Trio of supermassive black holes shake space-time

 

Helical jets from one supermassive black hole caused by a very closely orbiting companion (see blue dots). The third black hole is part of the system, but farther away and therefore emits relatively straight jets. © Roger Deane (large image); NASA Goddard (inset bottom left; modified from original).

Tight system of black holes in a distant galaxy

Astronomers have discovered three closely orbiting supermassive black holes in a galaxy more than 4 billion light years away. This is the tightest trio of black holes known to date and is remarkable since most galaxies have just one black hole, usually with a mass between 1 million to 10 billion times that of the Sun, at their centre. The discovery suggests that such closely packed supermassive black holes are far more common than previously thought.

An international research team, including Hans-Rainer Klöckner from the Max Planck Institute for Radio Astronomy in Bonn, Germany, performed VLBI (Very Long Baseline Interferometry) observations with radio telescopes at a number of frequencies to discover the inner two black holes of the triple system. The VLBI technique combines the signals from large radio antennas separated by up to 10. 000 kilometres to see details 50 times finer than that possible with the Hubble Space Telescope. In this project the Effelsberg 100m radio telescope took part in European VLBI network (EVN) observations covering two radio frequencies.

Galaxies are believed to evolve through merging and that should lead to multiple supermassive black holes in some of those galaxies at a given time. The source under investigation was found in the Sloan Digital Sky Survey (SDSS) and has the catalog number SDSS J1502+1115. It is a quasar, the nucleus of an active galaxy at a redshift of z = 0.39, corresponding to a distance of more than four billion light years. A triple black hole system has been identified in that source, with two tight companions separated by less than 500 light years.

"What remains extraordinary to me is that these black holes, which are at the very extreme of Einstein’s Theory of General Relativity, are orbiting one another at 300 times the speed of sound on Earth", says Roger Deane from the University of Cape Town/South Africa, the lead author of the paper. "Not only that, but using the combined signals from radio telescopes on four continents we are able to observe this exotic system one third of the way across the Universe. It gives me great excitement as this is just scratching the surface of a long list of discoveries that will be made possible with the Square Kilometre Array."

Such systems are important to understand for several reasons; in terms of galaxy evolution it is known that black holes influence how galaxies evolve, and understanding how often black holes themselves merge is key to this work. Furthermore, closely orbiting systems such as this are sources of gravitational waves in the Universe, if General Relativity is correct. Future radio telescopes such as the Square Kilometre Array (SKA) will be able to measure the gravitational waves from such systems as their orbits decrease.

At this point, very little is actually known about black hole systems that are so close to one another that they emit detectable gravitational waves. "This discovery not only suggests that close-pair black hole systems are much more common than previously expected, but also predicts that radio telescopes such as MeerKAT and African VLBI Network will directly assist in the detection and understanding of the gravitational wave signal", says Matt Jarvis from the Universities of Oxford and the Western Cape. "Further in the future the SKA will allow us to find and study these systems in exquisite detail, and really allow us gain a much better understanding of how black holes shape galaxies over the history of the Universe."

World map with radio telescopes of the EVN (European VLBI Network). Observations of SDSS J1502+1115 were performed at frequencies of 1.7 and 5 GHz within that network

While the VLBI technique was essential to discover the inner two black holes (which are in fact the second closest pair of supermassive black holes known), Deane and co-authors have also shown that the binary black hole presence can be revealed by much larger scale features. The orbital motion of the black hole is imprinted onto its large jets, twisting them into a helical or corkscrew-like shape. So even though black holes may be so close together that our telescopes can’t tell them apart, their twisted jets may provide easy-to find pointers to them, much like using a flare to mark your location at sea. This may provide a way for sensitive future telescopes like MeerKAT and the SKA to find binary black holes with much greater efficiency.

"We have found the first needle in the 'middle age' Universe and I hope that we will find much more and even closer systems of this kind in the near future", concludes Hans-Rainer Klöckner from the Max Planck Institute for Radio Astronomy, a co-author of the paper. "Such close-binaries will not only show us how supermassive black holes could grow or how they could alternate our space time, they will also help us to understand the inner workings and the interplay between jets and the accretion disc surrounding black holes." This discovery is a prime example of how radio astronomy is done nowadays; it is an international and close collaboration accessing data products from various facilities distributed all over the globe.

The future will be bright with the SKA, the biggest radio telescope ever being built, enabling such discoveries in international collaborations and hopefully Germany will find a way to support this endeavor also in future and enable its scientists and engineers to participate in the SKA project.

Background Information

The South African Government has made a major investment in astronomy, in funding what will the most sensitive radio telescope in the Southern Hemisphere, but also in the significant Human Capital Development programme. As someone who may not have become a professional astronomer without the support of these initiatives, Roger Deane is grateful to be able to produce internationally recognised research following the strong support received from SKA, South Africa (SA) and the SA Government. Four South African institutions are represented by the research team which is in itself a very positive signal for radio astronomy here. This demonstrates that South Africa has the scientific and technical expertise to be a world leader in this research area and contribute directly to gravitational wave experiments that will provide fundamental insights not only to astronomy, but also more broadly to physics.

