Milky Way Found to Exist on Outskirts of a Vast Supercluster of 100,000 Galaxies

Astronomers have determined that our own Milky Way galaxy is part of a newly identified ginormous supercluster of galaxies, which they have dubbed "Laniakea," which means "immense heaven" in Hawaiian. This discovery clarifies the boundaries of our galactic neighborhood and establishes previously unrecognized linkages among various galaxy clusters in the local Universe.The Milky Way resides in the outskirts of the supercluster, whose extent has for the first time been carefully mapped using these new techniques. This so-called Laniakea Supercluster is 500 million light-years in diameter and contains the mass of one hundred million billion Suns spread across 100,000 galaxies.

This new study also clarifies the role of the Great Attractor, a gravitational focal point in intergalactic space that influences the motion of our Local Group of galaxies and other galaxy clusters.

Within the boundaries of the Laniakea Supercluster, galaxy motions are directed inward, in the same way that water streams follow descending paths toward a valley. The Great Attractor region is a large flat bottom gravitational valley with a sphere of attraction that extends across the Laniakea Supercluster.

"We have finally established the contours that define the supercluster of galaxies we can call home," said lead researcher R. Brent Tully, an astronomer at the University of Hawaii at Manoa. "This is not unlike finding out for the first time that your hometown is actually part of much larger country that borders other nations."

Superclusters are among the largest structures in the known Universe. They are made up of groups, like our own Local Group, that contain dozens of galaxies, and massive clusters that contain hundreds of galaxies, all interconnected in a web of filaments. Though these structures are interconnected, they have poorly defined boundaries.

To better refine cosmic mapmaking, the researchers are proposing a new way to evaluate these large-scale galaxy structures by examining their impact on the motions of galaxies. A galaxy between structures will be caught in a gravitational tug-of-war in which the balance of the gravitational forces from the surrounding large-scale structures determines the galaxy's motion.

By using the GBT and other radio telescopes to map the velocities of galaxies throughout our local Universe, the team was able to define the region of space where each supercluster dominates. "Green Bank Telescope observations have played a significant role in the research leading to this new understanding of the limits and relationships among a number of superclusters," said Tully.

The name Laniakea was suggested by Nawa'a Napoleon, an associate professor of Hawaiian Language and chair of the Department of Languages, Linguistics, and Literature at Kapiolani Community College, a part of the University of Hawaii system. The name honors Polynesian navigators who used knowledge of the heavens to voyage across the immensity of the Pacific Ocean.

The GBT is the world's largest fully steerable radio telescope. Its location in the National Radio Quiet Zone and the West Virginia Radio Astronomy Zone protects the incredibly sensitive telescope from unwanted radio interference.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

A short video about Laniakea that gives the viewer a general sense of the structure of our home supercluster and of galaxy motions in the nearby universe is available at http://vimeo.com/104704518

Most distant object in the universe spotted, GRB Smashes Record for Most Distant Known Object

A really, really long time ago in a galaxy far away, a massive star exploded. On April 23, 2009, the Swift satellite detected that explosion. This spectacular gamma ray burst was seen 13 billion light years away, with a redshift of 8.2, the highest ever measured. As we hinted yesterday, this object is now the most distant known object, and the burst occurred when the Universe was only 630 million years old, a mere one-twentieth of its current age. This event, called GRB 090423, can tell us much about the early Universe. "We completely smashed the record with this one," said Edo Berger, a professor at Harvard University and a member of the team that first measured the burst’s origin. "This demonstrates for the first time that massive stars existed in the early Universe."

At 3:55 a.m. EDT on April 23, Swift detected a ten-second-long gamma-ray burst of modest brightness, and quickly slewed around to use its Ultraviolet/Optical and X-Ray telescopes on the burst location. Swift saw a fading X-ray afterglow but nothing in visible light. A number of ground based telescopes were alerted to the event and within three hours began to observe the distant GRB.

"This was a pretty amazing event," Berger told Universe Today. "Swift detected this gamma ray burst on April 23 and we immediately followed it up with the Gemini North Telescope in Hawaii, after it was demonstrated it did not have a visible light counterpart. That was the initial hint that this might be a distant object. We observed it in infrared and we found in the different infrared bands that there was a sharp break at a wavelength of about 1.1 microns."

The drop-out corresponds to a redshift of 8.2 and burst distance of about 13 billion light-years.

Other telescopes that made observations were the Very Large Telescope, STFC’s United Kingdom Infrared Telescope (UKIRT), The Telescopio Nazionale Galileo (TNG), the Okayama Astrophysical Observatory, the Fermi Space Telescope and the Plateau de Bure Interferometer.

