tagged w/ Universe
LONG BEACH, Calif. - Space is typically thought of as a very quiet place. But one team of astronomers has found a strange cosmic noise that booms six times louder than expected.
The roar is from the distant cosmos. Nobody knows what causes it.
Of course, sound waves can't travel in a vacuum (which is what most of space is), or at least they can't very efficiently. But radio waves can.
Radio waves are not sound waves; they are electromagnetic waves, situated on the low-frequency end of the light spectrum. Many objects in the universe, including stars and quasars, emit radio waves. Even our home galaxy, the Milky Way, emits a static hiss (first detected in 1931 by physicist Karl Jansky). Other galaxies send out a background radio hiss as well.
But the newly detected signal, described here at the 213th meeting of the American Astronomical Society on Wednesday, is far louder than astronomers expected.
There is "something new and interesting going on in the universe," said Alan Kogut of NASA's Goddard Space Flight Center in Greenbelt, Md.
A team led by Kogut detected the signal with a balloon-borne instrument named ARCADE (Absolute Radiometer for Cosmology, Astrophysics and Diffuse Emission).
In July 2006, the instrument was launched from NASA's Columbia Scientific Balloon Facility in Palestine, Texas, and reached an altitude of about 120,000 feet (36,500 meters), where the atmosphere thins into the vacuum of space.
ARCADE's mission was to search the sky for faint signs of heat from the first generation of stars, but instead they heard a roar from the distant reaches of the universe.
"The universe really threw us a curve," Kogut said. "Instead of the faint signal we hoped to find, here was this booming noise six times louder than anyone had predicted."
Detailed analysis of the signal ruled out primordial stars or any known radio sources, including gas in the outermost halo of our own galaxy.
Other radio galaxies also can't account for the noise — there just aren't enough of them.
"You'd have to pack them into the universe like sardines," said study team member Dale Fixsen of the University of Maryland. "There wouldn't be any space left between one galaxy and the next."
The signal is measured to be six times brighter than the combined emission of all known radio sources in the universe.
For now, the origin of the signal remains a mystery.
"We really don't know what it is," said team member Michael Seiffert of NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Not only has it presented astronomers with a new puzzle, it is obscuring the sought-for signal from the earliest stars. But the cosmic static may itself provide important clues to the development of galaxies when the universe was much younger, less than half its present age. Because the radio waves come from far away, traveling at the speed of light, they therefore represent an earlier time in the universe.
"This is what makes science so exciting," Seiffert said. "You start out on a path to measure something — in this case, the heat from the very first stars — but run into something else entirely, some unexplained."LONG BEACH, Calif. - Space is typically thought of as a very quiet place. But one team... more
Whatever gave birth to this monster can be real proud. The biggest black hole in the universe weighs in with a respectable mass of 18 billion Suns, and is about the size of an entire galaxy. Just like in the Arnold Schwarzenegger and Danny Devito flick “Twins”, the massive black hole has a puny twin hovering nearby. By observing the orbit of the smaller black hole, astronomers are able to test Einstein's theory of general relativity with stronger gravitational fields than ever before.
The biggest black hole beats out its nearest competitor by six times. Fortunately, it’s 3.5 billion light years away, forming the heart of a quasar called OJ287. Quasars are extremely bright objects in which matter spiraling into a giant black hole emits large amounts of radiation.
The smaller black hole, which weighs about 100 million Suns, orbits the larger one on an oval-shaped path every 12 years. It comes close enough to punch through the disc of matter surrounding the larger black hole twice each orbit, causing a pair of outbursts that make OJ287 suddenly brighten.
General relativity predicts that the smaller hole's orbit itself should rotate over time, so that the point at which it comes nearest its neighbor moves around in space. This effect is seen in Mercury's orbit around the Sun, on a much smaller scale.
In the case of OJ287, the tremendous gravitational field of the larger black hole causes the smaller black hole's orbit to precess at an impressive 39° each orbit. The precession changes where and when the smaller hole crashes through the disc surrounding its larger sibling.
About a dozen of the resulting bright outbursts have been observed to date, and astronomers led by Mauri Valtonen of Tuorla Observatory in Finland have analysed them to measure the precession rate of the smaller hole's orbit. That, along with the period of the orbit, suggests the larger black hole weighs a record 18 billion Suns.
