1 sdss supernova survey josh frieman supernova rates 2008, florence may 19, 2008
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SDSS Supernova Survey
Josh FriemanSupernova Rates 2008, Florence
May 19, 2008
Dark Energy and Dark Matter
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SDSS II Supernova Survey Goals• Obtain few hundred high-quality SNe Ia light curves in the `redshift
desert’ z~0.05-0.35 for continuous Hubble diagram• Detailed spectroscopic follow-up, including some with multiple
epochs, to study evolution and diversity of SN features• Probe Dark Energy in z regime complementary to other surveys• Well-observed sample to anchor Hubble diagram & train light-curve
fitters • Rolling search: determine SN/SF rates/properties vs. z, environment• Rest-frame u-band templates for z >1 surveys • Large survey volume: rare & peculiar SNe, probe outliers of
population• Enable time-domain science both in real time* & after the fact** *candidates immediately on the web+IAU circulars+VOEventNet **SN images & object catalogs all available publicly w/in ~2 months
Spectroscopic follow-up telescopes
R. Miquel, M. Molla
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SDSS 2.5 meter telescope SDSS-I: 2000-5Apache Point Observatory SDSS-II: 2005-8New Mexico
<#>
Stripe 82
Frieman, et al (2008); Sako, et al (2008)
Search Template Difference
g
r
i
Searching For Supernovae
• 2005– 190,020 objects
scanned
– 11,385 unique candidates
– 130 confirmed Ia
• 2006– 14,441 objects
scanned
– 3,694 unique candidates
– 193 confirmed Ia
• 2007 – 171 confirmed Ia
Spectroscopic Target Selection2 Epochs
SN Ia Fit
SN Ibc Fit
SN II Fit
31 Epochs
SN Ia Fit
SN Ibc Fit
SN II Fit
Fit with template library
Classification>90%accurate after 2-3 epochs
Redshifts 5-10% accurate
Sako etal 2008
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SN 2005 gb
z = 0.086, confirmed at ARC 3.5mPreliminary gri light curve and fit from low-z templates
Before After
Composite gri
images
SN and Host Spectroscopy
MDM 2.4m
NOT 2.6m
APO 3.5m
NTT 3.6m
KPNO 4m
WHT 4.2m
Subaru 8.2m
HET 9.2m
Keck 10m
Magellan 6m
TNG
SALT 10m
2005+2006
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Spectroscopic Follow-up
•1325 spectra taken over 3 seasons•Multi-epoch spectroscopy of selected low-redshift SNe
Spectroscopic Deconstruction
SN modelHost galaxy modelCombined model
Zheng, et al (2008)
Rolling survey leads to well-sampled*, well-constrained light curves
peaked after Sept. 7 peaked before Sept. 7
r=22.5*9 epochs of imaging per SN (median)
SDSS low-redshiftlight curvesfrom 2005 well-sampled, multi-band (u,z not shown)
Will use to trainLC fitters & anchor HubbleDiagram
2005-07:83 confirmedSNe Ia at z<0.12
gri
Dilday et al (2007) submitted
SDSS SN Photometry: Holtzman et al. (2007) submitted ``Scene modeling”
B.
Dild
ay
Redshift Distribution for SNe Ia
and counting
Peculiar SNe from SDSS
2005gj: SN Ia in dense circumstellar environment or SN IIn; more luminous than any normal Ia; Prieto et al (2007)
2005hk: underluminous; pure deflagration? Phillips et al (2007)
Collaborations with Carnegie Supernova Project
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Light Curve Fitting with MLCS2k2 and SALT-II
Model Survey Efficiency
Monte Carlo Simulations match data distributions
Use actual observing conditions (sky, zero-points, PSF, etc)
Extract RV distribution from SDSS SN data
D. Cinabro
€
RV =AV
E(B −V )=1.87 ± 0.59
Extract AV Distribution from SDSS
(no prior)
Future: Improved SN Ia Distances
TrainFitters
Fit Cosmology
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The Dark Energy Survey• Study Dark Energy using 4 complementary*
techniques: I. Cluster Counts II. Weak Lensing III. Baryon Acoustic
Oscillations IV. Supernovae
• Two multiband surveys: 5000 deg2 g, r, i, z, Y
to 24th mag Smaller area repeat for
SNe
• Build new 3 deg2 camera and Data management sytem Survey late 2011-2016 (525
nights) Response to NOAO AO
Blanco 4-meter at CTIO
*in systematics & in cosmological parameter degeneracies*geometric+structure growth: test Dark Energy vs. Gravity
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The DES Collaboration
FermilabUniversity of Illinois at Urbana-ChampaignUniversity of ChicagoLawrence Berkeley National LabNOAO/CTIODES Spain ConsortiumDES United Kingdom ConsortiumUniversity of MichiganOhio State UniversityUniversity of PennsylvaniaDES Brazil ConsortiumArgonne National Laboratory
The DES Instrument: DECam
3556 mm
1575 mm
Hexapod
Optical Lenses
F8 Mirror
CCDRead out
Filters Shutter
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DES CCDs
• 62 2kx4k fully depleted CCDs:
520 Megapixels
• Excellent red sensitivity
• Developed by LBNL
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90
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300 400 500 600 700 800 900 1000 1100
Wavelength (nm)
Quantum Efficiency (%)
Thinned CCD Deep DepletedLBNL high resistivity
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DES Supernovae
• Baseline survey: ~1000 hours over 5 years (5 months per yr), roughly evenly split between photometric and non-photometric; ~5 visits per lunation in griz(Y); 2 deep fields, 3 shallow fields (3 sq deg per field); some possible NIR follow-up on VISTA
• ~3500 well-measured SN Ia lightcurves to z~1
• Larger sample, improved z-band response (fully depleted CCDs) compared to ESSENCE, SNLS: reduce dependence on rest-frame u-band and Malmquist bias
• Spectroscopic follow-up of SN Ia subsample+`complete’ host galaxies (LBT, Magellan, Gemini, Keck, VLT,…) e.g., focus on ellipticals (low dust extinction)?
• What strategy would be optimal for rate measurements? What questions will you want to ask?
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Forecast Redshift Distribution