Subsequent observations the following night from other telescopes confirmed and refined the measurement. Previously, the most distant known object was a galaxy with a redshift of 6.96 discovered in 2006. The most distant GRB found September of 2008 had a redshift of 6.7. "We completely smashed the record with this one,"said Berger. "I think people were thinking it would happen step by step, but we kind of jumped things."

Berger said the burst itself was not unusual; it was a basic a run-of-the–mill GRB. But even that can convey a lot of information. "That might mean that even these early generations of stars are very similar to stars in the local universe, that when they die they seem to produce similar types of gamma ray bursts, but it might be a little early to speculate."


So what does this distant GRB tell us about the early Universe? "This happened a little more than 13 billion years ago," said Berger. "We've essentially been able to find gamma ray bursts throughout the Universe. The nearest ones are only about 100 million light years away, and this most distant one is 13 billion light years away, so it seems that they populate the entire universe. This most distant one demonstrates for the first time that massive stars exist at those very high red shifts. This is something people have suspected for a long time, but there was no direct observational proof. So that is one of the cool results from this observation."

Berger said this event also tells us that perhaps GRBs are the best objects to study which show how the early Universe evolved. "They are extremely bright and very easy to find, comparatively speaking, so they give us hope that this is the right approach. Over the years people have found high redshift quasars and galaxies, but my suspicion is that until the launch of the James Webb Space Telescope the middle of the next decade, this object will remain as the record holder. No other telescope, including the Hubble Space Telescope is capable of finding more distant objects."

Finding this distant object also demonstrates how telescopes around the world can work together. "It’s the combination of Swift pinpointing where these objects are located and the ground-based telescopes immediately responding to these positions and then demonstrating the distance," said Berger. "It's really a great synergy. We've been doing this for a long time now, and I think part of what has been driving this is the desire to find such distant objects.

Berger said astronomers have been speculating about such distant gamma rays bursts for quite some time and there are two missions being proposed to NASA as the next generation gamma ray telescopes. So, now, the fact that we've now found one at such a high distance makes those satellites more attractive for funding because this has now gone from being an idea or gut feeling to real observational proof."

Source: http://www.universetoday.com/2009/04/28/grb-smashes-record-for-most-distant-known-object/

The End of Everything

Written by Fraser Cain

Copy and paste from: http://www.universetoday.com/2007/07/25/the-end-of-everything/

It can be said that humans have a bit of a short term view of things. We're concerned about the end of summer, the next school year, and maybe even retirement. But these are just a blink of an eye in cosmic terms. Let's really think big, stare forward in time, and think about what the future holds for the Universe. Look forward millions, trillions, and even 10¹⁰⁰ years into the future. Let's consider the end of everything.

End of Humanity – 10,000 years
Modern humans originated in Africa about 200,000 years ago. Since then, we've gone on to inhabit every single corner of the globe. But this is just temporary. The vast majority of every species that has ever lived on Earth is now extinct. To think that humans can avoid the fate of every other creature is arrogant. Like all life on Earth, our time is limited. How long will we last?

There are many natural and man made disasters that could wipe us out. From an asteroidstrike to worldwide pandemic; global warming to a nearby supernova detonation – there are many ways we could go. Perhaps we'll wrap it up in a mass extinction event, such as the one that killed the dinosaurs 65 million years ago, or "the Great Dying", 251 million years ago that killed 70% of land species and 96% of all marine species.

Perhaps another species (intelligent cockroaches, rats) will evolve, and out compete with us in our niche. Or maybe we'll engineer our robotic replacements.

But a species can last tens or even hundreds of millions of years. So how can we predict when our number will be up?

There's no way to know, but there's a calculation that can help. It's called the Doomsday Argument, developed in 1983 by astrophysicist Brandon Carter. According to Carter, if you assume that half of the humans who will ever live have already been born, you get approximately 60 billion people. If you assume that another 60 billion are yet to be born, our high population levels only give us another 9,000 years or so. Or more precisely, there's a 95% chance that humanity will have ended by the year 11,000.

There are other calculations, but they give similar amounts, ranging from a few thousand to a few million years.

That's a long time, but not long enough to appreciate the future the Universe has in store for itself.

End of Life – 500 million years – 5 billion years
We thank the Sun for giving us energy. Without it, there'd be no life on Earth. It's ironic, then, that the Sun will eventually kill all life on Earth.

That's because the Sun is slowly heating up.

One of the most fascinating books about this topic is The Life and Death of Planet Earth by Peter Ward and Donald Brownlee. In their book, they chronicle how Sun's energy output is slowly increasing. In as soon as 500 million years, temperatures on Earth will rise to the point that most of the world will be a desert. The largest creatures won't be able to survive anywhere but the relatively cooler poles.

