Better Supernovae Measurements Aim To Improve Understanding of Dark Energy

May 22, 2009
Baltay and his team used the QUEST camera to find 185 nearby supernovae like the one pictured above. On the left is a raw image of a galaxy; the center image was taken a month later, during a supernova explosion. (Credit: Charles Baltay/Yale University)

(PhysOrg.com) -- A new technique for measuring the distances to supernovae more accurately than ever before has been developed by a team of scientists from Yale University, Lawrence Berkeley National Laboratory and a consortium of French laboratories.

Type Ia supernovae are exploding stars that made the discovery of dark energy possible in 1998. Astronomers continue to use supernovae to understand the acceleration of the universe’s expansion. In recent years, astronomers have only been able to measure the distances to these “standard candles” to within about 10 percent accuracy, and as such, can only test current models of dark energy to within a certain limit.

These supernovae are so bright that we can see them even when they are billions of away. Because supernovae all have roughly the same inherent brightness, astronomers compare this with how bright they appear to be from here on Earth to determine how far away they actually are. Differences in any given star’s composition, however, mean it can be slightly brighter or dimmer when it explodes, which has made extremely precise measurements of their distances difficult.

The team began looking for supernovae several years ago with the creation of the Nearby Supernovae Factory, the largest supernovae survey ever conducted. To find the supernovae, the team uses QUEST, the world’s largest optical camera, which was designed and developed at Yale. They have discovered 185 nearby supernovae to date, out of which 58 were analyzed for the current study.

“Measuring the distance to supernovae has been a major problem in astronomy ever since the discovery of dark energy,” said Charles Baltay, Yale’s Eugene Higgins Professor of Physics, and one of the paper’s authors. “To understand how dark energy behaved in the early universe, we needed to make more precise measurements.”

Now the team has discovered a way to measure the distances to these supernovae more precisely than ever before, as reported in the forthcoming issue of the journal Astronomy & Astrophysics. Using a telescope in Hawaii to analyze the supernovae’s light signatures, they looked at each star’s individual composition. Providing a custom analysis of its inherent brightness, they were able to determine its distance to better than six percent accuracy.

Next, the team hopes to continue analysis on the remaining nearby supernovae so that they can ultimately test predictions about the history of and its behavior in the .

“The excitement of science is not knowing what you’re going to find,” Baltay said. “But it’s nice that this first set of has already proved useful.”

Other members of the Yale team include David Rabinowitz, Richard Scalzo and Will Emmet.

More information: DOI: 10.1051/0004-6361/200911973

Provided by Yale University (news : web)

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User comments : 8

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NeilFarbstein
2.5 / 5 (2) May 22, 2009
it makes finding supernovas look easy
omatumr
1 / 5 (3) May 22, 2009
DARK ENERGY IS SIMPLY ASSUMED?

As an experimentalist, I strongly favor measurements.

But these quotes suggest that the authors of this study simply assume the existence of dark matter in interpreting the data.

1. QUOTE: Measuring the distance to supernovae has been a major problem in astronomy ever since the discovery of dark energy,END QUOTE

2. QUOTE: To understand how dark energy behaved in the early universe, we needed to make more precise measurements.END QUOTE

If so, my question to them is "What dark energy?"

With kind regards,
Oliver K. Manuel
http://www.omatumr.com



rwinners
3 / 5 (2) May 22, 2009
Dark matter is stuff that can't be seen, touched, smelled or in any other way sensed, but is assumed to exist because nothing else explains a certain observation.
Now, ask what dark energy is.
omatumr
1 / 5 (4) May 22, 2009
SOUNDS MORE LIKE RELIGION THAN SCIENCE

Dark matter is stuff that can't be seen, touched, smelled or in any other way sensed, but is assumed to exist because nothing else explains a certain observation.

Now, ask what dark energy is.

PPihkala
5 / 5 (2) May 23, 2009
SOUNDS MORE LIKE RELIGION THAN SCIENCE

Have you ever heard of people practizing religion who are keen to measure anything about it? These scientists have made advances in their measurement of distances to supernovas and want to make more. And any progress helps to better define the phenomena we currently call dark matter. Maybe some day we will know the reason for this phenomena, which may as well eliminate the need for it as a hypothesis.
Slotin
1 / 5 (2) May 23, 2009
..ask what dark energy is..
A surface tension effect of gravity field gradient, the vacuum around massive galaxies behaves like sparse bubbles or mercury droplets, which repels mutually at distance.

http://aetherwave...ter.html

dark matter itself can be explained in many ways
omatumr
1 / 5 (2) May 23, 2009
RELIGION OR SCIENCE?

SOUNDS MORE LIKE RELIGION THAN SCIENCE


Have you ever heard of people practizing religion who are keen to measure anything about it? . . . Maybe some day we will know the reason for this phenomena, which may as well eliminate the need for it as a hypothesis.


Yes, that would advance science.

I saw no evidence of Dark Energy in experimental data from precise, space-age measurements of variations in:

a.) Abundances of elements and isotopes in the solar system, and

b.) Rest masses of the 3,000 different types of atoms that comprise the entire VISIBLE universe.

The nuclear rest mass data are here:
http://tinyurl.com/2otxps

With kind regards,
Oliver K. Manuel
http://myprofile....anuelo09
Au-Pu
1 / 5 (1) May 23, 2009
"They" haven't discovered dark energy.
So far it remains a superstitious explanation for what they need but cannot find.
An explanation for the otherwise unexplainable.
Or if you prefer, as omatumr (above) suggested, its the religious solution.
If they do find it and prove and quantify it, then it will move into the realm of scientific reality.