Dark Matter and Dark Energy components chapter 7 Lecture 4.

Dark Matter and Dark Energy components

chapter 7

Lecture 4

The early universechapters 5 to 8

Particle Astrophysics , D. Perkins, 2nd edition, Oxford

5. The expanding universe6. Nucleosynthesis and baryogenesis7. Dark matter and dark energy components8. Development of structure in early universe

Slides + book http://w3.iihe.ac.be/~cdeclerc/astroparticles

Dark Matter - Dark Energy lect 4 3

Overview

• Part 1: Observation of dark matter as gravitational effects– Rotation curves galaxies, mass/light ratios in galaxies– Velocities of galaxies in clusters– Gravitational lensing– Bullet cluster

• Part 2: Nature of the dark matter :– Baryons and MACHO’s– Standard neutrinos– Axions

• Part 3: Weakly Interacting Massive Particles (WIMPs)• Part 4: Experimental WIMP searches: direct & indirect

detection• Part 5: Dark energy2014-15


Energy budget of universe today

2014-15

luminous1%

dark baryonic4%

Neutrino HDM<1%

cold dark matter

25%

dark energy

70%

• Today only 5% of the matter-energy consists of known particles

• 25% is Cold Dark Matter = new type of particles

• 70% is completely unknown 510

0.30rad

matter

2 3 420 0 0 01 1m rH t H t z t z t

Planck, 2013


Where should we look?

• Search for WIMPs in the Milky Way halo Indirect detection: expect WIMPs from the halo to annihilate with

each other to known particles Direct detection: expect WIMPs from the halo to interact in a

detector on Earth

2014-15

Dark matter halo

Luminous disk

Solar system

© ESO

Weakly Interacting

Massive Particles

Dark Matter - Dark Energy lect 4

three complementary roads

6

, , , ,γν,f f W W e

Indirect search experimentsdi

rect

sea

rch

expe

rimen

ts

Production at the LHC collider

p p

Model

2014-15


PART 4: WIMP DETECTIONIdentify the nature of dark matter with experiment

2014-15


DIRECT DETECTION EXPERIMENTS

2014-15

See Lecture 3


INDIRECT DETECTION EXPERIMENTS

2014-15


Indirect detection of WIMPs• Search for signals of annihilation of WIMPs in the Milky Way halo• accumulation near galactic centre or in heavy objects like the Sun or

Earth due to gravitational attraction• Detect the produced antiparticles, gamma rays, neutrinos

2014-15

WIMP WIM

Pe +, γ, υ, p

, , ,..

, ,

qq

ll e

W Z H


neutrinos from WIMP annihilations : IceCube

• Neutrinos from WIMP annihilations in the Sun

• Neutrinos from WIMP annihilations in galactic halo, galactic centre, dwarf spheroidal galaxies

• Neutrinos from WIMP annihilations in the centre of the Earth

2014-15


WIMPs accumulated in the Sun

2014-15

c

Detector

nμ

m

ν interaction

, ,...qq ll

1. WIMPs are captured 3 2SUNC

v m χNσ

2. WIMPs annihilate

1

2ANN SUNC

Capture rate

Annihilation rate


Search for GeV-TeV neutrinos from Sun

A few 100’000 atmospheric neutrinos per year from northern hemisphere

Max. a few 100 neutrinos per year from WIMPsin the Sun

signal

~1011 atmospheric muons per year from southern hemisphere

BG

BG

2014-15


No excess above known background

2014-15

DataBackground

• No significant signal found• Rate is compatible with

atmospheric background• Set upper limit on possible

neutrino flux and annihilation rate

ψ(deg)

Num

ber o

f eve

nts

Sign

al?

m

νμ


Combining direct and IceCube searches

2014-15

IceCube

W W

2SD p cm

A selection of SuperSymmetry models

~ ~Ann SUNC χNσ

Physical review letters 2013


Overview • Part 1: Observation of dark matter as gravitational effects

– Rotation curves galaxies, mass/light ratios in galaxies– Velocities of galaxies in clusters– Gravitational lensing– Bullet cluster


• Part 3: Weakly Interacting Massive Particles (WIMPs)• Part 4: Experimental WIMP searches• Part 5: Dark energy

2014-15

Dark Matter lect3 172014-15

Part 5: Dark Energy

ObservationsThe nature of Dark Energy

ΩΛ


Energy budget of universe today

2014-15

luminous1%

dark baryonic4%

Neutrino HDM<1%

cold dark matter

25%

dark energy

70%

• Today only 5% of the matter-energy consists of known particles

• 25% is Cold Dark Matter = new type of particles

• 70% is completely unknown 510

0.30rad

matter

2 3 420 0 0 01 1m rH t H t z t z t


OBSERVATIONS

SNIa surveysLink to cosmological parameters

2014-15

Dark Matter - Dark Energy lect 4 212014-15

Nobel Prize in Physics 2011


SNIa as standard candles (see lecture 1)• Supernovae Ia are very bright - very distant SN can be

observed• All have roughly the same luminosity curve which allows to

extract the absolute magnitude M• → effective magnitudes yield luminosity distance

