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A strange set of 48 galaxies appears to be rich in dark matter and lacking in stars, suggesting that they may be so-called "failed" galaxies, a new study reports. The galaxies in question are part of the Coma Cluster, which lies 300 million light-years from Earth and packs several thousand galaxies into a space just 20 million light-years across. To study them, Pieter van Dokkum of Yale University and his colleagues used the Dragonfly Telephoto Array in New Mexico. The array's eight connected Canon telephoto lenses allow the researchers to search for extremely faint objects that traditional telescope surveys miss. Often, such as when the researchers used the array to search for the faint glow that dark matter might create, the hunt comes up empty. But when van Dokkum and his colleagues looked toward the Coma Cluster, they found a pleasant surprise. "We noticed all these faint little smudges in the images from the Dragonfly telescope," van Dokkum told Space.com.The mysterious blobs nagged at van Dokkum, compelling him to look into the objects further. Fortuitously, NASA's Hubble Space Telescope had recently captured one of these objects with its sharp eye. "It turned out that they're these fuzzy blobs that look somewhat like dwarf spheroidal galaxies around our own Milky Way," van Dokkum said. "So they looked familiar in some sense … except that if they are at the distance of the Coma Cluster, they must be really huge." And with very few stars to account for the mass in these galaxies, they must contain huge amounts of dark matter, the researchers said. In fact, to stay intact, the 48 galaxies must contain 98 percent dark matter and just 2 percent "normal" matter that we can see. The fraction of dark matter in the universe as a whole is thought to be around 83 percent. But before making this claim, the team had to verify that these blobs really are as distant as the Coma Cluster. (In fact, the team initially thought the galaxies were much closer.). But even in the Hubble image the stars were not resolved. If Hubble — one of the most powerful telescopes in existence — can't resolve the stars, those pinpricks of light must be pretty far away, study team members reasoned. Now, van Dokkum and his colleagues have definitive evidence: They've determined the exact distance to one of the galaxies. The team used the Keck Telescope in Hawaii to look at one of the objects for two hours. This gave them a hazy spectrum, from which they were able to tease out the galaxy's recessional velocity — that is, how fast it is moving away from Earth. That measure traces back to the Hubble Telescope's namesake. In 1929, American astronomer Edwin Hubble discovered one of the simplest and most surprising relationships in astronomy: The more distant a galaxy, the faster it moves away from the Milky Way. Today, astronomers use the relationship to measure a galaxy's recessional velocity and thus calculate the galaxy's distance. In this case, the small fuzzy blob observed with Keck was moving away from Earth at 15.7 million mph (25.3 million km/h). That places it at 300 million light-years away from Earth, the distance of the Coma Cluster. So the verdict is officially in: These galaxies must be associated with the Coma Cluster and therefore must be extremely massive. "It looks like the universe is able to make unexpected galaxies," van Dokkum said, adding that there is an amazing diversity of massive galaxies. But the clusters still present a mystery: The team doesn't know why they have so much dark matter and so few stars.
One possibility is that these are "failed" galaxies. A galaxy's first supernova explosions will drive away huge amounts of gas. Normally, the galaxy has such a strong gravitational pull that most of the expelled gas falls back onto the galaxy and forms the next generations of stars. But maybe the strong gravitational pull of the other galaxies in the Coma Cluster interfered with this process, pulling the gas away. "If that happened, they had no more fuel for star formation and they were sort of stillborn galaxies where they started to get going but then failed to really build up a lot of stars," said van Dokkum, adding that this is the most likely scenario. Another possibility is that these galaxies are in the process of being ripped apart. But astronomers expect that if this were the case, the galaxies would be distorted and streams of stars would be flowing away from them. Because these effects don't appear, this scenario is very unlikely. The next step is to try to measure the individual motions of stars within the galaxies. If the team knew those stars' speeds, it could calculate the galaxies' exact mass, and therefore the amount of dark matter they contain. If the stars move faster, the galaxy is more massive. And if they move slower, the galaxy is less massive. However, this would require a better spectrum than the one the team has right now. "But it's not outside the realm of what's possible," van Dokkum assured. "It's just very hard." The original study has been published in Astrophysical Journal Letters. You can read it for free on the preprint site arXiv.org.
Though they look serene and silent from our vantage on Earth, stars are actually roiling balls of violent plasma. Test your stellar smarts with this quiz.
Excerpt from pressofatlanticcity.comBy FRED SCHAAF ...
