Wednesday, October 22, 2014

NASA's Fermi Satellite Finds Hints of Starquakes in Magnetar 'Storm'

NASA's Fermi Gamma-ray Space Telescope detected a rapid-fire "storm" of high-energy blasts from a highly magnetized neutron star, also called a magnetar, on Jan. 22, 2009. Now astronomers analyzing this data have discovered underlying signals related to seismic waves rippling throughout the magnetar.

A rupture in the crust of a highly magnetized neutron star, shown here in an artist's rendering, can trigger high-energy eruptions. Fermi observations of these blasts include information on how the star's surface twists and vibrates, providing new insights into what lies beneath. Image Credit: NASA's Goddard Space Flight Center/S. Wiessinger. Related multimedia from NASA Goddard's Scientific Visualization Studio

Such signals were first identified during the fadeout of rare giant flares produced by magnetars. Over the past 40 years, giant flares have been observed just three times -- in 1979, 1998 and 2004 -- and signals related to starquakes, which set the neutron stars ringing like a bell, were identified only in the two most recent events.

"Fermi's Gamma-ray Burst Monitor (GBM) has captured the same evidence from smaller and much more frequent eruptions called bursts, opening up the potential for a wealth of new data to help us understand how neutron stars are put together," said Anna Watts, an astrophysicist at the University of Amsterdam in the Netherlands and co-author of a new study about the burst storm. "It turns out that Fermi's GBM is the perfect tool for this work."

In the midst of SGR J1550-5418's 2009 burst storm, Swift's X-Ray Telescope captured an expanding halo produced by the magnetar's brightest bursts. The rings formed as X-rays from the brightest bursts scattered off of intervening dust clouds. Clouds closer to Earth produced larger rings. Image Credit: NASA/Swift/Jules Halpern, Columbia University. Download this video in additional formats from NASA Goddard's Scientific Visualization Studio

This image of NASA's Fermi Gamma-ray Space Telescope, shown here in May 2008 being readied for launch, highlights the spacecraft's instruments. The Gamma-ray Burst Monitor (GBM) is an array of 14 crystal detectors sensitive to short-lived gamma-ray blasts. Image Credit: NASA/Jim Grossmann. Unlabeled image

Neutron stars are the densest, most magnetic and fastest-spinning objects in the universe that scientists can observe directly. Each one is the crushed core of a massive star that ran out of fuel, collapsed under its own weight, and exploded as a supernova. A neutron star packs the equivalent mass of half-a-million Earths into a sphere about 12 miles across, roughly the length of Manhattan Island in New York City.

While typical neutron stars possess magnetic fields trillions of times stronger than Earth's, the eruptive activity observed from magnetars requires fields 1,000 times stronger still. To date, astronomers have confirmed only 23 magnetars.

Because a neutron star's solid crust is locked to its intense magnetic field, a disruption of one immediately affects the other. A fracture in the crust will lead to a reshuffling of the magnetic field, or a sudden reorganization of the magnetic field may instead crack the surface. Either way, the changes trigger a sudden release of stored energy via powerful bursts that vibrate the crust, a motion that becomes imprinted on the burst’s gamma-ray and X-ray signals.

It takes an incredible amount of energy to convulse a neutron star. The closest comparison on Earth is the 9.5-magnitude Chilean earthquake of 1960, which ranks as the most powerful ever recorded on the standard scale used by seismologists. On that scale, said Watts, a starquake associated with a magnetar giant flare would reach magnitude 23.

The 2009 burst storm came from SGR J1550−5418, an object discovered by NASA's Einstein Observatory, which operated from 1978 to 1981. Located about 15,000 light-years away in the constellation Norma, the magnetar was quiet until October 2008, when it entered a period of eruptive activity that ended in April 2009. At times, the object produced hundreds of bursts in as little as 20 minutes, and the most intense explosions emitted more total energy than the sun does in 20 years. High-energy instruments on many spacecraft, including NASA's Swift and Rossi X-ray Timing Explorer, detected hundreds of gamma-ray and X-ray blasts.

Speaking at the Fifth Fermi International Symposium in Nagoya, Japan, on Oct. 21, Watts said the new study examined 263 individual bursts detected by Fermi's GBM and confirms vibrations in the frequency ranges previously seen in giant flares. "We think these are likely twisting oscillations of the star where the crust and the core, bound by the super-strong magnetic field, are vibrating together," she explained. "We also found, in a single burst, an oscillation at a frequency never seen before and which we still do not understand."

A key element of the research is a new analysis technique developed by University of Amsterdam researcher Daniela Huppenkothen. Normally scientists search for oscillations in high-energy data by looking for variations aligned to a particular frequency. Such methods are best suited for finding a strong signal with little competition rather than a faint signal immersed in a bright and rapidly changing environment, such as a burst.

Huppenkothen likens the problem to detecting ripples from a stone tossed into a quiet pond. "Now imagine you're in the middle of the North Atlantic during a storm, searching for those ripples amidst huge waves in a churning sea," she explained. "Our old methods really weren't appropriate for this, but I have in effect developed a way of accounting for the rough sea so we can find ripples even in stormy conditions." 

A paper describing the research, which was led by Huppenkothen, appeared in the June 1 edition of The Astrophysical Journal.

While there are many efforts to describe the interiors of neutron stars, scientists lack enough observational detail to choose between differing models. Neutron stars reach densities far beyond the reach of laboratories and their interiors may exceed the density of an atomic nucleus by as much as 10 times. Knowing more about how bursts shake up these stars will give theorists an important new window into understanding their internal structure.

"Right now," added Watts, "we are waiting for more bursts -- and if we're lucky, a giant flare -- to take advantage of GBM's excellent capabilities."


Related Links

Chandra Archive Collection: Chandra's Archives Come to Life

Chandra Archive Collection
Credit NASA/CXC/SAO 
Instrument: ACIS 


JPEG (293.8 kb) - Large JPEG (2.2 MB) - More Images
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Every year, NASA's Chandra X-ray Observatory looks at hundreds of objects throughout space to help expand our understanding of the Universe. Ultimately, these data are stored in the Chandra Data Archive, an electronic repository that provides access to these unique X-ray findings for anyone who would like to explore them. With the passing of Chandra's 15th anniversary in operation on August 26, 1999, the archive continues to grow as each successive year adds to the enormous and invaluable dataset.

To celebrate Chandra's decade and a half in space, and to honor October as American Archives Month, a variety of objects have been selected from Chandra's archive. Each of the new images we have produced combines Chandra data with those from other telescopes. This technique of creating "multiwavelength" images allows scientists and the public to see how X-rays fit with data of other types of light, such as optical, radio, and infrared. As scientists continue to make new discoveries with the telescope, the burgeoning archive will allow us to see the high-energy Universe as only Chandra can. 

