The Coldest Spot in the Known Universe

A new ScienceCast video explores the strange quantum realm of NASA's new Cold Atom Lab.Play it

Everyone knows that space is cold. In the vast gulf between stars and galaxies, the temperature of gaseous matter routinely drops to 3 degrees K, or 454 degrees below zero Fahrenheit. 

It’s about to get even colder.

NASA researchers are planning to create the coldest spot in the known universe inside the International Space Station.

“We’re going to study matter at temperatures far colder than are found naturally,” says Rob Thompson of JPL. He’s the Project Scientist for NASA’s Cold Atom Lab, an atomic ‘refrigerator’ slated for launch to the ISS in 2016. "We aim to push effective temperatures down to 100 pico-Kelvin."

100 pico-Kelvin is just one ten billionth of a degree above absolute zero, where all the thermal activity of atoms theoretically stops. At such low temperatures, ordinary concepts of solid, liquid and gas are no longer relevant.  Atoms interacting just above the threshold of zero energy create new forms of matter that are essentially ... quantum. 

Quantum mechanics is a branch of physics that describes the bizarre rules of light and matter on atomic scales. In that realm, matter can be in two places at once; objects behave as both particles and waves; and nothing is certain: the quantum world runs on probability. 

It is into this strange realm that researchers using the Cold Atom Lab will plunge.

“We’ll begin,” says Thompson, “by studying Bose-Einstein Condensates.” 

In 1995, researchers discovered that if you took a few million rubidium atoms and cooled them near absolute zero, they would merge into a single wave of matter.  The trick worked with sodium, too.  In 2001, Eric Cornell of the National Institute of Standards & Technology and Carl Wieman of University of Colorado shared the Nobel Prize with Wolfgang Ketterle of MIT for their independent discovery of these condensates, which Albert Einstein and Satyendra Bose had predicted in the early 20^th century. 

If you create two BECs and put them together, they don't mix like an ordinary gas. Instead, they can "interfere" like waves: thin, parallel layers of matter are separated by thin layers of empty space. An atom in one BEC can add itself to an atom in another BEC and produce – no atom at all.

“The Cold Atom Lab will allow us to study these objects at perhaps the lowest temperatures ever,” says Thompson. 

The lab is also a place where researchers can mix super-cool atomic gasses and see what happens. 

“Mixtures of different types of atoms can float together almost completely free of perturbations,” explains Thompson, “allowing us to make sensitive measurements of very weak interactions.  This could lead to the discovery of interesting and novel quantum phenomena.” 

The space station is the best place to do this research. Microgravity allows researchers to cool materials to temperatures much colder than are possible on the ground. 

Thompson explains why: 

“It’s a basic principle of thermodynamics that when a gas expands, it cools. Most of us have hands-on experience with this. If you spray a can of aerosols, the can gets cold.” 

Quantum gases are cooled in much the same way.  In place of an aerosol can, however, we have a ‘magnetic trap.’  

“On the ISS, these traps can be made very weak because they do not have to support the atoms against the pull of gravity.  Weak traps allow gases to expand and cool to lower temperatures than are possible on the ground.” 

No one knows where this fundamental research will lead.  Even the “practical” applications listed by Thompson—quantum sensors, matter wave interferometers, and atomic lasers, just to name a few—sound like science fiction. “We’re entering the unknown,” he says. 

Researchers like Thompson think of the Cold Atom Lab as a doorway into the quantum world.  Could the door swing both ways?  If the temperature drops low enough, “we’ll be able to assemble atomic wave packets as wide as a human hair--that is, big enough for the human eye to see.”  A creature of quantum physics will have entered the macroscopic world. 

And then the real excitement begins. 

For more information about the Cold Atom Lab, visit coldatomlab.jpl.nasa.gov

Credits:

Author: Dr. Tony Phillips 

Production editor: Dr. Tony Phillips 

Credit: Science@NASA

Where the Wild Stars Are

Radiation and winds from massive stars have blown a cavity into the surrounding dust and gas, creating the Trifid nebula, as seen here in infrared light by NASA's Wide-field Infrared Survey Explorer, or WISE. Image credit: NASA/JPL-Caltech/UCLA.  Larger image

A storm of stars is brewing in the Trifid nebula, as seen in this view from NASA's Wide-field Infrared Survey Explorer, or WISE. The stellar nursery, where baby stars are bursting into being, is the yellow-and-orange object dominating the picture. Yellow bars in the nebula appear to cut a cavity into three sections, hence the name Trifid nebula.

Colors in this image represent different wavelengths of infrared light detected by WISE. The main green cloud is made up of hydrogen gas. Within this cloud is the Trifid nebula, where radiation and winds from massive stars have blown a cavity into the surrounding dust and gas, and presumably triggered the birth of new generations of stars. Dust glows in infrared light, so the three lines that make up the Trifid, while appearing dark in visible-light views, are bright when seen by WISE. 

The blue stars scattered around the picture are older, and they lie between Earth and the Trifid nebula. The baby stars in the Trifid will eventually look similar to those foreground stars. The red cloud at upper right is gas heated by a group of very young stars.

The Trifid nebula is located 5,400 light-years away in the constellation Sagittarius.

Blue represents light emitted at 3.4-micron wavelengths, and cyan (blue-green) represents 4.6 microns, both of which come mainly from hot stars. Relatively cooler objects, such as the dust of the nebula, appear green and red. Green represents 12-micron light and red, 22-micron light.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages and operates the recently activated NEOWISE asteroid-hunting mission for NASA's Science Mission Directorate. The results presented here are from the WISE all-sky survey mission, which operated before NEOWISE, using the same spacecraft, in 2010 and 2011. WISE was selected competitively under NASA's Explorers Program managed by the agency's Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah. The spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology, Pasadena. Caltech manages JPL for NASA.

