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Dark Energy and Supernovae
Wendy FreedmanCarnegie Observatories, Pasadena
CABeyond Einstein, SLAC, May 13, 2004
Understanding Dark Energy
Talks at this meeting
Type Ia Supernovae for Cosmology
Riess et al. 1998Perlmutter et al. 1999
First evidence for acceleration
Type Ia Supernovae for Cosmology
Advantages:• small dispersion • single objects (simpler than galaxies) • can be observed over wide z range
Challenges:• dust (grey dust)• chemical composition• evolution• photometric calibration (e.g., Vega)• environmental differences• lensing Systematics
Step 2
Type Ia supernovae as distance indicators
Luminosity Distances
Characterizing the Equation of State
Finding Supernova Candidates
High z Supernova Team
Supernova Spectra
Perlmutter et al. 1998
Type Ia SN diagnostics (restframe):• Si II – 4130 A• Ca II – 3950 A• Fe blends
Spectra of Supernovae
Even without spectra, colors turn out to be an extremely effective means of distinguishing Type Ia and II supernovae.
Riess et al. 2004
Type IIType I
State of the Art
Knop et al. 2003
State of the Art
Knop et al. 2003
State of the Art
Riess et al. 2004
• HST ACS data
177 supernovae; 7 new objects 1.25 < z < 1.8Evidence for deceleration at earlier matter-dominated epoch.
GOODS/ACS Supernova Candidates
Riess et al. 2004
GOODS / ACS Light Curves & Spectra
Riess et al. 2004
Constraints on Equation of State
Riess et al. 2004;Knop et al. 2003
Assuming: m = 0.27 § 0.04Corrections for reddening, metallicity,evolution well-understood
w0 = -1.05 § 0.2 § 0.1
Equation of State and Dark Matter Density : Combined Constraints
Tegmark et al (2004)
Assume flat universe
Consistency with cosmological constant
w = -1
Does the Dark Energy Density Vary with Time?
Wang & Tegmark (2004)
Recall Assumptions:
• flatness• m = 0.3 § 0.04
2004 Standard Cosmological Model
m = 0.3 = 0.70 = 1h = 0.7w = -1dw/dz = 0
A universe with a flat geometry composed of one third matter density, and two thirds dark energy.
Minimizing Systematics in era of precision cosmology
Grey Dust?
There is noevidence todate for gray dust.
The data areconsistentwith the presence of dark energy.Riess et al. 2004
Galactic Extinction Law
Cardelli, Clayton and Mathis 1989
AB / E(B-V) = 4.1
AI / E(B-V) = 1.7
B
I
V
R V = AV / E(B-V)
AU / E(B-V) = 4.9U
E(B-V) Distributions for SN1a
Knop et al. 2003
Supernova Ia Metallicities
Lentz et al. 1999 models
IRUV
optical•Lower fluxes for higher metallicity•Variation in level of UV continuum
.03 x solar
10x solar
Goals
• measurement of w to 5%• measurement of w’ to 12%
SNAP:
• Joint constraints with weak lensing• (better for SUGRA)
• CFHT Legacy Survey • ESSENCE• Carnegie Supernova Project (CSP)•Supernova Cosmology Project (SCP)•GOODS
Present/Future Supernova Projects
• LOTOSS (KAIT)• SN Factory• CSP
High z: Low z:
Future Supernova Projects:
• LSST, Panstarrs• Giant Magellan• SNAP• DESTINY
Ground-based supernova searches over next 5 years - 100s of supernovae - decreasing systematics
• ugriz light curves• observations to I’ ~ 28 mag• CFHT MegaCam• 2000 SN over 5 years• 0.1 < z < 1
CFHT Legacy Survey (SNLS)
ESSENCE
•VRI light curves• CTIO 4m Mosaic Imager• 200 SN over 5 years• share nights with Supermacho project• observe each field every 4 nights• 0.1 < z < 0.8
NOAO Science Archive:http://archive.noao.edu/nsa/
High z Supernova Team
• Automated supernova search•UBVRI light curves• Lick Observatory• 0 < z < ~0.15
LOTOSS / KAIT
Supernova Factory
Wood – Vasey et al 2004
• spectrophotometry• Univ. Hawaii• 0.32 – 1 m• NEAT, Palomar (search)• ~150 SNae per year• 3 years
2002: 35 candidates
Same search techniques as distant searches
Followup supernova projects
The Carnegie Supernova Project (CSP)
A restframe I-band Hubble diagram
Carnegie Supernova Project (CSP)
• Advantages:
- dust
- chemical composition - low dispersion
=> reduce systematics
Why an I-band Hubble diagram?