PSR B1509-58
PSR B1509-58 (upper left)
Pareidolia is the psychological phenomenon where people see recognizable shapes in clouds, rock formations, or otherwise unrelated objects or data. When Chandra's image of PSR B1509-58, a spinning neutron star surrounded by a cloud of energetic particles, was released in 2009, it quickly gained attention because many saw a hand-like structure in the X-ray emission. In this new image of the system, X-rays from Chandra in gold are seen along with infrared data from NASA's Wide-field Infrared Survey Explorer (WISE) telescope in red, green, and blue. Pareidolia may strike again in this image as some people report seeing a shape of a face in WISE's infrared data.

RCW 38
RCW 38 (upper right)
A young star cluster about 5,500 light years from Earth, RCW 38 provides astronomers a chance to closely examine many young, rapidly evolving stars at once. In this composite image, X-rays from Chandra are blue, while infrared data from NASA's Spitzer Space Telescope are orange and additional infrared data from the 2MASS survey appears white. There are many massive stars in RCW 38 that will likely explode as supernovas. Astronomers studying RCW 38 are hoping to better understand this environment as our Sun was likely born into a similar stellar nursery.

Hercules A
Hercules A (middle left):
Some galaxies have extremely bright cores, suggesting that they contain a supermassive black hole that is pulling in matter at a prodigious rate. Astronomers call these "active galaxies," and Hercules A is one of them. In visible light (colored red, green and blue, with most objects appearing white), Hercules A looks like a typical elliptical galaxy. In X-ray light, however, Chandra detects a giant cloud of multimillion-degree gas (purple). This gas has been heated by energy generated by the infall of matter into a black hole at the center of Hercules A that is over 1,000 times as massive as the one in the middle of the Milky Way. Radio data (blue) show jets of particles streaming away from the black hole. The jets span a length of almost one million light years.

Kes 73
Kes 73 (middle right):
The supernova remnant Kes 73, located about 28,000 light years away, contains a so-called anomalous X-ray pulsar, or AXP, at its center. Astronomers think that most AXPs are magnetars, which are neutron stars with ultra-high magnetic fields. Surrounding the point-like AXP in the middle, Kes 73 has an expanding shell of debris from the supernova explosion that occurred between about 750 and 2100 years ago, as seen from Earth. The Chandra data (blue) reveal clumpy structures along one side of the remnant, and appear to overlap with infrared data (orange). The X-rays partially fill the shell seen in radio emission (red) by the Very Large Array. Data from the Digitized Sky Survey optical telescope (white) show stars in the field-of-view.

Mrk 573
Mrk 573 (lower left):
Markarian 573 is an active galaxy that has two cones of emission streaming away from the supermassive black hole at its center. Several lines of evidence suggest that a torus, or doughnut of cool gas and dust may block some of the radiation produced by matter falling into supermassive black holes, depending on how the torus is oriented toward Earth. Chandra data of Markarian 573 suggest that its torus may not be completely solid, but rather may be clumpy. This composite image shows overlap between X-rays from Chandra (blue), radio emission from the VLA (purple), and optical data from Hubble (gold).

NGC 4736
NGC 4736 (lower right):
NGC 4736 (also known as Messier 94) is a spiral galaxy that is unusual because it has two ring structures. This galaxy is classified as containing a "low ionization nuclear emission region," or LINER, in its center, which produces radiation from specific elements such as oxygen and nitrogen. Chandra observations (gold) of NGC 4736, seen in this composite image with infrared data from Spitzer (red) and optical data from Hubble and the Sloan Digital Sky Survey (blue), suggest that the X-ray emission comes from a recent burst of star formation. Part of the evidence comes from the large number of point sources near the center of the galaxy, showing that strong star formation has occurred. In other galaxies, evidence points to supermassive black holes being responsible for LINER properties. Chandra's result on NGC 4736 shows LINERs may represent more than one physical phenomenon.

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington, DC. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.




Tuesday, October 21, 2014

Tiny "Nanoflares" Might Heat the Sun's Corona

A solar flare occurs when a patch of the Sun brightens dramatically at all wavelengths of light. During flares, solar plasma is heated to tens of millions of degrees in a matter of seconds or minutes. Flares also can accelerate electrons (and protons) from the solar plasma to a large fraction of the speed of light. These high-energy electrons can have a significant impact when they reach Earth, causing spectacular aurorae but also disrupting communications, affecting GPS signals, and damaging power grids.

Those speedy electrons also can be generated by scaled-down versions of flares called nanoflares, which are about a billion times less energetic than regular solar flares. "These nanoflares, as well as the energetic particles possibly associated with them, are difficult to study because we can't observe them directly," says Testa.

Testa and her colleagues have found that IRIS provides a new way to observe the telltale signs of nanoflares by looking at the footpoints of coronal loops. As the name suggests, coronal loops are loops of hot plasma that extend from the Sun's surface out into the corona and glow brightly in ultraviolet and X-rays.

IRIS does not observe the hottest coronal plasma in these loops, which can reach temperatures of several million degrees. Instead, it detects the ultraviolet emission from the cooler plasma (~18,000 to 180,000 degrees Fahrenheit) at their footpoints. Even if IRIS can't observe the coronal heating events directly, it reveals the traces of those events when they show up as short-lived, small-scale brightenings at the footpoints of the loops.

The team inferred the presence of high-energy electrons using IRIS high-resolution ultraviolet imaging and spectroscopic observations of those footpoint brightenings. Using computer simulations, they modeled the response of the plasma confined in loops to the energy transported by energetic electrons. The simulations revealed that energy likely was deposited by electrons traveling at about 20 percent of the speed of light.

The high spatial, temporal, and spectral resolution of IRIS was crucial to the discovery. IRIS can resolve solar features only 150 miles in size, has a temporal resolution of a few seconds, and has a spectral resolution capable of measuring plasma flows of a few miles per second.

Finding high-energy electrons that aren't associated with large flares suggests that the solar corona is, at least partly, heated by nanoflares. The new observations, combined with computer modeling, also help astronomers to understand how electrons are accelerated to such high speeds and energies - a process that plays a major role in a wide range of astrophysical phenomena from cosmic rays to supernova remnants. 

These findings also indicate that nanoflares are powerful, natural particle accelerators despite having energies about a billion times lower than large solar flares.

"As usual for science, this work opens up an entirely new set of questions. For example, how frequent are nanoflares? How common are energetic particles in the non-flaring corona? How different are the physical processes at work in these nanoflares compared to larger flares?" says Testa.