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

NASA-Sponsored 'Disk Detective' Lets Public Search for New Planetary Nurseries

Herbig-Haro 30 is the prototype of a gas-rich "young stellar object" disk around a star. The dark disk spans 40 billion miles (64 billion kilometers) in this image from NASA's Hubble Space Telescope, cutting the bright nebula in two and blocking the central star from direct view. Image credit NASA/Hubble/STScI.  Full image and caption

 

NASA is inviting the public to help astronomers discover embryonic planetary systems hidden among data from the agency's Wide-field Infrared Survey Explorer (WISE) mission through a new website, DiskDetective.org.

Disk Detective is NASA's largest crowdsourcing project whose primary goal is to produce publishable scientific results. It exemplifies a new commitment to crowdsourcing and open data by the United States government.

"Through Disk Detective, volunteers will help the astronomical community discover new planetary nurseries that will become future targets for NASA's Hubble Space Telescope and its successor, the James Webb Space Telescope," said James Garvin, the chief scientist for NASA Goddard's Sciences and Exploration Directorate.

WISE was designed to survey the entire sky at infrared wavelengths. From a perch in Earth orbit, the spacecraft completed two scans of the entire sky between 2010 and 2011. It took detailed measurements on more than 745 million objects, representing the most comprehensive survey of the sky at mid-infrared wavelengths currently available.

Astronomers have used computers to search this haystack of data for planet-forming environments and narrowed the field to about a half-million sources that shine brightly in infrared, indicating they may be "needles": dust-rich disks that are absorbing their star's light and reradiating it as heat.

"Planets form and grow within disks of gas, dust and icy grains that surround young stars, but many details about the process still elude us," said Marc Kuchner, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md. "We need more examples of planet-forming habitats to better understand how planets grow and mature."

But galaxies, interstellar dust clouds and asteroids also glow in infrared, which stymies automated efforts to identify planetary habitats. There may be thousands of nascent solar systems in the WISE data, but the only way to know for sure is to inspect each source by eye, which poses a monumental challenge.

Public participation in scientific research is a type of crowdsourcing known as citizen science. It allows the public to make critical contributions to the fields of science, technology, engineering and mathematics by collecting, analyzing and sharing a wide range of data. NASA uses citizen science to engage the public in problem-solving.

Kuchner recognized that spotting planetary nurseries is a perfect opportunity for crowdsourcing. He arranged for NASA to team up with the Zooniverse, a collaboration of scientists, software developers and educators who collectively develop and manage citizen science projects on the Internet. The result of their combined effort is Disk Detective.

Disk Detective incorporates images from WISE and other sky surveys in brief animations the website calls flip books. Volunteers view a flip book and classify the object based on simple criteria, such as whether the image is round or includes multiple objects. By collecting this information, astronomers will be able to assess which sources should be explored in greater detail, for example, to search for planets outside our solar system.

"Disk Detective's simple and engaging interface allows volunteers from all over the world to participate in cutting-edge astronomy research that wouldn't even be possible without their efforts," said Laura Whyte, director of citizen science at Adler Planetarium in Chicago, Ill., a founding partner of the Zooniverse collaboration.

The project aims to find two types of developing planetary environments. The first, known as a young stellar object disk, typically is less than 5 million years old, contains large quantities of gas, and often is found in or near young star clusters. For comparison, our own solar system is 4.6 billion years old. The second planetary environment, known as a debris disk, tends to be older than 5 million years, possesses little or no gas, and contains belts of rocky or icy debris that resemble the asteroid and Kuiper belts found in our own solar system. Vega and Fomalhaut, two of the brightest stars in the sky, host debris disks.

WISE was shut down in 2011 after its primary mission was completed. But in September 2013, it was reactivated, renamed Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), and given a new mission, which is to assist NASA's efforts to identify the population of potentially hazardous near-Earth objects (NEOs). NEOWISE also can assist in characterizing previously detected asteroids that could be considered potential targets for future exploration missions.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages and operates WISE for NASA's Science Mission Directorate. The WISE mission was selected competitively under NASA's Explorers Program managed by the agency's Goddard Space Flight Center. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah. The spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology, which manages JPL for NASA.

For more information about Disk Detective, please visit: http://www.diskdetective.org

For more information about NASA's WISE mission, visit: http://www.nasa.gov/wise


Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

J.D. Harrington 202-358-5241
Headquarters, Washington
j.d.harrington@nasa.gov

NASA's SDO Sees Lunar Transit

 

A rainbow of lunar transits as seen by NASA's Solar Dynamics Observatory. The observatory watches the sun in many different wavelengths of light, which are each colorized in a different color. Image Credit: NASA/SDO

On Jan 30, 2014, beginning at 8:31 a.m EST, the moon moved between NASA’s Solar Dynamics Observatory, or SDO, and the sun, giving the observatory a view of a partial solar eclipse from space. Such a lunar transit happens two to three times each year.  This one lasted two and one half hours, which is the longest ever recorded.  When the next one will occur is as of yet unknown due to planned adjustments in SDO's orbit.

Note in the picture how crisp the horizon is on the moon, a reflection of the fact that the moon has no atmosphere around it to distort the light from the sun.

NASA's Solar Dynamics Observatory captured this image of the moon crossing in front of its view of the sun on Jan. 30, 2014, at 9:00 a.m. EST. Image Credit: NASA/SDO

A movie of the moon crossing in front of the sun as seen by NASA’s Solar Dynamics Observatory on Jan 30, 2014. The sun appears to move because SDO’s fine guidance systems rely on seeing the whole sun to keep the images centered from exposure to exposure. Image Credit: NASA/SDO/Goddard Space Flight Center

Related Links:

• Download high resolution image and video files at: http://svs.gsfc.nasa.gov/vis/a010000/a011400/a011463/

Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, Md.