Contact: 

Dr. Hans-Rainer Klöckner

Phone:+49 228 525-314

Email: hkloeckner@mpifr-bonn.mpg.de

Max-Planck-Institut für Radioastronomie, Bonn

Dr. Roger Deane

Phone:+27 78 582-2308

Email: roger.deane@ast.uct.ac.za

University of Cape Town, Cape Town, South Africa

Dr. Norbert Junkes

Presse- und Öffentlichkeitsarbeit

Phone:+49 228 525-399

Email: njunkes@mpifr-bonn.mpg.de

Max-Planck-Institut für Radioastronomie, Bonn

Original Paper: 

• A close-pair binary in a distant triple supermassive black-hole system,  by R. P. Deane, Z. Paragi, M. J. Jarvis, M. Coriat, G. Bernardi, R. P. Fender, S. Frey, I. Heywood, H.-R. Klöckner, K. Grainge &  C. Rumsey, Nature Online, June 25, 2014, DOI: 10.1038/nature13454 (Link accessible after the  embargo expires).

Links:

• EVN - European VLBI Network

• Arecibo - Arecibo Radio Observatory

• GMRT - Giant Metre Wave Radio Telescope

• Effelsberg Radio Observatory

• AMI - Arcminute Microkelvin Imager

• JVLA - Karl G. Jansky Very Large Array

 

Source: Max Planck Institute for Radio Astronomy

Spinning Black Holes in Galactic Nuclei

An image of the galaxy NGC 1365, whose nucleus contains a massive black hole actively accreting material. Astronomers have used a series of X-ray observations to measure time variations in the iron emission line from the nucleus and thereby determine the value of the black hole's spin. Credit & Copyright:  SSRO-South (R. Gilbert, D. Goldman, J. Harvey, D. Verschatse) - PROMPT (D. Reichart) 

The nuclei of most galaxies contain a massive black hole. In our Milky Way, for example, the nuclear black hole contains about four million solar masses of material, and in other galaxies the black holes are estimated to have masses of hundreds of millions of suns, or even more. In dramatic cases, like quasars, these black holes are suspected of driving the observed bipolar jets of particles outward at nearly the speed of light. How they do this is not known, but scientists think that the spin of the black hole somehow plays a pivotal role.

A black hole is so simple (at least in traditional theories) that it can be completely described by just three parameters: its mass, its spin, and its electric charge. Even though it may have formed out of a complex mix of matter and energy, all the other specific details are lost when it collapses to a singular point. Astronomers are working to measure the spins of black hole in active galaxies in order to probe the connections between spin and jet properties.

One method for measuring black hole spin is X-ray spectra, by looking for distortions in the atomic emission line shapes from the very hot gas in the accreting disk of material around the black hole. Effects due to relativity in these extreme environments can broaden and skew intrinsically narrow emission lines into characteristic profiles that depend on the black hole spin value.

CfA astronomers Guido Risaliti, Laura Brenneman, and Martin Elvis, together with their colleagues, used joint observations from the NuSTAR and XMM-NEWTON space missions to examine the time-varying spectral shape of highly excited iron atoms in the nucleus of the galaxy NGC 1365, a well-studied active galaxy about sixty-six million light-years away and known for exhibiting time-variable line profiles. The team obtained four high quality observations of the source, catching it over an unprecedented range of absorption states, including one with very little line-of-sight absorption to the central nucleus. All the observations, despite the range of absorptions, displayed hallmarks of the innermost regions of the accretion flow. There have been disagreements within the community about the reliability of attributing observed line shapes to the black hole spin (rather than to other effects in the nucleus), but this new result not only demonstrates that it is possible, it shows that even single-epoch observations are likely to provide reliable measurements, making the task of studying other such systems more efficient.

Reference(s): 

"NuSTAR AND XMM-NEWTON Observations of NGC 1365: Extreme Absorption Variability and a Constant Inner Accretion Disk," D. J. Walton, G. Risaliti, F. A. Harrison, A. C. Fabian, J. M. Miller, P. Arevalo, D. R. Ballantyne, S. E. Boggs, L. W. Brenneman, F. E. Christensen, W. W. Craig, M. Elvis, F. Fuerst, P. Gandhi, B. W. Grefenstette C. J. Hailey, E. Kara, B. Luo, K. K. Madsen, A. Marinucci, G. Matt, M. L. Parker, C. S. Reynolds, E. Rivers, R. R. Ross, D. Stern, and W. W. Zhang, ApJ, 788,76, 2014

Source: Smithsonian Astrophysical Observatory

A Nearby Super-Earth with the Right Temperature but Extreme Seasons

Figure 1. Artistic representation of the potentially habitable exoplanet Gliese 832 c as compared with Earth. Gliese 832 c is represented here as a temperate world covered in clouds. The relative size of the planet in the figure assumes a rocky composition but could be larger for a ice/gas composition. 

