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CFHTLS SN Survey. SNLS The Good, the Bad, and the Ugly. Chris Pritchet U. Victoria ( SNLS West ). Some history …. Riess et al. 1998 Perlmutter et al. 1998. MegaCam – 1 deg x 1 deg. “Size matters …”. Anon. MegaCam at CFHT.

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snls the good the bad and the ugly
CFHTLS SN Survey

SNLS The Good, the Bad, and the Ugly

Chris Pritchet

U. Victoria (SNLS West)

Dark Energy Tucson 2004

some history
Some history …

Riess et al. 1998

Perlmutter et al. 1998

Dark Energy Tucson 2004

slide3
MegaCam – 1 deg x 1 deg

“Size matters …”

Anon.

Dark Energy Tucson 2004

megacam at cfht
MegaCam at CFHT
  • 40 x (2048 x 4612) chips (~ 400Megapixels)
  • good blue response

Dark Energy Tucson 2004

megacam at cfht1
MegaCam at CFHT

Dark Energy Tucson 2004

cfht legacy survey
XMM deep

VIMOS

SWIRE

GALEX

Cosmos/ACS

VIMOS

SIRTF

XMM …

Groth strip

Deep2

ACS …

XMM deep

CFHT Legacy Survey

470 nights (dark-grey) over 5 years (2003-2008)

  • SNLS - Deep (“SNe + galaxy evolution”)
    • 202 nights over 5 years
    • four 1 deg² fields (0226-04, 1000+02, 1419+53, 2215-18)
  • repeated observations in ugriz filters (360-950nm)
  • depth i’>24.5 (S/N=8, 1 hr); r’ > 28 in final stacked image
  • superb image quality (0.5-0.6 arcsec expected)
  • queue scheduling, excellent temporal sampling
  • ~1000 SNeIa over 5 yrs
  • spectroscopic followup plan (VLT, Gemini, Keck, Magellan)
  • Very Wide(“KBO”)
    • 1300 deg², +-2 deg from ecliptic,
    • short exposures
  • Wide (“lensing’)
    • 172 deg² in 3 patches

Dark Energy Tucson 2004

the team s
The Team(s)

France:

R. Pain (CB Chair), P. Astier, J. Rich …

Canada - U. Toronto:

R. Carlberg, A. Howell, T. Merrall,

K. Perrett, M. Sullivan

Canada - U. Victoria:

C. Pritchet (SN Coordinator),D. Balam,

D. Neill (Aug 2004)

US: S. Perlmutter + …

UK: I. Hook + …

Dark Energy Tucson 2004

goals of sn observations 1 cosmology
Goals of SN observations – 1.Cosmology
  • Λ, w=P/ρ
  • from Type Ia SNe (exploding white dwarfs)

P = wr, ρ(a) ~ a -3(1+w)

w = 0 matter w = -1 L w = 1/3 radiation

a(z)  w !

Linder 2002

relative to

w = -0.7 model

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science goals
Science goals
  • beat down intrinsic dispersion (±0.1–0.2 mag per SN) as N1/2

goal: ±0.01 mag error in a z bin

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expected precision on w m w l w
Expected precision on Wm, WL, w

Pain 2004

1000 up to z=0.9

Flat

Flat, dWm=0.03

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slide12
Other applications
    • SNeII cosmology: v(exp) gives intrinsic luminosity
    • galaxy evolution, correlation functions (deep stacked images)
    • variable AGN’s
    • other variable objects
    • SN properties vs galaxy properties
    • rates

Sullivan et al 2002

Perlmutter et al 1998

Dark Energy Tucson 2004

the stacks
The Stacks

Dark Energy Tucson 2004

snls current status
SNLS - Current Status
  • First SN discovered Mar 2003
  • Survey underway officially since Aug 2003

Mar 2003 Feb 2003 diff

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slide15
2 real time detection pipelines

working well - Ca-Fr agree

to i’=+24

  • psfmatch2 at work

diff 1999-2000

1999 2000

6hr I band 100''×100''

Dark Energy Tucson 2004

detections
Detections
  • 143 in 03B (candidates)
  • 80-90% overlap Ca-Fr to i’=24

Dark Energy Tucson 2004

reliability of faint detections
Reliability of Faint Detections

What fraction of i’=24.5 detections are real?

Answer: of 45 objects i’>24.5:

  • 2 psfmatch errors
  • 2 other/unknown
  • others (89%) showed real light variations (though not necessarily SNe)

Dark Energy Tucson 2004

detections vs radius deg
Detections vs radius [deg]

R [deg]

R [deg]

Dark Energy Tucson 2004

i detections vs seeing
i’ detections vs. seeing

Complex!

