Cosmology Archives

November 25, 2011December 24, 2015 by Jon Voisey

Quadruply Lensed Dwarf Galaxy 12.8 Billion Light Years Away

Galaxy Cluster MACS J0329.6-0211 lenses several background galaxies including a distant dwarf galaxy. CREDIT: A. Zitrin, et al.

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Gravitational lensing is a powerful tool for astronomers that allows them to explore distant galaxies in far more detail than would otherwise be allowed. Without this technique, galaxies at the edge of the visible universe are little more than tiny blobs of light, but when magnified dozens of times by foreground clusters, astronomers are able to explore the internal structural properties more directly.

Recently, astronomers at the University of Heidelberg discovered a gravitational lensed galaxy that ranked among the most distant ever seen. Although there’s a few that beat this one out in distance, this one is remarkable for being a rare quadruple lens.

The images for this remarkable discovery were taken using the Hubble Space Telescope in August and October of this year, using a total of 16 different colored filters as well as additional data from the Spitzer infrared telescope. The foreground cluster, MACS J0329.6-0211, is some 4.6 billion light years distant. In the above image, the background galaxy has been split into four images, labelled by the red ovals and marked as 1.1 – 1.4. They are enlarged in the upper right.

Assuming that the mass of the foreground cluster is concentrated around the galaxies that were visible, the team attempted to reverse the effects the cluster would have on the distant galaxy, which would reverse the distortions. The restored image, also corrected for redshift, is shown in the lower box in the upper right corner.

After correcting for these distortions, the team estimated that the total mass of the distant galaxy is only a few billion times the mass of the Sun. In comparison, the Large Magellanic Cloud, a dwarf satellite to our own galaxy, is roughly ten billion solar masses. The overall size of the galaxy was determined to be small as well. These conclusions fit well with expectations of galaxies in the early universe which predict that the large galaxies in today’s universe were built from the combination of many smaller galaxies like this one in the distant past.

The galaxy also conforms to expectations regarding the amount of heavy elements which is significantly lower than stars like the Sun. This lack of heavy elements means that there should be little in the way of dust grains. Such dust tends to be a strong block of shorter wavelengths of light such as ultraviolet and blue. Its absence helps give the galaxy its blue tint.

Star formation is also high in the galaxy. The rate at which they predict new stars are being born is somewhat higher than in other galaxies discovered around the same distance, but the presence of brighter clumps in the restored image suggest the galaxy may be undergoing some interactions, driving the formation of new stars.

November 2, 2011January 14, 2016 by Nancy Atkinson

TV Viewing Alert: New Mini-Series: Fabric of the Cosmos

A new 4-part mini-series debuts tonight on PBS station in the US, featuring theoretical physicist Brian Greene. The series is called “Fabric of the Cosmos” and is based on Greene’s 2004 book of the same name. It premieres tonight (Nov. 2, 2011) on NOVA, with subsequent episodes airing November 9, 16 and 23. The series will probe the most extreme realms of the cosmos, from black holes to dark matter, to time bending and parallel realities.

Check your local listings for time.

October 18, 2011December 24, 2015 by Nancy Atkinson

Guest Post by Author Peter Shaver: Cosmic Time Scales

This single all-sky image, captured by the Planck telescope, simultaneously captured two snapshots that straddle virtually the entire 13.7 billion year history of the universe. Credit: ESA

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Editor’s note: Peter Shaver is the author of the new book “Cosmic Heritage – Evolution from the Big Bang to Conscious Life.” Find out here how you can win a copy!

The universe has gone through a number of distinct phases. The first part of the first second is speculative, but the physics of the latter part is well know to us. In the first several minutes the lightest elements (hydrogen and helium) were formed.

Over the next 380,000 years the universe was a hot (but always cooling) plasma of electrons, nuclei and photons. At 380,000 years it was cool enough for electrons and nuclei to combine into atoms, in a process called recombination. The photons were freed from the plasma, and the universe became transparent for the first time. As the universe was opaque before recombination and transparent after, we see this epoch as a ‘wall’, and it is known as the cosmic microwave background.

What followed was a period known as the ‘cosmic dark ages’. The only light was that of the fading afterglow of the Big Bang, and the matter was comprised of the primordial elements and the exotic ‘dark matter’. During this time gravitational accretion slowly but surely produced larger and larger concentrations of matter, and when these became sufficiently dense, nuclear reactions could form and the first stars and galaxies were born. These lit up and ionized the universe again, some 400-500 million years after the Big Bang, in what is known as the ‘reionization epoch’.