Figure 2. Orbital analysis of Gliese 832 c, a potentially habitable world around the nearby red-dwarf star Gliese 832.Gliese 832 c orbits near the inner edge of the conservative habitable zone. Its average equilibrium temperature (253 K) is similar to Earth (255 K) but with large shifts (up to 25K) due to its high eccentricity (assuming a similar 0.3 albedo). Credit: PHL @ UPR Arecibo.

Figure 3. The Habitable Exoplanets Catalog now has 23 objects of interest including Gliese 832 c, the closest to Earth of the top three most Earth-like worlds in the catalog.

Figure 4. Stellar map with the position of all the stars with potentially habitable exoplanets including now Gliese 832 (lower left).

Gliese 832 c is the nearest best habitable world candidate so far

Gliese 832 c is the nearest best habitable world candidate so far An international team of astronomers, led by Robert A. Wittenmyer from UNSW Australia, report the discovery of a new potentially habitable Super-Earth around the nearby red-dwarf star Gliese 832, sixteen light years away. This star is already known to harbour a cold Jupiter-like planet, Gliese 832 b, discovered on 2009. The new planet, Gliese 832 c, was added to the Habitable Exoplanets Catalog along with a total of 23 objects of interest. The number of planets in the catalog has almost doubled this year alone. 

Gliese 832 c has an orbital period of 36 days and a mass at least five times that of Earth's (≥ 5.4 Earth masses). It receives about the same average energy as Earth does from the Sun. The planet might have Earth-like temperatures, albeit with large seasonal shifts, given a similar terrestrial atmosphere. A denser atmosphere, something expected for Super-Earths, could easily make this planet too hot for life and a "Super-Venus" instead. 

The Earth Similarity Index (ESI) of Gliese 832 c (ESI = 0.81) is comparable to Gliese 667C c (ESI = 0.84) and Kepler-62 e (ESI = 0.83). This makes Gliese 832 c one of the top three most Earth-like planets according to the ESI (i.e. with respect to Earth's stellar flux and mass) and the closest one to Earth of all three, a prime object for follow-up observations. However, other unknowns such as the bulk composition and atmosphere of the planet could make this world quite different to Earth and non-habitable. 

So far, the two planets of Gliese 832 are a scaled-down version of our own Solar System, with an inner potentially Earth-like planet and an outer Jupiter-like giant planet. The giant planet may well played a similar dynamical role in the Gliese 832 system to that played by Jupiter in our Solar System. It will be interesting to know if any additional objects in the Gliese 832 system (e.g. planets and dust) follow this familiar Solar System configuration, but this architecture remains rare among the known exoplanet systems. 

ContactsOriginal Research: 

Robert A. Wittenmyer 
rob@phys.unsw.edu.au

Mikko Tuomi
miptuom@utu.fi

Habitable Exoplanets Catalog: 
Abel Méndez 
abel.mendez@upr.edu

Additional Resources 

• Paper: GJ 832c: A super-earth in the habitable zone 

• Habitable Exoplanets Catalog

Souce: Planetary Habitability Laboratory - University of Puerto Rico at Arecibo

A curious supernova in NGC 2441

 NGC 2441 - Supernova SN199E

Credit: ESA/Hubble & NASA
Acknowledgement: Nick Rose

This bright spiral galaxy is known as NGC 2441, located in the northern constellation of Camelopardalis (The Giraffe). However, NGC 2441 is not the only subject of this new Hubble image; the galaxy contains an intriguing supernova named SN1995E, visible as a small dot at the approximate centre of this image. For a labelled view, see potw1425b.

Supernova SN1995E, discovered in 1995 as its name suggests is a type Ia supernova. This kind of supernova is found in binary systems, where one star — a white dwarf — drags matter from its orbiting companion until it becomes unstable and explodes violently. White dwarf stars all become unbalanced once they reach the same mass, meaning that they all form supernovae with the same intrinsic brightness. Because of this, they are used as standard candles to measure distances in the Universe.

But SN1995E may be useful in another way. More recent observations of this supernova have suggested that it may display a phenomenon known as a light echo, where light is scattered and deflected by dust along our line of sight, making it appear to “echo” outwards from the source. In 2006, Hubble observed SN1995E to be fading in a way that suggested its light was being scattered by a surrounding spherical shell of dust. 

These echoes can be used to probe both the environments around cosmic objects like supernovae, and the characteristics of their progenitor stars. If SN1995E does indeed have a light echo, it would belong to a very elite club; only two other type Ia supernovae have been found to display light echoes (SN1991T and SN1998bu).

NGC 2441 was first seen by Wilhelm Tempel in 1882, a German astronomer with a keen eye for comets. In total, Tempel observed and documented some 21 comets, several of which were named after him.