Excerpt from sciencerecorder.com
|This two-clocks-illustration shows the pattern of how two atomic clocks would desynchronize and then resynchronize due to a lump of dark matter sweeping through a Global Positioning System or other atomic clock based network. Photo courtesy of Andrei Derevianko, University of Nevada, Reno.|
Global Positioning System, or GPS for short, devices are typically used for navigation purposes. But this satellite network could also alert us to something else: the presence of dark matter. Dark matter is thought to form 80% of the universe, but is difficult to detect because it rarely interacts with ordinary matter. Its makeup is unknown, as it has never been viewed by science. Some have suggested that dark matter is a particle; however, a new study indicates that dark matter may consist of kinks in the quantum field.
According to Andrei Derevianko at the University of Nevada, Reno, and Maxim Pospelov at the Perimeter Institute in Waterloo, Ontario, Canada, dark matter may be made of quantum field cracks that can be detected by GPS. The theory is a revolutionary one, and would change the nature of time and space where the kinds are located.
One of these elements is time, which is tracked by the extremely accurate GPS system. With a network of satellites spanning 50,000 kilometers and traveling through space at 300 kilometers a second, a cosmic kink could disturb the GPS clocks. This quantum crack would require 170 seconds to jump across the networks.
GPS clocks could be interrupted by other factors, but Deverianko and Pospelov believe that only dark matter could disturb the system’s timekeeping in a certain way.
Derevianko is currently pulling data from 15 years of GPS records to search for signs of dark matter’s presence. If no fingerprints are detected, he will use the ground-based atomic clocks belonging to the Network for European Accurate Time and Frequency Transfer.
If dark matter is nothing more than cosmic kinks, it could give some people a new thing to grumble about. “I hear these stories about people getting lost using GPS,” said Derevianko. “Now they could have another excuse: maybe it was dark matter that caused them to lose their way.”
Excerpt from By Jeff Abell
News 4 San Antonio
BALTIMORE - Those who have skirted death often talk about their 'near-death' experiences.
At times, the stories sound like a scene from the twilight zone. But what some researchers discount as hallucinations, others are beginning to take a closer look. Some scientists now seem convinced the stories may actually be real.
Ellyn Dye is a professional writer who didn't quite learn the lessons of life until she discovered death.
"There really is more than who we human beings are," says Dye.
She made her life-changing discovery on a drive to the supermarket 30 years ago, not far from her Silver Spring home. Another motorist veered into her path sending Dye crashing.
"I had enough time to think, ‘oh my God he's.’ I felt no impact. I felt nothing. And the next thing I knew I was looking down from the top of my car," she says.
Dye was clinically dead and viewing her own crash scene from a distance. It was an out of body experience that sounded all too familiar.
"The tunnel of light showed up. You can see this bright, bright, light, but the most important part is you can feel it. I saw, almost immediately, saw all of my relatives who have passed. You know how happy they were to see me and how proud of me they are," Dye says.
Her experience confirmed what she had forever believed, that life exists even after death.
"And I really do think that the worst thing we can be is afraid," she adds.
"I never had a question whether it was real or not. It was real for me," says Jack Dunlavey. Five years ago, Dunlavey was knocking on death’s door. Not long after pulling his tractor out of the barn, it gave way to the soggy ground.
"Four thousand pounds is what the tractor guy told me," he says.
All 4,000 pounds overturned and landed on Dunlavey's back.
"Instantly, I knew I was going to die," he says.
What happened next is similar to what happened to Dye. A bright tunnel appeared and so did familiar faces.
"But when I walked in and floated into that, all my concerns were gone. As I was in there I also saw my parents coming toward me," Dunlavey says.
Scientists have long believed that these out of body experiences were simply hallucinations. But after studying the stories of more than 2,000 heart attack survivors, some researchers now seem convinced those "near death" experiences may actually be real. The study, which is the largest to date, found that more than 40 percent of survivors describe having some form of awareness long after they were declared dead.
"In general, they described seeing lights, getting peaceful, seeing relatives almost as if they were walking them to where they were going," says Dr. Sam Parnia.
But one New York surgeon says, "No, there's no life after death."
He adds that there is a scientific explanation for those near death experiences. For as long as five minutes after the heart stops neurons, he says, are still pumping images through the brain.
"So when we talk about that bright light, that's happening in your occipital lobe," the surgeon says.
"Some people can't comprehend that something like that can happen, but it’s getting more common now so people are starting to listen," says Dunlavey.
For Dye, the research bolsters what she's known for years.
"It doesn't convince me more that my experience was real because it was very real. I can say I saw all my relatives who have died. They were alive and more alive than they ever were on planet earth."
It took death for Dye to learn to live. She now leads a Maryland support group for those who have had near death experiences.