The activity increased exponentially, culminating in the ‘quasar epoch’ 2-4 billion years after the Big Bang, a frenetic period of chaotic star and galaxy formation, galaxy interactions, monster quasars and radio galaxies. This activity eventually began to drop off, although it still continues today; the incidence of quasars today is a thousand times less than it was at the peak of the quasar epoch. At 13.7 billion years, the universe has now reached a ‘dignified middle age’.

The ‘heavy elements’ such as carbon and oxygen, essential for life as we know it, are all produced in stars, and this process has been going on ever since the first stars formed. Each generation of stars ejects more heavy elements into the intergalactic medium, so the abundances of the heavy elements have been built up over time.

By the time the Sun and Earth were formed 4.6 billion years ago, over 8.4 billion years of star and planet formation had already taken place in the universe. Star formation still takes place today, so in total there have been over 13 billion years of star and planet formation.

Zooming in now to our planet, life started not long after the Earth itself formed, sometime between 3.8 and 3.5 billion years ago (bya). But for almost half the age of the Earth, the only forms of life were microorganisms such as bacteria. More complex life forms started to appear about 1-2 bya. Invertebrates, which appeared some 600 million years ago (mya), were the earliest multicellular life forms, and vertebrates appeared about 500 mya. Life invaded the land about 400 mya. The dinosaurs dominated from 240 mya until their extinction 66 mya, and then mammals gradually took over. Many species came and went. Our closest living relatives are the chimpanzees, which split off from our ancestral line 5-6 mya; our more recent relatives have all become extinct.

It is amazing to think how recently humans appeared on the cosmic scene. Our species only appeared about 200,000 years ago, our ancestors emerged out of Africa just 50,000 years ago, agriculture started 10,000 years ago, and we have had modern technology for only the last 100 years or so! We are newcomers to the universe.

We now know that there are planets orbiting other stars like our Sun, probably billions of them in our galaxy alone, and billions more in the billions of other galaxies. Given the huge timescale of the universe, any life on those planets is bound to be millions or billions of years more or less advanced than life on Earth. If it is less advanced, it would certainly not be able to communicate with us. If it is more advanced, its technology would probably be totally unrecognisable to us. Nevertheless, we are probably not alone in the universe.

Of course the timescales discussed above only cover the ‘conventional’ universe from the Big Bang to now. If there was a ‘preexisting’ multiverse, we have no idea how far back any ‘before’ may extend. And as the expansion of the universe is accelerating, the future of the universe may be very long indeed: trillions upon trillions of years.

Peter Shaver obtained a PhD in astrophysics at the University of Sydney in Australia, and spent most of his career as a senior scientist at the European Southern Observatory (ESO), based in Munich. He has authored or co-authored over 250 scientific papers, and edited six books on astronomy and astrophysics.

October 9, 2011December 24, 2015 by Jon Voisey

Abuse From Other Universes – A Second Opinion

Concentric circles interpreted as bruises from collisions with alternate universes. Image Credit: Feeney et al.

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At the end of last year, there was a flurry of activity from astronomers Gurzadyan and Penrose that considered the evidence of alternate universes or the existence of a universe prior to the Big Bang and suggested that such evidence may be imprinted on the cosmic microwave background as bruises of concentric circles. Quickly, this was followed by an announcement claiming to find just such circles. Of course, with an announcement this big, the statistical significance would need to be confirmed. A recent paper in the October issue of the Astrophysical Journal provides a second opinion.

The review was conducted by Amir Hajian at the Canadian Institute for Theoretical Astrophysics. To conduct the study, Hajian selected a large number of circles, similar to the ones reported in the previous studies and asked what the probability was that, randomly, the “edge” of the circles would contain hot-spots, similar to the ones predicted. These were then compared to the bruises reported by the other teams by examining their “variance” which is how much the points on the perimeter were spread around the average temperature.

Hajian notes that, with the resolution considered it would be possible to consider some 5 million circles. The results of his comparison demonstrated that it would be expected that some 0.3% of those should have features similar to the ones reported previously. With so many possibilities, this would imply that some 15,000 potential circles could be flagged as candidates for these cosmic bruises. Even the “best” candidate proposed in the Gurzadyan and Penrose study should still exist statistically.

As such, Hajian concludes that the features Gurzadyan and Penrose reported were not statistically anomalous. Hajian does not comment directly on Feeney et al.’s detection, but given theirs were constructed in a similar manner, it should be expected that they are similarly statistically insignificant. It would appear that if the fingerprints of other universes are embedded in the sky, they have been lost in the noise.

