DARK ENERGY RICHARD BATTYE JODRELL BANK OBSERVATORY SCHOOL OF PHYSICS AND ASTRONOMY UNIVERSITY OF...
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Transcript of DARK ENERGY RICHARD BATTYE JODRELL BANK OBSERVATORY SCHOOL OF PHYSICS AND ASTRONOMY UNIVERSITY OF...
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