The Accelerating Universe

Probing Dark Energy with Supernovae

Eric Linder

Berkeley Lab

Evidence for AccelerationEvidence for AccelerationSupernovae Ia:

DE , w=p/ , w´=dw/dz

Observation -- Magnitude-redshift relation

Age of universe:

Contours of t0 parallel CMB acoustic peak angle: t0=14.0±0.5 Gyr

[Flat universe, adiabatic perturbations]

CMB Acoustic Peaks:

Substantial dark energy, e.g. 0.49 < < 0.74

[Small GW contribution, LSS, H0]

Large Scale Structure:

Power spectrum Pk, Growth rate, “looks”

[simulations]

Supernova CosmologySupernova Cosmology

A Dark Energy UniverseA Dark Energy Universe

Tyson

Correlation of Age with CMB Peak Angle

Knox et al.DASI data only

CMB Power Spectrum and

Tegmark

CMB Power CMB Power SpectrumSpectrum

Matter Power SpectrumMatter Power Spectrum

CMB + 2dF (no SN)

Efstathiou et al.

MAP Sky CoverageMAP Sky Coverage Wright

Nov ‘01 Jan ‘02

Apr ‘02 Oct ‘02 Wright

• Supernova data shows an acceleration of the expansion, implying that the universe is dominated by a new Dark Energy!

• Remarkable agreement between Supernovae & recent CMB results.

Dark EnergyDark Energy

Credit STScI

Dark Energy TheoryDark Energy Theory

1970s – Why M ~ k?

1980s – Inflation! Not curvature.

1990s – Why M ~ ?

2000s – Quintessence! Not ?

Cosmological constant is an ugly duckling

Dynamic scalar field is a beautiful swan

Lensing =0.7+0.1-0.2 Chiba & Yoshii

Supernovae =0.72+0.08-0.09 SCP, HiZ

Ly Forest =0.66+0.09-0.13 D. Weinberg et al.

: Ugly Duckling: Ugly Duckling

Astrophysicist:

Einstein equations –

gab

p = -

Naturally, =const= PL

= 10120

Today M

Field Theorist:

Vacuum – Lorentz invariant

Tab ~ab = diag { -1, 1, 1, 1}

p = -

Naturally, Evac ~ 1019 GeV

E ~ meV

=0?

• Fine Tuning Puzzle – why so small?

• Coincidence Puzzle – why now?

Scalar Field: Beautiful SwanScalar Field: Beautiful Swan

Astrophysicist:

Friedmann equations –

(å/a)2=(8/3)(m+)

ä/a=-(4/3)(m++3p)

Field Theorist:

Lagrangian –

L=(1/2)a a-V()(1/2)2-V

Tab= ab - L gab

=K+V p=K-V w=p/ = (K+V) / (K-V) [-1, +1]

Slow Roll (Inflation)

K << V p=- w=-1

Free Field (kination)

V << K p=+ w=+1

Coherent Oscillations (Axions)

<V>=<K> p=0 w=0 (matter)

.

Fundamental PhysicsFundamental Physics

(a) = (0) e-3dlna(1+w) ~ a-3(1+w) w(z)=w0+w’z

Astrophysics Cosmology Field Theory

r(z) Equation of state w(z) V()

V ( ( a(t) ) )

SN

CMB

etc.

“Would be number one on my list of things to figure out”

- Edward Witten

“Right now, not only for cosmology but for elementary particle theory this is the bone in our throat”

- Steven Weinberg

Is =0 ? What is the dark energy?

Type Ia SupernovaeType Ia Supernovae

• Characterized by no Hydrogen, but with Silicon

• Progenitor C/O White Dwarf accreting from companion• Just before Chandrasekhar mass, thermonuclear runaway

Standard explosion from nuclear physics

1 Parameter Family Homogeneity1 Parameter Family Homogeneity

Hubble diagram – low zHubble diagram – low z

Hubble diagram - SCPHubble diagram - SCP

0.2 0.5 1

In flat universe: M=0.28 [.085 stat][.05 syst]

Prob. of fit to =0 universe: 1%

redshift z

0.2 0.4 0.6 0.8 1.0

Supernova CosmologySupernova Cosmology

Original Current (offset) Near Term Proposed

Supernovae Probes - GenerationsSupernovae Probes - Generations

SNAP: The Third GenerationSNAP: The Third Generation

Dark Energy Equation of StateDark Energy Equation of State

Hubble DiagramHubble Diagram

Dark Energy Exploration with SNAPDark Energy Exploration with SNAP

Current ground based compared with

Binned simulated data and a sample of

Dark energy models

Probing Dark Energy ModelsProbing Dark Energy Models

From Science GoalsFrom Science Goalsto Project Designto Project Design

Science• Measure M and

• Measure w and w (z)