(# of new detections) ~ (# nights elapsed since last detections)

Normalize # by dt before comparing with seeing

  • median ~0.4 SNe/night/field

Dark Energy Tucson 2004

spectral successes
Spectral successes
  • Getting the spectroscopy time in the first place!
  • working scheme for coordination of telescopes

Dark Energy Tucson 2004

spectral successes1
Spectral successes
  • Getting the spectroscopy time in the first place!
  • working scheme for coordination of telescopes
  • Nod & shuffle at Gemini

Dark Energy Tucson 2004

nod and shuffle gemini gmos
Nod and Shuffle – Gemini+GMOS

Dark Energy Tucson 2004

spectral successes2
Spectral successes
  • Toronto program for predicting type/phase
  • Getting the spectroscopy time in the first place!
  • working scheme for coordination of telescopes
  • Nod & shuffle at Gemini

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spec z photo z
+ SNIa  SNII AGNSpec-z / Photo-z

Spec confirmed

Slight over-estimate in photo-z, indicating that photometry is systematically faint

But this should be improved once we switch to Elixir

Sullivan, Howell et al 2004

Uses only two epochs of SNaproc photometry!

Dark Energy Tucson 2004

pre screening candidates agn
Pre-screening candidates – AGN

blue = AGN

red = Ia

green = II

AGN

what comes out of fitting code without knowing the true z

Dark Energy Tucson 2004

pre screening candidates sn agn
Pre-screening candidates – SN/AGN?

purple = AGN

red = Ia

green = II

(from spec)

SN/AGN?

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spectra statistics
Spectra Statistics

Dark Energy Tucson 2004

z 0 84 composite 4
z=0.84 composite (4)

Dark Energy Tucson 2004

recent light curves
Recent Light Curves

Perlmutter 2004

z=0.4-0.7

Dark Energy Tucson 2004

light curves
Light curves

Howell, Sullivan et al 2004

0.270

0.497

0.93

z

0.695

0.87

Dark Energy Tucson 2004

june 2003 i 1 hr c030622 07
June 2003 i’ 1 hr (c030622-07)

Sainton 2004

z=0.281 SN Iap t=-7d

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slide33
R6D4-9 = c030903-1

i’max= 24.05

z=0.95

time

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rudimentary hubble diagram
Rudimentary Hubble diagram

ΛCDM

  • Absolute calibration unknown
  • Relative filter-to-filter calibration not yet confirmed
  • Bias to brighter objects at higher-redshift
  • Preliminary photometry

EdS

= wrong z, not Ia

Howell, Sullivan et al 2004

Dark Energy Tucson 2004

web pages
Web pages
  • www.cfht.hawaii.edu/CFHTLS
  • http://legacy.astro.utoronto.ca – photometry, spectroscopy, finder charts, light curves, calendar, …
  • http://makiki.cfht.hawaii.edu:872/sne/

Dark Energy Tucson 2004

6 issues

6. Issues

“The Dirty Dozen”

Dark Energy Tucson 2004

ls vs pi
r’ i’ , less g’z’LS vs. PI
  • weather
  • instrument failures
  • engineering
  • validation rate
  • seeing
  • focus overheads

Dark Energy Tucson 2004

slide38
LS Deep - i’ and z’

Dark Energy Tucson 2004

slide39
2. Scheduling Issues – QSO has worked well, but …
    • how to handle demands of other surveys in bad weather? how to get more g’z’ in bad weather?
  • Image Quality - corrector problems

4. Calibration

      • how achievable is 0.01 mag precision?
      • zeropoints – esp.in colour (matching k-corr’s at different redshifts)
      • uniformity across array
      • variation in colour terms (esp u* and z’)
      • CFHT preprocessing pipeline (“Elixir”)
      • “phase closure”

Dark Energy Tucson 2004

conclusions
Conclusions
  • “The Ugly”:
      • less data than hoped for in 2003B
      • less g’z’
  • “The Bad”:
      • IQ – natural seeing and corrector
      • calibration/photometry issues to solve
  • “The Good”:
      • team
      • detection pipelines
      • spectroscopy
      • “ugly” and “bad” mostly understood and preventable in 2004A

Dark Energy Tucson 2004

slide41
--

Dark Energy Tucson 2004

telescope aperture vs focal plane area
Telescope Aperture vs. Focal Plane Area

total area in 3m+ telescopes [m2]

total CCD area [Megapix]

Dark Energy Tucson 2004

real fits
“Real” fits

Light-curve coverage at low redshift encompasses up to 15 epochs

Howell, Sullivan et al 2004

French and Canadian photometry not yet completely consistent, should be improved once we switch to Elixir.

Dark Energy Tucson 2004

real fits1
“Real” fits

Moving up in redshift

Coverage is still good

Howell, Sullivan et al 2004

Dark Energy Tucson 2004

real fits2
“Real” fits

Intermediate redshift

Howell, Sullivan et al 2004

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real fits3
“Real” fits

…and higher redshift…

Howell, Sullivan et al 2004

Dark Energy Tucson 2004

real fits4
“Real” fits

And “high” redshift.

Photometry is much nosier. Peak in i is about 24.2

Howell, Sullivan et al 2004

Dark Energy Tucson 2004

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