry + 2008Baldry + 2008

Thickness of theThickness of theline: sensitivityHI gas

22Papastergis et al 2012

EUCLID satellite1-What is dark energy: w P= w Equation of state and nature of DE, through expansion and growthEquation of state and nature of DE, through expansion and growthrates, 5 tools: Weak Lensing, BAO, RSD, Clusters, ISW

2-Gravity beyond Einstein: Testing modified gravity, by measuring growth rate exponent

3-The nature of dark matter, mTesting the CDM theory, and measuringTesting the CDM theory, and measuring neutrino mass

4- The seeds of cosmic structuresImprove by a factor 20, n= spectral index,

lit d f t23

8=amplitude of power spectrum, fNL= non-gaussianities

Mass and number of neutrinosWith extra mass-less neutrinos with one sterile massive neutrino

Planck coll (2013) Paper XVI-- thermal mass

Neutrino mass constraint from power-spectrum (free-streaming)Neff could be higher due to lepton asymmetryor the existence of a sterile neutrino

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or the existence of a sterile neutrinoWith Euclid (M) = 0.03 eV, (Neff) = 0.02

Predictions with EuclidPredictions with EuclidDeviations to the GR50 millions of galaxy z

f dlog/dlogaCoupled CDE c=0.2

f = dlog/dloga, where (t) is the growthfactorfactor

8 variance : amplitudeGR

Flat DGP model

of structures (normalisation)

f8 measured by theanisotropy RSD

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Majerotto et al 2012CDE, DGP, di Porto et al 2012

so opy S(GR) = 0.55f(z) ~m

Exploration of dark energy models with Euclid ( d hift l ith t WL)(redshifts only without WL)

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EUCLID Legacy

Wide survey 15 000 deg2y gDeep survey 40 deg2 (+2mag)

12 billion sources (3)50 million redshifts

A reservoir of targetsfor JWST,GAIA, ELT, ,ALMA, Subaru, VLT, etc …

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Strong Lensing: 60 SLACS

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Will become an industryStudy of sub structures Constraints on dark matterStudy of sub-structures Constraints on dark matter Similar number per unit surface then SKA 100 000

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Cold or Warm dark matter?Cold or Warm dark matter?

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CDM WDM

Make images with lensesa e ages t e sesCLASS B2045+265, VLA 15GHz

NIR, Keck

Dwarf G2: lens

Detect sub-structures as anomalouss b str ct res seen as

E=G1

flux ratios between images

Until now: only bright dwarfs found

sub-structures seen as brightness anomalies

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Until now: only bright dwarfs foundNo need of dark halos Sub-structure:

source or lens?

The tool of strong lensingThe tool of strong lensingB1938+666

Potential

HST NIRRadio (Merlin)

EVNsmooth + (pixel) EVN3masMcKean

32Model the sub-structures bothin the source and in the lens

Simple model of smooth source ~rSimple model of smooth source ~r

Data Model

SDSSJ120602 09 514229 5

33Résidual Source

SDSSJ120602.09+514229.5Vegetti et al 2010

Addition of a sub structureAddition of a sub-structure

34Msub = 107 MSmooth Potential

Vegetti et al 2009

Addition of a sub structure (2)Addition of a sub-structure (2)

35Msub = 108 MSmooth Potential

Vegetti et al 2009

Degeneracy source-lensDegeneracy source-lens

M = 109 MSmooth Potential Msub = 109 MSmooth Potential

Possible to detect M> 107 M on the Einstein ring, or

36Vegetti et al 2009

M> 109 M close to the ring

Present Constraints, 12 Einstein rings

The smallest M detectable

No « dark » structure detected,One bright sub-structure detectedThe smallest M detectable,

unit 1010M<z>=0.2, <> = 270km/s

ff

CDM

pente de la fonction de masse

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SDSS J0252+0039, Vegetti et al 2014 f< 0.006 mass fraction in the sub-structures < 1.90

CASTLES

Near IR

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Einstein rings in optical

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Einstein rings in radio

The first detection was in radio!50 years after the predictionof Einstein

MG1654+1346 Langston 1988

MG1131+0456, Hewitt 87 PKS1830, Jauncey 1991, , y

40B0218, Merlin Biggs et al 2001

Other data: time delayLens+ kinematics+delay+delayCurvature kHo, w (dark nergy)P= -w

k kk k

Ho HoFor a flat universe, Ho= 82km/s/MpcEt w=-1 5 w wEt w=-1.5Ho = 65km/s/Mpc, if open universe

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RXJ1131−1231, Suyu et al 2014 Ho Ho

Observations of lenses with ALMA

Grey: near-IR images with HST, VLT, SOARVieira et al 2013 (23/26 detected)Viei a et al 0 3 ( 3/ 6 detected)10 sources z > 4Red=870 m contours ALMA, 2min, 0.5’’

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Redshift spectro obtained with ALMA Cycle 0 (16 antennae instead of 60)

Statistical constraints with ALMA

An individual halo is detectable only if M> 108M butAn individual halo is detectable only if M> 10 M, but Statistical constraint on a multitude of halos M~106M

Dalal & Kochanek 2002, Hezaveh et al 2015Power spectrum of residuals

Th f th lThe power of the lensdepends on the mass concentration

Point sources = cstePoint sources = cste

Green curve: the slope of the massfunction is changed by 0 5function is changed by 0.5dn/dM ∝ M−

43Hezaveh et al 2015

Perspectives: strong lensingPerspectives: strong lensingS Kil A (SKA) ALMASquare Kilometre Array (SKA), ALMALarge Synoptic Survey Telescope (LSST) Euclid + telescopes to follow on the ground with high-fidelityEuclid + telescopes to follow on the ground with high-fidelity, Number of lenses >> 104