October 4, 2011December 24, 2015 by Nancy Atkinson

Accelerating Expansion of Universe Discovery Wins 2011 Nobel Prize in Physics

The accelerating, expanding Universe. Credit: NASA/WMAP

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Three scientists shared the 2011 Nobel Prize for physics for the discovery that the expansion of the universe is speeding up, the Nobel prize committee announced today. Half of the $1.5 million prize went to American Saul Perlmutter and the rest to two members of a second team which conducted similar work: American Adam Riess and U.S.-born Brian Schmidt, who is based in Australia. All three made the discovery through observations of distant supernovae.

Perlmutter is from the Lawrence Berkeley National Laboratory and University of California, Berkeley, and worked on the Supernova Cosmology Project. Schmidt is from the Australian National University and Riess is from the Johns Hopkins University and Space Telescope Science Institute, Baltimore. They worked together on the High-z Supernova Search Team.

In response to the announcement, Professor Sir Peter Knight, President of the Institute of Physics, said, “The recipients of today’s award are at the frontier of modern astrophysics and have triggered an enormous amount of research on dark energy.

“These researchers have opened our eyes to the true nature of our Universe. They are very well-deserved recipients.”

Source: IOP

September 30, 2011January 14, 2016 by Nancy Atkinson

New Simulation Shows How the Universe Evolved

Bolshoi Simulation

How has the universe evolved over time? A new supercomputer simulation has provided what scientists say is the most accurate and detailed large cosmological model of the evolution of the large-scale structure of the universe. Called the Bolshoi simulation, and it gives physicists and astronomers a powerful new tool for understanding cosmic mysteries such as galaxy formation, dark matter, and dark energy.

If the simulation is right, it is showing that the standard cosmological model is fairly spot-on.
Continue reading “New Simulation Shows How the Universe Evolved”

August 17, 2011December 24, 2015 by Nancy Atkinson

Now Available: 30 Free Lectures by Noted Astronomers

We just received a note from Andrew Franknoi and the Astronomical Society of the Pacific that they are making available, free of charge, 30 audio and video podcasts from talks given by distinguished astronomers on the latest ideas and discoveries in the field. Speakers include:

* Frank Drake, who began the experimental search for intelligent life among the stars,
* Mike Brown, who discovered most of the dwarf planets beyond Pluto (and whose humorous talk is entitled “How I Killed Pluto and Why it Had it Coming”),
* Natalie Batalha, project scientists on the Kepler Mission to find Earths around other stars,
* Alex Filippenko (national professor of the year) on finding black holes.

Recent topics added to the offerings include: multiple universes, Saturn’s moon Titan (with an atmosphere, rivers, and lakes), our explosive Sun, and whether we should expect doomsday in 2012.

The talks are part of the Silicon Valley Astronomy Lectures, jointly sponsored by NASA’s Ames Research Center, the Astronomical Society of the Pacific, the SETI Institute, and Foothill College.
They are available via the web and ITunes. For a complete list and to begin listening, go to:
http://www.astrosociety.org/education/podcast/

August 3, 2011December 24, 2015 by Vanessa Janek

Testing the Multiverse… Observationally!

Seven Year Microwave Sky (Credit: NASA/WMAP Science Team)

[/caption]The multiverse theory is famous for its striking imagery. Just imagine our own Universe, drifting among a veritable sea of spontaneously inflating “bubble universes”, each a self-contained and causally separate pocket of higher-dimensional spacetime. It’s quite an arresting picture. However, the theory is also famous for being one of the most criticized in all of cosmology. Why? For one, the idea is remarkably difficult, if not downright impossible, to test experimentally. But now, a team of British and Canadian scientists believe they may have found a way.

Attempts to prove the multiverse theory have historically relied upon examination of the CMB radiation, relic light from the Big Bang that satellites like NASA’s Wilkinson Microwave Anisotropy Probe, or WMAP, have probed with incredible accuracy. The CMB has already allowed astronomers to map the network of large-scale structure in today’s Universe from tiny fluctuations detected by WMAP. In a similar manner, some cosmologists have hoped to comb the CMB for disk-shaped patterns that would serve as evidence of collisions with other bubble universes.

Now, physicists at University College London, Imperial College London and the Perimeter Institute for Theoretical Physics have designed a computer algorithm that actually examines the WMAP data for these telltale signatures. After determining what the WMAP results would look like both with and without cosmic collisions, the team uses the algorithm to determine which scenario fits best with the actual WMAP data. Once the results are in, the team’s algorithm performs a statistical analysis to ensure that any signatures that are detected are in fact due to collisions with other universes, and are unlikely to be due to chance. As an added bonus, the algorithm also puts an upper limit on the number of collision signatures astronomers are likely to find.