The paper reporting this research is part of a special issue of the journal Science focusing on IRIS discoveries.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.


For more information, contact:

David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462

daguilar@cfa.harvard.edu

Christine Pulliam
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
617-495-7463

cpulliam@cfa.harvard.edu




Monday, October 20, 2014

'CT Scan' of Distant Universe Reveals Cosmic Web in 3D

Figure 1: 3D map of the cosmic web at a distance of 10.8 billion light years from Earth. The map was generated from imprints of hydrogen gas observed in the spectrum of 24 background galaxies, which are located behind the volume being mapped. This is the first time that large-scale structures in such a distant part of the Universe have been mapped directly. The coloring represents the density of hydrogen gas tracing the cosmic web, with brighter colors representing higher density. Credit: Casey Stark (UC Berkeley) and Khee-Gan Lee (MPIA).  Larger version for download

Figure 2: Close-up of 3D map of the distant Universe created by MPIA and UC astronomers. The filamentary structures seen in this map span distances of millions of light years, and represent the cosmic web at an earlier stage of cosmic evolution when the Universe was less than a quarter of its current age. The region of space seen here is at a distance of 10.8 billion years from Earth. The coloring represents the density of hydrogen gas tracing the cosmic web, with brighter colors representing higher density. The coloring represents the density of hydrogen gas tracing the cosmic web, with brighter colors representing higher density. Credit: Casey Stark (UC Berkeley) and Khee-Gan Lee (MPIA).  Larger version for download

Figure 3: Artist's impression illustrating the technique of Lyman-alpha tomography: as light from distant background galaxies (yellow arrows) travels through the Universe towards Earth, hydrogen gas in the foreground leaves a characteristic imprint ("absorption signature"). From this imprint, astronomers can reconstruct which clouds the light has encountered as it traverses the "cosmic web" of dark matter and gas that accounts for the biggest structures in our universe. By observing a number of background galaxies in a small patch of the sky, astronomers were able to create a 3D map of the cosmic web using a technique similar to medical computer tomography (CT) scans. The coloring represents the density of hydrogen gas tracing the cosmic web, with brighter colors representing higher density. The rendition of the cosmic web in this image is based on a supercomputer simulation of cosmic structure formation.  Credit: Khee-Gan Lee (MPIA) and Casey Stark (UC Berkeley).  Larger version for download

Figure 4: 3D map of the cosmic web at a distance of 10.8 billion years from Earth. The map was generated from imprints of hydrogen gas observed in the spectrum of 24 background galaxies, which are located behind the volume being mapped. This is the first time that large-scale structures in such a distant part of the Universe have been mapped directly. The coloring represents the density of hydrogen gas tracing the cosmic web, with brighter colors representing higher density.   Credit: Casey Stark (UC Berkeley) and Khee-Gan Lee (MPIA)

On the largest scales, matter in the Universe is arranged in a vast network of filamentary structures known as the 'cosmic web', its tangled strands spanning hundreds of millions of light years. Dark matter, which emits no light, forms the backbone of this web, which is also suffused with primordial hydrogen gas left over from the Big Bang. Galaxies like our own Milky Way are embedded inside this web, but fill only a tiny fraction of its volume.

Now a team of astronomers led by Khee-Gan Lee, a post-doc at the Max Planck Institute for Astronomy, has managed to create a three-dimensional map of a large region of the far-flung cosmic web nearly 11 billion light years away, when the Universe was just a quarter of its current age. Similar to a medical CT scan, which reconstructs a three-dimensional image of the human body from the X-rays passing through a patient, Lee and his colleagues reconstructed their map from the light of distant background galaxies passing through the cosmic web's hydrogen gas.

The use of the combined starlight of background galaxies for this purpose had been thought to be impossible with current telescopes – until Lee carried out calculations that suggested otherwise. Lee says: "I was surprised to find that existing large telescopes should already be able to collect sufficient light from these faint galaxies to map the foreground absorption, albeit at a lower resolution than would be feasible with future telescopes. Still, this would provide an unprecedented view of the cosmic web which has never been mapped at such vast distances."

Lee and his colleagues obtained observing time on one of the largest telescopes in the world: the 10m-diameter Keck I telescope at the W. M. Keck Observatory on Mauna Kea, Hawaii – but were plagued by a problem more terrestrial than cosmic. "We were pretty disappointed as the weather was terrible and we only managed to collect a few hours of good data. But judging by the data quality as it came off the telescope, it was already clear to me that the experiment was going to work," says Joseph Hennawi (MPIA), who was part of the observing team.

Although the astronomers only observed for 4 hours, the data they collected was completely unprecedented. Their absorption measurements using 24 faint background galaxies provided sufficient coverage of a small patch of the sky to be combined into a 3D map of the foreground cosmic web. A crucial element was the computer algorithm used to create the 3D map: due to the large amount of data, a naïve implementation of the map-making procedure would have required an inordinate amount of computing time. Fortunately, team members Casey Stark and Martin White (UC Berkeley and Lawrence Berkeley National Lab) devised a new fast algorithm that could create the map within minutes. "We realized we could simplify the computations by tailoring them to this particular problem, and thus use much less memory. A calculation that previously required a supercomputer now runs on a laptop", says Stark.

The resulting map of hydrogen absorption reveals a three-dimensional section of the universe 11 billions light years away – the first time the cosmic web has been mapped at such a vast distance. Since observing to such immense distances is also looking back in time, the map reveals the early stages of cosmic structure formation when the Universe was only a quarter of its current age, during an era when the galaxies were undergoing a major 'growth spurt'. The map provides a tantalizing glimpse of giant filamentary structures extending across millions of light years, and paves the way for more extensive studies that should reveal not only the structure of the cosmic web, but also details of its function – the ways that pristine gas is funneled along the web into galaxies, providing the raw material for the growth of galaxies through the formation of stars and planets.


Background information

The work described here will be published as K.G. Lee et al., "Lyα Forest Tomography from Background Galaxies: The first Megaparsec-Resolution Large-Scale Structure Map at z > 2" in the Astrophysical Journal Letters.

ADS entry of the article

The team members are Khee-Gan Lee, Joseph F. Hennawi, and Anna-Christina Eilers (Max Planck Institute for Astronomy), Casey Stark and Martin White, (UC Berkeley and Lawrence Berkeley National Laboratory), J. Xavier Prochaska (University of California at Santa Cruz, Lick Observatory), David Schlegel (Lawrence Berkeley National Laboratory), and Andreu Arinyo-i-Prats (Universitat de Barcelona).

This research received financial support from the National Geographic Society/Waitt Grants Program.


