Water ‘Way Out There

Detection of the earliest and most distant water. CREDIT: Milde Science Communication, STScI, CFHT, J.-C. Cuillandre, Coelum.

A long time ago in a galaxy far, far away there was water. Astronomers have found tell-tale signatures of water molecules in a galaxy more than 11 billion light years from Earth. Using the giant, 100-meter-diameter radio telescope in Effelsberg, Germany, along with the Very Large Array (VLA) in New Mexico, scientists detected the most distant water yet seen in the Universe. Previously, the most distant water had been seen in a galaxy less than 7 billion light-years from Earth. Since it is so far away, we’re actually seeing it as it was long ago; as when the Universe was one-sixth the age it is now. The astronomers were able to take advantage of two types of natural “amplification” to detect the water in this galaxy. The galaxy, dubbed MG J0414+0534 has a quasar — a supermassive black hole powering bright emission — at its core. In the region near the core, the water molecules are acting as masers, the radio equivalent of lasers, to amplify radio waves at a specific frequency. Additionally, another galaxy was used as a gravitational lens to magnify the radio signals used to detect the water molecules.

The astronomers say their discovery indicates that such giant water masers were more common in the early Universe than they are today. At the galaxy’s great distance, even the strengthening of the radio waves done by the masers would not by itself have made them strong enough to detect with the radio telescopes.

With the help of gravitational lensing from another galaxy, nearly 8 billion light-years away, located directly in the line of sight from MG J0414+0534 to Earth, the foreground galaxy’s gravity served as a lens to further brighten the more-distant galaxy and make the emission from the water molecules visible to the radio telescopes.

Effelsberg Telescope.
Effelsberg Telescope.

The astronomers first detected the water signal with the Effelsberg telescope. They then turned to the VLA’s sharper imaging capability to confirm that it was indeed coming from the distant galaxy. The gravitational lens produces not one, but four images of MG J0414+0534 as seen from Earth. Using the VLA, the scientists found the specific frequency attributable to the water masers in the two brightest of the four lensed images.

The radio frequency emitted by the water molecules was Doppler shifted by the expansion of the Universe from 22.2 GHz to 6.1 GHz.

“We were only able to discover this distant water with the help of the gravitational lens,” said Violette Impellizzeri, an astronomer with the Max-Planck Institute for Radioastronomy (MPIfR) in Bonn, Germany. “This cosmic telescope reduced the amount of time needed to detect the water by a factor of about 1,000,” she added.

Water masers have been found in numerous galaxies at closer distances. Typically, they are thought to arise in disks of molecules closely orbiting a supermassive black hole at the galaxy’s core. The amplified radio emission is more often observed when the orbiting disk is seen nearly edge-on. However, the astronomers said MG J0414+0534 is oriented with the disk almost face-on as seen from Earth.

“This may mean that the water molecules in the masers we’re seeing are not in the disk, but in the superfast jets of material being ejected by the gravitational power of the black hole,” explained John McKean, also of MPIfR.

The team’s paper will be published in the Dec. 18 edition of Nature.

Source: NRAO

‘Cosmic Eye’ Helps Focus on Distant Galaxy’s Formation

Cosmic Eye. Credit: Hubble Space Telescope

Using gravitational lensing, astronomers have been able to see a young star-forming galaxy in the distant universe as it appeared only two billion years after the Big Bang. Appropriately enough, the galaxy used as a zoom lens was the “Cosmic Eye” galaxy, named so because through the effect of gravitational lensing, it looks like a giant eye in space. The researchers, led by Dr. Dan Stark, of Caltech, say this distant galaxy may provide insights into how our own galaxy may have evolved to its present state.

The astronomers used the ten meter Keck telescope in Hawaii, which is equipped with a laser-assisted guide star adaptive optics (AO) to correct for blurring in the Earth’s atmosphere. By combining the powerful telescope with the magnifying effect of the gravitational field of the foreground galaxy – called gravitational lensing – they were able to study the distant star system, which lies 11 billion light years from Earth. The Cosmic Eye, the foreground galaxy, is 2.2 billion light years from Earth.

