1. SNLS: SuperNova Legacy Survey Jess Oundjian

2. What is SNLS?  The largest survey yet to measure the distance to, and the redshift of, far off supernovae.  Started in 2003 and lasting 5 years.  A team of 40 researchers from all over the world, working with some of the world’s largest telescopes.

3. The Purpose?  In finding the distance and red shift of several hundred far-off supernovae, astronomers hope to: - find out more about the acceleration of the expanding universe - place constraints on current cosmological models and therefore narrow down the possible options for our universe.

4. Background  1929: Edwin Hubble discovers expansion of universe.  1990’s: Turns out, universe is accelerating rather than slowing down due to gravity.  Astronomer’s used various models to explain this acceleration - all of which used Einstein’s previously discarded cosmological constant or dark energy.  Although we do not know what dark energy is exactly, it is now believed to make up about 75% of the universe.

5. Why Supernovae?  Supernovae:  Very bright  All roughly the same brightness.  Possible to measure their distances and use them as “standard candles” for measuring long distances in the Universe.

6. Into Perspective… This supernova is as bright as 100 billion Sun-like stars. It exploded 3 billion years ago. At the maximum of its brightness, it was 25 000 times less bright than the blue star seen in the middle of the image. This central blue star is 100 times less bright than the faintest star visible with the naked eye. Copyright CFHTLS/SNLS/Terapix

7. The Survey  Mostly carried out by the CFHT (Canada- France-Hawaii Telescope).  Using many of the largest telescopes worldwide, including the Gemini (many telescopes in both N and S hemispheres) and the Keck (Hawaii) observatories.

8. Consists of three different surveys from Solar System to Distant Universe:  Wide and Shallow - to investigate the outer edges of the Solar System.  Wide Synoptic - matter distribution and galaxy distribution Most importantly here:  Deep Synoptic Survey - detecting type Ia supernovae.

9. Deep Synoptic Survey  Aims to detect and observe as many as 700 Type Ia Supernovae.  Will lead to a better understanding of the early universe as well as a determination of the dark energy parameters with an unprecedented accuracy.  Galaxies and quasars will constitute statistical samples bringing strong constraints on galaxy evolution and global star formation history.

10. So far…  The first set of results, dating from 2003, the first year of the survey, have already placed strong constraints on cosmological models.  They show that their observations fit well with the existence of the cosmological constant.  They also support the theory that, unlike matter, dark energy does not dilute upon expansion.  In 2008, once the survey is complete, it is hoped that the results will open many more windows on our understanding of dark energy and the universe as a whole.

11. Works Cited  EDP Science Journals: http://www.edpsciences.org/journal/index.c fm?edpsname=aa&niv1=others&niv2=pres s_release&niv3=PRaa200512 http://www.edpsciences.org/journal/index.c fm?edpsname=aa&niv1=others&niv2=pres s_release&niv3=PRaa200512 http://www.edpsciences.org/journal/index.c fm?edpsname=aa&niv1=others&niv2=pres s_release&niv3=PRaa200512  CFHT Legacy Survey Homepage: http://www.cfht.hawaii.edu/Science/CFHL S/ http://www.cfht.hawaii.edu/Science/CFHL S/ http://www.cfht.hawaii.edu/Science/CFHL S/