Tag Archives: galaxy

First Signs of Self-interacting Dark Matter?

Dark matter may not be completely dark after all


Based on our current scientific understanding of the universe and various surveys like the Cosmic Microwave Background observations by Planck or WMAP, we still only know about 4-5% of the visible or baryonic matter. Rest of the 96-94% is still a mystery. This huge unknown portion of the dark universe is known to be comprised of the dark energy (the source of accelerating expansion of the universe)  and dark matter (the extra un-explained mass of the galaxies). Despite having indirect signatures suggesting their presence, we still are not able to observe these phenomena.

For the first time dark matter may have been observed interacting with other dark matter in a way other than through the force of gravity. Observations of colliding galaxies made with ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have picked up the first intriguing hints about the nature of this mysterious component of the Universe.

This image from the NASA/ESA Hubble Space Telescope shows the rich galaxy cluster Abell 3827. The strange pale blue structures surrounding the central galaxies are gravitationally lensed views of a much more distant galaxy behind the cluster. The distribution of dark matter in the cluster is shown with blue contour lines. The dark matter clump for the galaxy at the left is significantly displaced from the position of the galaxy itself, possibly implying dark matter-dark matter interactions of an unknown nature are occuring. Credit: ESO/R. Massey
This image from the NASA/ESA Hubble Space Telescope shows the rich galaxy cluster Abell 3827. The strange pale blue structures surrounding the central galaxies are gravitationally lensed views of a much more distant galaxy behind the cluster.
The distribution of dark matter in the cluster is shown with blue contour lines. The dark matter clump for the galaxy at the left is significantly displaced from the position of the galaxy itself, possibly implying dark matter-dark matter interactions of an unknown nature are occuring.
Credit:
ESO/R. Massey

Using the MUSE instrument on ESO’s VLT in Chile, along with images from Hubble in orbit, a team of astronomers studied the simultaneous collision of four galaxies in the galaxy cluster Abell 3827. The team could trace out where the mass lies within the system and compare the distribution of the dark matter with the positions of the luminous galaxies.

Although dark matter cannot be seen, the team could deduce its location using a technique called gravitational lensing. The collision happened to take place directly in front of a much more distant, unrelated source. The mass of dark matter around the colliding galaxies severely distorted spacetime, deviating the path of light rays coming from the distant background galaxy — and distorting its image into characteristic arc shapes.

Our current understanding is that all galaxies exist inside clumps of dark matter. Without the constraining effect of dark matter’s gravity, galaxies like the Milky Way would fling themselves apart as they rotate. In order to prevent this, 85 percent of the Universe’s mass [1] must exist as dark matter, and yet its true nature remains a mystery.

In this study, the researchers observed the four colliding galaxies and found that one dark matter clump appeared to be lagging behind the galaxy it surrounds. The dark matter is currently 5000 light-years (50 000 million million kilometres) behind the galaxy — it would take NASA’s Voyager spacecraft 90 million years to travel that far.

A lag between dark matter and its associated galaxy is predicted during collisions if dark matter interacts with itself, even very slightly, through forces other than gravity [2]. Dark matter has never before been observed interacting in any way other than through the force of gravity.

Lead author Richard Massey at Durham University, explains: “We used to think that dark matter just sits around, minding its own business, except for its gravitational pull. But if dark matter were being slowed down during this collision, it could be the first evidence for rich physics in the dark sector — the hidden Universe all around us.”

The researchers note that more investigation will be needed into other effects that could also produce a lag. Similar observations of more galaxies, and computer simulations of galaxy collisions will need to be made.

Team member Liliya Williams of the University of Minnesota adds: “We know that dark matter exists because of the way that it interacts gravitationally, helping to shape the Universe, but we still know embarrassingly little about what dark matter actually is. Our observation suggests that dark matter might interact with forces other than gravity, meaning we could rule out some key theories about what dark matter might be.”

This result follows on from a recent result from the team which observed 72 collisions between galaxy clusters [3] and found that dark matter interacts very little with itself. The new work however concerns the motion of individual galaxies, rather than clusters of galaxies. Researchers say that the collision between these galaxies could have lasted longer than the collisions observed in the previous study — allowing the effects of even a tiny frictional force to build up over time and create a measurable lag [4].

Taken together, the two results bracket the behaviour of dark matter for the first time. Dark matter interacts more than this, but less than that. Massey added: “We are finally homing in on dark matter from above and below — squeezing our knowledge from two directions.”

Notes
[1] Astronomers have found that the total mass/energy content of the Universe is split in the proportions 68% dark energy, 27% dark matter and 5% “normal” matter. So the 85% figure relates to the fraction of “matter” that is dark.

[2] Computer simulations show that the extra friction from the collision would make the dark matter slow down. The nature of that interaction is unknown; it could be caused by well-known effects or some exotic unknown force. All that can be said at this point is that it is not gravity.

All four galaxies might have been separated from their dark matter. But we happen to have a very good measurement from only one galaxy, because it is by chance aligned so well with the background, gravitationally lensed object. With the other three galaxies, the lensed images are further away, so the constraints on the location of their dark matter too loose to draw statistically significant conclusions.

[3] Galaxy clusters contain up to a thousand individual galaxies.

[4] The main uncertainty in the result is the timespan for the collision: the friction that slowed the dark matter could have been a very weak force acting over about a billion years, or a relatively stronger force acting for “only” 100 million years.

Source: ESO

The powerful gravity of a galaxy embedded in a massive cluster of galaxies in this Hubble Space Telescope image is producing multiple images of a single distant supernova far behind it. Both the galaxy and the galaxy cluster are acting like a giant cosmic lens, bending and magnifying light from the supernova behind them, an effect called gravitational lensing.

The image shows the galaxy's location within a hefty cluster of galaxies called MACS J1149.6+2223, located more than 5 billion light-years away. In the enlarged inset view of the galaxy, the arrows point to the multiple copies of the exploding star, dubbed Supernova Refsdal, located 9.3 billion light-years from Earth. The images are arranged around the galaxy in a cross-shaped pattern called an Einstein Cross. The blue streaks wrapping around the galaxy are the stretched images of the supernova's host spiral galaxy, which has been distorted by the warping of space.

