status of cosmology
DESCRIPTION
Status of Cosmology. Talk presented at the Topics in Astroparticle and Underground Physics (TAUP 2001) Conference Wendy L. Freedman Carnegie Observatories. STATUS OF COSMOLOGY. Cosmological Parameters. H 0 W 0 W 0 = W m + W L + W k W m W L - PowerPoint PPT PresentationTRANSCRIPT
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