First Weather Map of Brown Dwarf

PR Image eso1404a

Surface map of Luhman 16B recreated from VLT observations

 

PR Image eso1404b

Surface map of Luhman 16B recreated from VLT observations (annotated)

PR Image eso1404c

Artist's impression of Luhman 16B recreated from VLT observations

PR Image eso1404d

Surface map of Luhman 16B recreated from VLT observations

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Surface map of Luhman 16B recreated from VLT observations

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Wide-field view of the sky around the nearby brown dwarf pair

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Videos

PR Video eso1404a

Artist's impression of Luhman 16B recreated from VLT observations

PR Video eso1404b

Surface map of Luhman 16B recreated from VLT observations

PR Video eso1404c

Zooming in on the nearby brown dwarf Luhman 16B

PR Video eso1404d

Flying among the closest stars to the Solar System

   

ESO’s VLT charts surface of nearest brown dwarf

ESO's Very Large Telescope has been used to create the first ever map of the weather on the surface of the nearest brown dwarf to Earth. An international team has made a chart of the dark and light features on WISE J104915.57-531906.1B, which is informally known as Luhman 16B and is one of two recently discovered brown dwarfs forming a pair only six light-years from the Sun. The new results are being published in the 30 January 2014 issue of the journal Nature.

Brown dwarfs fill the gap between giant gas planets, such as Jupiter and Saturn, and faint cool stars. They do not contain enough mass to initiate nuclear fusion in their cores and can only glow feebly at infrared wavelengths of light. The first confirmed brown dwarf was only found twenty years ago and only a few hundred of these elusive objects are known.

The closest brown dwarfs to the Solar System form a pair called Luhman 16AB [1] that lies just six light-years from Earth in the southern constellation of Vela (The Sail). This pair is the third closest system to the Earth, after Alpha Centauri and Barnard's Star, but it was only discovered in early 2013. The fainter component, Luhman 16B, had already been found to be changing slightly in brightness every few hours as it rotated — a clue that it might have marked surface features.

Now astronomers have used the power of ESO's Very Large Telescope (VLT) not just to image these brown dwarfs, but to map out dark and light features on the surface of Luhman 16B.

Ian Crossfield (Max Planck Institute for Astronomy, Heidelberg, Germany), the lead author of the new paper, sums up the results: “Previous observations suggested that brown dwarfs might have mottled surfaces, but now we can actually map them. Soon, we will be able to watch cloud patterns form, evolve, and dissipate on this brown dwarf — eventually, exometeorologists may be able to predict whether a visitor to Luhman 16B could expect clear or cloudy skies.”

To map the surface the astronomers used a clever technique. They observed the brown dwarfs using the CRIRES instrument on the VLT. This allowed them not just to see the changing brightness as Luhman 16B rotated, but also to see whether dark and light features were moving away from, or towards the observer. By combining all this information they could recreate a map of the dark and light patches of the surface.

The atmospheres of brown dwarfs are very similar to those of hot gas giant exoplanets, so by studying comparatively easy-to-observe brown dwarfs [2] astronomers can also learn more about the atmospheres of young, giant planets — many of which will be found in the near future with the new SPHERE instrument that will be installed on the VLT in 2014.

Crossfield ends on a personal note: “Our brown dwarf map helps bring us one step closer to the goal of understanding weather patterns in other solar systems. From an early age I was brought up to appreciate the beauty and utility of maps. It's exciting that we're starting to map objects out beyond the Solar System!”

Notes

[1] This pair was discovered by the American astronomer Kevin Luhman on images from the WISE infrared survey satellite. It is formally known as WISE J104915.57-531906.1, but a shorter form was suggested as being much more convenient. As Luhman had already discovered fifteen double stars the name Luhman 16 was adopted. Following the usual conventions for naming double stars, Luhman 16A is the brighter of the two components, the secondary is named Luhman 16B and the pair is referred to as Luhman 16AB.

[2] Hot Jupiter exoplanets lie very close to their parent stars, which are much brighter. This makes it almost impossible to observe the faint glow from the planet, which is swamped by starlight. But in the case of brown dwarfs there is nothing to overwhelm the dim glow from the object itself, so it is much easier to make sensitive measurements.

More information

This research was presented in a paper, “A Global Cloud Map of the Nearest Known Brown Dwarf”, by Ian Crossfield et al. to appear in the journal Nature.

The team is composed of I. J. M. Crossfield (Max Planck Institute for Astronomy [MPIA], Heidelberg, Germany), B. Biller (MPIA; Institute for Astronomy, University of Edinburgh, United Kingdom), J. Schlieder (MPIA), N. R. Deacon (MPIA), M. Bonnefoy (MPIA; IPAG, Grenoble, France), D. Homeier (CRAL-ENS, Lyon, France), F. Allard (CRAL-ENS), E. Buenzli (MPIA), Th. Henning (MPIA), W. Brandner (MPIA), B. Goldman (MPIA) and T. Kopytova (MPIA; International Max-Planck Research School for Astronomy and Cosmic Physics at the University of Heidelberg, Germany).

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

• Research paper in Nature 
• MPIA press release
• Photos of the VLT
• The CRIRES instrument on the VLT

Contacts

Ian Crossfield
Max Planck Institute for Astronomy
Heidelberg, Germany
Tel: +49 6221 528 406
Email: ianc@mpia.de

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 

 

Hubble Helps Solve Mystery of Ultra-Compact, Burned-Out Galaxies

Development of Massive Elliptical Galaxies 

This graphic shows the evolutionary sequence in the growth of massive elliptical galaxies over 13 billion years, as gleaned from space-based and ground-based telescopic observations. The growth of this class of galaxies is quickly driven by rapid star formation and mergers with other galaxies.  Credit: NASA, ESA, S. Toft (Niels Bohr Institute), and A. Feild (STScI)

Astronomers combining the power of the Hubble Space Telescope, Spitzer and Herschel infrared space telescopes, and ground-based telescopes have assembled a coherent picture of the formation history of the most massive galaxies in the universe, from their initial burst of violent star formation through their appearance as high stellar-density galaxy cores and to their ultimate destiny as giant ellipticals.