The four images were spotted on Nov. 11, 2014. This Hubble image combines data from three months of observations taken in visible light by the Advanced Camera for Surveys and in near-infrared light by the Wide Field Camera 3.

Object Names: SN Refsdal, MACS J1149.6+2223


Credit: NASA, ESA, and S. Rodney (JHU) and the FrontierSN team; T. Treu (UCLA), P. Kelly (UC Berkeley), and the GLASS team; J. Lotz (STScI) and the Frontier Fields team; M. Postman (STScI) and the CLASH team; and Z. Levay (STScI)

Significant progress in dark matter studies: Hubble Sees Supernova Split into Four Images by Cosmic Lens

Some of astronomy’s biggest goals include the study of dark matter and dark energy. These two phenomena were indirectly observed in 20th century and the questions about their nature still puzzle us. Astronomers, cosmologists, particle physicists, theoretical physicists and researchers in other related areas are trying hard to find more and more clues about the nature of dark matter and dark energy which comprise of around 95% of our universe.

The powerful gravity of a galaxy embedded in a massive cluster of galaxies in this Hubble Space Telescope image is producing multiple images of a single distant supernova far behind it. Both the galaxy and the galaxy cluster are acting like a giant cosmic lens, bending and magnifying light from the supernova behind them, an effect called gravitational lensing. The image shows the galaxy’s location within a hefty cluster of galaxies called MACS J1149.6+2223, located more than 5 billion light-years away. In the enlarged inset view of the galaxy, the arrows point to the multiple copies of the exploding star, dubbed Supernova Refsdal, located 9.3 billion light-years from Earth.
The images are arranged around the galaxy in a cross-shaped pattern called an Einstein Cross. The blue streaks wrapping around the galaxy are the stretched images of the supernova’s host spiral galaxy, which has been distorted by the warping of space. The four images were spotted on Nov. 11, 2014. This Hubble image combines data from three months of observations taken in visible light by the Advanced Camera for Surveys and in near-infrared light by the Wide Field Camera 3.
Object Names: SN Refsdal, MACS J1149.6+2223
Credit: NASA, ESA, and S. Rodney (JHU) and the FrontierSN team; T. Treu (UCLA), P. Kelly (UC Berkeley), and the GLASS team; J. Lotz (STScI) and the Frontier Fields team; M. Postman (STScI) and the CLASH team; and Z. Levay (STScI)

Astronomers using NASA’s Hubble Space Telescope have spotted for the first time a distant supernova split into four images. The multiple images of the exploding star are caused by the powerful gravity of a foreground elliptical galaxy embedded in a massive cluster of galaxies.

This unique observation will help astronomers refine their estimates of the amount and distribution of dark matter in the lensing galaxy and cluster. Dark matter cannot be seen directly but is believed to make up most of the universe’s mass.

The gravity from both the elliptical galaxy and the galaxy cluster distorts and magnifies the light from the supernova behind them, an effect called gravitational lensing. First predicted by Albert Einstein, this effect is similar to a glass lens bending light to magnify and distort the image of an object behind it. The multiple images are arranged around the elliptical galaxy in a cross-shaped pattern called an Einstein Cross, a name originally given to a particular multiply imaged quasar, the bright core of an active galaxy.

The elliptical galaxy and its cluster, MACS J1149.6+2223, are 5 billion light-years from Earth. The supernova behind it is 9.3 billion light-years away.

Although astronomers have discovered dozens of multiply imaged galaxies and quasars, they have never seen a stellar explosion resolved into several images. “It really threw me for a loop when I spotted the four images surrounding the galaxy — it was a complete surprise,” said Patrick Kelly of the University of California, Berkeley, a member of the Grism Lens Amplified Survey from Space (GLASS) collaboration. The GLASS group is working with the Frontier Field Supernova (FrontierSN) team to analyze the exploding star. Kelly is also the lead author on the science paper, which will appear on March 6 in a special issue of the journal Science celebrating the centenary of Albert Einstein’s Theory of General Relativity.

When the four images fade away, astronomers predict they will have a rare opportunity to catch a rerun of the supernova. This is because the current four-image pattern is only one part of the lensing display. The supernova may have appeared as a single image some 20 years ago elsewhere in the cluster field, and it is expected to reappear once more within the next five years.

This prediction is based on computer models of the cluster, which describe the various paths the supernova light is taking through the maze of clumpy dark matter in the galactic grouping. Each image takes a different route through the cluster and arrives at a different time, due, in part, to differences in the length of the pathways the light follows to reach Earth. The four supernova images captured by Hubble, for example, appeared within a few days or weeks of each other.

The supernova’s various light paths are analogous to several trains that leave a station at the same time, all traveling at the same speed and bound for the same location. Each train, however, takes a different route, and the distance for each route is not the same. Some trains travel over hills. Others go through valleys, and still others chug around mountains. Because the trains travel over different track lengths across different terrain, they do not arrive at their destination at the same time. Similarly, the supernova images do not appear at the same time because some of the light is delayed by traveling around bends created by the gravity of dense dark matter in the intervening galaxy cluster.

“Our model for the dark matter in the cluster gives us the prediction of when the next image will appear because it tells us how long each train track is, which correlates with time,” said Steve Rodney of the Johns Hopkins University in Baltimore, Maryland, leader of the FrontierSN team. “We already missed one that we think appeared about 20 years ago, and we found these four images after they had already appeared. The prediction of this future image is the one that is most exciting because we might be able to catch it. We hope to come back to this field with Hubble, and we’ll keep looking to see when that expected next image appears.”

Measuring the time delays between images offers clues to the type of warped-space terrain the supernova’s light had to cover and will help the astronomers fine-tune the models that map out the cluster’s mass. “We will measure the time delays, and we’ll go back to the models and compare them to the model predictions of the light paths,” Kelly said. “The lens modelers, such as Adi Zitrin (California Institute of Technology) from our team, will then be able to adjust their models to more accurately recreate the landscape of dark matter, which dictates the light travel time.”

While making a routine search of the GLASS team’s data, Kelly spotted the four images of the exploding star on Nov. 11, 2014. The FrontierSN and GLASS teams have been searching for such highly magnified explosions since 2013, and this object is their most spectacular discovery. The supernova appears about 20 times brighter than its natural brightness, due to the combined effects of two overlapping lenses. The dominant lensing effect is from the massive galaxy cluster, which focuses the supernova light along at least three separate paths. A secondary lensing effect occurs when one of those light paths happens to be precisely aligned with a specific elliptical galaxy within the cluster. “The dark matter of that individual galaxy then bends and refocuses the light into four more paths,” Rodney explained, “generating the rare Einstein Cross pattern we are currently observing.”