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

Link:

• A curious supernova in NGC 2441 (annotated)

Source: ESA/Hubble - Space Telescope

'Cosmic own goal' another clue in hunt for dark matter

The visible galaxies in the Local Group simulation, shown in the lower right, only trace a tiny fraction of the vast number of dark matter halos, revealed in the upper left. Credit: John Helly, Till Sawala, James Trayford, Durham University.  Hi-Res image

Gas in the EAGLE Simulation, showing hot bubbles (red colours) surrounding large galaxies, connected by colder filaments (blue and green colours). Inserts zoom in on the Local Group around the Milky Way and show the distribution of gas, stars and dark matter. Credit: Richard Bower, John Helly, Sarah Nixon, Till Sawala, James Trayford, Durham University. Hi-Res Image

Description: The DiRAC Cosmology Machine, operated by Durham University has 6720 Intel Xeon Cores and 53,760 GByte of RAM. Credit: Till Sawala, Durham University. Hi-Res Image

 
The hunt for dark matter has taken another step forward thanks to new supercomputer simulations showing the evolution of our 'local Universe' from the Big Bang to the present day. Physicists at Durham University, UK, who are leading the research, say their simulations could improve understanding of dark matter, a mysterious substance believed to make up 85 per cent of the mass of the Universe.  The results will be presented at the National Astronomy Meeting in Portsmouth on Thursday 26 June.

Professor Carlos Frenk, Director of Durham University’s Institute for Computational Cosmology, said: "I've been losing sleep over this for the last 30 years. Dark matter is the key to everything we know about galaxies, but we still don’t know its exact nature. Understanding how galaxies formed holds the key to the dark matter mystery."

Scientists believe clumps of dark matter – or haloes – that emerged from the early Universe, trapped intergalactic gas and became the birthplaces of galaxies. Cosmological theory predicts that our own cosmic neighbourhood should be teeming with millions of small halos, but only a few dozen small galaxies have been observed around the Milky Way.

Prof. Frenk added: "We know there can't be a galaxy in every halo. The question is: why not?"

The Durham researchers believe their simulations answer this question, showing explicitly how and why millions of haloes around our galaxy and neighbouring Andromeda failed to produce galaxies and became barren worlds. They say the gas that would have made the galaxy was sterilized by the heat from the first stars that formed in the Universe and was prevented from cooling and turning into stars.

However, a few haloes managed to bypass this cosmic furnace by growing early and fast enough to hold on to their gas and eventually form galaxies.

Prof. Frenk, who will also receive the Royal Astronomical Society’s top award, the Gold Medal for Astronomy on the same day, added: "We have learned that most dark matter haloes are quite different from the 'chosen few' that are lit up by starlight. Thanks to our simulations we know that if our theories of dark matter are correct then the Universe around us should be full of haloes that failed to make a galaxy. Perhaps astronomers will one day figure out a way to find them."

Lead researcher Dr Till Sawala, also at the Institute for Computational Cosmology at Durham University, said the research was the first to simulate the evolution of our 'Local Group' of galaxies, including the Milky Way, Andromeda, their satellites and several isolated small galaxies, in its entirety.

Dr Sawala said: "What we’ve seen in our simulations is a cosmic own goal.  We already knew that the first generation of stars emitted intense radiation, heating intergalactic gas to temperatures hotter than the surface of the sun. After that, the gas is so hot that further star formation gets a lot more difficult, leaving haloes with little chance to form galaxies. We were able to show that the cosmic heating was not simply a lottery with a few lucky winners. Instead, it was a rigorous selection process and only haloes that grew fast enough were fit for galaxy formation."

The close-up look at the Local Group is part of the larger EAGLE project currently being undertaken by cosmologists at Durham University and the University of Leiden in the Netherlands. EAGLE is one of the first attempts to simulate – right from the start – the formation of galaxies in a representative volume of the Universe. By peering into the virtual Universe, the researchers find galaxies that look remarkably like our own, surrounded by countless dark matter haloes, only a small fraction of which contain galaxies.

Media contacts

NAM 2014 press office landlines: +44 (0) 02392 845176, +44 (0)2392 845177, +44 (0)2392 845178

Dr Robert Massey
Mob: +44 (0)794 124 8035
rm@ras.org.uk

Anita Heward
Mob: +44 (0)7756 034 243
anitaheward@btinternet.com

Dr Keith Smith
kts@ras.org.uk

Durham University Media Relations Team
+44 (0)191 334 6075
media.relations@durham.ac.uk

Science contacts

Dr Sawala and Prof. Frenk will be at the Royal Astronomical Society’s National Astronomy Meeting at the University of Portsmouth on Wednesday, June 25, and Thursday, June 26, 2014.

An ISDN radio line is available at the National Astronomy Meeting. To request its use please contact Sophie Hall at the University of Portsmouth on sophie.hall@port.ac.uk.

An ISDN radio line is also available at Durham University and bookings can be arranged via the Media Relations Team on the contact details above.


Further information

The work was funded by the UK's Science and Technology Facilities Council (STFC) and the European Research Council.

The Durham-led simulation was carried out on the “Cosmology Machine”, which is the part of the DiRAC national supercomputing facility for research in astrophysics and particle physics funded by the Department for Business, Innovation and Skills through the STFC. The Cosmology Machine – based at Durham University – has more than 5,000 times the computing power of typical PCs, and over 10,000 times the amount of memory.

