SN Survey with HSC
NAOKI YASUDA, MAMORU DOI (UTOKYO),
AND
TOMOKI MOROKUMA (NAOJ)
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
1 z z
dz '
Dl ( z )  c
H 0 0  m (1  z ' )3    (1  z ' ) 3(1 w)
Luminosity Normalization
Astier et al. 2006
Jha 2002
Reiss et al. (2007)
Complementarities
 Constraints from SN Ia
is complementary to the
constraints from LSS
 Independent attempt is
important
Astier et al. 2006
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
t
SNR Ia (t )  A M new (t )dt  BM new (t )
0
Delayed
Prompt
 Light curve shapes
depend on host galaxies
Sullivan et al. 2006
Faint
Bright
List of SN Survey
Survey
Telescope
Sky coverage
Filters
# SNe
Spectroscopy
Period
Main goals
Low-z searches; z < 0.1
LOTOSS
KAIT (70cm)
Northern
Hemisphere
BVRI
>200
Lick/Keck
1992-
Discover and follow
nearby SNe
European Supernova
Collaboration
2m and 4m
-
UBVRIZJHK
~20
Various 4m
20022006
SN Ia physics, early
epochs
Supernova Factory
NEAT (1.2m)
Northern
Hemisphere
BVRI
300
SNIFS
2002-
Establish local
Hubble diagram,
study systematic
Intermediate-z searches; 0.1 < z < 0.5
Carnegie Supernova
Project
1m, 2.5m, 6.5m
-
UBVRIYJH
~250
Dupont/Magellan
20042009
All SN types, I
Hubble diagram
SDSS II
Sloan 2.5m
300 deg2
ugriz
>300
Various 4m / Subaru
20052008
Fill in redshift gap
0.1 < z < 0.3
High-z searches; z > 0.5
Supernova
Cosmology Project
CTIO 4m
-
RI
~100
Keck/Gemini/VLT
19902000
Established
acceleration
High-z Supernova
Survey Tem
CTIO 4m
-
RI
~100
Keck/Gemini/VLT
1995-2001
Established
acceleration
Higher-z Supernova
Search
HST
GOODS Fields
RIz
17
Keck/Gemini/VLT/Magellan
20022004
z > 1 SNe
ESSENCE
CTIO 4m
36x0.36 deg2
RI
~200
Keck/Gemini/VLT/Magellan
20012007
w to 10%
SNLS
CFHT
4x1 deg2
ugriz
~700
Keck/Gemini/VLT/Magellan
20032008
w to 7%
Accelerating and
dustfree
HST
-
griz
~20
Keck/Gemini/VLT/Subaru
2005-
Distant SNe in
elliptical galaxies
PAENS/SHOES
HST
-
JHK
~15
???
2006-
Distant SNe
PanSTARRS-4
4x1.5m
~10,000 deg2
BVrIz
thousands
????
2011?
Dark Energy Survey
CTIO 4m
10,000 deg2
griz
thousands
????
2010-2015
LSST
7.5m
>20,000 deg2
ugriz
thousands
-
>2014
JDEM/SNAP/DUNE
/JEDI/DESTINY
Space
>10,000 deg2
optical/IR
~2000
onboard
>2015
Space missions
ESA-ESO Working Groups : Fundamental Cosmology (2006)
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
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=0.6-1.2
from 4FoV and 4month duration observation
Performance of Subaru/Suprime-Cam
 Number of candidates
 i < 25mag
1 month separation
 20-30 SNe / deg2 / month
 1,000 SNe / 4FoV / 3months
Oda et al. (2007)
 Photometry
 Good enough for light-curve
fitting for SNe @ z~1

Comparable to HST photometry
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?
Observing Strategy
 “Multi-color rolling search”
 Observe the same field repeatedly with multi colors
5nights (every 5 days) x 4months x 2 in (r,)i,z, and Y-bands:
~1000 SN light curves
Most SNe are observable over 2months


Maximum brightness
photometric typing / redshift

Not enough facilities for spectroscopy
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

Sample Observation Plan
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
Photometric Redshift
 Simulation
 Cosmology : M = 0.3,  = 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
Photo-z Results
Photo-z Results
Photo-z Results
Photo-z Results
Photo-z Results
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?
Cosmology
 Errors on M and w
reduce by a factor of 2
 Area encircled reduce by
a factor of 2
w( z )  w0  w  z
Contour : 1s
Contour : 1s
Cosmology
 Systematic error due to photo-z error
w( z )  w0  w  z
Contour : 1s
Contour : 1s
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)?

SN Ia rate, progenitor, …
 Do not need very accurate
redshift
 Correlation with host
galaxy

Brighter SNe are in later
spirals
 SN rate
 Two component model
Proportional to
 SFR
 Stellar mass
 Two evolutional path
 Effect on chemical
evolution
Neill et al. 2007
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.