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

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d a

pp

aren

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mag

nit

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max

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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