Contact

Khee-Gan Lee (first author)
Max Planck Institute for Astronomy
Heidelberg, Germany
Phone: (+49|0) 6221 –528 467
email:
lee@mpia.de

Joe Hennawi (co-author)
Max Planck Institute for Astronomy
Heidelberg, Germany
Phone: (+49|0) 6221 –528 263
email:
joe@mpia.de

Dr. Markus Pössel (public information officer)
Max Planck Institute for Astronomy
Heidelberg, Germany
Phone: (+49|0) 6221 –528 261
email:
pr@mpia.de




Sunday, October 19, 2014

The Debris Disk of a Solar-Type Star

An artist's conception of the planetary system around the nearby solar analog star, Tau Ceti, showing its five putative planets. Astonomers using far infrared observations find a debris disk around the star, and find a model that is consistent with five planets lying within the disk's inner edge at five astronomical units. Credit: NASA

Although thousands of exoplanets and hundreds of planetary systems (stars with multiple exoplanets) are now known, astronomers still don’t know whether our solar system is typical. The distributions of known planetary system parameters are strongly affected by observational biases that are not easy to disentangle from the true distributions. Moreover, our Solar system’s architecture (small rocky inner planets, large gaseous outer planets, and an outer debris disc made of many small objects) has not yet been seen in other systems, most likely due to these same biases. Long time baselines, for example, are required to discover planets at greater than a few astronomical units (one AU is the average distance of the Earth from the Sun) with all techniques except direct imaging, but direct imaging of planets around mature stars is difficult due to the low light from planets compared to their host stars.

Debris disks, because they are spread out over large areas, are easier to see, and structures in debris discs like rings or gaps can indicate the presence of additional planets. CfA astronomer David Wilner joined with his colleagues to search for clues of planets in the debris disc around τ Ceti, a nearby solar-type star located only ten light-years from the Sun. The infrared excess towards τ Ceti has been known for nearly three decades and has been attributed to warm dust particles in a debris disk.

The astronomers used the Herschel Space Telescope to study τ Ceti in far infrared wavelengths where the dust emission should be strongest. The carefully processed images reveal evidence for a uniform and symmetric debris disk with an inner edge about two to three AU from the star and an outer edge fifty-five AU from the star. For comparison, in our Solar system the Kuiper Belt of small objects begins at the orbit of Neptune (about thirty AU from the Sun) and extends out to about fifty AU (the colder Oort Belt of icy objects and comets extends much farther, to about fifty thousand AU).

In previous studies of τ Ceti, other astronomers had found preliminary evidence suggesting the possibility it hosted five planets. Wilner and his colleagues modeled the stellar system with their observed debris disk and including these possible planets and a range of other published observational data, and found that the system was consistent with the observations and could be stable. The putative planets would orbit between the debris disk's inner edge and the star. The scientists conclude by noting that a Jupiter-mass planet could not be present in this system, making it less than ideal as a Solar system analog. Future observations should be able to refine the picture further.

 
Reference(s): 
 
"The Debris Disc of Solar Analogue τ Ceti: Herschel Observations and Dynamical Simulations of the Proposed Multiplanet System," S. M. Lawler, J. Di Francesco, G. M. Kennedy, B. Sibthorpe, M. Booth, B. Vandenbussche, B. C. Matthews, W. S. Holland, J. Greaves, D. J. Wilner, M. Tuomi, J. A. D. L. Blommaert, B. L. de Vries, C. Dominik, M. Fridlund, W. Gear, A. M. Heras, R. Ivison and G. Olofsson, MNRAS 444, 2665, 2014.
  



Saturday, October 18, 2014

Revealing the secrets of galaxies – second CALIFA Data Release

Figure 1: CALIFA data example: Top row: Poststamp images of five galaxies.  Bottom row: Colour coded gas velocity maps of the same galaxies based on CALIFA IFS data.  Credit: Top row: SDSS | Bottom row: CALIFA team

Today, the second large data release of the CALIFA-Survey has been published to the astronomical community and the public. It contains an unprecedented amount of data on 200 galaxies in the local universe allowing astronomers to study in detail numerous galaxy properties regarding their composition, kinematics, formation history and evolution.

The Calar Alto Legacy Integral Field Area survey (CALIFA) is one of the largest surveys of galaxies which is based on an observing technique called "Integral Field Spectroscopy" (IFS). Already a single spectrum of an astronomical object provides important data beyond pure imaging because the light from the source is split into its wavelength-dependent components and shows characteristic signatures related to physical, chemical and dynamical properties. However, using the PMAS Spectrograph at Calar Alto Observatory, the team of the CALIFA Survey is even able to collect 2000 individual spectra for each galaxy which are covering the whole surface of each object.

The 2nd CALIFA data release now provides unique data on a representative sample of 200 galaxies in the local Universe. These spectra allow studies of the stellar content, ages, star formation history, as well as gas and dust properties. However, beyond spectral diagnostics the CALIFA data-cubes allow to study the spatial distribution of all these properties. Moreover, as a unique feature of imaging spectroscopy, the kinematic properties, i.e. motions of the stars and gas over the whole face of a galaxy, enable the inference of the structure of the galaxy, the formation history, and even the presence of dark matter.

Compared to the 1st data release in 2012 this 2nd release presents a much improved preparation of the material. Data is provided with two spectral setups (in low and high resolution) and for each galaxy the data cube contains about 2000 individual spectra. In total this adds up to about 800,000 spectra released in DR2. The data is freely available for anyone interested.


Important Links:
 


Contact

Dr. Glenn van de Ven (Member CALIFA managing board)
Max Planck Institute for Astronomy
Heidelberg, Germany
Phone: (+49|0) 6221 – 528 275
email:
glenn@mpia.de

Dr. Knud Jahnke (co-founding member, CALIFA)
Max Planck Institute for Astronomy
Heidelberg, Germany
Phone: (+49|0) 6221 – 528 398
email:
jahnke@mpia.de

Dr. Klaus Jäger (MPIA Scientific Coordinator, press officer)
Max Planck Institute for Astronomy
Heidelberg, Germany
Phone: (+49|0) 6221 – 528 379
email:
pr@mpia.de 



Friday, October 17, 2014

Milky Way Ransacks Nearby Dwarf Galaxies, Stripping All Traces of Star-Forming Gas

Artist's impression of the Milky Way. Its hot halo appears to be stripping away the star-forming atomic hydrogen from its companion dwarf spheroidal galaxies. Credit: NRAO/AUI/NSF 

Astronomers using the National Science Foundation’s Green Bank Telescope (GBT) in West Virginia, along with data from other large radio telescopes, have discovered that our nearest galactic neighbors, the dwarf spheroidal galaxies, are devoid of star-forming gas, and that our Milky Way Galaxy is to blame.

