Post on 30-Dec-2015
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
SNLS – The SuperNova Legacy SNLS – The SuperNova Legacy SurveySurvey
Mark Sullivan Mark Sullivan (University of Toronto)(University of Toronto)
on behalf of the SNLS on behalf of the SNLS collaborationcollaboration
http://cfht.hawaii.edu/SNLS/
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
The 5-year CFHT Legacy Survey… in 10 The 5-year CFHT Legacy Survey… in 10 minutesminutes
Utilises Utilises Megacam, Megacam, a 36CCD/1 sq deg a 36CCD/1 sq deg imagerimager
Deep/SNLS component has:Deep/SNLS component has:202 nights over 5 years202 nights over 5 years
Repeat observations over four fieldsRepeat observations over four fields
5 epochs per field per month (10 visits/month)5 epochs per field per month (10 visits/month)
g’r’i’z’ observed on each epoch (tweaked to g’r’i’z’ observed on each epoch (tweaked to allow for moon)allow for moon)
Hence rest-frame Hence rest-frame UBVRUBVR sampled every 3-4 sampled every 3-4 days in the SN rest-framedays in the SN rest-frame
Field NameField Name Other Other data/surveysdata/surveys
D1 D1
(02:26,-04)(02:26,-04)VIMOS, SWIRE, GALEX, VIMOS, SWIRE, GALEX,
XMM DeepXMM Deep
D2D2
(10:00,+02)(10:00,+02)COSMOS/ACS, VIMOS, COSMOS/ACS, VIMOS,
SIRTF, GALEX, XMM etc.SIRTF, GALEX, XMM etc.
D3D3
(14:19,+53)(14:19,+53)Groth Strip – ACS, DEEP-II, Groth Strip – ACS, DEEP-II,
GALEX etc.GALEX etc.
D4D4
(22:15,-18)(22:15,-18)XMM DeepXMM Deep
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Primary science goalsPrimary science goals
Primary goal: Use SNe Ia to determine “w”Primary goal: Use SNe Ia to determine “w”Many other talks for details on how SNe Ia can help Many other talks for details on how SNe Ia can help to constrain wto constrain wSNLS Goal: 1000 SNe Ia (across all redshifts)SNLS Goal: 1000 SNe Ia (across all redshifts)Calibration goal: 1-2% photometric accuracyCalibration goal: 1-2% photometric accuracy
SNLS provides many consistency checks SNLS provides many consistency checks on the use of SNe Ia, e.g.on the use of SNe Ia, e.g.
SN colour evolution – multi-colour consistency SN colour evolution – multi-colour consistency checkcheckDetailed studies of spectral evolution (e.g. talk by Detailed studies of spectral evolution (e.g. talk by P. Nugent + VLT/Gemini spectra)P. Nugent + VLT/Gemini spectra)Collaboration with Carnegie to construct rest-frame Collaboration with Carnegie to construct rest-frame I-band Hubble diagram (minimise dust extinction)I-band Hubble diagram (minimise dust extinction)
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Secondary goals – other SN scienceSecondary goals – other SN science
Type Ia/II SN ratesType Ia/II SN rates co-moving SF density (z), SNe Ia progenitor co-moving SF density (z), SNe Ia progenitor information information
SNe IIP as standard candles via expansion vel.SNe IIP as standard candles via expansion vel.Independent confirmation of accelerating Universe?Independent confirmation of accelerating Universe?