The research is part of a programme being conducted by the Virgo Consortium for supercomputer simulations, an international collaboration led by Durham University with partners in the UK, Germany, Holland, China and Canada. The new results on the Local Group involve, in addition to Durham University researchers, collaborators in the Universities of Victoria (Canada), Leiden (Holland), Antwerp (Belgium) and the Max Planck Institute for Astrophysics (Germany).

Institute for Computational Cosmology; Physics at Durham University.

Carlos Frenk receives Royal Astronomical Society Gold Medal: RAS announcement, Durham press release

Notes for editors

Durham University is a world top-100 university with a global reputation and performance in research and education.  The most recent UK league tables place Durham in the top echelon of British universities academically.  Durham is ranked fifth in the UK in the Complete University Guide 2014 and sixth in the Times and Sunday Times Good University Guide 2014; it is 26th in the world for the impact of its research (THE citations ratings) and in the world top 25 for the employability of its students by blue-chip companies world-wide (QS World University Rankings 2013/14). It is a residential Collegiate University: England’s third oldest university and at its heart is a medieval UNESCO World Heritage Site, of which it is joint custodians with Durham Cathedral. Durham is a member of the Russell Group of leading research-intensive UK universities.

Set up in 2007 by the European Union, the European Research Council (ERC) aims to stimulate scientific excellence in Europe by encouraging competition for funding between the very best, creative researchers of any nationality and age based in Europe. Since its launch, the ERC has awarded grants to over 4,000 researchers performing frontier research in Europe. The ERC operates according to an "investigator-driven", or "bottom-up" approach, allowing both early-career and senior scientists to identify new opportunities in all fields of research (Physical Sciences and Engineering, Life Sciences and Social Sciences and Humanities), without predetermined priorities. The ERC has a total budget of €13.1 billion under Horizon 2020, the new EU research and innovation programme for 2014 - 2020.

The RAS National Astronomy Meeting (NAM 2014) will bring together more than 600 astronomers, space scientists and solar physicists for a conference running from 23 to 26 June in Portsmouth. NAM 2014, the largest regular professional astronomy event in the UK, will be held in conjunction with the UK Solar Physics (UKSP), Magnetosphere Ionosphere Solar-Terrestrial physics (MIST) and UK Cosmology (UKCosmo) meetings. The conference is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and the University of Portsmouth. Meeting arrangements and a full and up to date schedule of the scientific programme can be found on the official website and via Twitter.

The University of Portsmouth is a top-ranking university in a student-friendly waterfront city. It's in the top 50 universities in the UK, in The Guardian University Guide League Table 2014 and is ranked in the top 400 universities in the world, in the most recent Times Higher Education World University Rankings 2013. 

Research at the University of Portsmouth is varied and wide ranging, from pure science – such as the evolution of galaxies and the study of stem cells – to the most technologically applied subjects – such as computer games design. Our researchers collaborate with colleagues worldwide, and with the public, to develop new insights and make a difference to people's lives. Follow the University of Portsmouth on Twitter.

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3800 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others. Follow the RAS on Twitter.

The Science and Technology Facilities Council (STFC) is keeping the UK at the forefront of international science and tackling some of the most significant challenges facing society such as meeting our future energy needs, monitoring and understanding climate change, and global security. The Council has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar. It enables UK researchers to access leading international science facilities for example in the area of astronomy, the European Southern Observatory. Follow STFC on Twitter.

Puzzling X-rays point to dark matter

Perseus galaxy cluster

Copyright: Chandra: NASA/CXC/SAO/E.Bulbul, et al.; XMM: ESA)

A new study of the Perseus galaxy cluster, shown in this image, and others using Chandra and XMM-Newton has revealed a mysterious X-ray signal in the data. The signal is also seen in over 70 other galaxy clusters using XMM-Newton. This unidentified signal requires further investigation to confirm both its existence and nature, but one possibility is that it represents the decay of ‘sterile neutrinos’, one proposed candidate to explain dark matter.

Mysterious signal in the Perseus galaxy cluster
Copyright: NASA/CXC/SAO/E.Bulbul, et al.

A new study of the Perseus galaxy cluster, shown in this image, and others using Chandra and XMM-Newton has revealed a mysterious X-ray signal in the data. This signal is represented in the circled data points in the inset, which is a plot of X-ray intensity as a function of X-ray energy. The signal is also seen in over 70 other galaxy clusters using XMM-Newton. This unidentified X-ray emission line – a spike of intensity centred on about 3.56 keV – requires further investigation to confirm both the signal’s existence and nature. One possibility is this signal is the decay of ‘sterile neutrinos’, one proposed candidate to explain dark matter.

Astronomers using ESA and NASA high-energy observatories have discovered a tantalising clue that hints at an elusive ingredient of our Universe: dark matter. 

Although thought to be invisible, neither emitting nor absorbing light, dark matter can be detected through its gravitational influence on the movements and appearance of other objects in the Universe, such as stars or galaxies. 

Based on this indirect evidence, astronomers believe that dark matter is the dominant type of matter in the Universe – yet it remains obscure. 

Now a hint may have been found by studying galaxy clusters, the largest cosmic assemblies of matter bound together by gravity. 

