R. Pain EDEN, Dec 7 2005 1

Reynald PainLPNHE, Univ. Paris, France

Probing Dark Energy with Supernovae

R. Pain EDEN, Dec 7 2005 2

Dark Energy with SNe : an active field

2003

1998

Today 2015?

?

R. Pain EDEN, Dec 7 2005 3

Outline

• Why/how supernovae ?

• Past and more recent SN constraints

• Today’s landscape

• Expected constraints from Future SN programs

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Cosmology with SNe Ia

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SNe Ia are not standard candles

Very Luminous events visible at cosmological

distances

Show little intrinsic dispersion

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SNe Ia Show Light Curve Shape Relationships (similar

to Cepheids P-L relation)

=> Allows us to measure distances to better than 5-8%

precision

Measuring distances

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Models ObservationsUsing radiative transfer

codes, this relationship is reproduced simply by increasing the abundance of 56Ni in the explosion.

Here this is characterized by increasing the effective temperature of the atmosphere.

SNe Ia modelisation

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Past and more recent SN projects

• ~1990->1998 : pioneer work : find distant SNe, measure LC, z => Discovery of the acceleration of the expansion of the Universe

• 1999 -> 2004 : More supernovae, higher redshifts Study of systematics (measure color, host galaxy types HST follow-up observations Search/discoveries with HST => confirmation, first constraints on w

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1998: first (precise enough) results

2 (independent) groups (High-z Team and SCP) present new results based on 42 (SCP) and 10 (HZT) high-redshift SNe and20-40 low-redshift SNe.

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1998 : HZT & SCP first “constraint” on w

w (cste, flat Universe) < -1/3 (99% CL)

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2003 : HST measured color

SCP 2003

+11 SN photometrically followed with HST allows event by event extinction correction

Updated Hubble diagramUsing a low extinction subset

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SCP 2003 (Knop et al.)

+CMB+2dF : w = -1.05+0.15-0.20 (stat) +/- 0.09 (syst)

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2003 results from HZT (Tonry et al.)

Hubble diagram of ~230 published SNe (70 z>0.3)

M,= 0.3, 0.7

0.3, 0.0

1.0, 0.0

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HZT 2003 (Tonry et al.)

-1.48 < w < -0.72 at 95% confidenceAssuming flat universe and M from 2dF

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SNe at higher redshift (Goods/ACS survey)

Probe the deceleration era

Find SN at z>1.2 using HST

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GOODS/ACS 2004: HST Supernovae

Expansion went from deceleration to acceleration

Exclude grey dust

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HST SNe : Riess et al. 2004 (GOODS/ACS)

- w (flat+CMB+LSS) = -1.02 +0.13 - 0.19 (w<-0.76 95%CL) - first “constraints” on w’

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1990-2004: the discovery phase

The « 1st generation » High-z SN projects (SCP, HZT, HHZT) have o(200) SN Ia up to z=1.7 (about 20 above z=1). The projected statistical uncertainties will match estimated level of systematic uncertainties

Need « 2nd generation » experiments with both high statistics o(1000) and better control of possible systematics

Both for high-redshift and low-redshifts SNe

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SNe Ia : Today’s landscape

low-z (z<0.1): Cfa (Harvard, UCB, ...) Carnegie (+IR) SN Factory/SNIFS

z ~ 0.1-0.3 : SDSS/SN

high- z: ESSENCE SNLS ACS/HST : PANS (Riess et al) Clusters (Perlmutter et al)

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SNLS – The SuperNova Legacy Survey

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Imaging observing strategy : “Rolling Search”

Each lunation (~18 nights) :repeated observations

(every 3-4 night) of2 fields in four bands (griz)+ufor as long as the fields stay

visible (~6 months)

for 5 years: expected total nb of SN : ~2000 (detected)

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SNLS :example of 2nd generation high-z survey

SNLS-04D3fk z=0.3578

SNLS-04D3gx z=0.91

As of Nov 15, 2005 : 226 SNe Ia+ Ia?