The distortion of light rays enlarged the distant galaxy eight times.

This allowed the scientists to determine the galaxy’s internal velocity structure and compare it to later star systems such as the Milky Way.

In the image, the red source in the middle is the foreground lensing galaxy, while the blue ring is the near-complete ring image of the background star-forming galaxy.

Watch a movie of the gravitational lensing view.

Research co-author Dr. Mark Swinbank, in The Institute for Computational Cosmology, at Durham University, said, “This is the most detailed study there has been of an early galaxy. Effectively we are looking back in time to when the Universe was in its very early stages.

Stark said, “Gravity has effectively provided us with an additional zoom lens, enabling us to study this distant galaxy on scales approaching only a few hundred light years.

“This is ten times finer sampling than previously. As a result for the first time we can see that a typical-sized young galaxy is spinning and slowly evolving into a spiral galaxy much like our own Milky Way.”

Data from the Keck Observatory was combined with millimeter observations from the Plateau de Bure Interferometer, in the French Alps, which is sensitive to the distribution of cold gas destined to collapse to form stars.

Dr. Swinbank added, “Remarkably the cold gas traced by our millimetre observations shares the rotation shown by the young stars in the Keck observations.

“The distribution of gas seen with our amazing resolution indicates we are witnessing the gradual build up of a spiral disk with a central nuclear component.”

These observations has astronomers looking forward to the capabilities of the European Extremely Large Telescope (E -ELT) and the American Thirty Metre Telescope (TMT), which are being built and will be available in about 10 years.

Source: Durham University

Clash of Clusters Separates Dark Matter From Ordinary Matter

Credit: X-ray(NASA/CXC/Stanford/S.Allen); Optical/Lensing(NASA/STScI/UC Santa Barbara/M.Bradac)


A powerful collision of galaxy clusters captured by NASA’s Hubble Space Telescope and Chandra X-ray Observatory provides evidence for dark matter and insight into its properties. Observations of the cluster known as MACS J0025.4-1222 indicate that a titanic collision has separated dark matter from ordinary matter. The images also provide an independent confirmation of a similar effect detected previously in a region called the Bullet Cluster. Like the Bullet Cluster, this newly studied cluster shows a clear separation between dark and ordinary matter.

MACS J0025 formed after an enormously energetic collision between two large clusters. Using visible-light images from Hubble, the team was able to infer the distribution of the total mass — dark and ordinary matter. Hubble was used to map the dark matter (colored in blue) using a technique known as gravitational lensing. The Chandra data enabled the astronomers to accurately map the position of the ordinary matter, mostly in the form of hot gas, which glows brightly in X-rays (pink).

As the two clusters that formed MACS J0025 (each almost a whopping quadrillion times the mass of the Sun) merged at speeds of millions of miles per hour, the hot gas in the two clusters collided and slowed down, but the dark matter passed right through the smashup. The separation between the material shown in pink and blue therefore provides observational evidence for dark matter and supports the view that dark-matter particles interact with each other only very weakly or not at all, apart from the pull of gravity.

On the Chandra website, there are two animations, one that shows the different views of this cluster viewed by the different observatories, and another depicting how the galaxies may have collided.

Bullet Cluster.  Credit:  NASA/CXC/CfA/STScI
Bullet Cluster. Credit: NASA/CXC/CfA/STScI

These new results show that the Bullet Cluster is not an anomalous case and helps answers questions about how dark matter interacts with itself.

Sources: HubbleSite, Chandra

Hubble Survey of Gravitational Lenses Yields Measure of Dark Matter in Distant Galaxies

Hubble Space Telescope image shows Einstein ring of one of the SLACS gravitational lenses, with the lensed background galaxy enhanced in blue. A. Bolton (UH/IfA) for SLACS and NASA/ESA.

