dark energy richard battye jodrell bank observatory school of physics and astronomy university of...
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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