• Network of telescopes united in– Supernova Cosmology Project SCP, (Perlmutter) up to z=1.4 –

have now data from 500 SN (http://supernova.lbl.gov/)– High-z SN search HZSNS (Schmidt & Riess, in 1990’s)

2014-15

10

2.5log

5log 251Mpc

M L cst

z M

LDm


Luminosity distance vs redshift - 1

• SN at redshift z emits light at time tE – is observed at time t0

• Light observed today travelled during time (t0 - tE ) • distance travelled depends on history of expansion• Proper distance DH from SN to Earth (lecture 1, part 2)

• For flat universe (k=0) with negligible radiation content

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00

EE

t

t

dct R t

R t

t HD 1

dz

zd

Ht


Luminosity distance vs redshift - 2

• Luminosity distance

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300 00 0

121

z z

m

cdz c dz

Ht z t

H H zD z

1 z HD zLD z

Luminosity distance DL vs redshift z

• Neglect radiation at low z – different examples

2014-15 Dark Matter - Dark Energy lect 4 25


normalise to empty universe

• normalise measurements to empty universe

• Deceleration parameter is zero – universe is ‘coasting’

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0 0 01, 0, 0k mt t t

02m

rt

q t t t

20 00

12

1 12

1

z

L

c dz c zD empty z z

H Hz

Hubble plot with high z SNIa


Empty universe: Ωm= Ωr=0 Ωk=1No accelerationno deceleration

Vacuum dominated & flat

Matter dominated& flat

Log

DL (

Mpc

)

Redshift Zpast

Far a

way &

dimmer

now

Influence of cosmological parameters• best fit

• Empty universe


Difference between measured logDL vs z and expected logDL vs z for empty universe

best fit

Empty universe

measurements


Measurements up to z=1.7

• Best fit

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0 00.27 0.73m t t

log logL LD measured D empty

…. empty--- Best fit

Δ(m

-M)=

ΔD

L

z

q(t)<0 acceleration q(t)>0 deceleration

pastpresent

http://supernova.lbl.gov


SN observations show acceleration

• Earlier universe : universe dominated by matter decelerates due to gravitational collapse :

• Recently : universe dominated by vacuum energy accelerates

• Acceleration = zero around z=0.5 when

• → Switch from deceleration (matter dominated) to acceleration (dark energy dominated)

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2m

rt

q t t t

2m

rt

t t


Fit ΛCDM model to observations

2014-15

m

pdg.lbl.gov

SN Ia distance-redshift surveys

CMB anisitropies survey by WMAP

Anisotropies in galaxy surveys


THE NATURE OF DARK ENERGY

Related to cosmological constant ?problems

2014-15


Dark vacuum Energy

• Observed present-day acceleration means that something = Dark Energy generates a negative pressure

• Yields gravitational repulsion like vacuum energy• Equation of state (see lecture 1)

• Fits to SNIa data yield that w is compatible with vacuum energy

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2vac

S

EP c cst

V

2

Pw

c

0.85 at 95% . .w C L


Related to cosmological constant Λ?

• In ΛCDM – ΩΛ is constant and related to Einsteins cosmological constant

• If Universe contains constant vacuum energy density related to Λ then we set

• A natural value would be the energy density at the Planck energy scale - energy and length scales

• And expected energy density

• Quantum field theory yields same value

2014-15

8 vacG

15 2

2 191.2 10def

PL

cM c GeV

G

351.6 10DEF

PLPL

L mM c


Cosmological constant problem

• Today vacuum energy density is of order of critical density

• Discrepancy of 100 orders of magnitude !!! • Did vacuum energy evolve with time?• There is no explanation yet • need high statistics data :

– Dark Energy Survey – start 2011 (http://www.darkenergysurvey.org/)

– WFIRST mission of NASA – launch 2020 (http://wfirst.gsfc.nasa.gov/ )

– ESA EUCLID mission – launch 2015-20 (http://www.esa.int )

2014-15

http://www.darkenergysurvey.org/

http://www.darkenergysurvey.org/

http://wfirst.gsfc.nasa.gov/

http://www.esa.int/

Dark Matter - Dark Energy lect 4 362014-15

3 11

wz

© J. Frieman1 0.2DarkEnergyw

Is wDE constant with time?


Alternatives

• Quintessence – 5th force : new type of scalar field• Mechanism analogue to inflation in early universe• Vacuum energy density would vary with time

• Maybe general relativity works differently at short distances

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2

Pw t

c 11 3w t


Summary

• Observations of SNIa emission show that the universe presently accelerates

• This can be explained by a constant dark vacuum energy contribution which dominates today

• In the ΛCDM model the dark energy is related to the cosmological constant introduced by Einstein

• There is yet no satisfactory explanation for the observed magnitude of the dark energy

2014-15


Overview

• Part 1: Observation of dark matter as gravitational effects– Rotation curves galaxies, mass/light ratios in galaxies– Velocities of galaxies in clusters– Gravitational lensing– Bullet cluster


• Part 3: Weakly Interacting Massive Particles (WIMPs)• Part 4: Experimental WIMP searches• Part 5: Dark energy2014-15

Dark Matter lect3 402014-15

Dark Matter and Dark Energy components chapter 7 Lecture 4.

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