Over the course of the next few billion years, evolution will seem to go reverse. The largest organisms and least heat tolerant animals will die out, leaving hardy insects and bacteria. Finally, it'll be so hot on the surface of the Earth that the oceans will boil away. There'll be no place to hide from the terrible temperatures. Only the organisms that live deep underground will survive, as they have already for billions of years.

End of the Earth – 7.5 billion years
As mentioned above, we exist because of the Sun's good graces. But as our star nears the end of its lifetime, it'll take our planet out as it goes; one way or another.

In approximately 5 billion years from now, the Sun will begin the final stage of its life, consuming the last of its hydrogen fuel supply. At that point, gravity will force the Sun to collapse, and only a small amount of hydrogen will remain in a shell wrapped around thestar's core. It will then expand into a red giant star, consuming each of the inner planets: firstMercury, then Venus, and finally encompassing even the orbit of Earth.

There is a controversy about whether or not a red giant Sun will actually burn up the Earth. In some scenarios, the change in the Sun's density as it expands causes the Earth to spiral out away from the Sun, keeping out of reach. In another scenario, the Sun's outer envelope will enclose the Earth. The additional friction will slow the Earth down, causing it to spiral down into the Sun.

Whatever the outcome, the Earth will be scorched to a cinder, and effectively destroyed, 5 billion years from now.

End of the Sun – 7.5 billion – 1 trillion years
When the Sun becomes a red giant, that's only the beginning of the end. With the end of its hydrogen, the Sun will have switched to fusing helium, then carbon, and finally oxygen. At that point, our Sun will lack the gravity to continue the fusion process. It will shut down, and shed its outside layers to form a planetary nebula, such as the ring nebula we can see in the night sky. It'll then settle down to live out the rest of its days as a white dwarf.

It will still retain most of its mass, but have a size no larger than the Earth's diameter. Once yellow-hot with the heat of fusion, the Sun will slowly cool down over time. Eventually, its temperature will match the background temperature of the Universe and it will become a cold black dwarf – an inert chunk of matter floating in the darkness of space.

Even the oldest white dwarfs still radiate at several thousand degrees Kelvin, so the Universe hasn't been around long enough for black dwarfs to exist.. yet. But give the Sun another 1 trillion years or so, and it should finally become a cold black dwarf.

End ofthe Solar System
Even though the Sun will have burned out billions of years from now,the planetsthat weren't consumed will remain. Perhaps even Earth will join that group. Certainly Jupiter, Saturn, the rest of theouter planets and the Kuiper belt objects will remain orbiting for eons.

A recently discovery, published in the journal Science, reported that astronomers had discovered a disk of rapidly rotating metallic material orbiting a white dwarf. Researchers built a simulation where they put hypothetical planets in orbit around a dying star, and found that the star's death wreaked havoc on the stability of a star system. Changes in the mass of a star causes planets to collide, and rearrange their orbits. Some spiral into their star, while others are ejected into interstellar space.

Once all these new gravitational interactions are worked out, all that might remain of our solar system is the white dwarf remnant of our Sun and the rapidly rotating disk of planetary wreckage surrounding it. Everything else will be lost to interstellar space.

End of Cosmology – 3 Trillion Years from Now
The Universe acts as a natural time machine. Since light moves at the speed of, well, light, we can look at distant objects and see them how they looked in the past. Look to the very ends of the visible Universe, and you see light that was emitted billions of years ago, shortly after the Big Bang.

It's handy, but there's a problem. That mysterious dark energy force, which is accelerating the expansion of the Universe is making the most distant galaxies move faster and faster away from us. Eventually, they will cross an event horizon and appear to be moving away from us faster than the speed of light. At this point, any light emitted by the galaxy will cease to reach us. Any galaxy that crosses this horizon will fade away from view, until its last photon reaches us. All galaxies will disappear from view forever.

According to a new research paper by Lawrence M. Krauss and Robert J. Scherrer, future astronomers living 3 trillion years from now will only see our own galaxy when they look into the night sky.

This accelerating expansion has another consequence as well. The cosmic microwave background radiation, which astronomers used to discover evidence of the Big Bang will have faded away too. Not only that, but the abundance of chemicals, which precisely match the amounts theorized for the Big Bang will be hidden by subsequent generations of stars.

And so, 3 trillion years from now, there won't be any trace of the Big Bang. No clues for future cosmologists to recognize that the Universe we live in started from a single point, and has been expanding ever since. The Universe will seem static and unchanging.