This solves a decade-long mystery as to how compact elliptical-shaped galaxies that existed when the universe was only 3 billion years old, or one-quarter of its current age of 13.8 billion years, already had completed star formation. These compact ellipticals have now been definitively linked directly to an earlier population of dusty starburst galaxies that voraciously used up available gas for star formation very quickly. Then they grew slowly through merging as the star formation in them was quenched, and they eventually became giant elliptical galaxies.

"This is the first time anybody has put together a representative spectroscopic sample of ultra-compact, burned-out galaxies with the high quality of infrared imaging of Hubble," said Sune Toft of the Dark Cosmology Center at the Niels Bohr Institute in Copenhagen.

"We at last show how these compact galaxies can form, how it happened, and when it happened," Toft added. "This basically is the missing piece in the understanding of how the most massive galaxies formed, and how they evolved into the giant ellipticals of today. This had been a great mystery for many years because just 3 billion years after the big bang we see that half of the most massive galaxies have already completed their star formation."

Even more surprising, said Toft, is that these massive, burned-out galaxies were once extremely compact, compared to similar elliptical galaxies seen today in the nearby universe. This means that stars had to be crammed together 10 to 100 times more densely than seen in galaxies today. "It's comparable to the densities of stars in globular clusters, but on the larger scale of a galaxy," said Toft.

In tying together an evolutionary sequence for these compact massive galaxies, Toft identified their progenitors as highly dust-obscured galaxies undergoing rapid star formation at rates that are thousands of times faster than in our Milky Way galaxy. Starbursts in these galaxies are likely ignited when two gas-rich galaxies collided. These galaxies are so dusty that they are almost invisible at optical wavelengths, but are bright at submillimeter wavelengths, where they were first identified nearly two decades ago by the SCUBA (Submillimeter Common-User Bolometer Array) camera on the James Clerk Maxwell Telescope in Hawaii.

Toft's team assembled, for the first time, representative samples of the two galaxy populations using the rich dataset in Hubble's COSMOS (Cosmic Evolution Survey) program.

They constructed the first representative sample of compact quiescent galaxies with accurate sizes and distances (spectroscopic redshifts) measured from the Hubble Space Telescope's CANDELS (Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey) and 3D-HST programs. 3D-HST is a near-infrared Hubble spectroscopic survey to study the physical processes that shape galaxies in the distant universe. The astronomers combined these data with observations from the Subaru telescope in Hawaii and NASA's Spitzer Space Telescope. This allowed for accurate stellar age estimates, from which they concluded that galaxies formed in intense starbursts 1 billion to 2 billion years earlier, in the very early universe.

The team then made the first representative sample of the most distant submillimeter galaxies using the rich COSMOS data from the Hubble, Spitzer, and Herschel space telescopes, and ground-based telescopes such as Subaru, the James Clerk Maxwell Telescope, and the Submillimeter Array. This multi-spectral information, stretching from optical light through submillimeter wavelengths, yielded a full suite of information about the sizes, stellar masses, star-formation rates, dust content, and precise distances of the dust-enshrouded galaxies present early on in the universe.

When Toft's team compared the samples of these two galaxy populations, they discovered a link between the compact elliptical galaxies and the submillimeter galaxies observed 1 billion to 2 billion years earlier. The observations show that the violent starburst activity in the earlier galaxies had the same characteristics that would have been predicted for progenitors to the compact elliptical galaxies. The team also calculated that the intense starburst activity only lasted about 40 million years before the interstellar gas supply was exhausted.

CONTACT

Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu
 
Sune Toft
Dark Cosmology Center, Niels Bohr Institute, Copenhagen, Denmark
011-45-3532-5908
sune@dark-cosmology.dk

Active Supermassive Black Holes Revealed in Merging Galaxies

A team of astronomers has conducted infrared observations of luminous, gas-rich, merging galaxies with the Subaru Telescope to study active, mass-accreting supermassive black holes (SMBHs). They found that at least one SMBH almost always becomes active and luminous by accreting a large amount of material (Figure 1). However, only a small fraction of the observed merging galaxies show multiple, active SMBHs. These results suggest that local physical conditions near SMBHs rather than general properties of galaxies primarily determine the activation of SMBHs.

Figure 1: Artist's rendition of an active, mass-accreting black hole in a luminous, gas-rich merging galaxy. (Credit: NAOJ)  

 

In this Universe, dark matter has a much higher mass than luminous matter, and it dominates the formation of galaxies and their large-scale structures. The widely accepted, cold-dark-matter based galaxy formation scenario posits that collisions and mergers of small gas-rich galaxies result in the formation of massive galaxies seen in the current Universe. Recent observations show that SMBHs with more than one-million solar masses ubiquitously exist in the center of galaxies. The merger of gas-rich galaxies with SMBHs in their centers not only causes active star formation but also stimulates mass accretion onto the existing SMBHs. When material accretes onto a supermassive black hole (SMBH), the accretion disk surrounding the black hole becomes very hot from the release of gravitational energy, and it becomes very luminous. This process is referred to as active galactic nucleus (AGN) activity; it is different from the energy generation activity by nuclear fusion reactions within stars. Understanding the difference between these kinds of activities is crucial for clarifying the physical processes of galaxy formation. However, observation of these processes is challenging, because dust and gas shroud both star-formation and AGN activities in merging galaxies. Infrared observations are indispensable for this type of research, because they substantially reduce the effects of dust extinction.