The two teams spent a week analyzing the object’s light, confirming it was the signature of a supernova. They then turned to the W.M. Keck Observatory on Mauna Kea, in Hawaii, to measure the distance to the supernova’s host galaxy.

The astronomers nicknamed the supernova Refsdal in honor of Norwegian astronomer Sjur Refsdal, who, in 1964, first proposed using time-delayed images from a lensed supernova to study the expansion of the universe. “Astronomers have been looking to find one ever since,” said Tommaso Treu of the University of California, Los Angeles, the GLASS project’s principal investigator. “The long wait is over!”

The Frontier Fields survey is a three-year program that uses Hubble and the gravitational-lensing effects of six massive galaxy clusters to probe not only what is inside the clusters but also what is beyond them. The three-year FrontierSN program studies supernovae that appear in and around the galaxy clusters of the Frontier Fields and GLASS surveys. The GLASS survey is using Hubble’s spectroscopic capabilities to study remote galaxies through the cosmic telescopes of 10 massive galaxy clusters, including the six in the Frontier Fields.

Supernova Refsdal and Galaxy Cluster MACS J1149.6+2223
Source: Hubblesite.org

Source: Hubble Site

This spectacular view from the NASA/ESA Hubble Space Telescope shows the rich galaxy cluster Abell 1689. The huge concentration of mass bends light coming from more distant objects and can increase their total apparent brightness and make them visible. One such object, A1689-zD1, is located in the box — although it is still so faint that it is barely seen in this picture.

New observations with ALMA and ESO’s VLT have revealed that this object is a dusty galaxy seen when the Universe was just 700 million years old.

Credit:
NASA; ESA; L. Bradley (Johns Hopkins University); R. Bouwens (University of California, Santa Cruz); H. Ford (Johns Hopkins University); and G. Illingworth (University of California, Santa Cruz)

An Old-looking Galaxy in a Young Universe

ALMA and VLT probe surprisingly dusty and evolved galaxy


One of the most distant galaxies ever observed has provided astronomers with the first detection of dust in such a remote star-forming system and tantalising evidence for the rapid evolution of galaxies after the Big Bang. The new observations have used ALMA to pick up the faint glow from cold dust in the galaxy A1689-zD1 and used ESO’s Very Large Telescope to measure its distance.

A team of astronomers, led by Darach Watson from the University of Copenhagen, used the Very Large Telescope’s X-shooter instrument along with the Atacama Large Millimeter/submillimeter Array (ALMA) to observe one of the youngest and most remote galaxies ever found. They were surprised to discover a far more evolved system than expected. It had a fraction of dust similar to a very mature galaxy, such as the Milky Way. Such dust is vital to life, because it helps form planets, complex molecules and normal stars.

The target of their observations is called A1689-zD1 [1]. It is observable only by virtue of its brightness being amplified more than nine times by a gravitational lens in the form of the spectacular galaxy cluster, Abell 1689, which lies between the young galaxy and the Earth. Without the gravitational boost, the glow from this very faint galaxy would have been too weak to detect.

This spectacular view from the NASA/ESA Hubble Space Telescope shows the rich galaxy cluster Abell 1689. The huge concentration of mass bends light coming from more distant objects and can increase their total apparent brightness and make them visible. One such object, A1689-zD1, is located in the box — although it is still so faint that it is barely seen in this picture. New observations with ALMA and ESO’s VLT have revealed that this object is a dusty galaxy seen when the Universe was just 700 million years old. Credit: NASA; ESA; L. Bradley (Johns Hopkins University); R. Bouwens (University of California, Santa Cruz); H. Ford (Johns Hopkins University); and G. Illingworth (University of California, Santa Cruz)
This spectacular view from the NASA/ESA Hubble Space Telescope shows the rich galaxy cluster Abell 1689. The huge concentration of mass bends light coming from more distant objects and can increase their total apparent brightness and make them visible. One such object, A1689-zD1, is located in the box — although it is still so faint that it is barely seen in this picture.
New observations with ALMA and ESO’s VLT have revealed that this object is a dusty galaxy seen when the Universe was just 700 million years old.
Credit:
NASA; ESA; L. Bradley (Johns Hopkins University); R. Bouwens (University of California, Santa Cruz); H. Ford (Johns Hopkins University); and G. Illingworth (University of California, Santa Cruz)

We are seeing A1689-zD1 when the Universe was only about 700 million years old — five percent of its present age [2]. It is a relatively modest system — much less massive and luminous than many other objects that have been studied before at this stage in the early Universe and hence a more typical example of a galaxy at that time.

A1689-zD1 is being observed as it was during the period of reionisation, when the earliest stars brought with them a cosmic dawn, illuminating for the first time an immense and transparent Universe and ending the extended stagnation of the Dark Ages. Expected to look like a newly formed system, the galaxy surprised the observers with its rich chemical complexity and abundance of interstellar dust.

For high resolution image : Click Here!

After confirming the galaxy’s distance using the VLT,” said Darach Watson, “we realised it had previously been observed with ALMA. We didn’t expect to find much, but I can tell you we were all quite excited when we realised that not only had ALMA observed it, but that there was a clear detection. One of the main goals of the ALMA Observatory was to find galaxies in the early Universe from their cold gas and dust emissions — and here we had it!

This galaxy was a cosmic infant — but it proved to be precocious. At this age it would be expected to display a lack of heavier chemical elements — anything heavier than hydrogen and helium, defined in astronomy as metals. These are produced in the bellies of stars and scattered far and wide once the stars explode or otherwise perish. This process needs to be repeated for many stellar generations to produce a significant abundance of the heavier elements such as carbon, oxygen and nitrogen.

Surprisingly, the galaxy A1689-zD1 seemed to be emitting a lot of radiation in the far infrared [3], indicating that it had already produced many of its stars and significant quantities of metals, and revealed that it not only contained dust, but had a dust-to-gas ratio that was similar to that of  much more mature galaxies.