An international team of astronomers have compiled the largest-ever single collection of “gravitational lens” galaxies, and their survey yielded information on the masses of galaxies, including an inference of the amount of dark matter. Gravitational lensing occurs when two galaxies happen to aligned with one another along our line of sight in the sky. The gravitational field of the nearer galaxy distorts the image of the more distant galaxy into multiple arc-shaped images. Sometimes this effect even creates a complete ring, known as an “Einstein Ring.” The findings of this survey helps settle a long standing debate over the relationship between and mass and luminosity in galaxies.

Using the Advanced Camera for Surveys on the Hubble Space Telescope to image galaxies that had been identified as gravitational lens galaxies by the Sloan Digital Sky Survey, the team was able to measure the distances to both galaxies in each “lensing” set, as well as measure the masses of each galaxy.

Gravitational lensing creates a “mirage” of a ring, and the Einstein ring images can be up to 30 times brighter than the image of the distant galaxy would be in the absence of the lensing effect. By combining Hubble and Sloan data into the Sloan Lens ACS (or SLACS) Survey, the team was able to make a mathematical model describing the lensing effect and use that model to illustrate what we would see if we could remove the lensing effect.

Animation of the lensing effect.

“The SLACS collection of lenses is especially powerful for science,” said Adam Bolton from the University of Hawaii, lead author of two papers describing these latest results. “For each lens, we measured the apparent sizes of the Einstein rings on the sky using the Hubble images, and we measured the distances to the two galaxies of the aligned pair using Sloan data. By combining these measurements, we were able to deduce the mass of the nearer galaxy.”

By considering these galaxy masses along with measurements of their sizes, brightnesses, and stellar velocities, the SLACS astronomers were able to infer the presence of “dark matter” in addition to the visible stars within the galaxies. Dark matter is the mysterious, unseeable material that is the majority of matter in the universe. And with such a large number of lens galaxies across a range of masses, they found that the fraction of dark matter relative to stars increases systematically when going from galaxies of average mass to galaxies of high mass.

Mosaic of the SLACS galaxies.  Credit:  SLACS and NASA/ESA.
Mosaic of the SLACS galaxies. Credit: SLACS and NASA/ESA.

Albert Einstein predicted the existence of gravitational lenses in the 1930’s, but the first example was not discovered until the late 1970s. Since then, many more lenses have been discovered, but their scientific potential has been limited by the disparate assortment of known examples. The SLACS Survey has significantly changed this situation by discovering a single large and uniformly selected sample of strong lens galaxies. The SLACS collection promises to form the basis of many further scientific studies.

Original News Source: University of Hawaii

Record Breaking “Dark Matter Web” Structures Observed Spanning 270 Million Light Years Across


It is well documented that dark matter makes up the majority of the mass in our universe. The big problem comes when trying to prove dark matter really is out there. It is dark, and therefore cannot be seen. Dark matter may come in many shapes and sizes (from the massive black hole, to the tiny neutrino), but regardless of size, no light is emitted and therefore it cannot be observed directly. Astronomers have many tricks up their sleeves and are now able to indirectly observe massive black holes (by observing the gravitational, or lensing, effect on light passing by). Now, large-scale structures have been observed by analyzing how light from distant galaxies changes as it passes through the cosmic web of dark matter hundreds of millions of light years across…

Dark matter is believed to hold over 80% of the Universe’s total mass, leaving the remaining 20% for “normal” matter we know, understand and observe. Although we can observe billions of stars throughout space, this is only the tip of the iceberg for the total cosmic mass.

Using the influence of gravity on space-time as a tool, astronomers have observed halos of distant stars and galaxies, as their light is bent around invisible, but massive objects (such as black holes) between us and the distant light sources. Gravitational lensing has most famously been observed in the Hubble Space Telescope (HST) images where arcs of light from young and distant galaxies are warped around older galaxies in the foreground. This technique now has a use when indirectly observing the large-scale structure of dark matter intertwining its way between galaxies and clusters.