These new radio observations, which are the highest sensitivity of their kind ever undertaken, reveal that within a well-defined boundary around our Galaxy, dwarf galaxies are completely devoid of hydrogen gas; beyond this point, dwarf galaxies are teeming with star-forming material.

The Milky Way Galaxy is actually the largest member of a compact clutch of galaxies that are bound together by gravity. Swarming around our home Galaxy is a menagerie of smaller dwarf galaxies, the smallest of which are the relatively nearby dwarf spheroidals, which may be the leftover building blocks of galaxy formation. Further out are a number of similarly sized and slightly misshaped dwarf irregular galaxies, which are not gravitationally bound to the Milky Way and may be relative newcomers to our galactic neighborhood.

“Astronomers wondered if, after billions of years of interaction, the nearby dwarf spheroidal galaxies have all the same star-forming ‘stuff’ that we find in more distant dwarf galaxies,” said astronomer Kristine Spekkens, assistant professor at the Royal Military College of Canada and lead author on a paper published in the Astrophysical Journal Letters.

Previous studies have shown that the more distant dwarf irregular galaxies have large reservoirs of neutral hydrogen gas, the fuel for star formation. These past observations, however, were not sensitive enough to rule out the presence of this gas in the smallest dwarf spheroidal galaxies.

By bringing to bear the combined power of the GBT (the world’s largest fully steerable radio telescope) and other giant telescopes from around the world, Spekkens and her team were able to probe the dwarf galaxies that have been swarming around the Milky Way for billions of years for tiny amounts of atomic hydrogen.

“What we found is that there is a clear break, a point near our home Galaxy where dwarf galaxies are completely devoid of any traces of neutral atomic hydrogen,” noted Spekkens. Beyond this point, which extends approximately 1,000 light-years from the edge of the Milky Way’s star-filled disk to a point that is thought to coincide with the edge of its dark matter distribution, dwarf spheroidals become vanishingly rare while their gas-rich, dwarf irregular counterparts flourish.

There are many ways that larger, mature galaxies can lose their star-forming material, but this is mostly tied to furious star formation or powerful jets of material driven by supermassive black holes. The dwarf galaxies that orbit the Milky Way contain neither of these energetic processes. They are, however, susceptible to the broader influences of the Milky Way, which itself resides within an extended, diffuse halo of hot hydrogen plasma.

The researchers believe that, up to a certain distance from the galactic disk, this halo is dense enough to affect the composition of dwarf galaxies. Within this “danger zone,” the pressure created by the million-mile-per-hour orbital velocities of the dwarf spheroidals can actually strip away any detectable traces of neutral hydrogen. The Milky Way thus shuts down star formation in its smallest neighbors.

"These observations therefore reveal a great deal about size of the hot halo and about how companions orbit the Milky Way," concludes Spekkens.

#  #  #

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


Contact: 

Charles E. Blue, Public Information Officer
(434) 296-0314
Email: cblue@nrao.edu



Turquoise-tinted plumes in the Large Magellanic Cloud

Credit: ESA/Hubble & NASA
Acknowledgement: Josh Barrington

The brightly glowing plumes seen in this image are reminiscent of an underwater scene, with turquoise-tinted currents and nebulous strands reaching out into the surroundings.

However, this is no ocean. This image actually shows part of the Large Magellanic Cloud (LMC), a small nearby galaxy that orbits our galaxy, the Milky Way, and appears as a blurred blob in our skies. The NASA/ESA Hubble Space Telescope has peeked many times into this galaxy, releasing stunning images of the whirling clouds of gas and sparkling stars (opo9944a, heic1301, potw1408a).

This image shows part of the Tarantula Nebula's outskirts. This famously beautiful nebula, located within the LMC, is a frequent target for Hubble (heic1206, heic1402). 

In most images of the LMC the colour is completely different to that seen here. This is because, in this new image, a different set of filters was used. The customary R filter, which selects the red light, was replaced by a filter letting through the near-infrared light. In traditional images, the hydrogen gas appears pink because it shines most brightly in the red. Here however, other less prominent emission lines dominate in the blue and green filters.

This data is part of the Archival Pure Parallel Project (APPP), a project that gathered together and processed over 1000 images taken using Hubble’s Wide Field Planetary Camera 2, obtained in parallel with other Hubble instruments. Much of the data in the project could be used to study a wide range of astronomical topics, including gravitational lensing and cosmic shear, exploring distant star-forming galaxies, supplementing observations in other wavelength ranges with optical data, and examining star populations from stellar heavyweights all the way down to solar-mass stars.

A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Josh Barrington.


Source:  ESA/Hubble - Space Telescope

Thursday, October 16, 2014

Hubble Finds Extremely Distant Galaxy through Cosmic Magnifying Glass

Hubble Uncovers One of the Smallest and Farthest Galaxies in the Universe
Credit: NASA, ESA, A. Zitrin (California Institute of Technology), and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI)

Artist's Illustration of a Giant Cosmic Magnifying Glass
Illustration Credit: NASA, ESA, and Z. Levay (STScI). Science Credit: NASA, ESA, A. Zitrin (Caltech), and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI)


Peering through a giant cosmic magnifying glass, NASA's Hubble Space Telescope has spotted one of the farthest, faintest, and smallest galaxies ever seen. The diminutive object is estimated to be over 13 billion light-years away.

This new detection is considered one of the most reliable distance measurements of a galaxy that existed in the early universe, said the Hubble researchers. They used two independent methods to estimate its distance.
The galaxy appears as a tiny blob that is only a small fraction of the size of our Milky Way galaxy. But it offers a peek back into a time when the universe was only about 500 million years old, roughly 3 percent of its current age of 13.7 billion years. Astronomers have uncovered about 10 other galaxy candidates at this early era. But this newly found galaxy is significantly smaller and fainter than most of those other remote objects detected to date.

"This object is a unique example of what is suspected to be an abundant, underlying population of extremely small and faint galaxies at about 500 million years after the big bang," explained study leader Adi Zitrin of the California Institute of Technology in Pasadena. "The discovery is telling us that galaxies as faint as this one exist, and we should continue looking for them and even fainter objects so that we can understand how galaxies and the universe have evolved over time."

The galaxy was detected as part of the Frontier Fields program, an ambitious three-year effort, begun in 2013, that teams Hubble with NASA's other Great Observatories — the Spitzer Space Telescope and the Chandra X-ray Observatory — to probe the early universe by studying large galaxy clusters. These clusters are so massive that their gravity deflects light passing through them, magnifying, brightening, and distorting background objects in a phenomenon called gravitational lensing. These powerful lenses allow astronomers to find many dim, distant structures that otherwise might be too faint to see.

