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SN Survey with HSC

Study on SN Ia as standard candles for cosmological distances, using large aperture telescopes, and multi-color photometric typing for cosmology research. Detection of 1,000 SNe @ z=0.6-1.2 with Subaru/Suprime-Cam. Comparison with other surveys like SDSS-II and SNLS.

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SN Survey with HSC

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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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