To better understand these activities, a team of astronomers at the National Astronomical Observatory of Japan (NAOJ), led by Dr. Masatoshi Imanishi, used Subaru Telescope’s Infrared Camera and Spectrograph (IRCS) and its adaptive optics system to observe infrared luminous merging galaxies at the infrared K-band (a wavelength of 2.2 micrometers) and L’-band (a wavelength of 3.8 micrometers). They used imaging data at these wavelengths to establish a method to differentiate the activities of deeply buried, active SMBHs from those of star formation. The radiative energy-generation efficiency from active, mass-accreting SMBHs is much higher than that of the nuclear fusion reactions inside stars. An active SMBH generates a large amount of hot dust (several 100 Kelvins), which produces strong infrared L’-band radiation; the relative strengths of the infrared K- and L’-band emission distinguish the active SMBH from star-forming activity. Since dust extinction effects are small at these infrared wavelengths, the method can detect even deeply buried, active SMBHs, which are elusive in optical wavelengths. Subaru Telescope’s adaptive optics system enabled the team to obtain high spatial resolution images that allowed them to effectively investigate emission that originates in active SMBHs in the nuclear regions of galaxies by minimizing emission contamination from galaxy-wide, star-forming activity. 

The team observed 29 infrared luminous gas-rich merging galaxies. Based on the relative strength of the infrared K- and L’-band emission at galaxy nuclei, they confirmed that at least one active SMBH occurs in every galaxy but one (Figure 2). This indicates that in gas-rich, merging galaxies, a large amount of material can accrete onto SMBHs, and many such SMBHs can show AGN activity.

Figure 2: Examples of infrared K-band images of luminous, gas-rich, merging galaxies. The image size is 10 arc seconds. North is up, and east is to the left. The individual images clearly show aspects of the merging process, such as interacting double galaxy nuclei and extended/bridging faint emission structure. (Credit: NAOJ) 

However, only four merging galaxies display multiple, active SMBHs (Figure 3). If both of the original merged galaxies had SMBHs, then we would expect that multiple SMBHs would occur in many merging galaxies. To observe these SMBHs as luminous AGN activity, the SMBHs must actively accrete material. The team’s results mean that not all SMBHs in gas-rich merging galaxies are actively mass accreting, and that multiple SMBHs may have considerably different mass accretion rates onto SMBHs. Quantitative measurement of the degree of mass accretion rates of SMBHs is usually based on the brightness of AGNs per unit SMBH mass (Figure 4). Comparison of SMBH-mass-normalized AGN luminosity (=AGN luminosity divided by SMBH mass) among multiple nuclei confirms the scenario of different mass accretion rates onto multiple SMBHs in infrared-luminous, gas-rich merging galaxies.

Figure 3: Infrared K-band and L’-band images of four luminous, gas-rich, merging galaxies that display multiple, active SMBHs. The image size is 10 arc seconds. North is up, and east is to the left. They show emission from multiple galaxy nuclei. The infrared K-band to L’-band emission strength ratios characterize emission of AGN-heated hot dust, not a star-formation-related one. (Credit: NAOJ)

Figure 4: The vertical axis is the comparison of SMBH-mass-normalized AGN luminosity (= AGN luminosity divided by SMBH mass) between multiple nuclei. The horizontal axis is the apparent separation of galaxy nuclei. 1 kilo-parsec corresponds to 30000 trillion kilometers (19000 trillion miles). The supermassive black-hole (SMBH) masses are derived from stellar emission luminosity at individual galaxy nuclei, because SMBH mass and galaxy stellar emission　luminosity are found to correlate in nearby galaxies. If both SMBHs have the same mass accretion rate, when normalized to the SMBH mass, then such objects are distributed around the horizontal solid line, at the value of unity in the vertical axis. Objects above the horizontal solid line are SMBHs with larger mass and show more active mass accretion, while those below have a smaller mass and show less active mass accretion.(Credit: NAOJ) 

The findings demonstrate that local conditions around SMBHs rather than general properties of galaxies dominate the mass accretion process onto SMBHs. Since the size scale of mass accretion onto SMBHs is very small compared to the galaxy scale, such phenomena are difficult to predict based on computer simulations of galaxy mergers. Actual observations are crucially important for best understanding the mass accretion process onto SMBHs that occurs during galaxy mergers.

Reference:

Imanishi, M. & Saito, Y. 2014 “Subaru Adaptive-optics High-spatial-resolution Infrared K- and L’-band Imaging Search for Deeply Buried Dual AGNs in Merging Galaxies”, Astrophysical Journal, Volume 780, article id. 106.

Source: Subaru Telescope

River of Hydrogen Flowing through Space Seen with Green Bank Telescope

This composite image contains three distinct features: the bright star-filled central region of galaxy NGC 6946 in optical light (blue), the dense hydrogen tracing out the galaxy’s sweeping spiral arms and galactic halo (orange), and the extremely diffuse and extended field of hydrogen engulfing NGC 6946 and its companions (red). The new GBT data show the faintly glowing hydrogen bridging the gulf between the larger galaxy and its smaller companions. This faint structure is precisely what astronomers expect to appear as hydrogen flows from the intergalactic medium into galaxies or from a past encounter between galaxies. 

 Credit: D.J. Pisano (WVU); B. Saxton (NRAO/AUI/NSF); Palomar Observatory – Space Telescope Science Institute 2nd Digital Sky Survey (Caltech); Westerbork Synthesis Radio Telescope

Using the National Science Foundation’s Robert C. Byrd Green Bank Telescope (GBT), astronomer D.J. Pisano from West Virginia University has discovered what could be a never-before-seen river of hydrogen flowing through space. This very faint, very tenuous filament of gas is streaming into the nearby galaxy NGC 6946 and may help explain how certain spiral galaxies keep up their steady pace of star formation.