In this new discovery, the lensing power of the mammoth galaxy cluster Abell 2744, nicknamed Pandora's Cluster, produced three magnified images of the same galaxy. Each magnified image makes the galaxy appear as much as 10 times larger and brighter than it would look without the intervening lens.

An analysis of the distant galaxy shows that it measures merely 850 light-years across, 500 times smaller than the Milky Way, and is estimated to have a mass of only 40 million suns. The galaxy's star formation rate is about one star every three years (one-third the star formation rate in the Milky Way). Although this may seem low, Zitrin said that given its small size and low mass, the tiny galaxy is in fact rapidly evolving and efficiently forming stars.

"Galaxies such as this one are probably small clumps of matter that are starting to form stars and shine light, but they don't have a defined structure yet," Zitrin said. "Therefore, it's possible that we only see one bright clump magnified due to the lensing, and this is one possibility as to why it is smaller than typical field galaxies of that time."

Zitrin's team spotted the galaxy's gravitationally multiplied images using near-infrared and visible-light photos of the galaxy cluster taken by Hubble's Wide Field Camera 3 and Advanced Camera for Surveys. But at first they didn't know how far away it was from Earth.

Normally, astronomers use spectroscopy to determine an object's distance. The farther away a galaxy, the more its light has been stretched by the universe's expansion. Astronomers can precisely measure this effect through spectroscopy, which characterizes an object's light.

But the gravitationally lensed galaxy and other objects found at this early epoch are too far away and too dim for astronomers to use spectroscopy. Astronomers instead analyze an object's color to estimate its distance. The universe's expansion reddens an object's color in predictable ways, which scientists can measure.

Members of Zitrin's team not only performed the color-analysis technique, but they also took advantage of the multiple images produced by the gravitational lens to independently confirm their distance estimate. The astronomers measured the angular separation between the three magnified images of the galaxy in the Hubble photos. The greater the angular separation due to lensing, the farther away the object is from Earth. To test this concept, the astronomers compared the three magnified images with the locations of several other multiply imaged objects lensed by Abell 2744 that are not as far behind the cluster. The angular distance between the magnified images of the closer galaxies was smaller.

"These measurements imply that, given the large angular separation between the three images of our background galaxy, the object must lie very far away," Zitrin explained. "It also matches the distance estimate we calculated, based on the color-analysis technique. So we are about 95 percent confident that this object is at a remote distance, at redshift 10 (a measure of the stretching of space since the big bang). The lensing takes away any doubt that this might be a heavily reddened, nearby object masquerading as a far more distant object."

Astronomers have long debated whether such early galaxies could have provided enough radiation to warm the hydrogen that cooled soon after the big bang. This process, called "reionization," is thought to have occurred 200 million to 1 billion years after the birth of the universe. Reionization made the universe transparent to light, allowing astronomers to look far back into time without running into a "fog" of cold hydrogen.

"We tend to assume that galaxies ionized the universe with their ultraviolet light," Zitrin said. "But we do not see enough galaxies or light that could do that. So we need to look at fainter and fainter galaxies, and the Frontier Fields and galaxy cluster lensing can help us achieve this goal."

The team's results appeared in the Sept. 5 online edition of The Astrophysical Journal Letters.

CONTACT

Felicia Chou
NASA Headquarters, Washington, D.C.
202-358-0257
felicia.chou@nasa.gov

Donna Weaver
Space Telescope Science Institute, Baltimore, Md.
410-338-4493

dweaver@stsci.edu


Slow-Growing Galaxies Offer Window to Early Universe

A small galaxy, called Sextans A, is shown here in a multi-wavelength mosaic captured by the European Space Agency's Herschel mission, in which NASA is a partner, along with NASA's Galaxy Evolution Explorer (GALEX) and the National Radio Astronomy Observatory's Jansky Very Large Array observatory near Socorro, New Mexico. Image credit: ESA/NASA/JPL-Caltech/NRAO.  Full image and caption

What makes one rose bush blossom with flowers, while another remains barren? Astronomers ask a similar question of galaxies, wondering how some flourish with star formation and others barely bloom.

A new study published in the Oct. 16 issue of the journal Nature addresses this question by making some of the most accurate measurements yet of the meager rates at which small, sluggish galaxies create stars. The report uses data from the European Space Agency's Herschel mission, in which NASA is a partner, and NASA's Spitzer Space Telescope and Galaxy Evolution Explorer (GALEX).

The findings are helping researchers figure out how the very first stars in our universe sprouted. Like the stars examined in the new study, the first-ever stars from billions of years ago took root in poor conditions. Growing stars in the early cosmos is like trying to germinate flower seeds in a bed of dry, poor soil. Back then, the universe hadn't had time yet to make "heavy metals," elements heavier than hydrogen and helium.

"The metals in space help act in some ways like a fertilizer to help stars grow," said George Helou, an author of the new study and director of NASA's Infrared Processing and Analysis Center (IPAC) at the California Institute of Technology, Pasadena. The lead author of the study is Yong Shi, who performed some of the research at IPAC before moving to Nanjing University in China. 

The two slow-going galaxies in the study, called Sextans A and ESO 146-G14, lack in heavy metals, just like our young and remote cosmos, only they are a lot closer to us and easier to see. Sextans A is located about 4,500 light-years from Earth, and ESO 146-G14 is more than 70,000 light-years away.

These smaller galaxies are late bloomers. They managed to travel through history while remaining pristine, and never bulked up in heavy metals (heavy metals not only help stars to form, but are also created themselves by stars).

"The metal-poor galaxies are like islands left over from the early universe," said Helou. "Because they are relatively close to us, they are especially valuable windows to the past." 

Studying star formation in poor growing environments such as these is tricky. The galaxies, though nearby, are still faint and hard to see. Shi and his international team wrangled the problem with a multi-wavelength approach. The Herschel data, captured at the longest infrared wavelengths of light, let the researchers see the cool dust in which stars are buried. The dust serves as a proxy for the total amount of gas in the region -- the basic ingredient of stars. To other telescopes, this dust is cold and invisible. Herschel, on the other hand, can pick up its feeble glow. 

Supporting radio-wavelength measurements of some of the gas in the galaxies came from the National Radio Astronomy Observatory's Jansky Very Large Array observatory near Socorro, New Mexico, and the Australia Telescope Compact Array observatory, near Narrabri.