End of the Milky Way
Galaxies collide. All you have to do is look out into space with a telescopeand see the fate that awaits our galaxy. In all directions we can see the interactions between the gravity of various galaxies. At first the encounters are violent; galaxies tear at each other, stripping off material, and generating huge swaths of star formation. The dormant supermassive black holes at their centres spring to live and become active galactic nuclei, gobbling up the newly delivered material.

Our future merger partner is barreling towards us right now: Andromeda. In approximately 2 billion years from now, our two galaxies will collide, and then pull apart. Then they'll collide again and again until they settle down into a new, larger galaxy: Milkomedia. The twin supermassive black holes will orbit one another, and eventually merge together into an even more massive black hole.

Our position in the galaxy will change; we'll probably be pushed out to the outer reaches of the galaxy's halo – at least 100,000 light years from the centre. Since the Sun will still have billions of years left, some future form of life on Earth might be around to watch these events unfold.

The merger process will be complete approximately 7 billion years from now.

That's not the end of the galaxy, though. It will still be an island in space, with stars orbiting a central core. Over a long period of time, though, estimated to be between 10¹⁹ 10²⁰ years. The galaxy will erode, with all the stars escaping into intergalactic space.

End of Stars – 100 trillion years from now
We can look out into the Milky Way and see stars forming all around us. There is still enough remaining gas and dust in the Milky Way to create whole new generations of stars. But when we look at other galaxies, we can see older, elliptical galaxies which have already used up their free gas and dust. Instead of the bright, hot stars we see in star forming regions, these aging red galaxies are cooling down.

One day there won't be newly forming stars at all. And then one day, the last star will use up the last of its hydrogen fuel, become a red giant and then fade away to a white dwarf. Even the dimmest stars, the cool red dwarfs will use up their fuel – although, it might taken another 10 trillion years or so. They too will turn into black dwarfs.

And so, in about 100 trillion years from now, every star in the Universe, large and small, will be a black dwarf. An inert chunk of matter with the mass of a star, but at the background temperature of the Universe.

The End of Regular Matter – 10³⁰ years
So now we have a Universe with no stars, only cold black dwarfs. There will also be neutron stars and black holes left over from the time where there were stars in the Universe. The Universe will be completely dark.

A future observer might notice the occasional flash, when some object interacts with a black hole. Its matter will spread out into an accretion disk around the black hole. And for a brief period, it will flare up, emitting radiation. But then it too will be added to the mass of the black hole. And everything will go dark again.

Chunks of matter and binary black dwarfs will merge together creating new black holes, and these black holes will be consumed by even larger black holes. It might be that in the far future, all matter will exist in a few, truly massive black holes.

But even if matter escapes this fate, it's doomed eventually. Some theories of physicspredict that protons are unstable over long periods of time. They just can't last. Any matter that wasn't consumed by a black hole will start to decay. The protons will turn into radiation, leaving a fine mist of electrons, positrons, neutrinos and radiation to spread out into space.

Theorists anticipate that all protons in the Universe will decay over the course of 10³⁰ years.

End of Black Holes – 10¹⁰⁰ Years
Black holes were thought to be one-way streets. Matter goes in, but it doesn't come out. But famed astrophysicist Stephen Hawking turned that concept on its head with his theory that black holes can evaporate. It's not much, and it's not fast, but black holes release a tiny amount of radiation back into space.

As it releases this radiation, the black hole actually loses mass, finally evaporating away entirely. The amount of radiation increases as the black hole loses mass. It's actually possible that it could generate a final burst of X-rays and gamma rays as it disappears completely. Future observers (who survived their protons decaying) might see the occasional flash in an otherwise dark universe.

And then in about 10¹⁰⁰ years, the last black hole will be gone. All that remains is the radiation emitted.

The End of Everything – 10¹⁰⁰ years and beyond
When the last black hole evaporates, all that will remain in the Universe are photons of radiation, and elementary particles that escaped capture by black holes. The temperature of the entire Universe will reach a final temperature just above absolute zero.

Dark energy may play some future role, continuing the expansion of the Universe, accelerating each of these elementary particles and photons away from each other until they're effectively cut off from one another. No future gravity will bring them together again.

Perhaps there will be another Big Bang someday. Perhaps the Universe is cyclical and the whole process will start up again.

Perhaps it won't, and this bleak future of a cold, dead Universe is all that awaits us. It's not happy, but it's awe inspiring to consider the long future ahead, and helps us appreciate the vibrant age we live in today.

Farthest known galaxy in the Universe discovered

HUBBLE EUROPEAN SPACE AGENCY INFORMATION CENTRE
Posted: February 15, 2004

An international team of astronomers may have set a new record in discovering what is the most distant known galaxy in the Universe. Located an estimated 13 billion light-years away, the object is being viewed at a time only 750 million years after the big bang, when the Universe was barely 5 percent of its current age.