Astronomers from the University of British Columbia (UBC) in Canada have observed the largest structures ever seen of a web of dark matter stretching 270 million light years across, or 2000 times the size of the Milky Way. If we could see the web in the night sky, it would be eight times the area of the Moons disk.

This impressive observation was made possible by using dark matter gravity to signal its presence. Like the HST gravitational lensing, a similar method is employed. Called “weak gravitational lensing”, the method takes a portion of the sky and plots the distortion of the observed light from each distant galaxy. The results are then mapped to build a picture of the dark matter structure between us and the galaxies.

The team uses the Canada-France-Hawaii-Telescope (CFHT) for the observations and their technique has been developed over the last few years. The CFHT is a non-profit project that runs a 3.6 meter telescope on top of Mauna Kia in Hawaii.

Understanding the structure of dark matter as it stretches across the cosmos is essential for us to understand how the Universe was formed, how dark matter influences stars and galaxies, and will help us determine how the Universe will develop in the future.

This new knowledge is crucial for us to understand the history and evolution of the cosmos […] Such a tool will also enable us to glimpse a little more of the nature of dark matter.” – Ludovic Van Waerbeke, Assistant Professor, Department of Physics and Astronomy, UBC

Source: UBC Press Release

Another Solar System Found with Saturn and Jupiter-Sized Planets


As the search for extrasolar planets continues, researchers are finding systems more and more like our own Solar System. And today researchers announced another significant find: a system with two planets smaller than Jupiter and Saturn. It’s almost starting to sound like home.

The report, due to be published in the February 15th edition of the journal Science discusses a series of observations made back on March 28, 2006. An experiment, known as the Optical Gravitational Microlensing Equipment (OGLE), detected the telltale signal of a microlensing event on a star 5,000 light-years away.

In case you weren’t up in the latest techniques for planetary discovery, a lensing event happens when two stars line up perfectly in the sky from our perspective on Earth. The closer star acts as a natural lens, magnifying the light from the more distant star.

The curve of light coming from the event is very specific, and astronomers know when they’re seeing a microlensing event, compared to something else like a nova or a variable star.

But there are special situations, where the light from the star brightens normally, but then has an additional distortion. The gravity from planets orbiting the closer star can actually create this additional distortion. And from this, astronomers can calculate their size (amazing!). Only 4 planets had been discovered this way so far.

Okay, enough back story.

The OGLE group announced their potential lensing event, and astronomers around the world sprung into action, gathering data for the entire time that the stars were lined up.

Researchers first calculated that there was a Saturn-sized planet orbiting the star, and then another group found that there had to be a Jupiter-sized planet as well.

“Even though we observed the micolensing effect of the Saturn for less than 0.3 percent of its orbit, the observations simply could not be explained without accounting for the orbit,�? said David Bennett, a research associate professor of astrophysics from the University of Notre Dame.

Unfortunately, viewing this planetary system was a one-time event. We’ll probably never see this star line up again, so there’s no way to perform any followup observations.

Original Source: University of Notre Dame News Release

Hubble Sees an Ancient Elliptical Galaxy


As galaxies come together through successive mergers they take on the splendid spiral shape like our own Milky Way. Keep merging those larger galaxies, though, and you’ll eventually get an elliptical galaxy – a gigantic diffuse cloud of ancient stars with little structure. Such a galaxy, NGC 1132, was recently photographed by the Hubble Space Telescope.

The elliptical galaxy NGC 1132 belongs in this class of galaxies called “giant ellipticals”. And the galaxy, with its constellation of dwarf galaxies is known as a “fossil group”. They’re the remnants and wreckage from past collisions between large galaxies.

In visible light, NGC 1132 looks like a single, isolated galaxy. But using a technique called gravitational lensing to map out the surrounding dark matter, astronomers found that it resides in a huge cloud of the stuff. In fact, NGC 1132 has as much dark matter as you might find in a group of tens or even hundreds of galaxies.