So just how big can these bad boys get? Craig Wheeler of the University of Texas in Austin, US, says it depends only on how long a black hole has been around and how fast it has swallowed matter in order to grow. "There is no theoretical upper limit," he says.
The most recent outburst occurred on 13 September 2007, as predicted by general relativity. "If there was no orbital decay, the outburst would have been 20 days later than when it actually happened," Valtonen told New Scientist, adding that the black holes are on track to merge within 10,000 years.
Wheeler says the observations of the outbursts fit closely with the expectations from general relativity. "The fact that you can fit Einstein's theory [so well] ... is telling you that that's working," he says.Whatever gave birth to this monster can be real proud. The biggest black hole in the... more
Now, on NOVA, take a thrill ride into a world stranger than science fiction, where you play the game, by breaking some rules, where a new view of the universe, pushes you beyond the limits of your wildest imagination. This is the world of string theory, a way of describing every force and all matter from an atom to earth, to the end of the galaxies—from the birth of time to its final tick—in a single theory, a theory of everything. Our guide to this brave new world is Brian Greene, the bestselling author and physicist.Now, on NOVA, take a thrill ride into a world stranger than science fiction, where you... more
"NASA held a phone-in press conference today wherein three astrophysicists reported the latest findings on dark energy. They have now "clearly seen" the effects of dark energy on the most massive collapsed objects in the universe. This new evidence has aligned scientists behind the central belief that 1) dark energy exists, 2) that it explains why we are seeing the universe expanding and accelerating, and 3) that Einstein's General Relativity theory is correct - so long as the cosmological constant is applied (something Einstein himself called his "greatest blunder")."
Look at that chart! Talk about feeling small in the universe, huh?"NASA held a phone-in press conference today wherein three astrophysicists... more
Dark energy maybe expanding the universe, but at the same time it is also stopping the growth of galaxies within it.
The same mystery force that is speeding up the expansion of the universe is also stunting the growth of the objects inside it, astronomers said on Tuesday.
After bulking up rapidly in the first 10 billion years of cosmic time, clusters of galaxies, the cloudlike swarms that are the largest conglomerations of matter in the universe, have grown anemically or not at all during the last five billion years, like sullen teenagers who suddenly refuse to eat.Dark energy maybe expanding the universe, but at the same time it is also stopping the... more
In one single, epic camera move we journey from Earth's surface to the outermost reaches of the universe on a grand tour of the cosmos, to explore newborn stars, distant planets, black holes and beyond.In one single, epic camera move we journey from Earth's surface to the outermost... more
A sugar molecule linked to the origin of life was discovered in a potentially habitable region of our galaxy.
The molecule, called glycolaldehyde, was spotted in a large star-forming area of space around 26,000 light-years from Earth in the less-chaotic outer regions of the Milky Way. This suggests the sugar could be common across the universe, which is good news for extraterrestrial-life seekers.
"This is an important discovery as it is the first time glycolaldehyde, a basic sugar, has been detected towards a star-forming region where planets that could potentially harbor life may exist," Serena Viti of University College London said in a press release.
Previously, glycolaldehyde had only been observed toward the center of the galaxy, where conditions are thought to be too extreme to host habitable planets.A sugar molecule linked to the origin of life was discovered in a potentially... more
Physicists don’t like coincidences. They like even less the notion that life is somehow central to the universe, and yet recent discoveries are forcing them to confront that very idea. Life, it seems, is not an incidental component of the universe, burped up out of a random chemical brew on a lonely planet to endure for a few fleeting ticks of the cosmic clock. In some strange sense, it appears that we are not adapted to the universe; the universe is adapted to us.
Call it a fluke, a mystery, a miracle. Or call it the biggest problem in physics. Short of invoking a benevolent creator, many physicists see only one possible explanation: Our universe may be but one of perhaps infinitely many universes in an inconceivably vast multiverse. Most of those universes are barren, but some, like ours, have conditions suitable for life.
