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HSC: Supernova Ia Survey for Cosmological Research

Explore the potential of HSC in detecting 1000 bright supernovae as standard candles to analyze cosmological distances and the accelerated expansion of the Universe. Contribute to understanding SN Ia progenitors, rates, and environmental effects.

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HSC: Supernova Ia Survey for Cosmological Research

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  1. SN Survey with HSC Naoki Yasuda, Mamoru Doi (Utokyo), ANDTomoki Morokuma (NAOJ)

  2. SN Ia as standard candle • Very bright (MB~-19.3) • Observable at cosmological distances (z~1.5) • Light-curve shape (Dm15, stretch) / luminosity relation • Broader light-curve -> intrinsically brighter • Accurate to ~7% • Accelerated expansion of the Universe

  3. Luminosity Normalization Astier et al. 2006 Jha 2002

  4. Reiss et al. (2007)

  5. Complementarities • Constraints from SN Ia is complementary to the constraints from LSS • Independent attempt is important Astier et al. 2006

  6. SN Ia progenitors • Sullivan et al. (2006) • SN Ia rate as a function of SFR of host galaxies • Two components • SN rate proportional to SFR and stellar mass • Light curve shapes depend on host galaxies Delayed Prompt Sullivanet al. 2006 Faint Bright

  7. List of SN Survey ESA-ESO Working Groups : Fundamental Cosmology (2006)

  8. Advantage of HSC • Large aperture • Other SN surveys except for LSST use 4m telescopes • SN Ia samples are limited to z<0.9 Extend to z~1.2 • Wide field • 1FoV is comparable to survey area of SNLS • High sensitivity in red bands (z-, Y-band) • Most energy of SN Ia @ z=1 fall in i-, z-, and Y-band

  9. Advantage of HSC • Large aperture • Other SN surveys except for LSST use 4m telescopes • SN Ia samples are limited to z<0.9 Extend to z~1.2 • Wide field • 1FoV is comparable to survey area of SNLS • High sensitivity in red bands (z-, Y-band) • Most energy of SN Ia @ z=1 fall in i-, z-, and Y-band • 1,000 SNe @ z=0.6-1.2from 4FoV and 4month duration observation

  10. Performance of Subaru/Suprime-Cam • Number of candidates • i < 25mag1 month separation 20-30 SNe / deg2 / month 1,000 SNe / 4FoV / 3months • Photometry • Good enough for light-curve fitting for SNe @ z~1 • Comparable to HST photometry Oda et al. (2007)

  11. Proposal • 1,000 SN Ia @ z = 0.6-1.2 combined with previous surveys • Expanding history of the Universe • Limit on the time variation of dark energy • SN Ia rate and its environmental effect, evolution • Clue to the progenitor of SN Ia • Two evolutionary channel?

  12. Observing Strategy • “Multi-color rolling search” • Observe the same field repeatedly with multi colors • Maximum brightness • photometric typing / redshift • Not enough facilities for spectroscopy 5nights (every 5 days) x 4months x 2 in (r,)i,z, and Y-bands: ~1000 SN light curvesMost SNe are observable over 2months

  13. Comparison with on-going SN Surveys • SDSS-II : ~60nights/yr x 3yrs (2.5m) 0.1 < z < 0.3 • SNLS : ~60nights/yr x 5yrs (3.6m) 0.3 < z < 0.8 • HSC : ~40nights/yr x 1yr (8.2m) 0.6 < z < 1.2 • 1,000 SNe from 4FoV, 4months • Much cheaper than HST

  14. Sample Observation Plan

  15. Photometric typing / redshift • Fitting to multi-epoch spectral templates • Typing • ~90% of SN Ia candidates are confirmed spectroscopically from the data of a few epochs (SDSS-II) -> details in Ihara’s talk • Redshift • Dz/(1+z) ~ 2-3% (SNLS) Guy et al. 2007

  16. Photometric Redshift • Simulation • Cosmology : WM = 0.3, WL = 0.7, w = -1, w’ = 0.0 • 1hour exposures of i-, z-, and Y-band at (-8, -3, 0, +3, +8) days from new moon over 3months • Stretch parameter : 0.96 +/- 0.11 (Max magnitude : +/- 0.2) • Explosion time : from -15 days to +15 days • Color is fixed to 0.0 : same intrinsic color and no extinction • Redshift : 0.8, 0.9, 1.0, 1.1, and 1.2 • Photo-z by light curve fitting program (SALT) • SALT is developed for SNLS analysis

  17. Photo-z Results

  18. Photo-z Results

  19. Photo-z Results

  20. Photo-z Results

  21. Photo-z Results

  22. Photo-z Results • Offset of mean value • Difference of spectral templates between light curve simulation (Hsiao template) and light curve fitting program (SALT)? • Dispersion • Dz/(1+z) ~ 1-2% • Catastrophic errors • Misidentification of colors • Degeneracy due to wavy feature of SNe spectrum?

  23. Cosmology • Errors on WM and w reduce by a factor of 2 • Area encircled reduce by a factor of 2 Contour : 1s Contour : 1s

  24. Cosmology • Systematic error due to photo-z error Contour : 1s Contour : 1s

  25. Cosmology • Redshift should be determined well below 1% level • Difficult only with photometric information • Need spectroscopic information • Combine with photo-z of host galaxies? • Different error properties are expected • Slitless (Grism) spectroscopy? • High sky noise • More observing time • Spectroscopy of host galaxies • Need large observing time • Only for elliptical hosts (no extinction)?

  26. SN Ia rate, progenitor, … • Do not need very accurate redshift • Correlation with host galaxy • Brighter SNe are in later spirals • SN rate • Two component modelProportional to • SFR • Stellar mass • Two evolutional path • Effect on chemical evolution Neillet al. 2007

  27. Summary • HSC can detect ~1000 SNe with reasonable observing time (~40 nights). • Photometric Redshift can be determined to 1-2% level. • For cosmology we need more accurate redshift. • Nature of SNe Ia and their evolution can be explored with large sample.

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