And once again, in visible light, its stars extend 120,000 light years from its centre. But in the X-ray spectrum, the glow extends 10 times as far – again, similar to a group of galaxies.

So where do fossil groups like this come from? Astronomers think they’re the end product of cosmic collisions, where a single large galaxy consumes all of its neighbors. It’s also possible they’re the result of a strange process, where something stopped moderate galaxies from forming, and only a single large galaxy came together in that region of space.

By analyzing galaxies like this, astronomers will get a better sense of galaxy evolution. It’ll help predict what’s going to happen when the Milky Way and Andromeda collide billions of years in the future.

Original Source: ESA/Hubble News Release

Forget Black Holes, How Do You Find A Wormhole?

An artists impression of what it would look like inside a wormhole. Pretty. (credit: Space.com)

Finding a black hole is an easy task… compared with searching for a wormhole. Suspected black holes have a massive gravitational effect on planets, stars and even galaxies, generating radiation, producing jets and accretion disks. Black holes will even bend light through gravitational lensing. Now, try finding a wormhole… Any ideas? Well, a Russian researcher thinks he has found an answer, but a highly sensitive radio telescope plus a truckload of patience (I’d imagine) is needed to find a special wormhole signature…

A wormhole connecting two points within spacetime.
Wormholes are a valid consequence of Einstein’s general relativity view on the universe. A wormhole, in theory, acts as a shortcut or tunnel through space and time. There are several versions on the same theme (i.e. wormholes may link different universes; they may link the two separate locations in the same universe; they may even link black and white holes together), but the physics is similar, wormholes create a link two locations in space-time, bypassing normal three dimensional travel through space. Also, it is theorized, that matter can travel through some wormholes fuelling sci-fi stories like in the film Stargate or Star Trek: Deep Space Nine. If wormholes do exist however, it is highly unlikely that you’ll find a handy key to open the mouth of a wormhole in your back yard, they are likely to be very elusive and you’ll probably need some specialist equipment to travel through them (although this will be virtually impossible).

Alexander Shatskiy, from the Lebedev Physical Institute in Moscow, has an idea how these wormholes may be observed. For a start, they can be distinguished from black holes, as wormhole mouths do not have an event horizon. Secondly, if matter could possibly travel through wormholes, light certainly can, but the light emitted will have a characteristic angular intensity distribution. If we were viewing a wormhole’s mouth, we would be witness to a circle, resembling a bubble, with intense light radiating from the inside “rim”. Looking toward the center, we would notice the light sharply dim. At the center we would notice no light, but we would see right through the mouth of the wormhole and see stars (from our side of the universe) shining straight through.

For the possibility to observe the wormhole mouth, sufficiently advanced radio interferometers would be required to look deep into the extreme environments of galactic cores to distinguish this exotic cosmic ghost from its black hole counterpart.

However, just because wormholes are possible does not mean they do exist. They could simply be the mathematical leftovers of general relativity. And even if they do exist, they are likely to be highly unstable, so any possibility of traveling through time and space will be short lived. Besides, the radiation passing through will be extremely blueshifted, so expect to burn up very quickly. Don’t pack your bags quite yet…

Source: arXiv publication

Using Gravity to Find Planets in the Habitable Zone


Astronomers have several techniques to discover planets. But one of the least used so far, gravitational microlensing, might be just the right technique to find planets in the habitable zone of nearby dwarf stars.

The first way astronomers find planets is with the radial velocity technique. This is where the gravity of a heavy planet yanks its parent star around so that the wobbling motion too and fro can be measured.

The second technique is through transits. This is where a planet dims the light coming from its parent star as it passes in front. By subtracting the light from when the planet isn’t in front of the star, astronomers can even measure its atmosphere.

The third way is through gravitational microlensing. When two stars are perfectly lined up, the closer star acts as a natural lens, brightening the light from the more distant star. Here on Earth, we see a star brighten in a very characteristic way, and then dim down again. A blip in the change of brightness can be attributed to a planet.