Data Set Requirements• Discoveries 3.8 mag before max

• Spectroscopy with S/N=10 at 15 Å bins

• Near-IR spectroscopy to 1.7 m

Statistical Requirements• Sufficient (~2000) numbers of SNe Ia

• …distributed in redshift

• …out to z < 1.7

Systematics RequirementsIdentified and proposed systematics:

• Measurements to eliminate / bound each one to +/–0.02 mag

Satellite / Instrumentation Requirements• ~2-meter mirror Derived requirements:

• 1-square degree imager • High Earth orbit

• Spectrograph • ~50 Mb/sec bandwidth (0.35 m to 1.7 m) •••

•••

Mission DesignMission Design

SNAP Survey FieldsSNAP Survey Fields

GigaCAM, a one billion pixel array Approximately 1 billion pixels ~140 Large format CCD detectors required, ~30 HgCdTe Detectors Larger than SDSS camera, smaller than H.E.P. Vertex Detector (1 m2) Approx. 5 times size of FAME (MiDEX)

GigaCAMGigaCAM

Focal Plane Layout with Fixed FiltersFocal Plane Layout with Fixed Filters

Q1

Q2

Q3

Q4

Step and Stare and RotationStep and Stare and Rotation

High-Resistivity CCD’sHigh-Resistivity CCD’s• New kind of CCD developed at LBNL • Better overall response than more costly “thinned” devices in use• High-purity silicon has better radiation tolerance for space applications• The CCD’s can be abutted on all four sides enabling very large mosaic arrays• Measured Quantum Efficiency at Lick Observatory (R. Stover):

LBNL CCD’s at NOAOLBNL CCD’s at NOAO

See September 2001 newsletter at http://www.noao.edu

1) Near-earth asteroids2) Seyfert galaxy black holes3) LBNL Supernova cosmology

Cover picture taken at WIYN 3.5m with LBNL 2048 x 2048 CCD(Dumbbell Nebula, NGC 6853)

Science studies to date at NOAO usingLBNL CCD’s:

Blue is H-alphaGreen is SIII 9532ÅRed is HeII 10124Å.

Science Goals – F21Science Goals – F21

Slit Plane

DetectorCamera

Prism

Collimator

Integral Field Unit Spectrograph DesignIntegral Field Unit Spectrograph Design

F o re -o p tic s(a n a m o rp h o s is )

T e le s c o p e e x it p u p il

S L IC E R M IR R O R

P U P IL M IR R O R S

S L IT M IR R O R S

Im a g e d th e re

In th e te le s c o p efo c a l p la n e

T e le s c o p e fo c a l p la n e im a g e d b y th efo re -o p tic s o n th e s l ic e r m ir ro r

S lic e s im a g e d b y th e p u p ilm ir ro rs o n th e s l i t m ir ro rs

E n tra n c e o f th es p e c tro g ra p h

S q u a re f ie ld

1 x 2 p ro p o r tio n e dim a g e

SNAP Design:

Images

Spectra

Redshift & SN Properties

Lightcurve & Peak Brightness

data analysis physics

M and

Dark Energy Properties

At every moment in the explosion event, each individual supernova is “sending” us a rich stream of information about its internal physical state.

What makes the SN measurement special?What makes the SN measurement special?Control of systematic uncertaintiesControl of systematic uncertainties

Time Series of Spectra = SN “CAT Scan”

Lightcurves and Spectra from SNAPLightcurves and Spectra from SNAP

• Goddard/Integrated Mission Design Center study in June 2001: no mission tallpoles

• Goddard/Instrument Synthesis and Analysis Lab. study in Nov. 2001: no technology tallpoles

Supernova RequirementsSupernova Requirements

Advantages of SpaceAdvantages of Space

Science ReachScience Reach

Key Cosmological Studies• Type II supernova • Weak lensing• Strong lensing • Galaxy clustering• Structure evolution• Star formation/reionization

-

-

SNAP: The Third GenerationSNAP: The Third Generation

Dark Energy Equation of StateDark Energy Equation of State

Precision CosmologyPrecision Cosmology

Tegmark

NOWSNAP

Primary Science Mission Includes…Primary Science Mission Includes…

Weak lensing galaxy shear

observed from space vs. ground

Bacon, Ellis, Refregier 2000

……And BeyondAnd Beyond

10 band ultradeep imaging survey

Feed NGST, CELT (as Palomar 48” to 200”, SDSS to 8-10m)