“We knew that the fuel for star formation had to come from somewhere. So far, however, we’ve detected only about 10 percent of what would be necessary to explain what we observe in many galaxies,” said Pisano. “A leading theory is that rivers of hydrogen – known as cold flows – may be ferrying hydrogen through intergalactic space, clandestinely fueling star formation. But this tenuous hydrogen has been simply too diffuse to detect, until now.”

Spiral galaxies, like our own Milky Way, typically maintain a rather tranquil but steady pace of star formation.
Others, like NGC 6946, which is located approximately 22 million light-years from Earth on the border of the constellations Cepheus and Cygnus, are much more active, though less-so than more extreme starburst galaxies. This raises the question of what is fueling the sustained star formation in this and similar spiral galaxies.

Earlier studies of the galactic neighborhood around NGC 6946 with the Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands have revealed an extended halo of hydrogen (a feature commonly seen in spiral galaxies, which may be formed by hydrogen ejected from the disk of the galaxy by intense star formation and supernova explosions). A cold flow, however, would be hydrogen from a completely different source: gas from intergalactic space that has never been heated to extreme temperatures by a galaxy’s star birth or supernova processes.  

Using the GBT, Pisano was able to detect the glow emitted by neutral hydrogen gas connecting NGC 6946 with its cosmic neighbors. This signal was simply below the detection threshold of other telescopes. The GBT’s unique capabilities, including its immense single dish, unblocked aperture, and location in the National Radio Quiet Zone, enabled it to detect this tenuous radio light.

Astronomers have long theorized that larger galaxies could receive a constant influx of cold hydrogen by syphoning it off other less-massive companions.

In looking at NGC 6946, the GBT detected just the sort of filamentary structure that would be present in a cold flow, though there is another probable explanation for what has been observed. It’s also possible that sometime in the past this galaxy had a close encounter and passed by its neighbors, leaving a ribbon of neutral atomic hydrogen in its wake.

If that were the case, however, there should be a small but observable population of stars in the filaments. Further studies will help to confirm the nature of this observation and could shine light on the possible role that cold flows play in the evolution of galaxies.

These results are published in the Astronomical Journal.

The 100-meter GBT is operated by the National Radio Astronomy Observatory (NRAO) and located in the National Radio Quiet Zone and the West Virginia Radio Astronomy Zone, which protect the incredibly sensitive telescope from unwanted radio interference.

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

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

The whirl of stellar life

M51 or NGC 5194

Copyright: ESA / Herschel / XMM-Newton. Acknowledgements: "Physical Processes in the Interstellar Medium of Very Nearby Galaxies" Key Programme, Christine Wilson

The Whirlpool Galaxy, also known as M51 or NGC 5194, is one of the most spectacular examples of a spiral galaxy. With two spiral arms curling into one another in a billowing swirl, this galaxy hosts over a hundred billion stars and is currently merging with its companion, the smaller galaxy NGC 5195.

Around 30 million light-years away, the Whirlpool Galaxy is close enough to be easily spotted even with binoculars. Using the best telescopes available both on the ground and in space, astronomers can scrutinise its population of stars in extraordinary detail.

In this image, observations performed at three different wavelengths with ESA’s Herschel and XMM-Newton space telescopes are combined to reveal how three generations of stars coexist in the Whirlpool Galaxy.

The infrared light collected by Herschel – shown in red and yellow – reveals the glow of cosmic dust, which is a minor but crucial ingredient in the interstellar material in the galaxy’s spiral arms. This mixture of gas and dust provides the raw material from which the Whirlpool Galaxy’s future generations of stars will take shape.

Observing in visible and ultraviolet light, astronomers can see the current population of stars in the Whirlpool Galaxy, since stars in their prime shine most brightly at shorter wavelengths than infrared. Seen at ultraviolet wavelengths with XMM-Newton and portrayed in green in this composite image are the galaxy’s fiercest stellar inhabitants: young and massive stars pouring powerful winds and radiation into their surroundings.

The image also shows the remains of previous stellar generations, which shine brightly in X-rays and were detected by XMM-Newton. Shown in blue, these sources of X-rays are either the sites where massive stars exploded as supernovae in the past several thousand years, or binary systems that host neutron stars or black holes, the compact objects left behind by supernovae.

 Source: ESA - Space Images

Fast and Furious: Shock Heated Gas in Colliding Galaxies

NGC 6240

Credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, 

and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

Not all galaxies are neatly shaped, as this new NASA/ESA Hubble Space Telescope image of NGC 6240 clearly demonstrates. Hubble previously released an image of this galaxy back in 2008, but the knotted region, shown here in a pinky-red hue at the centre of the galaxies, was only revealed in these new observations from Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys.

NGC 6240 lies 400 million light-years away in the constellation of Ophiuchus (The Serpent Holder). This galaxy has an elongated shape with branching wisps, loops and tails. This mess of gas, dust and stars bears more than a passing resemblance to a butterfly and, though perhaps less conventionally beautiful, a lobster.

This bizarrely-shaped galaxy did not begin its life looking like this; its distorted appearance is a result of a galactic merger that occurred when two galaxies drifted too close to one another. This merger sparked bursts of new star formation and triggered many hot young stars to explode as supernovae. A new supernova was discovered in this galaxy in 2013, named SN 2013dc. It is not visible in this image, but its location is indicated here.

At the centre of NGC 6240 an even more interesting phenomenon is taking place. When the two galaxies came together, their central black holes did so too. There are two supermassive black holes within this jumble, spiralling closer and closer to one another. They are currently only some 3000 light-years apart, incredibly close given that the galaxy itself spans 300 000 light-years. This proximity secures their fate as they are now too close to escape each other and will soon form a single immense black hole.