Expect ~700 by survey end (2008.5)

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SNLS First year Hubble diagram

Final sample : 45 nearby + 71 SNLS SN

In a w=-1 Flat CDM universe:M = 0.263 +/- 0.042 (stat) +/- 0.032 (syst)

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SNLS first year constraint on Dark Energy

solid contours : SNLSdotted contours : Baryon Acoustic Peak (BAO), Eisenstein 2005

(68.3, 95.5 and 99.7% CL)

M = 0.271 +/- 0.021 (stat) +/- 0.007 (syst)

w = -1.023 +/- 0.090 (stat) +/- 0.054 (syst)

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Future SN programs

• SNLS/ESSENCE and planned 4m surveys

• Other future ground based projects

• Space projects

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Future SN programs

By 2008-9 SNLS/ESSENCE + Nearby SNe should reach :w (cte)~0.07 - no (significant) constraints on w’ (wa) will reach a new (theirs) systematic floor 

also very difficulty with upcoming 4m Wide Field projects : DES, DarkCam

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Future ground based SN projects

• Pan Starrs :

Simultaneous observing with

Four 1.8m telescopes of

3 deg2 fov (0.3’’ pixels)

• LSST :

One 8m telescope with

9 deg2 fov

=> 250000 SN/an !

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Precision cosmology with SN Ia

Detect/follow SN Ia from Space e.g. SNAPProposed 1999 Now running/waiting for NASA/DOE JDEM AO (2007+)

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Lightcurves and Spectroscopy from space

- Multicolor high S/N lightcurves up to z~2

- SN spectral identification up to redshifts z~1.7

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SNAP: strategy - precision on w

Area : 2x7.5 sq. deg.

Cadence : 4 days

Total duration : 3 yr

60% imaging - 40% spectro

Total nb of SN : ~ 2000

contraints on w vsM

(statistics + systematics)

+ 300 nearby SNe z>0.1

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SNAP: probing DE models

w´=0.08 w0=0.05

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JDEM/DESTINY

Selected by NASA for « Einstein Probes 2yr Conceptual Studies »

=1.8m telescope 0.25 deg. carrés - NIR 0.9->1.7 all grism R=100 (spectrophotometry) L2 orbitSurvey: 4 h exposure 7.5 sq. deg. 1.5 sq. deg./day (cadence 5 days)

2000 SNe 0.5<z<1.7 in 2 yrs Calibration with ESSENCE/LSST (z<1)

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Dark Universe Explorer (DUNE)

Proposed (2004) as weak lensing probe 1.2 m telescope 0.5 sq. deg. Imager visible only - 1 filter Currently in phase O study at French Space Agency If approved .. launch by 2011-12 ?

A SN program for DUNE 2x60 sq deg. (UBVRIZ, I=26) - cadence: 4days Photométric id of SNe (UBV restframe) Ground based spectroscopy (host galaxies) => 10000 SNe 0.1<z<1 in ~18 months statistical uncertainties on w, w’ o(80%xSNAP) calibration/systematic uncertainties ?

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SNLS vs DUNE vs SNAP

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Summary

• SNe Ia are excellent distance indicators. Significant constraints on w require combining with constraints from other experiments (M)

• « 1st generation » SN experiments have reached their systematic limit

• 2nd generation projects are getting more and higher quality data. Toward building a Hubble diagram with ~1000 SN Ia

Expected precision on (flat Univ., constant) w by 2008-9 : +/- 0.05 (stat) +/-0.05 (syst)

• Percent precision on w and significant precision on w’ (wa) with SN will require experiment in space.

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3 bands: color compatibility (UBV rest frame)

U3 = U(measured) – U(from B + V)

SNe Ia UBV relations seemsreproducible and redshift independent:- Redundancy of distances - small uncertainties in k-corrections

SNLS

nearby

Use (redundant) imaging to id SNe and control systematics ?

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Images

Spectra

Redshift & spectral properties

Light Curves

data analysis physics

M and

w and w’

SNAP concept

Observables :

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SNF (goal:300 SNe)

SNLS (goal:700 SNe)

DUNE (goal:10000 SNe)

SNAP/Destiny (goal:2000 SNe)

SNLS vs DUNE vs SNAP (simulation)