Status of Cosmology

Talk presented at the Topics in Astroparticle and Underground Physics (TAUP 2001) Conference

Wendy L. FreedmanCarnegie Observatories

Cosmological Parameters

H0

= m + + k

m

t0 Age = f(H0,m,)

EBL

STATUS OF COSMOLOGY

Assumptions

• Homogeneity and isotropy

• General relativity

• Hot big bang

Hubble (1929)

Local Group: ~ 1 Mpc Supernovae: ~400 Mpc Virgo cluster: ~15 Mpc Hubble radius:~3000h-1 Mpc

1 pc = 3.26 light years

Hubble H0 Key Project (2001)

Freedman et al. (2001), Ap.J.

1st tick mark

Hubble (1929)

Homogeneity and Isotropy

LocalLas Campanas Redshift SurveyCfA Redshift

Survey

Homogeneity and Isotropy

Anglo Australian Redshift Survey March, 2001

COBE map

Power Spectrum

m h1.00 0.250.35 0.70

~ mh ~ 0.25 0.05

Guzzo(2001)

Lineweaver, 1998

CMB Anisotropies

• Robust measure of 0 • Large degeneracies Hu, Sugiyama & Silk (1995), Lineweaver (2001)

H0=70

CMB Anisotropies: Netterfield et al. (2001)

mCurrent evidence:

Galaxy kinematics Cluster baryons

• fb ~ 10-20%• b h2 = 0.02• m ~ 0.3-0.4

X-ray gas Lensing

m ~ 0.3

Limits: e.g. Carroll, Press & Turner 1992

• Negative : For m <1, t0 > 10 Gyr, H0>40

> -7, • Positive :

For m <1, H0 < 100, high-z objects

< 2, • RECALL: (Planck scale)

> -2 x 10-29 g/cm-3

< 4 x 10-29 g/cm-3

vac ~ 1092 g/cm-3

•“only” ~1060 discrepancy (electroweak)

Type Ia supernovae + CMB constraintsm = 0.3, =0.7

•Riess et al. 1998 Perlmutter et al. 1998

Carroll Lambda plot

Carroll (2001)

i

Evolution of density parameters in the universe

Current values:m = 0.3, =0.7, r = 5 x 10-5

•Current epoch special•Very brief interval where m and comparable.

Timing Coincidence

• Infrared observations of supernovae:• Advantages: - dust Hamuy, Krisciunas, Phillips, Freedman, et al.

- chemical composition

•UBVRIJHK observations• H0

•

Hamuy et al. (2001)

Direct Measure of the Expansion Rate

Loeb (1998) : Lyman alpha clouds

•~2 m/s/CENTURY!• not yet feasible

Freedman (2001)

Evolution of the Fine Structure Constant

• Webb et al.

astro-ph/

0012539

t0 : The Age of the Universe

• white dwarf cooling

• nucleocosmochronology

• globular cluster evolution

t0

• First measurement of stellar uraniumU/Th

Cayrel (2001)

t0 = 12.6 3 Gyr

Biggest uncertainty:production ratios

t0

• Globular clusters

Chaboyer (2001)

t0=13.5 2 Gyr

Biggest uncertainty: DISTANCE SCALE

H0

• Distance Scale

• Gravitational lens time delays

• Sunyaev-Zel’dovich effect

H0 Key Project• Discovery of Cepheids using HST

• Intercompare several distance methods

• Tests for systematic errors

• Goal: H0 to 10%

Freedman et al. 1994

Progress in Distance Scale

M33 M31

, HST

= 5 log d (pc) - 5

VRIB

M100

M100 – HST

WFPC2 image

Virgo cluster galaxy

SN 1994DCepheids

Supernovae,

Tully-Fisher,

etc.

Key Project Results

Freedman et al. (2001), ApJ astro-ph/0012376

Key Project Results (2)

Freedman et al. (2001)

H0 = 72 3 (stat.) 7 (sys.) km/sec/Mpc

Largest uncertainties:Local distance scale, HST calibration

Expansion Ages

H0 =70 m

t0 (Gyr)

Open 0.2 0 12 1

Open 0.3 0

11 1

Flat 0.2 0.8 15 1.5

Flat 0.3 0.7 13.5 1.5

Flat 1.0 0 9 1

o

Gravitational LensingDdDds 2

2 Dsct = (1+zd)

Refsdal 1964, 1966

• ~6 time delays measured• H0 ~ 60 – 70 km/sec/Mpc• systematics ~20-30% level• dark matter distribution unknown => model dependence/degeneracy with H0

Sunyaev-Zel’dovich Effect

• 33 clusters

• H0 = 63 3 (statistical)

30% (systematic) • Carlstrom et al. (2001)

Birkinshaw (1999)

Extragalactic Background Light

• Olber’s paradox• Star formation history of universe• Baryonic mass processed in stars• Metal production in the universe

IEBL

(m)

NOTE: optical + IR background light = ~10% of that in CMB ~100 nW/m2/sr

Star Formation History of Universe

Steidel et al. (1998)

Galaxy Number CountsStar Formation Rate

• Slope of luminosity

function < 0.4 (converges)• (1+z)4 surface brightness

dimming severe problem

Redshifting M51 and M101

Kuchinski, Freedman, Madore & Trewhella (2001)

•At progressively

higher z, start

to lose even the

brightest galaxies

•Distant surveys

very incomplete1500 A

z~1 z~2

z~3 z~4

Difficulty of Measuring the EBL

• The optical EBL is faint!• Terrestrial airglow and zodiacal light dominate.

HST

Bernstein, Freedman & Madore (2001)

Total EBL • Total EBL

0.1 to 1000 m:

Bernstein, Freedman & Madore (2001)

U V I

HST IRASCOBE:DIRBEFIRAS

EBL (0.1 to 1000 m)

100 35 nWm-2sr-1

•~30% of light from stellar nucleosynthesis reradiated by dust

EBL Results

• The integrated background light is ~2x greater than

accounted for by galaxies detected individually.

• The spectral distribution of the background light is

similar to that of ordinary galaxies.

• No new exotic population of objects is required

(~60% undetected galaxies, ~30% missing light

from detected galaxies).

• The mass associated with starlight contributes ~1%

of the critical density.

• The metal production and star formation rate in the

universe has been underestimated by a factor of ~2.

Summary of Cosmological Parameters

H072 8 km/sec/Mpc (rms)

0 1.03 0.06

m 0.3 0.1

0.7 0.3

t0 13 2 Gyr

h0t0 0.96 0.13

EBL/ crit 0.011 0.004