Although the exact origin of galactic dust remains obscure,” explains Darach Watson, “our findings indicate that its production occurs very rapidly, within only 500 million years of the beginning of star formation in the Universe — a very short cosmological time frame, given that most stars live for billions of years.”

The findings suggest A1689-zD1 to have been consistently forming stars at a moderate rate since 560 million years after the Big Bang, or else to have passed through its period of extreme starburst very rapidly before entering a declining state of star formation.

Prior to this result, there had been concerns among astronomers that such distant galaxies would not be detectable in this way, but A1689-zD1 was detected using only brief observations with ALMA.

Kirsten Knudsen (Chalmers University of Technology, Sweden), co-author of the paper, added, “This amazingly dusty galaxy seems to have been in a rush to make its first generations of stars. In the future, ALMA will be able to help us to find more galaxies like this, and learn just what makes them so keen to grow up.”

Notes

[1] This galaxy was noticed earlier in the Hubble images, and suspected to be very distant, but the distance could not be confirmed at that time.

[2] This corresponds to a redshift of 7.5.

[3] This radiation is stretched by the expansion of the Universe into the millimetre wavelength range by the time it gets to Earth and hence can be detected with ALMA.

Source : ESO

This small extract from the VISTA VVV survey of the central parts of the Milky Way shows the famous Trifid Nebula to the right of centre. It appears as faint and ghostly at these infrared wavelengths when compared to the familiar view at visible wavelengths. This transparency has brought its own benefits — many previously hidden background objects can now be seen clearly. Among these are two newly discovered Cepheid variable stars, the first ever spotted on the far side of the galaxy near its central plane.

Credit:
ESO/VVV consortium/D. Minniti

VISTA Stares Right Through the Milky Way

New infrared view of the Trifid Nebula reveals new variable stars far beyond


A new image taken with ESO’s VISTA survey telescope reveals the famous Trifid Nebula in a new and ghostly light. By observing in infrared light, astronomers can see right through the dust-filled central parts of the Milky Way and spot many previously hidden objects. In just this tiny part of one of the VISTA surveys, astronomers have discovered two unknown and very distant Cepheid variable stars that lie almost directly behind the Trifid. They are the first such stars found that lie in the central plane of the Milky Way beyond its central bulge.

This small extract from the VISTA VVV survey of the central parts of the Milky Way shows the famous Trifid Nebula to the right of centre. It appears as faint and ghostly at these infrared wavelengths when compared to the familiar view at visible wavelengths. This transparency has brought its own benefits — many previously hidden background objects can now be seen clearly. Among these are two newly discovered Cepheid variable stars, the first ever spotted on the far side of the galaxy near its central plane. Credit: ESO/VVV consortium/D. Minniti
This small extract from the VISTA VVV survey of the central parts of the Milky Way shows the famous Trifid Nebula to the right of centre. It appears as faint and ghostly at these infrared wavelengths when compared to the familiar view at visible wavelengths. This transparency has brought its own benefits — many previously hidden background objects can now be seen clearly. Among these are two newly discovered Cepheid variable stars, the first ever spotted on the far side of the galaxy near its central plane.
Credit:
ESO/VVV consortium/D. Minniti

As one of its major surveys of the southern sky, the VISTA telescope at ESO’s Paranal Observatory in Chile is mapping the central regions of the Milky Way in infrared light to search for new and hidden objects. This VVV survey (standing forVISTA Variables in the Via Lactea) is also returning to the same parts of the sky again and again to spot objects that vary in brightness as time passes.

A tiny fraction of this huge VVV dataset has been used to create this striking new picture of a famous object, the star formation region Messier 20, usually called the Trifid Nebula, because of the ghostly dark lanes that divide it into three parts when seen through a telescope.

The familiar pictures of the Trifid show it in visible light, where it glows brightly in both the pink emission from ionised hydrogen and the blue haze of scattered light from hot young stars. Huge clouds of light-absorbing dust are also prominent. But the view in the VISTA infrared picture is very different. The nebula is just a ghost of its usual visible-light self. The dust clouds are far less prominent and the bright glow from the hydrogen clouds is barely visible at all. The three-part structure is almost invisible.

In the new image, as if to compensate for the fading of the nebula, a spectacular new panorama comes into view. The thick dust clouds in the disc of our galaxy that absorb visible light allow through most of the infrared light that VISTA can see. Rather than the view being blocked, VISTA can see far beyond the Trifid and detect objects on the other side of the galaxy that have never been seen before.

By chance this picture shows a perfect example of the surprises that can be revealed when imaging in the infrared. Apparently close to the Trifid in the sky, but in reality about seven times more distant [1], a newly discovered pair of variable stars has been found in the VISTA data. These are Cepheid variables, a type of bright star that is unstable and slowly brightens and then fades with time. This pair of stars, which the astronomers think are the brightest members of a cluster of stars, are the only Cepheid variables detected so far that are close to the central plane, but on the far side of the galaxy. They brighten and fade over a period of eleven days.

Notes

[1] The Trifid Nebula lies about 5200 light-years from Earth, the centre of the Milky Way is about 27 000 light-years away, in almost the same direction, and the newly discovered Cepheids are at a distance of about 37 000 light-years.

More Related Images: http://hubblesite.org/newscenter/archive/releases/2015/02/image/a/

Hubble’s High-Definition Panoramic View of the Andromeda Galaxy

The largest NASA Hubble Space Telescope image ever assembled, this sweeping view of a portion of the Andromeda galaxy (M31) is the sharpest large composite image ever taken of our galactic neighbor. Though the galaxy is over 2 million light-years away, the Hubble telescope is powerful enough to resolve individual stars in a 61,000-light-year-long section of the galaxy’s pancake-shaped disk. It’s like photographing a beach and resolving individual grains of sand. And, there are lots of stars in this sweeping view — over 100 million, with some of them in thousands of star clusters seen embedded in the disk. This ambitious photographic cartography of the Andromeda galaxy represents a new benchmark for precision studies of large spiral galaxies which dominate the universe’s population of over 100 billion galaxies. Never before have astronomers been able to see individual stars over a major portion of an external spiral galaxy. Most of the stars in the universe live inside such majestic star cities, and this is the first data that reveal populations of stars in context to their home galaxy.