[Why hasn’t this been done? HARD! IR detectors on large telescopes]
Wavelength-Redshift Coverage
CSP
HST
CSP
CSP: • 0<z<0.2 comparison UBVRIJHK
• 0.3<z<0.8 VRI restframe
HST:• 0.5<z<1.5• UBV(R) restframe
EssenceCFHTLS
Overview of Carnegie Supernova
Project
Swope 1-meter Magellan 6.5-meterDupont 2.5-meter
Low z: High z:
•u’BVr’I’YJH photometry• Dupont spectroscopy
• r’i’YJ photometry • Magellan spectroscopy
• ~200 nights over 5 years• ~200 SNIa• 0.2 < z < 0.8
• C40 9 month campaigns over 5 years• densely sampled photometry and spectroscopy 0 < z < 0.2• SNIa and SNII
Goals:• minimize systematics• accurate reddenings, K-corrections• H0 (H-band observations
for Cepheids + SNIa)• dark energy• peculiar flows• physics of SNI and II
Carnegie Supernova
ProjectMagellan
Jha 2002
PANIC
• ~30 observed to date• UBVRIJHK light curves• excellent sampling
Carnegie Supernova Project
Krisciunas et al. (2002)
SN2001el
Recent results on Nearby supernovae:
• decline rate versus magnitude• BVIH• H-band promising as distance indicator
Carnegie Supernova Project
Krisciunas et al.
• decline rate versus magnitude JHK
Carnegie Supernova Project
Krisciunas et al. (2004)
Carnegie Supernova Project
Krisciunas et al.
JHK Hubble diagrams
Redshift in CMB frame (km/sec)
E
xtin
ctio
n-c
orr
ecte
d a
pp
aren
t
mag
nit
ud
e at
max
imu
m
Future supernova projects- 1000s of supernovae- similar precision at
high redshifts to upcoming low redshift surveys - decreased systematics
•Highly ranked in Decadal Survey•Optimized for time domain•7 square degree field•6.5m effective aperture•24th mag in 20 sec•15 TBytes/night (current ESSENCE 20 GBytes/night)•Real-time analysis
Large Synoptic Survey Telescope (LSST)
Panstarrs
Future Plans (Carnegie High z)
Magellan
The Giant Magellan Telescope (GMT)
• Roger Angel mirrors• Seven 8.4-meter mirrors; f/0.7• 21.5-meter aperture, 25.3-meter baseline• A consortium of partners currently including Carnegie, Harvard/Smithsonian, University of Arizona, MIT, and the University of Michigan *• Funds are in place for the 18-month conceptual design phase
Highest Priority Capabilities:1. Narrow field, high dynamic range AO 2. Wide field, optical spectroscopy
Dark Matter (lensing) and dark energy studies.
Supernovae 1<z<2
HST Treasury (Large) Proposals (Cycle 13)
• Riess et al. : Double high z sample
• Filippenko et al. : UV nearby survey
Future Surveys (Space): JDEM
SNAP
SNAP focal plane
DESTINY: Dark EnergySpace Telescope
SNAP Target Precision
Current Status of Cosmological Parameter Measurements
• WMAP (+ one ofH0 , LSS, SNae) is consistent with a FLAT universe
• Consistent model with h = 0.72 m = 0.27 = 0.73 w = -1Wright, 2004