Link

• Images of Hubble

Source: ESA/Hubble - Space Telescope

RX J1532.9+3021: Extreme Power of Black Hole Revealed

RX J1532.9+3021 (labeled)

Credit X-ray: NASA/CXC/Stanford/J.Hlavacek-Larrondo et al,  

Optical: NASA/ESA/STScI/M.Postman & CLASH team 

JPEG (675.7 kb) - Large JPEG (6 MB) - Tiff (13.9 MB) - More Images
View on the Sky (WWT)

Chandra X-ray and HST optical images of the galaxy cluster RX J1532.9+3021, located about 3.9 billion light years from Earth. A labeled version of the combined X-ray/optical image is also given. The labels show the location of two enormous X-ray cavities, created by jets from a central supermassive black hole that have pushed aside hot gas. 

Astronomers have used NASA's Chandra X-ray Observatory and a suite of other telescopes to reveal one of the most powerful black holes known. The black hole has created enormous structures in the hot gas surrounding it and prevented trillions of stars from forming.

The black hole is in a galaxy cluster named RX J1532.9+3021 (RX J1532 for short), located about 3.9 billion light years from Earth. The image here is a composite of X-ray data from Chandra revealing hot gas in the cluster in purple and optical data from the Hubble Space Telescope showing galaxies in yellow. The cluster is very bright in X-rays implying that it is extremely massive, with a mass about a quadrillion - a thousand trillion - times that of the sun. At the center of the cluster is a large elliptical galaxy containing the supermassive black hole.

The large amount of hot gas near the center of the cluster presents a puzzle. Hot gas glowing with X-rays should cool, and the dense gas in the center of the cluster should cool the fastest. The pressure in this cool central gas is then expected to drop, causing gas further out to sink in towards the galaxy, forming trillions of stars along the way. However, astronomers have found no such evidence for this burst of stars forming at the center of this cluster.

This problem has been noted in many galaxy clusters but RX J1532 is an extreme case, where the cooling of gas should be especially dramatic because of the high density of gas near the center. Out of the thousands of clusters known to date, less than a dozen are as extreme as RX J1532. The Phoenix Cluster is the most extreme, where, conversely, large numbers of stars have been observed to be forming.

What is stopping large numbers of stars from forming in RX J1532? Images from the Chandra X-ray Observatory and the NSF's Karl G. Jansky Very Large Array (VLA) have provided an answer to this question. The X-ray image shows two large cavities in the hot gas on either side of the central galaxy (mouse over the image for a labeled version). The Chandra image has been specially processed to emphasize the cavities. Both cavities are aligned with jets seen in radio images from the VLA. The location of the supermassive black hole between the cavities is strong evidence that the supersonic jets generated by the black hole have drilled into the hot gas and pushed it aside, forming the cavities.

Shock fronts - akin to sonic booms - caused by the expanding cavities and the release of energy by sound waves reverberating through the hot gas provide a source of heat that prevents most of the gas from cooling and forming new stars.

The cavities are each about 100,000 light years across, roughly equal to the width of the Milky Way galaxy. The power needed to generate them is among the largest known in galaxy clusters. For example, the power is almost 10 times greater than required to create the well-known cavities in Perseus.

Although the energy to power the jets must have been generated by matter falling toward the black hole, no X-ray emission has been detected from infalling material. This result can be explained if the black hole is "ultramassive" rather than supermassive, with a mass more than 10 billion times that of the sun. Such a black hole should be able to produce powerful jets without consuming large amounts of mass, resulting in very little radiation from material falling inwards.

Another possible explanation is that the black hole has a mass only about a billion times that of the sun but is spinning extremely rapidly. Such a black hole can produce more powerful jets than a slowly spinning black hole when consuming the same amount of matter. In both explanations the black hole is extremely massive.

A more distant cavity is also seen at a different angle with respect to the jets, along a north-south direction. This cavity is likely to have been produced by a jet from a much older outburst from the black hole. This raises the question of why this cavity is no longer aligned with the jets. There are two possible explanations. Either large-scale motion of the gas in the cluster has pushed it to the side or the black hole is precessing, that is, wobbling like a spinning top.

A paper describing this work was published in the November 10th, 2013 issue of The Astrophysical Journal and is available online. The first author is Julie Hlavacek-Larrondo from Stanford University. The Hubble data used in this analysis were from the Cluster Lensing and Supernova survey, led by Marc Postman from Space Telescope Science Institute.

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.

Fast Facts for RX J1532.9+3021: 


Scale: Image is 1.6 arcmin on a side (About 1.6 million light years)
Category: Groups & Clusters of Galaxies
Coordinates (J2000): RA 15h 32m 53.80s | Dec +30° 20' 57.60" 
Constellation: Corona Borealis
Observation Date: 3 pointings between Aug 2001 and Nov 2011 
Observation Time: 30 hours 3 min (1 day, 6 hours, 3 min) 
Obs. ID: 1649, 1665, 14009 
Instrument: ACIS
References: Hlavacek-Larrondo, J. et al. 2013, ApJ, 777, 163; arXiv:1306.0907
Color Code:  X-ray (Purple); Optical (Yellow)
Distance Estimate:  3.9 billion light years (z = 0.361) 

Source:  NASA’s Chandra X-ray Observatory

Seeing double

QSO 0957+561 - "Twin Quasar"

Credit: ESA/Hubble & NASA

In this new Hubble image two objects are clearly visible, shining brightly. When they were first discovered in 1979, they were thought to be separate objects — however, astronomers soon realised that these twins are a little too identical! They are close together, lie at the same distance from us, and have surprisingly similar properties. The reason they are so similar is not some bizarre coincidence; they are in fact the same object.

These cosmic doppelgangers make up a double quasar known as QSO 0957+561, also known as the "Twin Quasar", which lies just under 14 billion light-years from Earth. Quasars are the intensely powerful centres of distant galaxies. So, why are we seeing this quasar twice?