Click here for more related images

The panorama is the product of the Panchromatic Hubble Andromeda Treasury (PHAT) program. Images were obtained from viewing the galaxy in near-ultraviolet, visible, and near-infrared wavelengths, using the Advanced Camera for Surveys and the Wide Field Camera 3 aboard Hubble. This view shows the galaxy in its natural visible-light color, as photographed with Hubble’s Advanced Camera for Surveys in red and blue filters July 2010 through October 2013.

DETAILS ABOUT THIS IMAGE:

The largest NASA Hubble Space Telescope image ever assembled, this sweeping bird’s-eye view of a portion of the Andromeda galaxy (M31) is the sharpest large composite image ever taken of our galactic next-door neighbor. Though the galaxy is over 2 million light-years away, the Hubble telescope is powerful enough to resolve individual stars in a 61,000-light-year-long stretch of the galaxy’s pancake-shaped disk. It’s like photographing a beach and resolving individual grains of sand. And, there are lots of stars in this sweeping view — over 100 million, with some of them in thousands of star clusters seen embedded in the disk.

This ambitious photographic cartography of the Andromeda galaxy represents a new benchmark for precision studies of large spiral galaxies that dominate the universe’s population of over 100 billion galaxies. Never before have astronomers been able to see individual stars inside an external spiral galaxy over such a large contiguous area. Most of the stars in the universe live inside such majestic star cities, and this is the first data that reveal populations of stars in context to their home galaxy.

Hubble traces densely packed stars extending from the innermost hub of the galaxy, seen at left. Moving out from this central galactic bulge, the panorama sweeps from the galaxy’s central bulge across lanes of stars and dust to the sparser outer disk. Large groups of young blue stars indicate the locations of star clusters and star-forming regions. The stars bunch up in the blue ring-like feature toward the right side of the image. The dark silhouettes trace out complex dust structures. Underlying the entire galaxy is a smooth distribution of cooler red stars that trace Andromeda’s evolution over billions of years.

Because the galaxy is only 2.5 million light-years from Earth, it is a much bigger target in the sky than the myriad galaxies Hubble routinely photographs that are billions of light-years away. This means that the Hubble survey is assembled together into a mosaic image using 7,398 exposures taken over 411 individual pointings.

The panorama is the product of the Panchromatic Hubble Andromeda Treasury (PHAT) program. Images were obtained from viewing the galaxy in near-ultraviolet, visible, and near-infrared wavelengths, using the Advanced Camera for Surveys and the Wide Field Camera 3 aboard Hubble. This cropped view shows a 48,000-light-year-long stretch of the galaxy in its natural visible-light color, as photographed with Hubble’s Advanced Camera for Surveys in red and blue filters July 2010 through October 2013.

The panorama is being presented at the 225th Meeting of the Astronomical Society in Seattle, Washington.

Source: Hubble Site

The enormous structure, dubbed the Fermi Bubbles, was discovered five years ago as a gamma-ray glow on the sky in the direction of the galactic center. The balloon-like features have since been observed in X-rays and radio waves. But astronomers needed NASA's Hubble Space Telescope to measure for the first time the velocity and composition of the mystery lobes. 

Credit: Hubble Site

Hubble Discovers that Milky Way Core Drives Wind at 2 Million Miles Per Hour

At a time when our earliest human ancestors had recently mastered walking upright, the heart of our Milky Way galaxy underwent a titanic eruption, driving gases and other material outward at 2 million miles per hour.

Now, at least 2 million years later, astronomers are witnessing the aftermath of the explosion: billowing clouds of gas towering about 30,000 light-years above and below the plane of our galaxy.

The enormous structure was discovered five years ago as a gamma-ray glow on the sky in the direction of the galactic center. The balloon-like features have since been observed in X-rays and radio waves. But astronomers needed NASA’s Hubble Space Telescope to measure for the first time the velocity and composition of the mystery lobes. They now seek to calculate the mass of the material being blown out of our galaxy, which could lead them to determine the outburst’s cause from several competing scenarios.

Astronomers have proposed two possible origins for the bipolar lobes: a firestorm of star birth at the Milky Way’s center or the eruption of its supermassive black hole. Although astronomers have seen gaseous winds, composed of streams of charged particles, emanating from the cores of other galaxies, they are getting a unique, close-up view of our galaxy’s own fireworks.

“When you look at the centers of other galaxies, the outflows appear much smaller because the galaxies are farther away,” said Andrew Fox of the Space Telescope Science Institute in Baltimore, Maryland, lead researcher of the study. “But the outflowing clouds we’re seeing are only 25,000 light-years away in our galaxy. We have a front-row seat. We can study the details of these structures. We can look at how big the bubbles are and can measure how much of the sky they are covering.”

Fox’s results will be published in The Astrophysical Journal Letters and will be presented at the American Astronomical Society meeting in Seattle, Washington.

The giant lobes, dubbed Fermi Bubbles, initially were spotted using NASA’s Fermi Gamma-ray Space Telescope. The detection of high-energy gamma rays suggested that a violent event in the galaxy’s core aggressively launched energized gas into space. To provide more information about the outflows, Fox used Hubble’s Cosmic Origins Spectrograph (COS) to probe the ultraviolet light from a distant quasar that lies behind the base of the northern bubble. Imprinted on that light as it travels through the lobe is information about the velocity, composition, and temperature of the expanding gas inside the bubble, which only COS can provide.

The enormous structure, dubbed the Fermi Bubbles, was discovered five years ago as a gamma-ray glow on the sky in the direction of the galactic center. The balloon-like features have since been observed in X-rays and radio waves. But astronomers needed NASA's Hubble Space Telescope to measure for the first time the velocity and composition of the mystery lobes.  Credit: Hubble Site
The enormous structure, dubbed the Fermi Bubbles, was discovered five years ago as a gamma-ray glow on the sky in the direction of the galactic center. The balloon-like features have since been observed in X-rays and radio waves. But astronomers needed NASA’s Hubble Space Telescope to measure for the first time the velocity and composition of the mystery lobes.
Credit: Hubble Site

Fox’s team was able to measure that the gas on the near side of the bubble is moving toward Earth and the gas on the far side is travelling away. COS spectra show that the gas is rushing from the galactic center at roughly 2 million miles an hour (3 million kilometers an hour).