Host galaxy studies (SNLS fields have a Host galaxy studies (SNLS fields have a wealth of wealth of HSTHST imaging + ugriz deep host imaging + ugriz deep host photometry)photometry)
In summary: a wealth of exciting SN scienceIn summary: a wealth of exciting SN science
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
How it worksHow it works
Data reduced in real-time by ElixirData reduced in real-time by Elixir
Two independent search pipelinesTwo independent search pipelines
PSF-match the “reference” and “epoch” imagesPSF-match the “reference” and “epoch” images
Subtract…Subtract…
… … and search the difference imagesand search the difference images
Real candidate
PSFmatch errors from saturated
objects easily rejected
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
DetectionsDetections
~90% agreement between the two pipelines to ~90% agreement between the two pipelines to i’=24.5i’=24.5
As of May 2004, the database contains (over 4 fields):As of May 2004, the database contains (over 4 fields):222 AGN candidates222 AGN candidates
328 SN candidates (of all flavours…)328 SN candidates (of all flavours…)
282 “repeatedly varying” stellar objects282 “repeatedly varying” stellar objects
Even with ~120 hours/semester of 8-10m Even with ~120 hours/semester of 8-10m spectroscopic time, we cannot hope to follow all spectroscopic time, we cannot hope to follow all these candidatesthese candidates
However – we have a wealth of real-time photometric However – we have a wealth of real-time photometric information – unprecedented when compared to information – unprecedented when compared to
previous surveysprevious surveys
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Photometric pre-screeningPhotometric pre-screening
So, we use a SN photo-z technique to So, we use a SN photo-z technique to identify our priority candidatesidentify our priority candidates
Performs a least-squares fit to 2-3 epochs of data Performs a least-squares fit to 2-3 epochs of data over (over (phasephase,,redshiftredshift,,stretchstretch,reddening) to a Ia ,reddening) to a Ia spectral templatespectral template
Non-SNe Ia screened out (colour e.g. g’-r’, rise-Non-SNe Ia screened out (colour e.g. g’-r’, rise-time..)time..)
(conservative cuts)(conservative cuts)
Identifies priority candidates for follow-up – Identifies priority candidates for follow-up – especially valuable in poor weather conditionsespecially valuable in poor weather conditions
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Photometric-redshift analysisPhotometric-redshift analysis
(all spectroscopic redshifts from March May 2004)
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Current statusCurrent status
Survey “proper” commenced Aug 1, 2003Survey “proper” commenced Aug 1, 2003(pre-survey March (pre-survey March July 2003) July 2003)
Atrocious winter on Mauna Kea, some technical Atrocious winter on Mauna Kea, some technical issuesissues
All observing is queue-scheduled – big advantage All observing is queue-scheduled – big advantage in poor weather conditionsin poor weather conditions
New priority agreements – SNLS has priority on New priority agreements – SNLS has priority on time-critical nightstime-critical nights
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Current status – typical light-curvesCurrent status – typical light-curves
Typical time-sampling from early
(pre-survey and start of survey) SN
discoveries
(this shows real-time Elixir photometry only)
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
How many SNe will there be?How many SNe will there be?
Cumulative number of supernovae (to end April 2004)
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
How many SNe will there be?How many SNe will there be?
Cumulative number of supernovae to survey end
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
How many SNe will there be?How many SNe will there be?
Cumulative number of supernovae – with photometric typing and a host
redshift
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Current status – N(Current status – N(zz))
Current spectroscopic N(z)
(includes SNe from September 2003 April 2004)
~70 SNe Ia from an 8 month period
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Current status – N(Current status – N(zz))
Total predicted number of detected SNe (detection efficiency calculated by J. Guy)
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Current status – N(Current status – N(zz))
Total predicted number of spectroscopically followed SNe
Distribution appears
as expected to z=0.6
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Predicted cosmological constraintsPredicted cosmological constraints
Constraints on w expected after 5 years based on current survey
progress
(Red indicates constraints using ΩM
determination from CFHTLS “wide” )
Padua: 1604 Padua: 1604 →→ 2004 – Supernovae as cosmological lighthouses 2004 – Supernovae as cosmological lighthouses
Want to know more?Want to know more?
Check out these websites for all the Check out these websites for all the details:details:
Project overview, collaboration members, Project overview, collaboration members, publications:publications:
http://cfht.hawaii.edu/SNLS/http://cfht.hawaii.edu/SNLS/
Candidate database, real-time candidate lists:Candidate database, real-time candidate lists:
http://legacy.astro.utoronto.ca/http://legacy.astro.utoronto.ca/
Also: see posters by A. Howell and S. BasaAlso: see posters by A. Howell and S. Basa