While their method may sound fairly straightforward, the researchers are quick to acknowledge the difficulty of the task at hand. As UCL researcher and co-author of the paper Dr. Hiranya Peiris put it, “It’s a very hard statistical and computational problem to search for all possible radii of the collision imprints at any possible place in the sky. But,” she adds, “that’s what pricked my curiosity.”

The results of this ground-breaking project are not yet conclusive enough to determine whether we live in a multiverse or not; however, the scientists remain optimistic about the rigor of their method. The team hopes to continue its research as the CMB is probed more deeply by the Planck satellite, which began its fifth all-sky survey on July 29. The research is published in Physical Review Letters and Physical Review D.

Source: UCL

July 1, 2011December 24, 2015 by Vanessa Janek

Ancient Galaxies Fed On Gas, Not Collisions

The Sombrero Galaxy. Credit: ESO/P. Barthe

[/caption]The traditional picture of galaxy growth is not pretty. In fact, it’s a kind of cosmic cannibalism: two galaxies are caught in ominous tango, eventually melding together in a fiery collision, thus spurring on an intense but short-lived bout of star formation. Now, new research suggests that most galaxies in the early Universe increased their stellar populations in a considerably less violent way, simply by burning through their own gas over long periods of time.

The research was conducted by a group of astronomers at NASA’s Spitzer Science Center in Pasadena, California. The team used the Spitzer Space Telescope to peer at 70 distant galaxies that flourished when the Universe was only 1-2 billion years old. The spectra of 70% of these galaxies showed an abundance of H alpha, an excited form of hydrogen gas that is prevalent in busy star-forming regions. Today, only one out of every thousand galaxies carries such an abundance of H alpha; in fact, the team estimates that star formation in the early Universe outpaced that of today by a factor of 100!

This split view shows how a normal spiral galaxy around our local universe (left) might have looked back in the distant universe, when astronomers think galaxies would have been filled with larger populations of hot, bright stars (right). Image credit: NASA/JPL-Caltech/STScI

Not only did these early galaxies crank out stars much faster than their modern-day counterparts, but they created much larger stars as well. By grazing on their own stores of gas, galaxies from this epoch routinely formed stars up to 100 solar masses in size.

These impressive bouts of star formation occurred over the course of hundreds of millions of years. The extremely long time scales involved suggest that while they probably played a minor role, galaxy mergers were not the main precursor to star formation in the Universe’s younger years. “This type of galactic cannibalism was rare,” said Ranga-Ram Chary, a member of the team. “Instead, we are seeing evidence for a mechanism of galaxy growth in which a typical galaxy fed itself through a steady stream of gas, making stars at a much faster rate than previously thought.” Even on cosmic scales, it would seem that slow and steady really does win the race.

Source: JPL

July 1, 2011December 24, 2015 by Vanessa Janek

Most Distant Quasar Opens Window Into Early Universe

[/caption]Astronomers have uncovered yet another clue in their quest to understand the Universe’s early life: the most distant quasar ever observed. At a redshift of 7.1, it is a relic from when the cosmos was just 770 million years old – just 5% of its age today.

Quasars are extremely old, outrageously luminous balls of radiation that were prevalent in the early Universe. Each is thought to have been fueled at its core by an incredibly powerful supermassive black hole. The most recent discovery (which carries the romantic name ULAS J1120+0641) is noteworthy for a couple of reasons. First of all, its supermassive black hole weighs approximately two billion solar masses – an impressive feat of gravity so soon after the Big Bang. It is also incredibly bright, given its great distance. “Objects that lie at such large distance are almost impossible to find in visible-light surveys because their light is stretched by the expansion of the universe,” said Dr. Simon Dye of the University of Nottingham, a member of the team that discovered the object. “This means that by the time their light gets to Earth, most of it ends up in the infrared part of the electromagnetic spectrum.” Due to these effects, only about 100 visible quasars exist in the sky at redshifts higher than 7.

Up until recently, the most distant quasar observed was at a redshift of 6.4; but thanks to this discovery, astronomers can probe 100 million years further into the history of the Universe than ever before. Careful study of ULAS J1120+0641 and its properties will enable scientists to learn more about galaxy formation and supermassive black hole growth in early epochs. The research was published in the June 30 issue of Nature.

For further reading, see related paper by Chris Willot, Monster in the Early Universe

Source: EurekAlert