“This is exactly the signature we knew we would get if this was a bipolar outflow,” explained Rongmon Bordoloi of the Space Telescope Science Institute, a co-author on the science paper. “This is the closest sightline we have to the galaxy’s center where we can see the bubble being blown outward and energized.”

The COS observations also measure, for the first time, the composition of the material being swept up in the gaseous cloud. COS detected silicon, carbon, and aluminum, indicating that the gas is enriched in the heavy elements produced inside stars and represents the fossil remnants of star formation.

COS measured the temperature of the gas at approximately 17,500 degrees Fahrenheit, which is much cooler than most of the super-hot gas in the outflow, thought to be at about 18 million degrees Fahrenheit. “We are seeing cooler gas, perhaps interstellar gas in our galaxy’s disk, being swept up into that hot outflow,” Fox explained.

This is the first result in a survey of 20 faraway quasars whose light passes through gas inside or just outside the Fermi Bubbles — like a needle piercing a balloon. An analysis of the full sample will yield the amount of mass being ejected. The astronomers can then compare the outflow mass with the velocities at various locations in the bubbles to determine the amount of energy needed to drive the outburst and possibly the origin of the explosive event.

One possible cause for the outflows is a star-making frenzy near the galactic center that produces supernovas, which blow out gas. Another scenario is a star or a group of stars falling onto the Milky Way’s supermassive black hole. When that happens, gas superheated by the black hole blasts deep into space. Because the bubbles are short-lived compared to the age of our galaxy, it suggests this may be a repeating phenomenon in the Milky Way’s history. Whatever the trigger is, it likely occurs episodically, perhaps only when the black hole gobbles up a concentration of material.

“It looks like the outflows are a hiccup,” Fox said. “There may have been repeated ejections of material that have blown up, and we’re catching the latest one. By studying the light from the other quasars in our program, we may be able to detect the fossils of previous outflows.”

Galactic winds are common in star-forming galaxies, such as M82, which is furiously making stars in its core. “It looks like there’s a link between the amount of star formation and whether or not these outflows happen,” Fox said. “Although the Milky Way overall currently produces a moderate one to two stars a year, there is a high concentration of star formation close to the core of the galaxy.”

Source: Hubble Site

Credit: X-ray: NASA/CXC/INAF/P.Tozzi, et al; Optical: NAOJ/Subaru and ESO/VLT; Infrared: ESA/Herschel

NASA’s Chandra Weighs Most Massive Galaxy Cluster in Distant Universe

Using NASA’s Chandra X-ray Observatory, astronomers have made the first determination of the mass and other properties of a very young, distant galaxy cluster.

The Chandra study shows that the galaxy cluster, seen at the comparatively young age of about 800 million years, is the most massive known cluster with that age or younger. As the largest gravitationally- bound structures known, galaxy clusters can act as crucial gauges for how the Universe itself has evolved over time.

The galaxy cluster was originally discovered using ESA’s XMM-Newton observatory and is located about 9.6 billion light years from Earth. Astronomers used X-ray data from Chandra that, when combined with scientific models, provides an accurate weight of the cluster, which comes in at a whopping 400 trillion times the mass of the Sun. Scientists believe the cluster formed about 3.3 billion years after the Big Bang.

Credit: X-ray: NASA/CXC/INAF/P.Tozzi, et al; Optical: NAOJ/Subaru and ESO/VLT; Infrared: ESA/Herschel
Credit: X-ray: NASA/CXC/INAF/P.Tozzi, et al; Optical: NAOJ/Subaru and ESO/VLT; Infrared: ESA/Herschel

The cluster is officially named XDCP J0044.0-2033, but the researchers have nicknamed it “Gioiello”, which is Italian for “jewel”. They chose this name because an image of the cluster contains many sparkling colors from the hot, X-ray emitting gas and various star-forming galaxies within the cluster. Also, the research team met to discuss the Chandra data for the first time at Villa il Gioiello, a 15th century villa near the Observatory of Arcetri, which was the last residence of prominent Italian astronomer Galileo Galilei.

“Finding this enormous galaxy cluster at this early epoch means that there could be more out there,” said Paolo Tozzi of the National Institute for Astrophysics (INAF) in Florence, Italy, who led the new study. “This kind of information could have an impact on our understanding of how the large scale structure of the Universe formed and evolved.”

Previously, astronomers had found an enormous galaxy cluster, known as “El Gordo,” at a distance of 7 billion light years away and a few other large, distant clusters. According to the best current model for how the Universe evolved, there is a low chance of finding clusters as massive as the Gioiello Cluster and El Gordo. The new findings suggest that there might be problems with the theory, and are enticing astronomers to look for other distant and massive clusters.

“The hint that there might be problems with the standard model of cosmology is interesting,” said co-author James Jee of the University of California in Davis, “but we need bigger and deeper samples of clusters before we can tell if there’s a real problem.”

The Chandra observation of the Gioiello Cluster lasted over 4 days and is the deepest X-ray observation yet made on a cluster beyond a distance of about 8 billion light years.

“Unlike the galaxy clusters that are close to us, this cluster still has lots of stars forming within its galaxies,” said co-author Joana Santos, also from INAF in Florence. “This gives us a unique window into what galaxy clusters are like when they are very young.”

 

In the past, astronomers have reported finding several galaxy cluster candidates that are located more than 9.5 billion light years away. However, some of these objects turned out to be protoclusters, that is, precursors to fully developed galaxy clusters.

The researchers also note that there are hints of uneven structure in the hot gas. These may be large clumps that could have been caused by collisions and mergers with smaller clusters of galaxies and provides clues to how the cluster became so hefty at its early age. The authors expect that the cluster is still young enough to be undergoing many such interactions.

A paper describing these results will appear in an upcoming issue of The Astrophysical Journal and is available online. NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Mass., controls Chandra’s science and flight operations.

An interactive image, a podcast, and a video about these findings are available at:
http://chandra.si.edu

For Chandra images, multimedia and related materials, visit:
http://www.nasa.gov/chandra

 

Source: Chandra X-Ray Observatory

A combined Hubble/ALMA image of NGC 1266. The zoom-in section shows the molecular gas being propelled by the black hole's jets (red and blue), the central ALMA data (yellow) indicate the dense molecular gas. Credit: NASA/ESA Hubble; ALMA (NRAO/ESO/NAOJ)

‘Perfect Storm’ Suffocating Star Formation around a Supermassive Black Hole

High-energy jets powered by supermassive black holes can blast away a galaxy’s star-forming fuel — resulting in so-called “red and dead” galaxies: those brimming with ancient red stars yet little or no hydrogen gas available to create new ones.