Meanwhile, archived data from Spitzer and GALEX were used to look at the rate of star formation. Spitzer sees shorter-wavelength infrared light, which comes from dust that is warmed by new stars. GALEX images capture ultraviolet light from the shining stars themselves. 

Putting all these pieces together enabled the astronomers to determine that the galaxies are plodding along, creating stars at rates 10 times lower than their normal counterparts.

"Star formation is very inefficient in these environments," said Shi. "Extremely metal-poor nearby galaxies are the best way to know what went on billions of years ago."

The heavy metals in present-day galaxies help star formation to flourish through cooling effects. For a star to form, a ball of gas needs to fall in on itself with the help of its own gravity. Ultimately, the material has to become dense enough for atoms to fuse and ignite, creating starlight. But as this cloud collapses, it heats up and puffs back out again, counteracting the process. Heavy metals cool everything down by radiating away the heat, enabling the cloud to condense into a star. 

How stars in the early universe were able to do this without the cooling benefits of heavy metals remains unknown. 

Studies like this shine light on the very first stellar buds, giving us a glimpse into the roots of our cosmic history.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. The GALEX mission, which ended in 2013, was also managed by JPL for NASA and led by Caltech. JPL served as the NASA Herschel Project Office for the European Space Agency's Herschel mission, which also ended in 2013.

Data from Spitzer and Herschel are accessible through the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.


Media Contact

Whitney Clavin
818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov




NASA's Hubble Telescope Finds Potential Kuiper Belt Targets for New Horizons

Artist's Impression of Kuiper Belt Object (Annotated)

This is an artist's impression of a Kuiper Belt object (KBO), located on the outer rim of our solar system at a staggering distance of 4 billion miles from the Sun. Unlike asteroids, KBOs have not been significantly heated by the Sun, and so are thought to represent a pristine, well preserved, deep-freeze sample of what the outer solar system was like following its birth 4.6 billion years ago. A Hubble survey uncovered three KBOs, ranging from 27 to 35 miles across, that are potentially reachable by NASA's New Horizons spacecraft after it passes by Pluto in mid-2015.


The Sun appears as a bright star at image center in this graphic, which represents the view from the KBO. The Earth and other inner planets are too close to the Sun to be seen in this illustration. The bright "star" to the left of the Sun is the planet Jupiter, and the bright object below the Sun is the planet Saturn. Two bright pinpoints of light to the right of the Sun, midway to the edge of the frame, are the planets Uranus and Neptune, respectively. The planet positions are plotted for late 2018 when the New Horizons probe reaches a distance of 4 billion miles from the Sun. The Milky Way appears in the background. .  Illustration Credit: NASA, ESA, and G. Bacon (STScI)

Kuiper Belt Object 1110113Y

A Kuiper Belt object (KBO) that is potentially reachable by NASA's Pluto-bound New Horizons probe is visible in multiple exposures taken with the Hubble Space Telescope. Hubble tracked the KBO (named 1110113Y or "PT1") moving against the crowded background field of stars in the constellation Sagittarius. The object is no bigger than 19 to 28 miles across, and it is a deep-freeze relic of what the outer solar system was like 4.6 billion years ago, during the period when the Sun formed. As the KBO orbits the Sun, its position noticeably shifts between exposures taken approximately 10 minutes apart. Following an initial proof of concept of the Hubble pilot observing program in June, the New Horizons team was awarded telescope time by the Space Telescope Science Institute for a wider survey in July. When the search was completed in early September, the team identified this KBO as "definitely reachable" by the New Horizons spacecraft. Credit: NASA, ESA, SwRI, JHU/APL, and the New Horizons KBO Search Team

Hubble's Search for Kuiper Belt Objects

A Kuiper Belt object (KBO) that is potentially reachable by NASA's Pluto-bound New Horizons probe is visible in multiple exposures taken with the Hubble Space Telescope. Hubble tracked the KBO (labeled PT1) moving against the crowded background field of stars in the summer constellation Sagittarius. The object is no bigger than 19 to 28 miles across, and it is a deep-freeze relic of what the outer solar system was like 4.6 billion years ago, during the period when the Sun formed. The image at right shows the KBO at an estimated distance of approximately 4 billion miles from Earth. As the KBO orbits the Sun, its position noticeably shifts between exposures taken approximately 10 minutes apart. Following an initial proof of concept of the Hubble pilot observing program in June, the New Horizons team was awarded telescope time by the Space Telescope Science Institute for a wider survey in July. When the search was completed in early September, the team identified this KBO as "definitely reachable" by the New Horizons spacecraft. Credit: NASA, ESA SwRI, JHU/APL, and the New Horizons KBO Search Team


Peering out to the dim, outer reaches of our solar system, NASA's Hubble Space Telescope has uncovered three Kuiper Belt objects (KBOs) the agency's New Horizons spacecraft could potentially visit after it flies by Pluto in July 2015.

The KBOs were detected through a dedicated Hubble observing program by a New Horizons search team that was awarded telescope time for this purpose.

"This has been a very challenging search, and it's great that in the end Hubble could accomplish a detection — one NASA mission helping another," said Alan Stern of the Southwest Research Institute (SwRI) in Boulder, Colorado, principal investigator of the New Horizons mission.

The Kuiper Belt is a vast rim of primordial debris encircling our solar system. KBOs belong to a unique class of solar system objects that has never been visited by spacecraft and which contain clues to the origin of our solar system.

The KBOs that Hubble found are each about 10 times larger than typical comets, but only about 1-2 percent of the size of Pluto. Unlike asteroids, KBOs have not been heated by the Sun, and are thought to represent a pristine, well preserved, deep-freeze sample of what the outer solar system was like following its birth 4.6 billion years ago. The KBOs found in the Hubble data are thought to be the building blocks of dwarf planets such as Pluto.

The New Horizons team started to look for suitable KBOs in 2011 using some of the largest ground-based telescopes on Earth. They found several dozen KBOs, but none were reachable within the fuel supply available aboard the New Horizons spacecraft.

"We started to get worried that we could not find anything suitable, even with Hubble, but in the end the space telescope came to the rescue," said New Horizons science team member John Spencer of SwRI. "There was a huge sigh of relief when we found suitable KBOs; we are 'over the moon' about this detection."
Following an initial proof of concept of the Hubble pilot observing program in June, the New Horizons team was awarded telescope time by the Space Telescope Science Institute for a wider survey in July. When the search was completed in early September, the team identified one KBO that is "definitely reachable" and two other potentially accessible KBOs that will require more tracking over several months to know whether they too are accessible by the New Horizons spacecraft.