Galaxy clusters not only contain hundreds of galaxies, but also a huge amount of hot gas filling the space between them. 

However, measuring the gravitational influence of such clusters shows that the galaxies and gas make up only about a fifth of the total mass – the rest is thought to be dark matter. 

The gas is mainly hydrogen and, at over 10 million degrees celsius, is hot enough to emit X-rays. Traces of other elements contribute additional X-ray ‘lines’ at specific wavelengths. 

Examining observations by ESA’s XMM-Newton and NASA’s Chandra spaceborne telescopes of these characteristic lines in 73 galaxy clusters, astronomers stumbled on an intriguing faint line at a wavelength where none had been seen before.  

“If this strange signal had been caused by a known element present in the gas, it should have left other signals in the X-ray light at other well-known wavelengths, but none of these were recorded,” says Dr Esra Bulbul from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, USA, lead author of the paper discussing the results. 

“So we had to look for an explanation beyond the realm of known, ordinary matter.” 

The astronomers suggest that the emission may be created by the decay of an exotic type of subatomic particle known as a ‘sterile neutrino’, which is predicted but not yet detected. 

Ordinary neutrinos are very low-mass particles that interact only rarely with matter via the so-called weak nuclear force as well as via gravity. Sterile neutrinos are thought to interact with ordinary matter through gravity alone, making them a possible candidate as dark matter.  

“If the interpretation of our new observations is correct, at least part of the dark matter in galaxy clusters could consist of sterile neutrinos,” says Dr Bulbul. 

 The surveyed galaxy clusters lie at a wide range of distances, from more than a hundred million light-years to a few billion light-years away. The mysterious, faint signal was found by combining multiple observations of the clusters, as well as in an individual image of the Perseus cluster, a massive structure in our cosmic neighbourhood. 

The implications of this discovery may be far-reaching, but the researchers are being cautious. Further observations with XMM-Newton, Chandra and other high-energy telescopes of more clusters are needed before the connection to dark matter can be confirmed. 

“The discovery of these curious X-rays was possible thanks to the large XMM-Newton archive, and to the observatory’s ability to collect lots of X-rays at different wavelengths, leading to this previously undiscovered line,” comments Norbert Schartel, ESA’s XMM-Newton Project Scientist. 

“It would be extremely exciting to confirm that XMM-Newton helped us find the first direct sign of dark matter. 

“We aren't quite there yet, but we’re certainly going to learn a lot about the content of our bizarre Universe while getting there.” 

More information

 

“Detection of an unidentified emission line in the stacked X-ray spectrum of galaxy clusters,” by E. Bulbul et al. is published in the 1 July 2014 issue of the Astrophysical Journal. 

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




Esra Bulbul
Harvard-Smithsonian Center for Astrophysics
Cambridge, MA, USA
Phone: +1-617-496-7565
Email: ebulbul@cfa.harvard.edu

Norbert Schartel




XMM-Newton Project Scientist




Tel: +34 91 8131 184




Email: Norbert.Schartel@sciops.esa.int

Source: ESA

Discovery of exotic supernova sees Dark Energy Survey start off with a bang!

The Milky Way rises over the Cerro Tololo Inter-American Observatory in northern Chile. The Dark Energy Survey operates from the largest telescope at the observatory, the 4-metre Victor M. Blanco Telescope (left). Credit: Andreas Papadopoulos. https://www.ras.org.uk/images/stories/NAM/2014/des1.jpg

Before (left) and after (center) images of the region where DES13S2cmm was discovered. On the right is a subtraction of these two images, showing a bright new object at the center -- a supernova. Credit: Dark Energy Survey. https://www.ras.org.uk/images/stories/NAM/2014/des2.jpg

The first images taken by the Dark Energy Survey (DES) after the survey began in August 2013 have revealed a rare, ‘superluminous’ supernova that erupted in a galaxy 7.8 billion light years away. The stellar explosion, called DES13S2cmm, easily outshines most galaxies in the Universe and could still be seen in the data six months later, at the end of the first of what will be five years of observing by DES. The event was discovered by Andreas Papadopoulos, a postgraduate student from the University of Portsmouth, who will present the discovery at the National Astronomy Meeting 2014 in Portsmouth on Wednesday, 25 June.

upernovae are very bright, shining anywhere from one hundred million to a few billion times brighter than the Sun for weeks on end. Thousands of these brilliant stellar deaths have been discovered over the last two decades, and the word ‘supernova’ itself was coined 80 years ago. But superluminous supernovae are a recent discovery, only being recognized as a distinct class of objects in the past 5 years. These cosmic explosions are 10-50 times brighter at their peak than the brightest normal type of supernovae and, unlike other supernovae, their explosive origins remain a mystery.

"Fewer than forty such supernovae have ever been found and I never expected to find one in the first DES images!" said Papadopoulos. "As they are rare, each new discovery brings the potential for greater understanding – or more surprises."

It turns out that even within this select group, DES13S2cmm is unusual. The rate that it is fading away over time is much slower than for most other superluminous supernovae that have been observed to date. This change in brightness over time, or 'light curve', gives information on the mechanisms that caused the explosion and the composition of the material ejected.