The idea is controversial. Critics say it doesn’t even qualify as a scientific theory because the existence of other universes cannot be proved or disproved. Advocates argue that, like it or not, the multiverse may well be the only viable nonreligious explanation for what is often called the “fine-tuning problem”—the baffling observation that the laws of the universe seem custom-tailored to favor the emergence of life.Physicists don’t like coincidences. They like even less the notion that life is... more
Something may be out there. Way out there.
On the outskirts of creation, unknown, unseen "structures" are tugging on our universe like cosmic magnets, a controversial new study says.
Everything in the known universe is said to be racing toward the massive clumps of matter at more than 2 million miles (3.2 million kilometers) an hour—a movement the researchers have dubbed dark flow.
The presence of the extra-universal matter suggests that our universe is part of something bigger—a multiverse—and that whatever is out there is very different from the universe we know, according to study leader Alexander Kashlinsky, an astrophysicist at NASA's Goddard Space Flight Center in Maryland.
The theory could rewrite the laws of physics. Current models say the known, or visible, universe—which extends as far as light could have traveled since the big bang—is essentially the same as the rest of space-time (the three dimensions of space plus time).
Picturing Dark Flow
Dark flow was named in a nod to dark energy and dark matter—two other unexplained astrophysical phenomena.
The newfound flow cannot be explained by, and is not directly related to, the expansion of the universe, though the researchers believe the two types of movement are happening at the same time.
In an attempt to simplify the mind-bending concept, Kashlinsky says to picture yourself floating in the middle of a vast ocean. As far as the eye can see, the ocean is smooth and the same in every direction, just as most astronomers believe the universe is. You would think that beyond the horizon, therefore, nothing is different.
"But then you discover a faint but coherent flow in your ocean," Kashlinsky said. "You would deduce that the entire cosmos is not exactly like what you can see within your own horizon."
There must be an out-of-sight mountain river or ravine pushing or pulling the water. Or in the cosmological case, Kashlinsky speculates that "this motion is caused by structures well beyond the current cosmological horizon, which is more than 14 billion light-years away."
(More below.)Something may be out there. Way out there. On the outskirts of creation, unknown,... more
Discovery-News.com: After a three-billion mile journey into the outer reaches of the solar system, the Stardust spacecraft has landed at it's permanent home. Dave Mosher brings us up to speed. Kasey-Dee Gardner produces. Discovery-News.com: After a three-billion mile journey into the outer reaches of the... more
Recently identified electrical activity on Saturn's largest moon bolsters arguments that Titan is the kind of place that could harbor life. Recently identified electrical activity on Saturn's largest moon bolsters... more
Washington, Oct 22 : A team of cosmologists from the University of the Basque Country has determined that the accelerated expansion of the Universe can be explained by dark 'phantom' energy.
To explain the majority of the phenomena occurring in the Universe, complicated calculations with a computer are required and which have to be based on appropriate mathematical models.
This is what the Gravitation and Cosmology research team at the University of the Basque Country (UPV/EHU) is involved in: analyzing models capable of explaining the evolution of the Universe.
One of the phenomena that standard models of physics have not yet been able to explain is that of the accelerated expansion of the Universe.
Although Einstein proposed a static model to describe the cosmos, today it is well known, thanks to supernovas amongst other things, that it is, in fact, expanding.
By measuring the quantity of light that gets to us from a supernova, we can calculate its distance from us, and its colour indicates the speed at which it is distancing itself from us.
The more reddish it is, the faster it is travelling. In other words, comparing two supernovas, the one that is distancing itself more slowly from us is a more bluish colour.
According to observations by astrophysiscists, besides supernovas distancing themselves from us, they are doing so more and more rapidly, i.e. distancing themselves at an accelerated velocity, just like the rest of the material of the Universe.
The energy known to exist in the Universe, however, is not sufficient to cause such acceleration.
Thus, the theory most widely accepted within the scientific community is that there exists a 'dark energy', i.e. an energy that we cannot detect except by the gravitational force that it produces.
In fact, it is believed that 73 percent of the energy of the Universe is dark.
The unique characteristic of dark energy known to us is that it possesses repulsive gravitational force. That is, unlike the gravity we know on Earth, this force tends to distance stars, galaxies and the rest of the structures of the Universe from each other.
This would explain why the expansion of the Universe is not constant, but accelerated.
Such powerful dark energy is known as phantom energy, with which the Universe is able to expand to such an extent that the structures we know today would disappear.