Now astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that black holes don’t have to be nearly so powerful to shut down star formation. By observing the dust and gas at the center NGC 1266, a nearby lenticular galaxy with a relatively modest central black hole, the astronomers have detected a “perfect storm” of turbulence that is squelching star formation in a region that would otherwise be an ideal star factory.
This turbulence is stirred up by jets from the galaxy’s central black hole slamming into an incredibly dense envelope of gas. This dense region, which may be the result of a recent merger with another smaller galaxy, blocks nearly 98 percent of material propelled by the jets from escaping the galactic center.

 Artist illustration of the central region of NGC 1266 near its central black hole with jet and gas motions indicated (yellow and white arrows, respectively). The large-scale gas motions induce turbulence on smaller scales, preventing star formation. Credit: B. Saxton (NRAO/AUI/NSF)
Artist illustration of the central region of NGC 1266 near its central black hole with jet and gas motions indicated (yellow and white arrows, respectively). The large-scale gas motions induce turbulence on smaller scales, preventing star formation. Credit: B. Saxton (NRAO/AUI/NSF)

“Like an unstoppable force meeting an immovable object, the molecules in these jets meet so much resistance when they hit the surrounding dense gas that they are almost completely stopped in their tracks,” said Katherine Alatalo, an astronomer with the California Institute of Technology in Pasadena and lead author on a paper published in the Astrophysical Journal. This energetic collision produces powerful turbulence in the surrounding gas, disrupting the first critical stage of star formation. “So what we see is the most intense suppression of star formation ever observed,” noted Alatalo.

Previous observations of NGC 1266 revealed a broad outflow of gas from the galactic center traveling up to 400 kilometers per second. Alatalo and her colleagues estimate that this outflow is as forceful as the simultaneous supernova explosion of 10,000 stars. The jets, though powerful enough to stir the gas, are not powerful enough to give it the velocity it needs to escape from the system.
“Another way of looking at it is that the jets are injecting turbulence into the gas, preventing it from settling down, collapsing, and forming stars,” said National Radio Astronomy Observatory astronomer and co-author Mark Lacy.

The region observed by ALMA contains about 400 million times the mass of our Sun in star-forming gas, which is 100 times more than is found in giant star-forming molecular clouds in our own Milky Way. Normally, gas this concentrated should be producing stars at a rate at least 50 times faster than the astronomers observed in this galaxy.

Previously, astronomers believed that only extremely powerful quasars and radio galaxies contained black holes that were powerful enough to serve as a star-forming “on/off” switch.

A combined Hubble/ALMA image of NGC 1266. The zoom-in section shows the molecular gas being propelled by the black hole's jets (red and blue), the central ALMA data (yellow) indicate the dense molecular gas. Credit: NASA/ESA Hubble; ALMA (NRAO/ESO/NAOJ)
A combined Hubble/ALMA image of NGC 1266. The zoom-in section shows the molecular gas being propelled by the black hole’s jets (red and blue), the central ALMA data (yellow) indicate the dense molecular gas. Credit: NASA/ESA Hubble; ALMA (NRAO/ESO/NAOJ)

“The usual assumption in the past has been that the jets needed to be powerful enough to eject the gas from the galaxy completely in order to be effective at stopping start formation,” said Lacy.

To make this discovery, the astronomers first pinpointed the location of the far-infrared light being emitted by the galaxy. Normally, this light is associated with star formation and enables astronomers to detect regions where new stars are forming. In the case of NGC 1266, however, this light was coming from an extremely confined region of the galaxy. “This very small area was almost too small for the infrared light to be coming from star formation,” noted Alatalo.

With ALMA’s exquisite sensitivity and resolution, and along with observations from CARMA (the Combined Array for Research in Millimeter-wave Astronomy), the astronomers were then able to trace the location of the very dense molecular gas at the galactic center. They found that the gas is surrounding this compact source of the far-infrared light.

Under normal conditions, gas this dense would be forming stars at a very high rate. The dust embedded within this gas would then be heated by young stars and seen as a bright and extended source of infrared light. The small size and faintness of the infrared source in this galaxy suggests that NGC 1266 is instead choking on its own fuel, seemingly in defiance of the rules of star formation.

The astronomers also speculate that there is a feedback mechanism at work in this region. Eventually, the black hole will calm down and the turbulence will subside so star-formation can begin anew. With this renewed star formation, however, comes greater motion in the dense gas, which then falls in on the black hole and reestablishes the jets, shutting down star formation once again.

NGC 1266 is located approximately 100 million light-years away in the constellation Eridanus. Leticular galaxies are spiral galaxies, like our own Milky Way, but they have little interstellar gas available to form new stars.

More Information

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

 

Source: ALMA Observatory

Fig. 1: ESO/S. Ramstedt (Uppsala University, Sweden) & W. Vlemmings (Chalmers University of Technology, Sweden)

ALMA reveals Mira’s secret life

Studying red giant stars tells astronomers about the future of the Sun — and about how previous generations of stars spread the elements needed for life across the Universe. One of the most famous red giants in the sky is called Mira A, part of the binary system Mira which lies about 400 light-years from Earth. In this image ALMA reveals Mira’s secret life.

Mira A is an old star, already starting to throw out the products of its life’s work into space for recycling. Mira A’s companion, known as Mira B, orbits it at twice the distance from the Sun to Neptune.

Mira A is known to have a slow wind, which gently molds the surrounding material. ALMA has now confirmed that Mira’s companion is a very different kind of star, with a very different wind. Mira B is a hot, dense white dwarf with a fierce and fast stellar wind.

Fig. 1: ESO/S. Ramstedt (Uppsala University, Sweden) & W. Vlemmings (Chalmers University of Technology, Sweden)
Fig. 1: ESO/S. Ramstedt (Uppsala University, Sweden) & W. Vlemmings (Chalmers University of Technology, Sweden)

New observations show how the winds from the two stars have created a fascinating, beautiful and complex nebula. The remarkable heart-shaped bubble at the center is created by Mira B’s energetic wind inside Mira A’s more relaxed outflow. The heart, which formed some time in the last 400 years or so, and the rest of the gas surrounding the pair show that they have long been building this strange and beautiful environment together.

