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The Carnegie Supernova Project
Wendy Freedman
Carnegie Observatories
Cosmology 2007
San Servolo, Italy
August 30, 2007
State of the Art (2007): Type Ia Supernovae
HST ACS data
Knop et al. 2003
Riess et al. 2004
Wood-Vasey et al. 2007
Astier et al. 2006
WLF et al. 2007
Carnegie Supernova Project: Primary Goals
1. Reduce systematics (reddening,
calibration, K-corrections…)
2. I-band restframe Hubble diagram
=> observations in the near-IR (>1m)
“Y” , J bands
(To date only UBV restframe…)
Carnegie Supernova Project
Swope 1-meter
Low z:
Dupont 2.5-meter
•u’BVg’r’i’YJHK
photometry
• 2.5-meter
• C40
9 month spectroscopy
campaigns
over 5 years (1350 nights)
• densely sampled photometry
and spectroscopy 0 < z < 0.1
• 100 SNe Ia, 100 SNe II
Magellan 6.5-meter
High z:
• YJ photometry
• Magellan 6.5-meter
• ~100 SNe Ia at completion
• observations near max
• 0.2 < z < 0.8
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
Nick Suntzeff
Pamela Wyatt
http://www.ociw.edu/csp/
Collaborators:
Ray Carlberg, Chris Pritchet, Mark
Sullivan, Kathy Perrett, Andy
Howell (CFHT SN Legacy)
Alex Filippenko, Weidong Li (LOSS)
Nick Suntzeff (ESSENCE)
Josh Friemann, Masao Sato (SDSS-II)
Dan Kelson, Eric Hsiao
CSP Collaborations
High z:
• CFHT Legacy Survey
• ESSENCE
Low z:
• LOTOSS (KAIT)
• SN Factory
Intermediate z:
• SDSS-II
CSP followup and collaboration
Carnegie Supernova Project: Systematics
Minimize effects due to:
1.
2.
3.
4.
Reddening
K-corrections
Environment
Calibration**
Overview: WLF 2005, astro-ph/0411176
1. Galactic reddening
2. Host reddening
3. Supernova Dust
Nugent et al (2002)
1. Galactic Extinction Law
U
B
AU / E(B-V) = 4.9
AB / E(B-V) = 4.1
V
I
AI / E(B-V) = 1.7
R V = AV / E(B-V)
Cardelli, Clayton and Mathis 1989
2. Improved K-corrections
Eric Hsiao
Univ. Victoria
astro-ph 0703529
CSP {
Ca triplet
Thesis:
Improvement to
Standard (Nugent)
K-corrections
New spectra, at
many epochs and
including i-band
coverage (including
CSP low-z data).
CSP Low z Targets
Low z
supernovae
Examples of CSP Low-z Light Curves
Carnegie Supernova Project
• SN 2006X
• NGC 4321
(M100)
• Type Ia
• Spectra from
du Pont and
Magellan /
LDSS2
SN2006X
Nidia Morell
Magellan High-z IR Observations:
Two Examples
d149wcc4_11
(ESSENCE)
z ~ 0.3
c040117-14
(CFHT Legacy)
z ~ 0.6
Target
Template
Difference
Carnegie Supernova Project: High z
SNLS
SDSS-II
ESSENCE
• 58 SN Ia
as of 3/07
Number
• 41 with
templates
Redshift z
 16 with
complete
reductions,
reddenings
Carnegie Supernova Project: High z
i’-band
light curves: low z
High z:
1st peak
2nd peak
• Observe premaximum
• Follow 3-7
epochs
 Less than 10
days after
maximum
• Gaps less than
5 days
Redshift
Carnegie Supernova Project: High z
J
z =Y0.59
i
r
z = 0.62
z = 0.32
.
gri : SDSS-II
Y: Magellan
Y
z = 0.52
z = 0.62
i
ri: SNLS
YJ: Magellan
g
z = 0.43
.
r
C. Burns
Carnegie Supernova Project: High z
Y
J
• Use optical data to
determine decline
rates (m15(B) ).
.
• Use both optical and
near-IR data to
solve for reddening.
• Use YJ light curves
to solve for the
distance modulus.
Template light curves from Prieto et al. (2006) nearby sample
Carnegie Supernova Project: High z
*PRELIMINARY*
16 Type Ia
supernovae
Riess et al. gold
Astier et al.
Magellan
First I-band
Hubble diagram
at z > 0.07
• small scatter at I
• better than current
low-z sample
Redshift
Carnegie Supernova Project:
Fisher-Matrix Constraints on
wo and 
Current CSP
(50 SN Ia)
100 SN Ia
150 SN Ia
Chris Burns
WMAP plus H0 Key Project priors
95% confidence contours
CSP Allows for k-correction and color errors**
Stage I SNLS
(71 SN Ia)
Astier et al
(2006)
Carnegie Supernova Project:
Fisher-Matrix Constraints on
wo and 
Current CSP
(50 SN Ia)
100 SN Ia
150 SN Ia
Chris Burns
WMAP plus H0 Key Project priors
95% confidence contours
Stage II SNLS
(700 SN Ia)
Carnegie Supernova Project: High z
*PRELIMINARY*
maximum
likelihood
CSP+BAO:
M = 0.3 ± 0.1
w = -0.9 ± 0.2
95% confidence
Assumption:
• flat universe
W=P/
SNe Ia & The GMT
SNe studies
are limited by
confusion
0.5 seeing
HST 1.5m
GMT AO
GMT AO will
address this
GMT Science
Working
Group
--P. McCarthy
The Giant Magellan Telescope (GMT)
Alt-az structure
Seven 8.4-m primary mirrors
• Cast borosilicate honeycomb
• 25.3-m enclosed diameter
• 24.5-m diffraction equivalent
• 21.5-m equivalent aperture
3.2-m adaptive Gregorian
secondary mirror
GMT Institutions
• Australia
• Carnegie Observatories
• Harvard University
• Smithsonian Astrophysical
Observatory
• Texas A&M University
• University of Arizona
• University of Michigan
• University of Texas, Austin
• + …OTHERS TBD
Summary






First restframe I-band Hubble diagram for 0.2 < z < 0.7
Dispersion lower than for UBV
Lower sensitivity to reddening
Improved K-corrections
Preliminary Results: w = -0.9§ 0.2 (95% confidence)
Final sample 4-5 times greater
•
Low redshift : tests of systematics
•
High redshift: I-band Hubble diagram
• “Local” calibration for JDEM