This research group considers that the phantom energy model may be the most suitable to explain the accelerated expansion of the Universe. Washington, Oct 22 : A team of cosmologists from the University of the Basque Country... more
Gamma-ray bursts are by far the brightest and most powerful explosions in the Universe, second only to the Big Bang itself. So it might seem a bit surprising that a group of them has gone missing.
A single gamma-ray burst (GRB) can easily outshine an entire galaxy containing hundreds of billions of stars. Powerful telescopes can see them from clear across the Universe. And because the deeper you look into space, the farther back in time you see, astronomers should be able to see GRBs from the time when the very first stars were forming after the Big Bang.
Yet they don't. Gamma-ray bursts from that early epoch seem to be missing, and astronomers are wondering where they are.
"This is one of the biggest questions in the gamma-ray business," says astrophysicist Neil Gehrels of the Goddard Space Flight Center. "It's something we're going to be talking a lot about today at the GRB Symposium."
Gehrels has joined about a hundred of his colleagues from 25 countries for the 6th Huntsville Gamma-ray Burst Symposium underway this week in Huntsville, Alabama. Missing gamma-ray bursts are one of the top mysteries on the agenda.
Until recently, experts were grappling with an even more fundamental question about GRBs: what the heck are they? Astronomers had observed these astonishing bursts since the 1960s, but nobody could imagine an event powerful enough to create them.
The answer eventually came from Stan Woosley, a theoretical astrophysicist at the University of California in San Diego. He suggested that when young, supermassive stars with low metal content collapse under their own weight to form black holes, the stars' rotation funnels the explosive energy into two streamlined jets that shoot out from the stars' poles, like the axis of a gyro. We only see the burst if one of these two jets happens to be pointed toward Earth. The concentration of energy into narrow jets is why GRBs that we do observe appear so remarkably bright.
The first waves of star formation after the Big Bang should have produced plenty of metal-poor supermassive stars ripe for collapse. If true, GRBs from that epoch should be abundant. So where are they?
One possibility is they're not missing at all.
"Part of the problem is that burst profiles get stretched out by the expansion of the Universe, so it is harder to recognize them as bursts in the first place," explains astrophysicist Lynn Cominsky of Sonoma State University. "The bursts could be happening, but we're not noticing them."
Another trouble is the afterglow—the fading debris that tells so much about a burst, including its distance. "Afterglows from the most distant GRBs may be too red shifted to be seen by current generations of telescopes," she notes.
see caption"Red shift" is how much the wavelength of light is stretched when it travels to us across the expanding Universe. The farther away a thing is, the more its light is stretched, and the greater the red shift. Until recently, the largest red shift ever measured for a GRB was 6.3. Then, last month, Gehrels and colleagues using NASA's Swift satellite found one with a red shift of 6.7 or 12.8 billion light years away. So far, that's the record.
"Gamma-ray bursts are predicted in the red shift range 10 to 20, but so far no one has seen anything beyond 6.7," says Cominsky.
The luminous afterglow of such distant bursts would be red shifted all the way into the infrared. "There's a huge effort right now to try to get those infrared observations," Gehrels says, but in the meantime it's difficult to verify whether a candidate 7+ GRB is truly that far away.
As infrared telescopes improve, scientists should eventually be able to measure the distance to GRBs with red shifts greater than 7 — if they exist. And that's a big IF. What if the missing GRBs really are missing?
"That would teach us something very interesting about the Universe," says Gehrels.Gamma-ray bursts are by far the brightest and most powerful explosions in the... more
"The "termination shock" sounds like the stuff science fiction movies are made of. In reality, it marks the boundary between our solar system and interstellar space. The invisible "shock" forms as our sun's solar winds begin to encounter the gases and magnetic fields of outer space, which slows the winds down abruptly.
On October 19, NASA will launch the first spacecraft designed to image and map the interactions that take place in this boundary zone. The Interstellar Boundary Explorer, or IBEX, will be propelled from the Kwajalein Atoll into a high-altitude orbit that will eventually take it about 200,000 miles from Earth, where it will capture images of processes taking place in the termination shock and beyond...""The "termination shock" sounds like the stuff science fiction movies... more