Stages of a Big Project ***

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1 Stages of a Big Project *** The Five stages of SDSS: 1. Denial 2. Anger 3. Bargaining 4. Depression 5. Acceptance *** With apologies to Elizabeth Kubler Ross

2 The Carnegie Supernovae Project Wendy Freedman Carnegie Observatories SDSS: From Asteroids to Cosmology Chicago, August 18, 2008

3 Supernovae Prior to SDSS-II Intermediate redshift desert

4 Wood-Vasey et al WLF et al SNe Ia and Cosmology: State of the Art HST ACS data Knop et al Riess et al Astier et al. 2006

5 Type-Ia Supernovae Progenitor is a white dwarf accreting material from a binary companion. As the white dwarf approaches the Chandrasekhar mass, a thermonuclear runaway is triggered. Standardizable candles

6 Type-Ia Supernovae (con t) Rise time: ~ 20 days Decay time: ~ 2 months Brightness: M B ~ 19.5 at peak Found in all types of galaxies Type Ia Type Ic. Si II Spectral Classification: No hydrogen in the spectra Early spectra: Si, Ca, Mg (absorption features) Late spectra: Fe, Ni (emission features )

7 Caveats for Supernovae and the determination of w I. A very wide range of w and H 0 combinations are consistent with the current CMB and supernova data. There is a severe degeneracy between w or Ω Λ and H 0.

8 WMAP: Relax Constraint of Flat Universe Dashed line Ω k = Ω Λ Range of non-flat models consistent with WMAP data Spergel et al. 2006

9 Caveats for Supernovae and the determination of w II. The determination of w from supernovae alone requires the assumption of a flat Universe.

10 SNe alone can t measure w Slide due to Ned Wright Model with w = -1 and w = -0.9 agree to within ± 2 millimag, after adjusting Ω m, Ω Λ and M (the absolute magnitude or Hubble constant)

11 SNe alone can t measure w Slide due to Ned Wright Model with w = 0 and w = -0.1 agree to within ± 1 millimag

12 Type Ia Supernovae for Cosmology Advantages: small dispersion direct measure of acceleration can be observed over wide z range straightforward empirical tests of systematics

13 Systematic Dust extinction Evolution Photometric calibration Malmquist bias K-corrections Lensing Treatment Multi-band photometry including near-ir High-resolution spectroscopy New calibration of standard stars optical through near-ir to <1% accuracy High S/N light curves and spectra; requirement of pre-rise data Library of supernova spectra with broad wavelength, temporal and Δ m 15 coverage. Measure the average flux for a large number of supernovae in each redshift bin.

14 Dark Energy Task Force Report: Albrecht et al. SN-II 700 SNe 500 nearby SN-III spectra 2000 SNe SN-IV LSST 300,000 SNe SN-IVspace 2000 SNe optimistic pessimistic w = -1 Ω Λ = 0.73

15 DETF Forecast: Combining Techniques Stage II space Stage IV BAO+SN +WL (P and O) Contours 95% CL Note: all same priors Albrecht et al. 2006

16 Carnegie Supernova Project: Primary Goals 1. I-band restframe Hubble diagram Observations in the near-ir (>1μm) Y, J bands To date only UBV restframe 2. Reduce systematics (reddening, calibration, K-corrections ) Multi-wavelength observations

17 Carnegie Supernova Project Swope 1-meter Dupont 2.5-meter Magellan 6.5-meter

18 Carnegie Supernova Project Swope 1-meter Dupont 2.5-meter Magellan 6.5-meter Low z: High z: u BVg r i YJHK photometry 2.5-meter spectroscopy C40 9 month campaigns over 5 years (1350 nights) densely sampled photometry and spectroscopy 0 < z < SNe Ia, 100 SNe II YJ photometry Magellan 6.5-meter ~75 SNe Ia at completion observations near max 0.2 < z < 0.7

19 Carnegie Supernova Project (CSP) Chris Burns Carlos Contreras Gaston Folatelli Wendy Freedman (PI, High z) Mario Hamuy Barry Madore Nidia Morell Eric Persson Mark Phillips (PI, Low z) Miguel Roth Max Stritzinger Nick Suntzeff Collaborators: Ray Carlberg, Chris Pritchet, Mark Sullivan, Kathy Perrett, Andy Howell (CFHT SN Legacy) Alex Filippenko, Weidong Li (LOSS) Nick Suntzeff (ESSENCE) Josh Friemann (SDSS-II) Dan Kelson, Eric Hsiao

