Tuesday March 15, 2005 SCIENCE 5 news@michigandaily.com DIGGING UP A COSMIC PAST Archaeological astronomers glimpse back in time and discover the most distant galaxy yet By Ryan Anderson For the Daily niversity research fellow Christopher Mullis and his international team of astronomers are cosmic archaeologists. Just as conventional archaeologists dig through the accumulated sediment of hundreds and thousands of years to uncover relics from long ago, his group searches the skies for relics of a much younger universe. Rather than shovels and picks, they travel back in time using telescopes, and they dig much deeper. They recently discovered an ancient object that pushes the limits of the observational universe to only five billion years after the universe began. The object that they found is a massive galaxy cluster nine- billion light years away, the farthest ever observed. A light year is the distance light travels in one year, meaning that light from the cluster has been traveling across the vacuum of space for two-thirds the lifetime ofthe universe. In making the discovery, Mullis worked with astronomers from the European Southern Observatory, the Max Planck Institute for This gas, Extraterrestrial Physics and the Astronomical heated Institute at Potsdam. A galaxy cluster is during cluster the name astronomers foo is give to groups of gal- formation, is axies that are trapped what allowed together by their mutual gravitation. the tEach galaxy is made of hundreds of billions of make their stars like the sun, and there can be thousands record- of galaxies in a clus- ter. Galaxy clusters breaking find. take billions of years to coalesce from an unstable assortment of partially formed galaxies into a mature cluster. Clusters interact with one another to form the largest structures in the universe. "Clusters are often difficult to find based on visual obser- vations," Mullis said. "However, they glow brightly in X- ray light due to the hundred-million-degree gas that fills the space between the galaxies." This gas, heated during cluster formation, is what allowed the team to make their record-breaking find. The team used a complex computer program to search through archived images from the XMM Newton X-ray satel- lite and identify possible distant clusters. XMM-Newton was launched in 1999 by the European Space Agency. Its wide field of view and excellent light-gathering ability make it well suited for detecting faint, distant objects. The cluster was dis- GRAPHICS BY MATT DANIELS LEFT: Nine billion light years spans the distance between the distant galaxy XMMU J2235 and Earth. RIGHT: Diagram of the distribution of galaxy clusters from Earth to XMMU J2235. The number of galaxy clusters decreases the further the distance away from the Earth because the younger universe produces much larger clusters than the present-day universe. covered in the background of an image of a black hole. The cluster's X-ray signal is extraordinarily faint, Mullis said. The entire signal from the galaxy cluster is made up of a scant 280 photons, gathered during an exposure last- ing 12.5 hours. As a comparison, on a sunny day, your eye receives 10 quadrillion photons every second. To measure the distance to the cluster, the team made opti- cal observations from the ESO Very Large Telescope in South America. By passing light through a spectrograph - an instrument that separates the light from a source according to wavelength, much like a prism - astronomers can tell what chemical elements are present in the object they are observing. Because the universe is constantly expanding, light that leaves an object long ago gets stretched out during its journey. Astronomers call this increase in wavelength "redshift." The more redshifted an object is, the farther away it is. Using the unique spectral fingerprints of certain elements to measure this change, Mullis said the "eureka" moment came in late 2004, when he analyzed the spectra from the cluster and determined an astonishing distance of nine billion light years. "We see an evolved cluster at five billion years (since the Big Bang). That means it was forming at something like two or three billion years," Mullis said. "The general expecta- tion is that at higher distances clusters get more youthful, so (this discovery) is particularly exciting." Gus Evrard, a University professor of astronomy and phys- ics, said fully developed clusters at this distance are expect- ed from current theoretical models of the universe. "In that respect, theory is actually ahead of observation," Evrard said. There have been protoclusters found at distances still greater than the cluster found by Mullis and his team. Those objects, however, are not well-formed and lack the multi-mil- lion-degree gas that characterizes a fully evolved cluster. Evrard compared the situation to population density in a sparsely populated state. There are bound to be counties with a higher population than the surrounding area, but those are not the same as a full-fledged city. Mullis and his team have discovered the farthest and therefore most ancient "city" of galaxies known. "The finding of such a large cosmic structure at this age ... is expected in a universe dominated by dark energy but not in a universe dominated by dark matter," Evrard said. Dark matter is the mysterious "missing mass" that cosmologists believe makes up almost a quarter of the total mass/energy budget of our uni- verse. The amount of dark matter in the universe determines the structures that will form and how large they become. By searching for the earliest formed clusters, astronomers hope to get an estimate of the universe's dark matter content. The current estimate is that dark matter makes up about one quarter of the total mass/energy in the universe, Mullis said. Dark energy is the energy contained in the vacuum of space itself. It governs the rate of expansion of the universe. Measuring the redshift of distant clusters helps cosmolo- gists measure that expansion and get an estimate of the dark energy content. Current estimates place dark energy at three quarters of the total, Mullis said. This amount of dark energy leads to the surprising con- clusion that the universe is not only expanding, but acceler- ating. Normal matter makes up only a small percent of the total energy density. The vast majority of the universe is made of matter and energy that we do not understand. The discovery of such a distant cluster by analyzing archived images from XMM-Newton was relatively easy, Mullis said. This bodes well for the discovery of many more super-distant galaxy clusters in the future, he added. With a whole range of distant clusters to study, astrono- mers will be able to infer the fundamental parameters of the universe, and conclude how it evolved from the Big Bang to the structures that we observe today. 