200 lenses of excellent quality

Sub-structures M> 108M, Th f ti f DM i th b t t ill bThe fraction of DM in the sub-structures will be contrained to f < 0.005+0.001 (lower than CDM predictions)

Anomalies in the flux ratio between images, kinematicsAlso method of time delays between images (variable QSO)

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The bullet cluster Gas X

Rare cas of violent collision, allowing Masse totale

to separate components Limit on DM/mDM < 1 cm2/gF difi d it d f lli i l tt

V=4700km/s (Mach 3)

For modified gravity, need of non-collisionnal matter:neutrinos or dark baryons

Abell 520z=0.201

Red = gas XContours = lensesDark mattercoïncides with the gas Xb t oid of gala iesbut void of galaxies

Collisions DM/mDM~ 4cm2/gCollisions DM/mDM 4cm /g

Or else existence of galaxies in 3?

Mahdavi et al 2007, Clowe et al 2012

BlueDark matter Red=X

Mahdavi et al 2007, Clowe et al 2012Jee et al 2012, Jee et al 2014

Controversy: A520, z=0.199yThe total mass derivation made with different maps

Mahdavi+07: central peak of DM

Okabe & Umetsu 08:i t ithin agreement withMahdavi+07;Jee+12; 14

But notClowe+12.

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Okabe & Umetsu 2008Okabe & Umetsu 2008

Subaru I band+ lensing Subaru I band

+ X-rayy

Galaxy density+ lensing

X-ray+ lensing

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Jee et al 2012

S l ( Ab ll 1942 b 00 i ll 02)Several cases (e.g. Abell 1942, Erben+00 et Miralles+02);The detection of dark matter is not always significant

Deeper observations measure weaker galaxies With a different orientation/deformation,

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,With more signal/noise some dark structures disappear

Clowe et al 2012Clowe et al 2012

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9 random realisations possible

MCC: Merging cluster collaborationMCC: Merging cluster collaboration

How many cases observed? Only 5-6 until now!

Perspective of many more significant cases in the future Perspective of many more significant cases in the future

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El Gordo, massive and very rare for CDM z=0.87

2 clusters with M = 1.4 & 0.7 1015 M

52Jee et al 2014

El Gordo total massEl Gordo, total massThe peak of hot gas is displacedp g poutside galaxies, at 62kpcThe total mass is off- centered with respect

h ll lto the stellar clusters

53Jee et al 2014

The musquet ballcluster (0 7 Gyr)cluster (0.7 Gyr)

Red: hot gasg(X-rays)

hiWhite contours:Stellar mass

Subaru (ground) HST (space)

Grey images :Total mass from

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lensesDM/mDM < 7 cm2/g

Small bulletsSmall bullets

G lGalaxy groups,Strong lensing, 2-component modelWhite contoursWhite contours M~2 1014 M

DM/mDM < 10 cm2/gDM DM

Hot X-ray gas in blueGastaldello et al 2014Gastaldello et al 2014

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MACS J0025-1222: « Baby bullet »yz = 0.586 Finally very massive also! M = 6 1014 M,

V=2000km/sV 2000km/s

56m < 4 cm2/gBradac et al 2008

Pandora cluster:Abell 2744

Strong lensing with 11 galaxiesShear HST, VLT, SubaruAbell 2744 At least 5 componentsHot gas sometimes farther fromthe centre than galaxies

z=0.308 Merten et al 2011the centre than galaxiesSlingshot effect /m < 3 cm2/gg

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ParabolaeParabolae

High frequences(South Africa)

Mid FrequencePhased arrays

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y

L FLow Frequences(Australia)

More than 900 stations, each containing about 300 individual dipoles, plus 96-parabolae Telescope ‘SKA1-Survey’, including the present array ofp y g p yASKAP 36 parabolae

59www.skatelescope.org

LSST Large Synoptic Survey TelescopeLSST Large Synoptic Survey TelescopeLSST observes the whole southern sky up to +15°y pwith a field of view of 10 sq.deg

Two planned surveys:The main oneDeep extended survey: 18 000 square degrees withDeep extended survey: 18 000 square degrees withu: 26.1 g: 27.4 r: 27.5 i: 26.8 z: 26.1 y: 24.9

Very deep survey, focus10% of time: ~30 selected fields 300°2

C i 15 1h / i hContinuous poses 15sec. 1hour/night

All the sky visited 800 times with poses of 30s

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All the sky visited 800 times with poses of 30s Alerts on variable objects released everywhere in 60s.

Data reduction, managing SKA

A huge challenge, for SKA: a few Petabytes/secComputers Petaflops working continuously (~108 PC)A few Exabytes/hour parabolae=10x global internetA few Exabytes/hour, parabolae=10x global internet, Phased arrays =100x global internet traffic!

LSST: more than half of the cost is due to data processing!LSST: more than half of the cost is due to data processing!1-2 millions alerts per night, available inthe whole word in 60sec

15 Tbytes /night15 Tbytes /night Every 3 days, observation of the whole sky 20 000 square degreesCamera 3200 Megapixels, 10 sq deg, 15sec /pose

Euclid: 100Gbytes /jourLSST

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Conclusion: perspectives

SKA: observations of HI and the extended rotation curves ofgalaxies up to z=5, Evolution of dark matter

Euclid & SKA: discovery of 104-105 strong lenses, caracterisationof the DM fraction in sub-structuresof the DM fraction in sub structures

Euclid + LSST: weak lensing tomography, DM cartography

Euclid, growth rate of structures (RSD)Constraints on modified gravityConstraints on modified gravity

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