Paris - Apr29, 2 005 Reynald Pain 1998-2003 : Concordance model Today’s question : Cosmological Constant, Vacuum Energy or Dark Energy ? SNe Ia prefer a non zero
Dec 16, 2015
Paris - Apr29, 2005 Reynald Pain
1998-2003 : Concordance model
Today’s question :
Cosmological Constant, Vacuum Energy
or Dark Energy ?
SNe Ia prefer
a non zero
Paris - Apr29, 2005 Reynald Pain
Outline:
• Cosmology with SNe Ia
• Why keep studying SNe Ia ?
• SNLS - the SuperNova Legacy Survey
Paris - Apr29, 2005 Reynald Pain
SNe Ia are not standard candles
Very Luminous events visible at cosmological
distances
Show little intrinsicdispersion
Paris - Apr29, 2005 Reynald Pain
SNe Ia Show Light Curve Shape Relationships
(similar to Cepheids P-L relation)
=> Allows to measure distances to better than
5-8% precision
Measuring distances
Paris - Apr29, 2005 Reynald Pain
Models ObservationsUsing radiative transfer
codes, this relationship is reproduced simply by increasing the abundance of 56Ni in the explosion.
Here this is characterized by increasing the effective temperature of the atmosphere.
SNe Ia modelisation
Paris - Apr29, 2005 Reynald Pain
Why keep collecting SNe Ia ?
• Probe Dark Energy Cosmological constant or Dark Energy ?
• Study sytematics - Extinction : Host galaxy/inter-galactic « grey » dust - Evolution : Are nearby and distant SNe Ia alike ?
Paris - Apr29, 2005 Reynald Pain
HST measured color
SCP 2003
+11 SN photometrically followed with HST allows event by event extinction correction
Updated Hubble diagramUsing a low extinction subset
Paris - Apr29, 2005 Reynald Pain
“Morphological” Hubble diagram
SCP 2002
Is there a host galaxy effect ?
Paris - Apr29, 2005 Reynald Pain
SNe at higher redshift (Goods/ACS survey)
Probe the deceleration era
Find Sne at z>1.2 using HST
Paris - Apr29, 2005 Reynald Pain
GOODS/ACS 2004: HST Supernovae
Expansion went from deceleration to acceleration
Exclude grey dust
Paris - Apr29, 2005 Reynald Pain
Probe Dark Energy
Source w
Matter 0Radiation 1/3Cosmo Cte -1Scalar field (cte) -1 Cosmic strings -1/3Domain wall -2/3“Quintessence” <~-0.8“Phantom Energy” <-1
Other sources : w = p/Cosmological constant : p=-
Paris - Apr29, 2005 Reynald Pain
But:
Ongoing high-z SN projects (SCP, HZT, HHZT) have o(200) SN Ia up to z=1.7 (about 20 above z=1). The projected statistical uncertainties will match estimated level of systematic uncertainties
=> Need 2nd generation experiments with both high statistics o(1000) and better control of possible systematics
Paris - Apr29, 2005 Reynald Pain
Imaging survey with Megacam at CFHT
CFHT : 3.6 m (1979)Megacam (CEA/DAPNIA) : 1 deg2 , 4O CCD 2k*4K, = 328 Mpixel
First light : fall 2002
Paris - Apr29, 2005 Reynald Pain
Observation strategy : “Rolling Search”
Part of the CFHTLS/Deep survey
~ 40 nights/yr during 5 years
Repeated observations (every 3-4n) of4 sq. deg. in
ugriz
Paris - Apr29, 2005 Reynald Pain
CFHT Legacy Survey/deep
XMM deepVIMOSSWIREGALEX
Cosmos/ACSVIMOSSIRTFXMM …
Groth stripDeep2ACS …
XMM deep
Four 1 degFour 1 deg² ² fields (0226-04, 1000+02, 1419+53, 2215-18)fields (0226-04, 1000+02, 1419+53, 2215-18)
superb image quality (0.5-0.6 arc sec.)superb image quality (0.5-0.6 arc sec.)queue scheduling, excellent temporal samplingqueue scheduling, excellent temporal samplingdepth i’>24.5 (S/N=8, 1 hr); r’ > 28 in final stacked imagedepth i’>24.5 (S/N=8, 1 hr); r’ > 28 in final stacked image
