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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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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