Geometry of a lensing event.
Unlike the other two methods, microlensing allows you to reach out and see planets at tremendous distances – even clear across the galaxy. The problem with microlensing is that it’s a one-time opportunity. You’re never going to see those stars line up in just the same way again.

But Rosanne Di Stefano and Christopher Night from the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA think there’s another way microlensing could be used. In their research paper entitled, Discovery and Study ofNearby Habitable Planets with Mesolensing, the researchers propose that many stars have a high probability of becoming a lens.

Instead of watching the sky, hoping to see a lensing event, you watch specific stars and wait for them to pass in front of a more distant star.

These high-probablility lenses are known as mesolenses. By studying a large number of dwarf stars, they expect that many of them should pass in front of a more distant star as often as once a year. And if pick your targets carefully, like dwarf stars moving in front of the Magellanic Clouds, you might get even more opportunities.

Unlike other methods of planet detection, gravitational lensing relies on light from a more distant star. It is therefore important to ask what fraction of nearby dwarfs will pass in front of bright sources and so can be studied with lensing. Within 50 pc, there are approximately 2 dwarf stars, primarily M dwarfs, per square degree.

For less massive red dwarf stars, you should be able to see them at a distance of 30 light years, and for Sun-mass stars out to a distance of 3,000 light years. These stars are close enough that if a planet is detected in the habitable zone, followup techniques should be possible to confirm the discovery.

They calculated that there are approximately 200 dwarf stars passing in front of the Magellanic Clouds right now. And many of these will have lensing events with the stars in the dwarf galaxies.

Large Magellanic Cloud. Image credit: NASA
Instead of monitoring specific stars, previous surveys have just watched tens of millions of stars per night – hoping for any kind of lensing event. Even though 3,500 microlensing candidates have been discovered so far, they tend to be with stars at extreme ranges. Even if there were planets there, they wouldn’t show up in the observations.

But if you pick your stars carefully, and then watch them for lensing events, the researchers believe you should see that brightening on a regular basis. You could even see the same star brighten several times, and make follow-up observations on its planets.

And there’s another advantage. Both the radial velocity and transit methods rely on the planet and star being perfectly lined up from our vantage point. But a microlensing event still works, even if the planetary system is seen face on.

By using this technique, the researchers think that astronomers should turn up lensing events on a regular basis. Some of these stars will have planets, and some of these planets will be in their star’s habitable zone.

Original Source: Arxiv

Searching for Objects Even Stranger Than Black Holes


Black holes are already plenty bizarre. Imagine all the mass of several suns compressed down into an object of potentially infinitely small size. But what if you could find an object that’s even stranger: a theoretical “naked singularity”; a black hole spinning so quickly that it lacks an event horizon. A point in space where the density is infinite, yet still visible from the outside.

Here’s the current thinking on black holes. They’re formed when a large star collapses in on itself, lacking the outward pressure to counteract the inward pull of gravity. Once the object reaches a certain size its pull becomes so great that nothing, not even light can escape. The black hole surrounds itself in a shroud of darkness called the event horizon. Any object or radiation that passes through this event horizon is inevitably sucked down into the black hole. And that’s why they’re thought to be black.

But what if that’s not always correct? What if there are circumstances where black holes might not be black at all? It would take some serious spinning, however.

All the black holes discovered so far are thought to be spinning, sometimes more than 1,000 times a second. But in theory, if you could get a black hole spinning ludicrously fast, so that the angular momentum of its spin overcomes the gravitational pull of its mass, it should be able to shed its event horizon. A black hole with 10 times the mass of our Sun would need to be spinning a few thousand times a second.

And here’s the cool part. According to researchers from Duke University and Cambridge, an object spinning like this should be detectable by its gravitational lensing. This is where a massive object, like a black hole, acts like a natural lens to focus the light from a more distant object. If the researchers are right, astronomers should be able to see a telltale signature on the lensed light using existing instruments (or those coming soon).

Their research was published in the September 24th issue of the research journal Physical Review D.

Original Source: Duke University News Release