Quasars to z=10

GRB afterglows to z=15

Galaxy populations and morphology to coadd m=32

Galaxy evolution studies, merger rate

Stellar populations, distributions, evolution

Epoch of reionization thru Gunn-Peterson effect

Low surface brightness galaxies in H’ band, luminosity function

Ultraluminous infrared galaxies

Kuiper belt objects

Proper motion, transient, rare objects

SNAP CollaborationSNAP Collaboration

G. Aldering, C. Bebek, W. Carithers, S. Deustua, W. Edwards, J. Frogel, D. Groom, S. Holland, D. Huterer*, D. Kasen, R. Knop, R. Lafever, M. Levi, E. Linder, S. Loken, P. Nugent, S. Perlmutter, K. Robinson (Lawrence Berkeley National Laboratory)

E. Commins, D. Curtis, G. Goldhaber, J. R. Graham, S. Harris, P. Harvey, H. Heetderks, A. Kim, M. Lampton, R. Lin, D. Pankow, C. Pennypacker, A. Spadafora, G. F. Smoot (UC Berkeley)

C. Akerlof, D. Amidei, G. Bernstein, M. Campbell, D. Levin, T. McKay, S. McKee, M. Schubnell, G. Tarle , A. Tomasch (U. Michigan)

P. Astier, J.F. Genat, D. Hardin, J.- M. Levy, R. Pain, K. Schamahneche (IN2P3)

A. Baden, J. Goodman, G. Sullivan (U.Maryland)

R. Ellis, A. Refregier* (CalTech)

A. Fruchter (STScI)

L. Bergstrom, A. Goobar (U. Stockholm)

C. Lidman (ESO)

J. Rich (CEA/DAPNIA)

A. Mourao (Inst. Superior Tecnico,Lisbon)

12 institutions, ~50 researchers

SNAP at the American Astronomical Society SNAP at the American Astronomical Society Jan. 2002 MeetingJan. 2002 Meeting

Oral Session 111. Science with Wide Field Imaging in Space:The Astronomical Potential of Wide-field Imaging from Space S. Beckwith (Space Telescope Science Institute)Galaxy Evolution: HST ACS Surveys and Beyond to SNAP G. Illingworth (UCO/Lick, University of California)Studying Active Galactic Nuclei with SNAP P.S. Osmer (OSU), P.B. Hall (Princeton/Catolica)Distant Galaxies with Wide-Field Imagers K. M. Lanzetta (State University of NY at Stony Brook)Angular Clustering and the Role of Photometric Redshifts A. Conti, A. Connolly (University of Pittsburgh)SNAP and Galactic Structure I. N. Reid (STScI)Star Formation and Starburst Galaxies in the Infrared D. Calzetti (STScI)Wide Field Imagers in Space and the Cluster Forbidden Zone M. E. Donahue (STScI)An Outer Solar System Survey Using SNAP H.F. Levison, J.W. Parker (SwRI), B.G. Marsden (CfA)

Oral Session 116. Cosmology with SNAP:Dark Energy or Worse S. Carroll (University of Chicago)The Primary Science Mission of SNAP S. Perlmutter (Lawrence Berkeley National Laboratory)SNAP: mission design and core survey T. A. McKay (University of Michigan Sensitivities for Future Space- and Ground-based Surveys G. M. Bernstein (Univ. of Michigan)Constraining the Properties of Dark Energy using SNAP D. Huterer (Case Western Reserve University)Type Ia Supernovae as Distance Indicators for Cosmology D. Branch (U. of Oklahoma)Weak Gravitational Lensing with SNAP A. Refregier (IoA, Cambridge), Richard Ellis (Caltech)Strong Gravitational Lensing with SNAP R. D. Blandford, L. V. E. Koopmans, (Caltech)Strong lensing of supernovae D.E. Holz (ITP, UCSB)

Poster Session 64. Overview of The Supernova/Acceleration Probe:Supernova / Acceleration Probe: An Overview M. Levi (LBNL)The SNAP Telescope M. Lampton (UCB)SNAP: An Integral Field Spectrograph for SN Identification R. Malina (LAMarseille,INSU), A. Ealet (CPPM)SNAP: GigaCAM - A Billion Pixel Imager C. Bebek (LBNL)SNAP: Cosmology with Type Ia Supernovae A. Kim (LBNL)SNAP: Science with Wide Deep Fields E. Linder (LBNL)

Resource for the Science CommunityResource for the Science Community

• SNAP main survey will be 4000x larger (and as deep) than the biggest HST deep survey, the ACS survey

• Complementary to NGST: target selection for rare objects

• Can survey 1000 sq. deg. in a year to I=29 or J=28 (AB mag)

• Archive data distributed

• Guest Survey Program

Whole sky can be observed every few months

• Galaxy populations and morphology to coadded m=31 • Quasars to redshift 10• Epoch of reionization through Gunn-Peterson effect• Lensing projects: Mass selected cluster catalogs Evolution of galaxy-mass correlation function Maps of mass in filaments