Dr Mark Sullivan of Southampton University led the program to obtain spectroscopy of DES13S2cmm using the Very Large Telescope at Cerro Paranal, Chile. "Its unusual, slow decline was not apparent at first," said Sullivan, "but as more data came in and the supernova stopped getting fainter, we would look at the light curve and ask ourselves, 'what is this?'"

Understanding the origins of DES13S2cmm is proving difficult. Radioactive decay is known to power normal supernovae, but not from such extreme amounts of material.

"We have tried to explain the supernova as a result of the decay of the radioactive isotope Nickel-56," explained Dr Chris D'Andrea of the University of Portsmouth, co-author on the research, "but to match the peak brightness, the explosion would need to produce more than three times the mass of our Sun of the element. And even then the behaviour of the light curve doesn’t match up."

The team are now investigating alternative explanations, including that DES13S2cmm is a normal supernova that has created at its core a magnetar -- an exotic neutron star spinning hundreds of times per second, producing a magnetic field a trillion times stronger than that on Earth. Energy from the magnetar is then injected into the supernova, making the explosion exceptionally bright. "Neither model is a particularly compelling match to the data," noted D’Andrea.

With DES starting its second season in August, the hunt is on for more superluminous supernovae.

"With so few known, it’s hard to really understand their properties in detail," said Prof. Bob Nichol of the University of Portsmouth. "DES should find enough of these objects to allow us to understand superluminous supernovae as a population. But if some of these discoveries prove as difficult to interpret as DES13S2cmm, we’re prepared for the unusual!"

Media contacts

NAM 2014 press office landlines: +44 (0) 02392 845176, +44 (0)2392 845177, +44 (0)2392 845178

Dr Robert Massey
Mob: +44 (0)794 124 8035
rm@ras.org.uk

Anita Heward
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anitaheward@btinternet.com

Dr Keith Smith
kts@ras.org.uk

An ISDN line is available for radio interviews. To request its use, please contact Sophie Hall via sophie.hall@port.ac.uk

Science contact

Andreas Papadopoulos
Institute of Cosmology and Gravitation
University of Portsmouth
andreas.papadopoulos@port.ac.uk

Dr Chris D’Andrea
Institute of Cosmology and Gravitation
University of Portsmouth
chris.dandrea@port.ac.uk

 

Further information

The Dark Energy Survey is a 5 year, 525 night optical imaging survey using DECam, a purpose-built wide-field imaging camera installed and commissioned on the 4-meter Blanco Telescope at Cerro Tololo Inter-American Observatory, Chile. Over the course of the survey DES will find and measure over 5000 supernovae and map 300 million galaxies. Six universities in the United Kingdom (Cambridge, Edinburgh, Nottingham, Portsmouth, Sussex, UCL) are members of the International DES Collaboration. The DES optical corrector was constructed at UCL with funding provided by STFC and the UK DES collaboration.

Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência e Tecnologia, the Deutsche Forschungsgemeinschaft and the Collaborating Institutions in the Dark Energy Survey.

The Collaborating Institutions are Argonne National Laboratories, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the Eidgenoessische Technische Hochschule (ETH) Zurich, Fermi National Accelerator Laboratory, the University of Edinburgh, the University of Illinois at Urbana-Champaign, the Institut de Ciencies de l'Espai (IEEC/CSIC), the Institut de Fisica d'Altes Energies, the Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universität and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, the Ohio State University, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, and Texas A&M University.

Notes for editors

The RAS National Astronomy Meeting (NAM 2014) will bring together more than 600 astronomers, space scientists and solar physicists for a conference running from 23 to 26 June in Portsmouth. NAM 2014, the largest regular professional astronomy event in the UK, will be held in conjunction with the UK Solar Physics (UKSP), Magnetosphere Ionosphere Solar-Terrestrial physics (MIST) and UK Cosmology (UKCosmo) meetings. The conference is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and the University of Portsmouth. Meeting arrangements and a full and up to date schedule of the scientific programme can be found on the official website and via Twitter.

The University of Portsmouth is a top-ranking university in a student-friendly waterfront city. It's in the top 50 universities in the UK, in The Guardian University Guide League Table 2014 and is ranked in the top 400 universities in the world, in the most recent Times Higher Education World University Rankings 2013. Research at the University of Portsmouth is varied and wide ranging, from pure science – such as the evolution of galaxies and the study of stem cells – to the most technologically applied subjects – such as computer games design. Our researchers collaborate with colleagues worldwide, and with the public, to develop new insights and make a difference to people's lives. Follow the University of Portsmouth on Twitter.

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3800 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others. Follow the RAS on Twitter.

The Science and Technology Facilities Council (STFC) is keeping the UK at the forefront of international science and tackling some of the most significant challenges facing society such as meeting our future energy needs, monitoring and understanding climate change, and global security. The Council has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar. It enables UK researchers to access leading international science facilities for example in the area of astronomy, the European Southern Observatory. Follow STFC on Twitter.