By looking at stars like Mira A and Mira B scientists hope to discover how our galaxy’s double stars differ from single stars in how they give back what they have created to the Milky Way’s stellar ecosystem. Despite their distance from one another, Mira A and its companion have had a strong effect on one another and demonstrate how double stars can influence their environments and leave clues for scientists to decipher.

Other old and dying stars also have bizarre surroundings, as astronomers have seen using both ALMA and other telescopes. But it’s not always clear whether the stars are single, like the Sun, or double, like Mira. Mira A, its mysterious partner and their heart-shaped bubble are all part of this story.

More information

The new observations of Mira A and its partner are presented in this paper.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Source: ALMA Observatory

Radio-optical overlay image of galaxy J1649+2635. Yellow is visible-light image; Blue is the radio image, indicating the presence of jets.

Credit: Mao et al., NRAO/AUI/NSF, Sloan Digital Sky Survey

Strange Galaxy Perplexes Astronomers

With the help of citizen scientists, a team of astronomers has found an important new example of a very rare type of galaxy that may yield valuable insight on how galaxies developed in the early Universe. The new discovery technique promises to give astronomers many more examples of this important and mysterious type of galaxy.

The galaxy they studied, named J1649+2635, nearly 800 million light-years from Earth, is a spiral galaxy, like our own Milky Way, but with prominent “jets” of subatomic particles propelled outward from its core at nearly the speed of light. The problem is that spiral galaxies are not supposed to have such large jets.

“The conventional wisdom is that such jets come only from elliptical galaxies that formed through the merger of spirals. We don’t know how spirals can have these large jets,” said Minnie Mao, of the National Radio Astronomy Observatory (NRAO).

Radio-optical overlay image of galaxy J1649+2635. Yellow is visible-light image; Blue is the radio image, indicating the presence of jets. Credit: Mao et al., NRAO/AUI/NSF, Sloan Digital Sky Survey
Radio-optical overlay image of galaxy J1649+2635. Yellow is visible-light image; Blue is the radio image, indicating the presence of jets.
Credit: Mao et al., NRAO/AUI/NSF, Sloan Digital Sky Survey



J1649+2635 is only the fourth jet-emitting spiral galaxy discovered so far. The first was found in 2003, when astronomers combined a radio-telescope image from the Karl G. Jansky Very Large Array (VLA) and a visible-light image of the same object from the Hubble Space Telescope. The second was revealed in 2011 by images from the Sloan Digital Sky Survey and the VLA, and the third, found earlier this year, also was discovered by combining radio and visible-light images.

“In order to figure out how these jets can be produced by the ‘wrong’ kind of galaxy, we realized we needed to find more of them,” Mao said.

To do that, the astronomers looked for help. That help came in the form of large collections of images from both radio and optical telescopes, and the hands-on assistance of volunteer citizen scientists. The volunteers are participants in an online project called the Galaxy Zoo, in which they look at images from the visible-light Sloan Digital Sky Survey and classify the galaxies as spiral, elliptical, or other types. Each galaxy image is inspected by multiple volunteers to ensure accuracy in the classification.

So far, more than 150,000 Galaxy Zoo participants have classified some 700,000 galaxies. Mao and her collaborators used a “superclean” subset of more than 65,000 galaxies, for which 95 percent of those viewing each galaxy’s image agreed on the classification. About 35,000 of those are spiral galaxies. J1649+2635 had been classified by 31 Galaxy Zoo volunteers, 30 of whom agreed that it is a spiral.

Next, the astronomers decided to cross-match the visible-light spirals with galaxies in a catalog that combines data from the NRAO VLA Sky Survey and the Faint Images of the Radio Sky at Twenty Centimeters survey, both done using the VLA. This job was done by Ryan Duffin, a University of Virginia undergraduate working as an NRAO summer student. Duffin’s cross-matching showed that J1649+2635 is both a spiral galaxy and has powerful twin radio jets.

“This is the first time that a galaxy was first identified as a spiral, then subsequently found to have large radio jets,” Duffin said. “It was exciting to make such a rare find,” he added.

Jets such as those seen coming from J1649+2635 are propelled by the gravitational energy of a supermassive black hole at the core of the galaxy. Material pulled toward the black hole forms a rapidly-rotating disk, and particles are accelerated outward along the poles of the disk. The collision that presumably forms an elliptical galaxy disrupts gas in the merging galaxies and provides “fuel” for the disk and acceleration mechanism. That same disruption, however, is expected to destroy any spiral structure as the galaxies merge into one.

J1649+2635 is unusual not only because of its jets, but also because it is the first example of a “grand design” spiral galaxy with a large “halo” of visible-light emission surrounding it. 

“This galaxy presents us with many mysteries. We want to know how it became such a strange beast,” Mao said. “Did it have a unique type of merger that preserved its spiral structure? Was it an elliptical that had another collision that made it re-grow spiral arms? Is its unique character the result of interaction with its environment?”

“We will study it further, but in addition, we need to see if there are more like it,” Mao said.

“We hope that with projects like the Galaxy Zoo and another called Radio Galaxy Zoo, those thousands of citizen scientists can help us find many more galaxies like this one so we can answer all our questions,” Mao said. Mao and her colleagues have dubbed these rare galaxies “Spiral DRAGNs,” an acronym for the technical description, “Double-lobed Radio sources Associated with Galactic Nuclei.”

Mao and Duffin worked with Frazer Owen, Emmanuel Momjian, and Mark Lacy, also of the NRAO; Bill Keel of the University of Alabama; Glenn Morrison of the University of Hawaii and the Canada-France-Hawaii Telescope; Tony Mroczkowski of the Naval Research Laboratory; Susan Neff of NASA’s Goddard Space Flight Center; Ray Norris of CSIRO Astronomy and Space Science in Australia; Henrique Schmitt of the Naval Research Laboratory; and Vicki Toy and Sylvain Veilleux of the University of Maryland. The scientists are reporting their findings in theMonthly Notices of the Royal Astronomical Society. 

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

Source: NRAO