20 Corrections for Dust Extinction R V = A V / E(B-V) U B V I Complications: Several potential sources: (MW, host, circumstellar, IGM) Intrinsic color vs reddening degeneracy low z: <E(B-V)> = 0.12 ± 0.14 high z: <E(B-V)> = 0.06 ± 0.13 Cardelli, Clayton and Mathis 1989

21 Reddening / Intrinsic Color Current largest systematic effect Degeneracy between reddening and intrinsic color CSP: Two independent approaches 1. Solve for individual reddenings using unreddened sample (Phillips et al. 1999) 2. Use a reddening-free magnitude, w w = i R λ (B-V) = i 0 R λ (Β-V) 0 Folatelli et al. 2009

22 Improved K-corrections 125 spectra covering I band CSP { Ca triplet match spectral templates to observed colors uncertainties range from ± to ± 0.1 mag Hsiao et. al astro-ph

23 CSP Approach Internal double-blind tests photometric zero points galaxy template subtraction light-curve templates decline-rates, max light magnitudes reddenings

24 Other Effects UV Spectra Local Template Mean High z Sullivan et al. (2003) Ellis et al. (2007) Spiral galaxies host slower (and more luminous) SNe Ia The scatter in the Hubble diagram is a function of galaxy type (lower for E s) Effect of metallicity and environment on cosmology appears to be small

25 CSP Collaborations Low z: LOTOSS (KAIT) SN Factory Intermediate z: SDSS-II High z: CFHT Legacy Survey ESSENCE CSP follow-up and collaboration

26 The Low-z CSP PI: Mark Phillips SN2006X

27 Sources for Low-z Supernovae LOSS + many others CSP Low z Target Sample: 100 SNe Ia 100 SN II 25 SN Ibc

28 Low-z SNe Ia: Optical Light Curves 0.90 Δm 15 (B) 1.83

29 Examples of CSP Low-z Light Curves

30 Carnegie Supernova Project Low-z SN 2006X NGC 4321 (M100) Spectra from du Pont and Magellan / LDSS2 SN2006X Nidia Morell

31 Absolute Magnitude Versus Decline Rate BV Hubble Diagrams 20 well-observed SNe Ia Folatelli, Phillips et al. (in prep.) WLF, Sturch, Madore, Burns et al. (in prep.)

32 Carnegie Supernova Project: High z SNLS SDSS-II ESSENCE 74 SN Ia observed with 0.11 < z < 0.70 Number 56 with at least one template Redshift z 23 with complete reductions, reddenings

33 Carnegie Supernova Project: High z Example i -band light curves: low z High z: CSP 1 st peak 2 nd peak Observe premaximum Follow 3-7 epochs Less than 10 days after maximum Gaps less than 5 days

34 Carnegie Supernova Project: High z I-band (YJ) photometry from Magellan Optical BVR photometry from: SNLS ESSENCE SDSS-II J z Y= 0.59 i r z = 0.52 i Template light curves based on low-redshift CSP data.

35 Carnegie Supernova Project: High z I-band (YJ) photometry from Magellan Optical BVR photometry from: SNLS ESSENCE SDSS-II J z Y= 0.59 i r z = 0.52 e.g., Magnitude uncertainties <Y> z ± ± ±

36 B. Madore CSP Template Light Curves u i r V g B Light curve parameters: Determine Δ m 15 decline rate values and time of max using χ 2 minimization CSP Low z example light curves: use for templates

37 Carnegie Supernova Project i - band CSP data: 23 Type Ia supernovae 0.18 < z < Type Ia supernovae 0.01 < z < 0.07 First I-band Hubble diagram at z > 0.07 WLF et al. (2008)

38 Carnegie Supernova Project: High z BAO CSP Joint constraints CSP + BAO data: Eisenstein et al Assumptions: w = -1 w a = 0 Ω DE > 0 at a >>3-σ confidence level. Ω DE = 0.72 ± 0.08 (stat) ± 0.05 (sys)

39 Carnegie Supernova Project: High z Joint constraints CSP+BAO (Eisenstein 2005): W 0 CSP BAO BAO CSP Ω M = 0.28 ± 0.02 (stat) w 0 = ± 0.09 (stat) ± 0.08 (sys) Ω M Systematic errors included Assume flatness

40 Summary of Cosmological Parameters Future: 100 SNe Ia (low z) Currently ~1/3 of 75 SNe Ia (high z) final sample Comparable uncertainties to other optical surveys of larger sizes due to smaller systematic uncertainties.

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