Redshift 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 Total
Ia 7 8 11 13 14 15 15 16 16 16 131
Ib/c + II 12 16 20 16 12 — — — — — 76
Expected nb of SN per semester
Paris - Apr29, 2005 Reynald Pain
SNLS- The Spectroscopic surveyGoals : - spectral id of SNe up to z~0.9 - redshift (host galaxy) - detailled study of a subsample of SNe, Type IIs (complementary programs, …)
Where? : - VLT Large program (service) : 240h in 2003+2004 - Gemini : 60h/semester - Keck : 3n/year (1st semester) - Magellan : 2n/semester
Paris - Apr29, 2005 Reynald Pain
Find candidates: How it works
• Two independent search pipelines• PSF-match the “reference” and “new” images• Subtract…• … and search the difference images
Real candidate
PSFmatch errors from saturated
objects easily rejected
Paris - Apr29, 2005 Reynald Pain
Current status – typical light-curves
Typical time-sampling and light-curve coverage
Paris - Apr29, 2005 Reynald Pain
Current status – N(z)
Total predicted number of spectroscopically followed SNe
Distribution appears as expected
out to z=0.9
~115 SN Ia from a 12
month period
SNe from Sep 2003 Sep 2004
Paris - Apr29, 2005 Reynald Pain
SNLS : 1st year Hubble diagram
72 SN at z = 0.2 - 0.95 + historical Calan-Tololo SNe
constraint on w (flat Universe)
Paris - Apr29, 2005 Reynald Pain
Summary
• SNe Ia are excellent distance indicators • Ongoing SN experiments are reaching the
systematic limit• 2nd generation projects are getting more
and higher quality data. Toward building a Hubble diagram with ~1000 SN Ia
• SNLS has collected ~160 SNIa in ~1.5 yr. 4 more years to go: expect many more SNe
Paris - Apr29, 2005 Reynald Pain
Precision cosmology with SN Ia
Detect/follow SN Ia from Space e.g. SNAPProposed 1999 Now running for NASA/DOE JDEM AO (2006?)
Paris - Apr29, 2005 Reynald Pain
Images
Spectra
Redshift & spectral properties
Light Curves
data analysis physics
M and
w and w’
SNAP concept
Observables :
Paris - Apr29, 2005 Reynald Pain
SNAP: strategy - precision on w
Area : 2x7.5 sq. deg.
Cadence : 4 days
Total duration : 3 yr
60% imaging - 40% spectro
Total nb of SN : ~ 2000
contraints on w vsM
(statistics + systematics)
+ 300 nearby SNe z>0.1
Paris - Apr29, 2005 Reynald Pain
An alternative observing strayegy
Basic concept Many SNe - Precise space imaging Ground based spectroscopy
Survey: 100 sq deg. (UBVRIZ, I=26) + 10 sq. deg. (IZJHK, I=28) Cadence: 4days (50% on deep survey) Photométric id of SNe (UBV restframe) Ground based spectroscopy (host galaxies) => 12000 SNe 0.1<z<2 in ~18 months better statistical uncertainties on w, w’ calibration/systematic uncertainties ?
Paris - Apr29, 2005 Reynald Pain
JDEM/DESTINYSelected by NASA for « Einstein Probes
2yr Conceptual Studies » =1.8m telescop 0.25 deg. carrés - NIR 0.9->1.7 all grism R=100 (spectrophotometry) L2 orbitSurvey: 4 h exposure 7.5 sq. deg. 1.5 sq. deg./day (cadence 5 days)
2000 SNe 0.5<z<1.7 in 2 yrs Calibration with ESSENCE/LSST (z<1)
Paris - Apr29, 2005 Reynald Pain
Dark Universe Explorer (DUNE) Proposed (2004) as weak lensing probe 1.2-1.5 m telescope 0.25-0.5 sq. deg. Imager visible only - 1-2 filter In phase O study at French Space Agency If approved .. launch by 2011-12 ?
A SN program for DUNE ? 100 sq deg. (UBVRIZ, I=26) - cadence: 4days Photométric id of SNe (UBV restframe) Ground based spectroscopy (host galaxies) => 10000 SNe 0.1<z<1 in ~9 months statistical uncertainties on w, w’ o(80%xSNAP) calibration/systematic uncertainties ?