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Physics Professors Scope Out the Universe

Brian Meadows and Michael Sokoloff will help develop a telescope capable of collecting 10 square degrees of sky every 15 seconds—all night—for 10 years.

Date: 11/3/2009
By: Kim Burdett
Phone: (513) 556-8577
Brian Meadows, a physics professor in McMicken College of Arts and Sciences, is the principle investigator for a $197,000 National Science Foundation grant that will enable researchers to develop a facility that addresses unanswered questions about dark matter and dark energy.

Meadows, collaborating with fellow UC physics professor Michael Sokoloff, will work in the planning of the Large Synoptic Survey Telescope (LSST), a uniquely powerful facility that will be the most ambitious sky survey to date.

Brian Meadows.
Brian Meadows will work with other scientists on the planning of the LSST (including fellow UC physics professor Michael Sokoloff) in an effort to learn more about dark matter and dark energy.

Tell us about the LSST.

The LSST will be built and used by a large consortium of researchers principally from astronomy/astrophysics/cosmology as well as from particle physics. Mike Sokoloff and I are part of the particle physics community who have joined this consortium.  

Our interest in the LSST will be in its ability to map out the distribution of dark matter in the universe. The LSST will afford a unique opportunity to see and map out the distribution of dark matter using gravitational lensing—a feature predicted by Einstein by which even invisible mass can still bend light from distant galaxies. The resulting lensing will be visible when the light arrives here on Earth, though it is weak enough that extreme astrometric precision is necessary. The details of the dark matter distribution will help us to understand more about the dark energy and the underpinning notions of the cosmology of our universe.

What is it about dark matter and dark energy that you are trying to find?

Dark matter differs from ordinary matter in that it is unable to emit, reflect or absorb light. Its existence is inferred mostly from the observed motions of stars in orbit around their galaxy centers. It is ubiquitous in the universe, and it accompanies the normal matter we see in other stars and galaxies as well as in our own solar system and Milky Way galaxy.

The amazing thing is the amount of dark matter that appears to exist. Cosmologists estimate it comprises almost a quarter of the universe, while ordinary matter’s contribution is only four percent. The remaining 70 percent of the universe—dark energy—is even more amazing and mysterious.  

What will the LSST do that isn’t already accessible to the field of particle astrophysics?

LSST in profile.
The 8.4-meter LSST will use a special three-mirror design, creating an exceptionally wide field of view and will have the ability to survey the entire sky in only three nights. (Photo: Todd Mason, Mason Productions Inc. / LSST Corporation)

Laboratory-based experiments have helped reach a good understanding of the Standard Model that embodies the laws governing the behavior of ordinary matter. It is hoped that the large accelerator (called the LHC) at CERN in Europe will reveal new physics in the form of new particles that are not a feature of the SM. It is possible these particles will belong to what we know as dark matter, but understanding their basic interactions with other matter may be difficult from this accelerator alone.

Astronomical observations are a promising way to observe how dark matter behaves. The scale and detail of its distribution, the way it behaves when galaxies collide as well as more precise (Earth-bound) measurements at lower energy accelerators are all required to try to understand these interactions.

What are the broader implications of the LSST?

A large number of additional astronomical studies are planned for the LSST from conventional studies of planetary, stellar and galactic observations, to the distribution and frequency of super-novae (exploding stars) and more. The LSST will also track near-Earth objects, such as comets, minor planets and space debris. A function of considerable public interest is that the LSST will also provide early warning of rogue asteroids that might be heading our way!

The LSST will gather astronomical data (in the southern hemisphere) at an unprecedented rate. It will collect 10 square degrees of sky every 15 seconds—all night—for 10 years. Each 15 seconds exposure will be encoded in three billion pixels in its large digital camera. The data will be made available to anyone who wants to study it within the first minute it is taken. Google is one of the LSST collaborators and will, no doubt, post the images—probably in searchable form—for public consumption soon after the data are collected.

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