DARK ENERGY

RICHARD BATTYE

JODRELL BANK OBSERVATORYSCHOOL OF PHYSICS AND ASTRONOMY

UNIVERSITY OF MANCHESTER

PHENOMENOLOGY &PRESENT/FUTURE OBSERVATIONS

PLAN OF TALK

DARK ENERGY PHENOMENOLOGY

CURRENT OBSERVATIONAL STATUS

FUTURE COSMOLOGICAL TESTS - REVIEW

CLUSTER SURVEYS WITH THE SZ EFFECT

EFECTS OF DARK ENERGYMODELS : THERE IS MORE TO LIFE THAN w !LINEAR PERTURBATIONS

CMB ALONESNe ALONECMB + 2dF + SNe

WEAK LENSING (TALK BY ANDY TAYLOR)NUMBER COUNTSP(k,z) - BARYONIC OSCILLATIONSX-CORRELATION BETWEEN CMB AND LSS

AN EXAMPLE OF NUMBER COUNTS

EFFECT OF PERTURBATIONS

WORK WITH ADAM MOSS

WORK WITH JOCHENWELLER

SNe Ia

BASIC OBSERVATIONAL SITUATION

CMB2dF/SDSS

TRIANGULARARGUMENT

+

DARK ENERGY PHENOMENOLOGY

DARK ENERGY PRESSURE TO DENSITY RATIO :

w=-1 COSMOLOGICAL CONSTANT

SCALAR FIELDS : QUINTESSENCE

TOPOLOGICAL DEFECT LATTICES

MODIFICATIONS TO GRAVITY ?

SUPER-HORIZON PERTURBATIONS !

COSMIC STRINGS : w=-1/3DOMAIN WALLS : w=-2/3

EASY TO MODEL GIVEN A LAGRANGIAN

MODELLED AS A RELATIVISTIC SOLID

ie A FLUID WITH RIGIDITY

ASSUME FLAT UNIVERSE

NB POSSIBLE NON-MINIMAL COUPLING TO GRAVITY

TWO CLASSES OF TESTSGEOMETRICAL GROWTH OF STRUCTURE

ONLY DEPENDS ON w !

ANGULAR DIAMETERDISTANCE

LUMINOSITYDISTANCE

GROWTH DEPENDS ON w AND ALSO ON THE PROPERTIES OF

THE DARK ENERGY

LINEAR REGIME :

NON-LINEAR REGIME :

(i) MASS FUNCTION(ii) SPHERICAL COLLAPSE

(*) OFTEN GEOMETRIC DEPENDENCE AS WELL

EXAMPLES OF GEOMETRICAL TESTSTYPE Ia SUPERNOVAE PEAK IN CMB POWER SPECTRUM

degeneracy degeneracy (l>100)

GROWTH OF DENSITY PERTURBATIONS

NEWTONIAN THEORY

N-BODY SIMULATIONS(VIRGO COLLABORATION)

GROWTH HALTS AT L DOMINATION

INTEGRATED SACHS-WOLFE EFFECT

trec t0

PHOTONTRAJECTORY

DF

FOR STATIONARY POTENTIALS :

GRAVITATIONAL POTENTIALS DECAY ONCE DARK ENERGY DOMINATES :

THIS MODIFIES CMB POWER SPECTRUM AT LOW lBREAKS GEOMETRICAL DEGENERACY - BUT MODEL DEP

DIFFERENT MODELS FOR DE

EQUATIONS OF MOTION FOR A GENERAL FLUID

NON-ADIABATIC (SCALAR FIELD)

ADIABATIC(SOLID)

(Hu; Weller & Lewis; Bean & Dore)

(Bucher & Spergel;Battye, Bucher & Spergel)

LOW l CMB POWER SPECTRUM

SCALAR FIELD

SOLID

W=-1/3 W=-2/3 W=-4/3LCDM

PRESENT

OBSERVATIONALSTATUS

CMB DATA ALONE

BEST FIT MODELS

ISOTROPICSOLID DARK ENERGY

NO PERTURBATIONS IN DE

SCALAR FIELD DARK ENERGY

THIS ANALYSIS FAVOURS w=-1/3 COSMIC STRING MODELS

SUPERNOVA DATA

CMB + 2dF + SNe

SCALAR FIELDDARK ENERGY

NO PERTURBATIONS

ISOTROPICSOLID DARK ENERGY

NB : CMB ALMOST BURNTOUT IN TERMS OF DE, BUT ~2000 SNe CAN BE JDEMAND OTHERS

MESSAGE : TAKE CARE WITH w !

FUTUREOBSERVATIONAL

TESTS

NUMBER COUNTS

EXAMPLES : RADIO SOURCES GRAVITATIONAL LENSES

CLUSTERS (X-RAY, SZ, REDSHIFT SURVEYS)

SKY COVERAGE

SELECTION FUNCTION :FLUX LIMITED

COMOVING NUMBER DENSITY- EVOLUTION

NUMBER COUNTS : CLUSTERS

1 per 200 deg1 per 2 deg10 per 1 deg

2

2

2

DEPENDENCE ON COSMOLOGY

LCDM

= 0.4W

w=-0.8+0.3z

s= 0.728

SURVEY YIELD CALCULABLE

TOTAL NUMBER OF OBJECTS LARGE

REDSHIFT DEPENDENCE

NOISE RATHER THAN CONFUSION DOMINATED

CONTROL OF SYSTEMATICS

NUMBER COUNTS : IMPORTANT FEATURES

ACCURATE CORRELATION BETWEEN MASS AND PROXY (EG FLUX)

POISSON ERRORS

SEPARATE OPTICAL SURVEY?

