AAPCOS 2015

DARK MATTER DETECTION

Viktor Zacek, Université de Montréal Saha Institute of Nuclear Physics October 2015 • Most probably there are 10 Mio DM particles in this room

• They swirl around with a speed of 500 000 km/h

• About 1012 particles traverse you during this presentation

• Nevertheless we do not feel them because they interact

super weakly & super rarely Sun • And yet: they dominate the structure and future of the Universe!

• …but what is DM and how to detect it ? Lecture I • Evidences for Dark Matter • Present knowledge of the matter content of the Universe • Dark Matter and structure of the Universe • What Dark Matter can and cannot be

Lecture II • DM detection – rates and limits • Backgrounds and their mitigation • A guided tour through SNOLAB • Status of direct search experiments Lecture III • Status of indirect search experiments • Accelerator searches • Other candidate searches • Future directions THE DARK MATTER PROBLEM - FIRST INDICATIONS

• Studies kinetic energies of 8 galaxies of the Coma Cluster . finds velocities are much larger than expected (virial theorem) Fritz Zwicky, 1937 . apparently Coma cluster contains 200 x more mass than is visible in form of galaxies

The “hidden mass” problem becomes a “key problem” of modern cosmology

DARK MATTER & GALACTIC ROTATION CURVES

v2 GM(r) rot  r r 2 Vera Rubin, 1974

1 v  r ퟏ 풗 ∝ 풓풐풕 풓

Doppler shift of star light and of HI distribution DARK MATTER & GALACTIC ROTATION CURVES

v2 GM(r) rot  r r 2 Vera Rubin, 1974

ퟏ 풗 ∝ 풓풐풕 풓 For vrot = ct. M (r) must increase linearly with r

For large r halos of galaxies start to overlap

Doppler shift of star light and of HI distribution

Mhalo > 10 x (Mlum + Mgas) DARK MATTER IN OUR MILKY WAY

1kpc = 3.259 103 Ly 2 vrotr   0.3 m /cm3 M (r)  DM p G 2MASS two Micron All Sky Survey …only 5-10% of matter visible! DARK MATTER FURTHER OUT

. Size of Local group 2.2 MLy . MW & M31 dominate Local Group V= 3x105 km/h . Enormous gravit. pull between the two galaxies

. Invisible mass > 10 x MMW . Local group at fringe of Virgo cluster

Virgo cluster v  1.6x106 km/h

v  2 x 106 km/h . Size of Virgo cluster 50MLy . Local group pulled towards Virgo cluster

. invisible mass > 10 x Mvis Virgo Cluster pulled towards an invisible “Great Attractor” VIRGOHI21: A GALAXY OF DARK MATTER ! (50 M Ly)

Visible spectrum RF-hydrogen emission

1000 x more Dark Matter than hydrogen!

M  0.1 MMW

(Feb. 2005) DARK MATTER AROUND CLUSTERS OF GALAXIES

Stellar mass 15% of

galaxy masses

Abell 2029 ( 100 Mpc) . a cluster of thousands of galaxies . surrounded by gigantic clouds of hot gas DM mass 95% of 6 . T 10 K cluster mass DARK MATTER AT AT LARGER SCALES

Gravitational lensing . grav. potential  causes time delay 2 of light (Shapiro)  refractive index n 풏 = ퟏ − ퟐ흋/풄ퟐ

2 2 ∆ = − 훻 푛푑푙 = − 훻 휑푑푙 푐2  푐2 

HST CL0024+1654 • provides evidence of large masses between source and MW

• recently 3D reconstruction of clusters of Dark Matter Mdark>50 Mvis

THE BULLET CLUSTER IE0657-56 ( 1 Gpc)

High velocity merger of clusters of galaxies 4500 km/s 108K

DM: “collision less”

Mdark > 49 Mvis

M. Markewitch et al: HST, Magellan, Chandra (August 2006)

THE CETUS CLUSTER MACSJ0025.4 (6x109 LY)

HST, Chandra (August 2008) DARK MATTER & DYNAMICS OF THE UNIVERSE

m  2 E  R m M = mass of Universe kin 2 R = radius of Universe mM R E  G m = mass of a border pot R M galaxy v m 4 3 E pot  G (v R ) R 3 Energy density of vacuum

2 v = c /8G Ekin + Epot = Etot m . GMm 1 R 2 (  mc2 R2 )  E 2 R 6 tot « Friedmann equation »

 adds to gravitation! THE FRIEDMANN EQUATION

1 8G A. Einstein: R  g R   T  g  2  c4  

m . GMm 1 mc2 R 2 (  mc2R2 )  E  k 2 R 6 tot 2

dE pot Mm 1 2 k : curvature of space! F    G 2  mc R dR R 3  k = 0: flat  k > 0: closed  k < 0 open attractive repulsive (Robertson-Walker metric)

HUBBLES LAW & CRITICAL DENSITY

v = H R Hubbles law! R(t)  H(t)R(t) 0 H = 72 km s-1Mpc-1 (today!) 0 m . GMm 1 mc2 R 2 (  mc2R2 )  E  k 2 R 6 tot 2

2  R  8 kc2     H (t)2  G(   )     V 2   = c2/8G  R   3 R  v Friedmann equation 3H 2   “critical density”  k = 0 (for =0) c 8G THE CRITICAL DENSITY  = 0

3H 2   c 8G today:  1proton/m3 -26 3 c = 1.9 10 kg/m

Mass parameter m = 0/ c  =v/c 0: present day value

tot  m 

tot > 1 closed U.

tot < 1 open U.

tot = 1 flat, euclidean, critical U. ...but lum  0.01 ( 1!) HOW TO MEASURE  ?

