Transcript SNLS: SuperNova Legacy Survey

SNLS: SuperNova Legacy
Survey
Jess Oundjian
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.
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.
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.
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.
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
The Survey
 Mostly carried out by
the CFHT (CanadaFrance-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.
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.
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.
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.
Works Cited
 EDP Science Journals:
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/CFHLS
/