NEED TO AVOID CONTAMINATION

IS THE MASS PROXY UNBIASED ?

BARYONIC OSCILLATIONS

z=500

z=100

z=0BARYONSCDM

OSCILLATIONS TRANSFERRED FROM BARYONS TO CDM

(EISENSTEIN 2003)

z=20

DEPENDENCE ON PARAMETERS

w=-1/3

w=-2/3

w=-1

PLOTTED RELATIVE TO ZERO BARYONS BREAKS GEOMETRICAL DEGENERACY NON-LINEAR SCALE SMALLER AT HIGH z REQUIRES UNDERSTANDING OF BIAS

BARYONIC OSCILLATIONS : STATUS

EFFECT DETECTED IN (i) SDSS LUMINOUS RED GALAXY SURVEY (ii) 2dF (Cole et al 2005)

(EISENSTEIN et al astro-ph 2005)

X-CORRELATION : LSS & CMB

ISW EFFECT LARGE-SCALE STRUCTURE

bias selection function=0 for matter dominated universes

CROSS-CORRELATE

WHERE

SENSITIVE TO ISW AND HENCE PERTURBATIONS IN DE

COULD BE USED TO DISTINGUISH DE MODELS

(CRITTENDEN & TUROK 1996)

X-CORRELATION : STATUS

XRB CROSS CORRELATION(Boughn & Crittenden, Nature 2004)

X-ray Background 2.4-2.8s(Boughn & Crittenden)

NVSS (Radio)

1.8-2.3s(Boughn & Crittenden)

2MASS (Infra-red)

2.5s(Afshordi, Loh & Strauss)

SDSS (Optical)

90-95% confidence (Scranton et al)

LCDM prediction

= 1W m

FUTURE REDSHIFT SURVEYS LARGE NUMBER OF OBJECTS

LARGE COSMOLOGICAL VOLUME

ACCURATE REDSHIFTS

BIAS - WHAT IF IS SCALE DEPENDENT?

PLANNED SURVEYS - AN INCOMPLETE LIST

POISSON ERRORS ARE DOMINANT SOURCE OF ERRORS

WIDE AREA DEEP SURVEYS

PHOTOMETRIC V SPECTRSCOPIC

Dark Energy Survey OPT 10^8 gal to z~1 PHOTO-z 2009DarkCam on VISTA OPT/IR " PHOTO-z

2009KAOS OPT out to z~3.5! SPEC-z

2012LSST OPTPHOTO-z 2012SKA RADIO 10^9 gal to z~1.5SPEC-z 2015

CLUSTER SURVEYSUSING THESZ EFFECT

THERMAL SUNYAEV-ZELDOVICH EFFECT

DT INDEPENDENT OF z :

QUANTIFYING THE THERMAL SZ EFFECT

x = f/56.4GHz

TARGETED OBSERVATIONS

RYLE TELESCOPE VERY SMALL ARRAY(Lancaster et al 2004)

1ST GENERATION INSTRUMENTS ~ 50deg

8x3.5m ANTENNAEOWENS VALLEY, CAn=30GHz & 90GHzLINK WITH CARMA

10x3.7m ANTENNAECAMBRIDGE n=15GHzTsys=25K, Dn=6GHzRYLE TELESCOPE

AMI SZA

2

- INTERFEROMETERS

2ND GENERATION INSTRUMENTS-LARGE AREA OR VERY DEEP SURVEYS

GROUND BASED : SPT, ACT, APEX-SZ

SPACE MISSIONS : PLANCK

MULTI-ELEMENT FOCAL PLANE ARRAYS HIGH RESOLUTION ~1', 100-5000 deg BOLOMETERS ~150GHz TOTAL POWER -NEED A DRY SITE ~1000-10000 CLUSTERS

MULTI-FREQUENCY 30GHz-850GHz LOW RESOLUTION ~5'-10' POWERFUL REJECTION OF SYSTEMATICS ALL-SKY ~5000-10000 NEARBY CLUSTERS

2

INPUT PHYSICS : SIMPLE MODEL

e

e

e

ee

e

e

ee

e

SPHERICAL AND VIRIALIZED

ISOTHERMAL

DISTRIBUTION IN M & z

GAS PROFILE

SPHERICAL COLLAPSE

NUMERICAL SIMULATIONS

CORE RADIUS

VIRIALRADIUS

COMPUTING THE SELECTION FUNCTION

MAXIMAL

8'

4'

2'

1'

16'

COSMOLOGICAL DEPENDENCE

DIFFERENCEBETWEEN

L AND w=-0.8+0.3zFOR 1 sq. deg

AT LEAST 750 sq degNEEDED

SPT

PLANCK

SIMULATED DATA

AMI/SZA

SIMULATED CONSTRAINTS

CENTRAL CONTOUR CORRESPONDS TO SPT

FIDUCIAL MODEL: w=-0.8+0.3z

COMPLEMENTARITY TO SNe Ia

SNe

SZ

+16%

-12%

MASS-TEMPERATURE RELATION

CONCLUSIONS DARK ENERGY APPEARS TO EXIST

GOOD MICROSCOPIC MODELS SCARCE

PHENOMOLOGICAL DESCRIPTION REQUIRED

IN PRINCIPLE MANY WAYS TO TEST IT

MANY SYSTEMATIC ISSUES TO BE ADDRESSED

VARIATION IN w DIFFICULT

DARK ENERGY EXPERIMENTS COST ~ 10 MILLION £/$/EUROS