A new galaxy (split into two ?images? marked with an ellipse and a circle) was detected in this image taken with the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope. The extremely faint galaxy is so far away that its visible light has been stretched into infrared wavelengths, making the observations particularly difficult. Credit: European Space Agency, NASA, J.-P. Kneib (Observatoire Midi-Pyrenees) and R. Ellis (Caltech)

The primeval galaxy was identified by combining the power of the NASA/ESA Hubble Space Telescope and CARA?s W. M. Keck Telescopes on Mauna Kea in Hawaii. These great observatories got a boost from the added magnification of a natural ?cosmic gravitational lens? in space that further amplifies the brightness of the distant object.

The newly discovered galaxy is likely to be a young galaxy shining during the end of the so-called ?Dark Ages? - the period in cosmic history which ended with the first galaxies and quasars transforming opaque, molecular hydrogen into the transparent, ionized Universe we see today.

The new galaxy was detected in a long exposure of the nearby cluster of galaxies Abell 2218, taken with the Advanced Camera for Surveys on board the Hubble Space Telescope. This cluster is so massive that the light of distant objects passing through the cluster actually bends and is amplified, much as a magnifying glass bends and magnifies objects seen through it. Such natural gravitational ?telescopes? allow astronomers to see extremely distant and faint objects that could otherwise not be seen. The extremely faint galaxy is so far away its visible light has been stretched into infrared wavelengths, making the observations particularly difficult.

?As we were searching for distant galaxies magnified by Abell 2218, we detected a pair of strikingly similar images whose arrangement and colour indicate a very distant object,? said astronomer Jean-Paul Kneib (Observatoire Midi-Pyrenees and California Institute of Technology), who is lead author reporting the discovery in a forthcoming article in the Astrophysical Journal.

Analysis of a sequence of Hubble images indicate the object lies between a redshift of 6.6 and 7.1, making it the most distant source currently known. However, long exposures in the optical and infrared taken with spectrographs on the 10-meter Keck telescopes suggests that the object has a redshift towards the upper end of this range, around redshift 7.

Redshift is a measure of how much the wavelengths of light are shifted to longer wavelengths. The greater the shift in wavelength toward the redder regions of the spectrum, the more distant the object is.

?The galaxy we have discovered is extremely faint, and verifying its distance has been an extraordinarily challenging adventure,? said Dr. Kneib. ?Without the 25 x magnification afforded by the foreground cluster, this early object could simply not have been identified or studied in any detail at all with the present telescopes available. Even with aid of the cosmic lens, the discovery has only been possible by pushing our current observatories to the limits of their capabilities!?

Gravitational lenses produce different shaped images depending on the shape of the lensing body. If the lens is spherical then the image appears as an Einstein ring ? a ring of light; if the lens is elongated then the image is an Einstein cross ? it appears split into four distinct images; and if the lens is a galaxy cluster, like Abell 2218, then arcs and arclets (banana-shaped images) of light are formed. Credit: European Space Agency

Using the combination of the high resolution of Hubble and the large magnification of the cosmic lens, the astronomers estimate that this object, although very small - only 2,000 light-years across - is forming stars extremely actively. However, two intriguing properties of the new source are the apparent lack of the typically bright hydrogen emission line and its intense ultraviolet light which is much stronger than that seen in star- forming galaxies closer by.

?The properties of this distant source are very exciting because, if verified by further study, they could represent the hallmark of a truly young stellar system that ended the Dark Ages? added Dr. Richard Ellis, Steele Professor of Astronomy at Caltech, and a co-author in the article.

The team is encouraged by the success of their technique and plans to continue the search for more examples by looking through other cosmic lenses in the sky. Hubble?s exceptional resolution makes it ideally suited for such searches.

?Estimating the abundance and characteristic properties of sources at early times is particularly important in understanding how the Universe reionized itself, thus ending the Dark Ages,? said Mike Santos, a former Caltech graduate student, now a postdoctoral researcher at the Institute of Astronomy, Cambridge, UK. ?The cosmic lens has given us a first glimpse into this important epoch. We are now eager to learn more by finding further examples, although it will no doubt be challenging.?

?We are looking at the first evidence of our ancestors on the evolutionary tree of the entire Universe,? said Dr. Frederic Chaffee, director of the W. M. Keck Observatory, home to the twin 10-meter Keck telescopes that confirmed the discovery. ?Telescopes are virtual time machines, allowing our astronomers to look back to the early history of the cosmos, and these marvellous observations are of the earliest time yet.?