Some 4 billion light-years from Earth — and directly in our line of sight — is the huge galaxy YGKOW G1. This galaxy was the first ever observed gravitational lens, an object with a mass so great that it can bend the light from objects lying behind it. This phenomenon not only allows us to see objects that would otherwise be too remote, in cases like this it also allows us to see them twice over.

Along with the cluster of galaxies in which it resides, YGKOW G1 exerts an enormous gravitational force. This doesn't just affect the galaxy's shape, the stars that it forms, and the objects around it — it affects the very space it sits in, warping and bending the environment and producing bizarre effects, such as this quasar double image.

This observation of gravitational lensing, the first of its kind, meant more than just the discovery of an impressive optical illusion allowing telescopes like Hubble to effectively see behind an intervening galaxy. It was evidence for Einstein's theory of general relativity. This theory had identified gravitational lensing as one of its only observable effects, but until this observation no such lensing had been observed since the idea was first mooted in 1936.

Links:

• ESA/Hubble release: Gravitational telescope creates space invader mirage
• ESA/Hubble release: Lenses galore — Hubble finds large sample of very distant galaxies
• ESA/Hubble release: Hubble finds double Einstein ring

Source:  ESA/Hubble - Space Telescope

Herschel discovers water vapour around dwarf planet Ceres

Artist’s impression of Ceres

Copyright: ESA/ATG medialab

ESA’s Herschel space observatory has discovered water vapour around Ceres, the first unambiguous detection of water vapour around an object in the asteroid belt. 

With a diameter of 950 km, Ceres is the largest object in the asteroid belt, which lies between the orbits of Mars and Jupiter. But unlike most asteroids, Ceres is almost spherical and belongs to the category of ‘dwarf planets’, which also includes Pluto. 

It is thought that Ceres is layered, perhaps with a rocky core and an icy outer mantle. This is important, because the water-ice content of the asteroid belt has significant implications for our understanding of the evolution of the Solar System.

Water detection on Ceres
Copyright: Adapted from Küppers et al. 

When the Solar System formed 4.6 billion years ago, it was too hot in its central regions for water to have condensed at the locations of the innermost planets, Mercury, Venus, Earth and Mars. Instead, it is thought that water was delivered to these planets later during a prolonged period of intense asteroid and comet impacts around 3.9 billion years ago. 

While comets are well known to contain water ice, what about asteroids? Water in the asteroid belt has been hinted at through the observation of comet-like activity around some asteroids – the so-called Main Belt Comet family – but no definitive detection of water vapour has ever been made. 

Now, using the HIFI instrument on Herschel to study Ceres, scientists have collected data that point to water vapour being emitted from the icy world’s surface. 

“This is the first time that water has been detected in the asteroid belt, and provides proof that Ceres has an icy surface and an atmosphere,” says Michael Küppers of ESA’s European Space Astronomy Centre in Spain, lead author of the paper published in Nature.

Artist’s impression of Ceres
Copyright: ESA/ATG medialab/Küppers et al.

Although Herschel was not able to make a resolved image of Ceres, the astronomers were able to derive the distribution of water sources on the surface by observing variations in the water signal during the dwarf planet’s 9-hour rotation period. Almost all of the water vapour was seen to be coming from just two spots on the surface. 

“We estimate that approximately 6 kg of water vapour is being produced per second, requiring only a tiny fraction of Ceres to be covered by water ice, which links nicely to the two localised surface features we have observed,” says Laurence O’Rourke, Principal Investigator for the Herschel asteroid and comet observation programme called MACH-11, and second author on the Nature paper. 

The most straightforward explanation of the water vapour production is through sublimation, whereby ice is warmed and transforms directly into gas, dragging the surface dust with it, and thus exposing fresh ice underneath to sustain the process. Comets work in this fashion. 

The two emitting regions are about 5% darker than the average on Ceres. Able to absorb more sunlight, they are then likely the warmest regions, resulting in a more efficient sublimation of small reservoirs of water ice. 

An alternative possibility is that geysers or icy volcanoes – cryovolcanism – play a role in the dwarf planet’s activity. 

Much more detailed information on Ceres is expected soon, as NASA’s Dawn mission is currently en route there for an arrival in early 2015. It will provide close-up mapping of the surface and monitor how the water activity is generated and varies with time. 

“Herschel’s discovery of water vapour outgassing from Ceres gives us new information on how water is distributed in the Solar System. Since Ceres constitutes about one fifth of the total mass of asteroid belt, this finding is important not only for the study of small Solar System bodies in general, but also for learning more about the origin of water on Earth,” says Göran Pilbratt, ESA’s Herschel Project Scientist.

“Localised sources of water vapour on dwarf planet (1) Ceres,” by M. Küppers et al. is published in Nature 23 January 2014. 

Ceres was observed on four occasions between November 2011 and March 2013 initially as part of the MACH-11 (Measurements of 11 Asteroids and Comets with Herschel) Guaranteed Time Programme, and complemented by two additional Director’s Discretionary Time observations that confirmed the tentative detection and measured the variation in water vapour as a function of rotation period. 

For further information, please contact:
 
Markus Bauer

ESA Science and Robotic Exploration Communication Officer


Tel: +31 71 565 6799


Mob: +31 61 594 3 954


Email: markus.bauer@esa.int

Michael Küppers
European Space Agency, ESAC
Email: michael.kueppers@sciops.esa.int

Laurence O’Rourke
Programme PI for MACH-11
European Space Agency, ESAC
Email: Laurence.O’Rourke@esa.int

Göran Pilbratt
ESA Herschel Project Scientist
Tel: +31 71 565 3621
Email: gpilbratt@rssd.esa.int

Source: ESA/Herschel