# Presentation: 313811

## The Supernova Legacy Survey

***Mark Sullivan ***
*University of Toronto*
*http://legacy.astro.utoronto.ca/*
*http://cfht.hawaii.edu/SNLS/*

## The SNLS collaboration

- Paris Group
- Reynald Pain, Pierre Astier, Julien Guy, Nicolas Regnault, Christophe Balland, Delphine Hardin, Jim Rich, + ...

- UK
- Gemini PI: Isobel Hook, Richard McMahon, + ...

- USA
- LBL: Saul Perlmutter, + ...
- CIT: Don Neill

***Full list of collaborators at: http://cfht.hawaii.edu/SNLS/****** ***

- Victoria Group
- Chris Pritchet, Dave Balam, + ...

- Toronto Group
- Ray Carlberg, Alex Conley, Andy Howell, Kathy Perrett, Mark Sullivan

**The SNLS collaboration**

- Marseille Group
- Stephane Basa, Dominique Fouchez, + ...

## Supernova Legacy Survey (2003-2008)

**Megaprime**

- 5 year survey, goal: 500 distant SNe Ia to measure “w”
- Uses CFHT/“Megacam”
- 36 CCDs, good blue response
- 4 filters for good k-corrections and color measurement

## CFHT-LS Organisation

| CFHT-LS (imaging) – 2003-2008 |  |
| --- | --- |
| DEEP | WIDE |
| Galaxy studies
Time sequenced dataset (202n over 5 years) | Cosmic shear
Clusters |

- SNLS** **collaboration
- Data-processing
- Major Spectroscopic Program
- Gemini (Canada/UK/USA)
- 120 hrs/yr (60:40:20)
- VLT (France/Other Euros)
- 120 hrs/yr
- Keck (through LBL)
- 40 hrs/yr
- Cosmological analyses

- Magellan near-IR study (Freedman et al.)
- Rest-frame I-band Hubble diagram

- Keck SN Ia UV study (Ellis/Sullivan et al.)
- LRIS high-S/N - metallicity through UV lines
- Testing accuracy of k-corrections in the UV

- SN IIP study (Nugent/Sullivan/Ellis et al.)
- Using SNe IIP as standard candles
- Independent Hubble diagram to z=0.5

## SNLS: Current status

- Survey running for nearly 4 years
- ~310 confirmed distant SNe Ia (+ 50-60 not yet processed)
- ~ Largest single telescope sample of SNe
- “On track” for 500 **spectroscopically confirmed** SNe Ia by survey end (>1000/>2000 total SNIa/All SN light-curves)

## Calibration

- Calibrate to Landolt system because of low-z sample
- Calibrations to SDSS and Smith et al. also exist
- Understanding of Landolt/CFHT filters
- Uniformity correction work underway
- SNLS:
- Observes the same field for 5 years, excellent tertiary standards
- Observes dense star fields for “super-flat” corrections
- Observes SDSS calibration fields
- Observes secondary calibrators

## Uniformity variations (pre-Elixir)

- 9x4 CCDs
- 8% edge to corner

- Regnault et al.

## Uniformity variations (post-Elixir)

- Less obvious radial pattern, but residuals at 2% level remain

- Regnault et al.

## Filter shifts versus mosaic position

- Regnault et al.

## SNLS 1st year

- SNLS 1st year

- ΩM = 0.263 ± 0.042 (stat) ± 0.032 (sys)
- <w>=-1.02 ± 0.09 (stat) ± 0.054 (sys)

- Astier et al. 2006

## “Third year” SNLS Hubble Diagram (preliminary)

- “Third year” SNLS Hubble Diagram (**preliminary**)

- 3/5 years of SNLS
- ~240 distant SNe Ia
- rms ~ 0.17mag

- Independent analysis to 1st year:
- Different calibration route
- Different photometric methods
- Different SN light-curve analysis tools

- Preliminary

## “Third year” SNLS Hubble Diagram (preliminary)

- “Third year” SNLS Hubble Diagram (**preliminary**)

- ΩM=0.3, Ωλ=0

- ΩM=1.0, Ωλ=0

- Best-fit for SNLS+flatness

- Preliminary

- (error was 0.042 in A06)

## Cosmological Constraints (Preliminary)

- Cosmological Constraints (**Preliminary**)

- SNLS+BAO (No flatness)

- SNLS + BAO + simple WMAP + Flat

- BAO

- BAO

- SNe

- SNe

- WMAP-3

- 6-7% measure of <w>

- Future Prospects with SNLS – v1

- End of Survey?
- Replace with CFH12k I filter?
- Replace with new i’ filter?
- Replace with borrowed i’ filter?
- Redesign survey strategy?`

## Future Prospects with SNLS – v2

- Current constraints on <w>: <w>=-1 to ~6-7% (stat)
- <w> >-0.8 excluded at 3-sigma level
- At survey end a 4-5% statistical measure will be achieved:
- 500 SNLS + **200(?) SDSS** + new local samples
- Improved external constraints (BAO, WMAP, WL)
- Systematic errors becoming ever more important

## Summary

- SNLS is a well-controlled, calibrated and understood experiment
- Current SN Ia measurement determine <w> to ~ 6-7%
- In 2-3 years, 4-5% will be achieved