This was a needle-in-a-haystack search for the New Horizons team because the elusive KBOs are extremely small, faint, and difficult to pick out against myriad background stars in the constellation Sagittarius, which is in the present direction of Pluto. The three KBOs identified are each a whopping 1 billion miles beyond Pluto. Two of the KBOs are estimated to be as large as 34 miles (55 kilometers) across, and the third is perhaps as small as 15 miles (25 kilometers).

The New Horizons spacecraft, launched in 2006 from Florida, is the first mission in NASA's New Frontiers Program. Once a NASA mission completes its prime mission, the agency conducts an extensive science and technical review to determine whether extended operations are warranted.

The New Horizons team expects to submit such a proposal to NASA in late 2016 for an extended mission to fly by one of the newly identified KBOs. Hurtling across the solar system, the New Horizons spacecraft would reach the distance of 4 billion miles from the Sun at its farthest point roughly three to four years after its July 2015 Pluto encounter. Accomplishing such a KBO flyby would substantially increase the science return from the New Horizons mission as laid out by the 2003 Planetary Science Decadal Survey.

CONTACT

Dwayne Brown
Headquarters, Washington, D.C.
202-358-0257
dwayne.c.brown@nasa.gov

Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.edu

Source: HubbleSite

Wednesday, October 15, 2014

Construction Secrets of a Galactic Metropolis

Artist's impression of a protocluster forming in the early Universe

 
APEX view of the region around the Spiderweb Galaxy

 
The Spiderweb Galaxy and its surroundings (full ACS view)

Wide-field image of the Spiderweb Galaxy (ground-based image)

 

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Videos

Artist’s impression of a protocluster forming in the early Universe
Artist’s impression of a protocluster forming in the early Universe


APEX reveals hidden star formation in protocluster

Galaxy clusters are the largest objects in the Universe held together by gravity but their formation is not well understood. The Spiderweb Galaxy (formally known as MRC 1138-262 [1]) and its surroundings have been studied for twenty years, using ESO and other telescopes [2], and is thought to be one of the best examples of a protocluster in the process of assembly, more than ten billion years ago.

But Helmut Dannerbauer (University of Vienna, Austria) and his team strongly suspected that the story was far from complete. They wanted to probe the dark side of star formation and find out how much of the star formation taking place in the Spiderweb Galaxy cluster was hidden from view behind dust.

The team used the LABOCA camera on the APEX telescope in Chile to make 40 hours of observations of the Spiderweb Cluster at millimetre wavelengths — wavelengths of light that are long enough to peer right through most of the thick dust clouds. LABOCA has a wide field and is the perfect instrument for this survey.
Carlos De Breuck (APEX project scientist at ESO, and a co-author of the new study) emphasises: “This is one of the deepest observations ever made with APEX and pushes the technology to its limits — as well as the endurance of the staff working at the high-altitude APEX site, 5050 metres above sea level.

The APEX observations revealed that there were about four times as many sources detected in the area of the Spiderweb compared to the surrounding sky. And by carefully comparing the new data with complementary observations made at different wavelengths they were able to confirm that many of these sources were at the same distance as the galaxy cluster itself and must be parts of the forming cluster.

Helmut Dannerbauer explains: “The new APEX observations add the final piece needed to create a complete census of all inhabitants of this mega star city. These galaxies are in the process of formation so, rather like a construction site on Earth, they are very dusty.”

But a surprise awaited the team when they looked at where the newly detected star formation was taking place. They were expecting to find this star formation region on the large filaments connecting galaxies. Instead, they found it concentrated mostly in a single region, and that region is not even centred on the central Spiderweb Galaxy in the protocluster [3].

Helmut Dannerbauer concludes: “We aimed to find the hidden star formation in the Spiderweb cluster — and succeeded — but we unearthed a new mystery in the process; it was not where we expected! The mega city is developing asymmetrically.

To continue the story further observations are needed — and ALMA will be the perfect instrument to take the next steps and study these dusty regions in far greater detail.

Notes

 

[1] The Spiderweb Galaxy contains a supermassive black hole and is a powerful source of radio waves — which is what led astronomers to notice it in the first place.

[2] This region had been intensively observed by a variety of ESO telescopes since the mid-1990s. The redshift (and hence the distance) of the radio galaxy MRC1138-262 (the Spiderweb Galaxy) was first measured at La Silla. The first visitor mode FORS observations on the VLT discovered the protocluster and afterwards further observations were made with ISAAC, SINFONI, VIMOS and HAWK-I. The APEX LABOCA data complement optical and near-infrared datasets from ESO telescopes. The team also used a 12-hour VLA image to cross-identify the LABOCA sources in the optical images.

[3] These dusty starbursts are thought to evolve into elliptical galaxies like those seen around us today in nearby galaxy clusters.

More information

 

This research was presented in a paper, “An excess of dusty starbursts related to the Spiderweb galaxy”, by Dannerbauer, Kurk, De Breuck et al., to appear online in the journal Astronomy & Astrophysics on 15 October 2014.


APEX is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. Operation of APEX at Chajnantor is entrusted to ESO.


The team is composed of H. Dannerbauer (University of Vienna, Austria), J. D. Kurk (Max-Planck-Institut für extraterrestrische Physik, Garching, Germany), C. De Breuck (ESO, Garching, Germany), D. Wylezalek (ESO, Garching, Germany), J. S. Santos (INAF–Osservatorio Astrofisico di Arcetri, Florence, Italy), Y. Koyama (National Astronomical Observatory of Japan, Tokyo, Japan [NAOJ]; Institute of Space Astronomical Science, Kanagawa, Japan), N. Seymour (International Centre for Radio Astronomy Research, Curtin University, Perth, Australia), M. Tanaka (NAOJ; Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, Japan), N. Hatch (University of Nottingham, United Kingdom), B. Altieri (Herschel Science Centre, European Space Astronomy Centre, Villanueva de la Cañada, Spain [HSC]), D. Coia (HSC), A. Galametz (INAF–Osservatorio di Roma, Italy), T. Kodama (NAOJ), G. Miley (Leiden Observatory, the Netherlands), H. Röttgering (Leiden Observatory), M. Sanchez-Portal (HSC), I. Valtchanov (HSC), B. Venemans (Max-Planck Institut für Astronomie, Heidelberg, Germany) and B. Ziegler (University of Vienna).


ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links


Contacts

 

Helmut Dannerbauer
University of Vienna
Vienna, Austria
Tel: +43 1 4277 53826
Email:
helmut.dannerbauer@univie.ac.at

Carlos De Breuck
ESO APEX Project Scientist
Garching bei München, Germany
Tel: +49 89 3200 6613
Email:
cdebreuc@eso.org

Richard Hook
ESO, Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email:
rhook@eso.org

Source: ESO