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Status of the Supernova Legacy Survey (SNLS) Isobel Hook University of Oxford

Status of the Supernova Legacy Survey (SNLS) Isobel Hook University of Oxford. SNe Ia provide direct evidence for accelerating Universe Results inconsistent with W M =1 spatially flat cosmology (SNe too faint) SN data favor L >0. with 16 ACS-discovered SNe z<1.5 (Riess et al 2004).

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Status of the Supernova Legacy Survey (SNLS) Isobel Hook University of Oxford

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  1. Status of the Supernova Legacy Survey (SNLS) Isobel Hook University of Oxford

  2. SNe Ia provide direct evidence for accelerating Universe Results inconsistent with WM=1 spatially flat cosmology (SNe too faint) SN data favor L>0

  3. with 16 ACS-discovered SNe z<1.5(Riess et al 2004) Riess et al (1998) If universe is flat then data require L > 0

  4. High-z Team Riess et al 1998: WM=0.28 +/-0.1 Tonry et al 2003 WM=0.28 +/- 0.05 Riess et al 2004 WM=0.29 + 0.05–0.03 SCP Perlmutter et al 1999: WM=0.28 +0.09 -0.08 + 0.05-0.04 Knop et al 2004 : WM= 0.25 +0.07-0.06 +/-0.04 SN constraints on WM (W=1) The rest made up by “dark energy”

  5. Cosmological constant fits the data but… Fine tuning problem? Other possibilities include quintessence Differentiate via the equation of state<w=p/r> Distinguishing w=-0.8 and w=-1 at 3σ requires ≈700 SNeIa with 0.15<z<0.9 – which SNLS will provide The nature of the dark energy

  6. Knop et al 2003 Current Constraints on w • Assumptions: • Flat Universe • w constant in time • 2dF:  M h = 0.2 ± 0.03 • KP: h = 0.72 ± 0.08 Riess et al 2004 w = –1.02 +0.13 – 0.19

  7. Chris Pritchet: U. Victoria Ray Carlberg: U. Toronto Andy Howell: U. Toronto Mark Sullivan: U. Toronto Arif Babul: U. Victoria David Balam: U. Victoria Sara Ellison: U. Victoria F.D.A. Hartwick: U. Victoria Henk Hoekstra: CITA Don Neill: U. Toronto Julio Navarro: U. Victoria Kathy Perrett: U. Toronto David Schade: HIA Pierre Astier : CNRS-IN2P3, Paris Eric Aubourg Christophe Balland Luc Simard: HIA Peter Stetson: HIA Sidney van den Bergh: HIA Jon Willis: U. Victoria Isobel Hook: U. Oxford Justin Bronder: U. Oxford Richard McMahon: U. Cambridge Reynald Pain: CNRS-IN2P3, Paris Saul Perlmutter:LBNL Robert Knop: U. Vanderbilt James Rich: CEA-Saclay Nic Walton: U. Cambridge Eric Smith: Vanderbilt University Greg Aldering: LBNL Lifan Wang: LBNL Rachel Gibbons: LBNL Vitaly Fadayev: LBNL SNLS collaboration http://cfht.hawaii.edu/SNLS/ Stephane Basa Sylvain Baumont Sebastien Fabbro Melanie Filliol Ariel Goobar: Stockholm Delphine Guide Julien Guy Delphine Hardin Nicolas Regnault Tony Spadafora: LBNL Max Scherzer: LBNL Harish Agarwal: LBNL Herve Lafoux Vincent Lebrun Martine Mouchet Ana Mourao Nathalie Palanques Gregory Sainton Canada, France, UK, US, Sweden, Portugal

  8. SNLS Goals • Primary goal: Use SNe Ia to determine “w” • SNLS Goal: 1000 SNe Ia (across all redshifts) • Calibration goal: 1-2% photometric accuracy • SNLS advantages: • Rolling search • Queue observing • Multi-colour lightcurves • Spectroscopic follow up • SNLS provides many consistency checks • SN colour evolution – multi-colour photometry check • Detailed studies of spectral evolution (Gemini/VLT/Keck spectra) [Bronder et al.]

  9. CFHT imaging • 36 CCD imager MegaCam • 1 deg x 1 deg • CFHT-LS (DEEP) • 4 Fields • 202 queue nights over 5 yrs • Started August 03 • 5 epochs per field/month • (u),g’r’i’z’ • Top priority : 1 hr in i’ • every 2-3 nights • i~24.9 AB with S/N=10

  10. SNLS Rolling Search Real-time lightcurves

  11. Gemini N and S 2003B to 2005B: 60 hrs /semester PI: I. Hook VLT 240 hrs periods 71-74 Continuation requested P75-78 PI: R. Pain SNLS spectroscopy • Goal : measure redshifts and Types for SNLS candidates • Fainter targets with Gemini, others at VLT • Supplemented with spectra from Keck & Magellan

  12. SN i=24.0 Example Gemini/GMOS Nod & Shuffle spectrum 2 hr exposure Wavelength

  13. Host Galaxy spectrum

  14. SiII Extracted spectrum • Smoothed spectrum allowing for: • template host galaxy subtraction • Reddening Best match template SN

  15. Spectroscopic Summary to date To Jun 2005: 191 SNIa/Ia? < z > = 0.60 All close to maximum light (within ~10 days) 1st yr Gemini spectra: Howell et al (2005) VLT spectra: Basa et al (2005)

  16. First Year Results – Hubble Diagram (Astier et al. in prep) First year results (72 SNeIa) consistent with an accelerating Universe: ΩΛ~0.7 in a flat universe

  17. Comparison with previous SN results • Comparison of SNLS first year (72 SNe) to previous SN results – Knop et al 2003 (~50 SNe) • Shaded area shows projected end-of-survey constraints • Superior colour and time sampling of SNLS allows tighter constraints on the cosmological parameters than any previous SN sample.

  18. SNLS Preliminary constraints on w(Astier et al in prep.)

  19. Preliminary results and predictions for end of survey • w constraints with no prior on WM • Assumes flat universe • With prior on WM (e.g. from CFHT-LS weak lensing) should measure w to +/- 0.07 (stat)

  20. Conclusions • Measurements of m and zof Type Ia SNe provide direct measurement of the acceleration of the Universe • Can measure M,w during the epoch of dark energy • Independent and complementary technique to CMB and galaxy redshift surveys • SNLS will constrain w to ~ +/-0.07, & hence the nature of the dark energy • SNLS will be the definitive high-z SN data set for ~10 years

  21. More Information • See these websites for all details: Project overview, collaboration members, publications: • http://cfht.hawaii.edu/SNLS/ Candidate database, real-time candidate lists: • http://legacy.astro.utoronto.ca/ • Watch out for the first SNLS cosmology publication soon!

  22. The End

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