'Super mice' may help strengthen bones By Phil Svabik Daily Staff Reporter Move over Mickey, Minnie and even Mighty Mouse, because while cartoonists have created mice able to withstand falling anvils, researchers at the University have engineered mice with a bone structure that even the world's most famous mice might be envious of. Molecular and Integrative Physiology Prof. Ormond MacDougald and his fellow researchers have recently been experimenting with mice that have been genetically altered to produce less adi- pocytes, or fat cells, and produce four times more osteoblasts, or bone cells. Using these "super mice," researchers are on their way to better understand- ing one possible mechanism for the development of osteoporosis in older adults, which may also help lead to a drug to treat the disease. To produce the mice used in the study, an artifi- cial sequence of DNA was injected into fertilized mouse eggs, causing these genetically altered mice to produce more of a certain signaling protein, called WntlOb (pronounced Wint ten b) inside their bone marrow. Signaling proteins regulate the development of tissues in the body. With higher levels of Wntl0b, the mice developed stronger and larger bones than usual. There is a patent pending on the genetically altered mice. "There are many pharmaceutical companies that are very actively developing very small molecules or other approaches to activate this pathway with the hope of providing a drug that could be used to increase bone formation," MacDougald said. "Most of the drugs that are out there just inhibit the reabsorption of bone, and this would be a valu- able tool within the tool kit that doctors have in treating osteoporosis," he added. Wntl0b is part of a family of 19 other Wnt signaling proteins, which all help determine the type of cells that bone marrow stem cells will become. These stem cells can give rise to many different tissues such as bone, fat, cartilage and connective tissue. The Wntl~b signaling pathway can either block the formation of undifferentiated cells to fat cells, or encourage the production of bone cells, MacDou- gald said. The findings from this study at the University will help researchers better understand how osteoporosis develops. Osteoporosis is a disease characterized by a decrease in bone mass. Left untreated, it can lead to a very high susceptibility to bone fractures and breaks. The discovery that the WntlOb signaling protein causes an increase in bone cell formation helps researchers to better understand one mecha- nism of bone formation and may possibly help lead to drugs capable of regenerating lost bone mass. The National Osteoporosis Foundation esti- mates that 55 percent of Americans over the age of 50 have osteoporosis, the vast majority of these being women who can lose 20 percent of their bone mass within a decade after menopause. As the baby boomer generation continues to age, these figures will likely increase, pushing the demand for medi- cations to help prevent and cure the disease However, Rackham student Christina Bennett, researcher and first author of the WntlOb mice article, which was published Feb. 21, hopes a drug might be created as a result of the study, but does not necessarily think the findings will lead directly to a cure-all drug. "Wnt's are also involved in cancer so one of the concerns would be if you stimulate Wnt signaling you could also cause bone cancer," Bennett said, though noting that cancer was not observed in any of the mice involved in the study. She added that in the development of a drug, a different protein or other molecule aside from WntlOb that has the same effect but would be safer could be used instead. Previous research conducted by MacDougald and other researchers last year showed that an excess of WntlOb in fat cells of mice, instead of within the bone marrow, causes the mice to have 50 percent less body fat. This previous research on super skin- ny mice, also could help researchers better under- stand and treat obesity. "This would be a valuable tool within the tool kit that doctors have in treating osteoporosis." - Ormond MacDougald Molecular and Integra- tive Physiology Prof. Bennett is quick to point out that a decrease in the fat cells as a side effect of a Wnt10b derived drug to increase bone mass in osteoporosis patients wouldn't necessarily be detrimental. "But isn't that the perfect drug? I think a decrease of fat in bone marrow or elsewhere wouldn't be a negative thing," she said. To quantitatively analyze the size and density of the bones within the studied mice, the research team utilized micro-computerized tomography, a type of three-dimensional X-ray machine. Mac- Dougald said the results showed that the bones were stronger and larger and the mice were more resistant to bone loss that occurs along with estro- gen depletion, which is similar to post-menopaus- al bone loss in women. The researchers would not say exactly where they plan to go from here, but they do want to continue to study Wnt signaling and gain a better understanding of precisely how Wnts, especially Wnt10b, function. WRITE FOR THE SCIENCE PAGE! 763- 2459 Place an ad in The Michigan Daily's Summer Sublet Section and get cash for your house or apartment this spring/summer. Early Bird Rate: $35 for ads placed on or before March 17th, 2oo5. Standard Rate: $45 for ads placed after March 17th, 2oo5. Final Deadline: March 24th, 2oo5. Published on: March 31st, 2oo5. Refer to the classified section of the Daily for more info! Call an Account Executive at -64-0557, or stop by our office at 42o Maynard. E-mail: classified@michigandaily.com space IS LImI eD, so reserve You "s TODa Y! COURTESY OF ORMOND MACDOUGALD X-rays of femur mice bones with different Wnt10b levels. The left bone has increased Wnt10b protein levels causing a firmer bone development. The middle has normal levels, and the right has a decrease of Wnt10b, resulting in fractures. for more information call 734/998-6251 College of Literature, Science, and the Arts Twenty-Sixth Distinguished Senior Faculty Lecture Interpreting cck Art In New Mexico The University of Michigan Denartment of Dermatoloav