Count all the components of the Universe! . Luminous matter, stars . DM from galaxies and their rotation curves . DM in clusters of galaxies . DM inferred from x-ray clouds around clusters of galaxies . DM from large scale flows of galaxies . DM by gravitational lensing

+ Measure the geometry of the Universe! EVOLUTION OF THE UNIVERSE

Planck

Phase transition @T 10-35s with factor x 1050 expansion  space flat FAR AWAY IS LONG AGO

J. Primack, G. Gelmini B FROM BIG BANG NUCLEOSYNTHESIS

n + p  D T + p  4 He 3He + n  4He p + D  3He D + D  4He n + D  T He + T  7Li

…well understood

no elements A = 5 / 8 heavy elements @ T ~ 106 y

Yi = fct( b, T, n, n , …) light el. abund. consistent over O(9)

b = 0.04  0.007 c CURRENT EVIDENCE FOR 

2003 SN Type Ia Redshift

m = 0.3,  = 0.7 …AND THERE IS A COSMIC COINCIDENCE ?!

 ~ m just now?? THE 2.7K COSMIC MICROWAVE RADIATION (CMB)

1965 accidental discovery by A. Penzias & R.Wilson (1978 NP)

Perfect and isotropic black body spectrum of 2.725±0.001 K

8휋ℎ 푓3푑푓 휖 푓 푑푓 = 3 푐 푒푥푝 ℎ푓 푘퐵푇 − 1 Energy density

Preservation of bb-spectrum if f &T scale with (1+z);

Explains low temperature today  matter & radiation @ 2K are not in equilibrium!

Earlier U. very much hotter  thermal equilibrium of matter & radiation

CMB is a “relic radiation” which you could see as noise at home on a CTR TV!!!

U. Is expanding! First proof of hot BB-theory …a revolution in cosmology THE ANISOTROPY OF THE COSMIC MW BACKGROUND

Image of early Universe imprinted on temp. anisotropy of CMB

WMAP 2001

T/T  10-5

Planck 2013 . 300 ky after BB photons decouple from matter T  6000 K . before decoupling: plasma oscill./ of photon-baryon “liquid”  sound waves . CMB: snap shot of sound waves when rad. decoupled . Today light red shifted by 1/1000  2.7 K . Smallness of T/T  visible Universe once causally connected  Inflation! . Image of quantum fluctuation at 1019 GeV

Angular diameter of the moon

Expansion in spherical harmonics of CMB temp. field

Multipole development  angular scale . l number of cycles in the sky . =  / l

. lpeak = 200 / tot 0 . lpeak = 197  6 (0.9 )

( Ang. size of moon: 0.50 )

Curvature of Universe: tot “Cosmic variance” (only one Universe) Baryon density small: b PLANCK RESULTS: Other :

 tot = 0.9890.02 Inflation :  tot = 1

b = 0.049 0.007 BBN: b = 0.039

dm = 0.262 0.007 clusters of galaxies, grav. lensing

hot x-ray gas : m = 0.3

 = 0.69 0.02 SN1a –redshift :  = 0.7

H0 = 67.31.2 km/sec/Mpc HST: H0 =72 4 km/sec/Mpc

T0= 13.81 0.058 Gyr HST: 11 Gyr DM & DEVELOPMENT OF STRUCTURE

• BB creates DM + ord. Matter • DM decouples early • DM clumps • Ordinary matter flows in • Galaxies form • Galaxies trace DM distribution DO GALAXIES TRACE THE DM DISTRIBUTION ?

COSMOS EVOLUTION SURVEY: (Jan. 2007)

- First large scale 3D reconstruction of DM distribution - HST, ESO VLT, Magellan, Subaru, XMM Newton

Near infra red HST Grav. lensing

DM > six times more abundant than ordinary matter 3 slices of red shift

6.5 By ago

5 By ago 3.5 By ago

Growing clumpiness of DM & ordinary matter flowing in

WHAT IS THE STRUCTURE AT LARGE SCALE

SLOAN DIGITAL SKY SURVEY

> 100 Mpc

- 2.5m telescope Apache Point - 120 Megapixels - 2008 1.6 M galaxies - 2011 map covers 35% of sky WHAT KIND OF MATTER CAN EXPLAIN LSS?

Baryonic matter @ t = 225s (BBN) cannot clump to form voids (200MLy) filaments & superclusters

…structures thinned out by Hubble expansion

Assume DM decouples earlier @ t < tBBN and interacts weakly

• longer time to develop structure • baryons fall into grav. troughs

• galaxy formation ok • Large scale structure ok LSS AND DARK MATTER SPEED

COLD DM • non relativistic ∆푻 • non-baryonic (CMB ~ퟏퟎ−ퟓ) 푻 • weak interaction w. baryonic matter • clump on small scale HOT DM • smaller clusters first

∆푻 . non-baryonic (CMB ~ퟏퟎ−ퟓ) 푻 . relativistic . weak interaction with ord.matter . e.g. massive ’s . before decoupling structures washed out . superclusters form first cdm-hdm1-princeton.mpeg LSS AND DARK MATTER SPEED

cdm-hdm1-princeton.mpeg LARGE SCALE STRUCTURE

Best fit: 5% baryons 25% dark matter 70% dark energy

(x)   ikx 2  (x)    (k)e P(k)   k  k

The larger the scale we average the more uniform becomes the Universe! Convincing Evidence for Dark Matter at all Scales!

Rotation curve Velocity flow Cluster kinematics

Lensing Hot X-ray gas

Bullet Cluster Large scale structure BB nucleosynthesis CMB anisotropy The Concordance Model