Jupiter's Moons Remain Slightly Illuminated, Even in Eclipse

Astronomers using the Subaru Telescope and Hubble Space Telescope have found that Jupiter's Galilean satellites (Io, Europa, Ganymede, and Callisto) remain slightly bright (up to one millionth of their normal state) even when in the Jovian shadow and not directly illuminated by the Sun (Figure 1). The effect is particularly pronounced for Ganymede and Callisto. The finding was made by researchers at Tohoku University, Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency (ISAS/JAXA), National Astronomical Observatory of Japan (NAOJ), and elsewhere.

Figure 1: Images of Ganymede and Callisto while eclipsed by Jupiter obtained during their eclipse. Top left is Ganymede observed through Subaru Telescope, top right is Ganymede through Hubble Space Telescope, bottom left is Callisto from Subaru Telescope, respectively. Each frame is 4 arcsec x 4 arcsec, and the black circle indicates the apparent diameter of the object. A short movie linked here shows the Europa's eclipse as it goes into the shadow of Jupiter. From the top of the video is Europa, Ganymede, and Jupiter, respectively. (Credit: NAOJ/JAXA/Tohoku University)

The mechanism of this phenomenon is still under investigation, but the researchers suggest that indirect forward scattering of sunlight by hazes in the upper Jovian atmosphere could be the reason for the illumination. This effect is similar to the one that causes Earth's moon to look red during a total lunar eclipse.

The type of continuous observations of the Galilean satellites in eclipse made by the Japanese team also provides a much better basis for studying the hazes in Jupiter's atmosphere, which are difficult to study otherwise (Note 1). In addition, this detailed study method for a planetary atmosphere will provide new insights about the atmospheres of exoplanets, which are only beginning to be studied. 

Dr. Kohji Tsumura (FRIS, Tohoku University), the PI on the project, explained that this unexpected finding is really the outcome of attempts to measure diffuse light from the distant universe. "It is a serendipitous discovery made as a by-product of a cosmological study," he said. "It is very interesting that it provides us a new method to investigate the atmosphere of Jupiter and of exoplanets. I will keep studying from nearby space (the solar system and exoplanets) out to the farthest universe through this project."

The research team started its observations using IRCS and AO188 on Subaru Telescope in February of 2012. The idea was to detect the diffuse light from the most distant parts of the universe. To do this, team members planned to use the Galilean satellites in eclipse as "occulters" to block distant background emissions. This would allow an extremely accurate separation of the background light from the very bright foreground radiation from our solar system (known as the zodiacal light).

The team assumed that the Galilean satellites would be "dark" while in Jupiter's shadow, and the difference in brightness[??] between the dark satellite as an occulter and its surrounding sky would allow the team to determine the still-unknown level of background emission from the distant universe. Instead, they found an unexpected surprise: Ganymede and Callisto were still somewhat "bright" (illuminated) even when eclipsed (relative to the expected level of near-zero). Their eclipsed luminosity was one millionth of their un-eclipsed brightness, which is low enough that this phenomenon has been undetected until now (Figure 2).

Figure 2: Schematic drawing of how to measure the background light. By measuring the difference between the light from the eclipsed satellite and the surrounding sky data, one would obtain the background light information, if the eclipsed satellite is completely dark. It turned out that there is still a faint light reflected off from the satellite during the eclipse. (Credit: NAOJ/JAXA/Tohoku University)

To understand why the Galileans remain ever-so-slightly bright even when they're in eclipse, the project team of astronomers and planetary scientists considered several theories based on their multi-band observational data, including data from Spitzer Space Telescope. The most plausible is that the Galilean satellites are still illuminated during eclipse by sunlight that is scattered by hazes in the Jovian upper atmosphere. By comparison, the sunlight refracted in the atmosphere does not contribute to the illumination during the eclipse.

Although Jupiter is a familiar planet, there are many unresolved issues about its atmosphere. One example is the origin of the cloud particles composing Jupiter's banded appearance. The cloud particles are assumed to grow from tiny particles called aerosols or hazes. Researchers expect that those hazes form somewhere in the upper part of Jupiter's atmosphere, which is very difficult to observe (Figure 3). The unexpected discovery of haze-induced brightening of the Galileans provides a new way to study the mysterious part of Jupiter's atmosphere. In addition, since astronomers usually observe the planets in our solar system by reflected sunlight, one of the unique aspects of these new observations at Jupiter is that observers can precisely measure the transmitted sunlight through the planetary atmosphere (Note 2).

Figure 3: A schematic image of the model to show that the Galilean satellites eclipsed in Jovian shadow are illuminated by scattered sunlight by the haze in the Jovian upper atmosphere. The size and the distance of the satellites are not to the scale. This process is similar to one that causes red color of the Earth's Moon during its total eclipse. (Credit: NAOJ/JAXA/Tohoku University/NASA)

This new method of studying the upper atmosphere of Jupiter via transmitted sunlight provides a basis for the study of other planetary systems. Exoplanet discoveries now occur quite regularly and atmospheres around some of them have been investigated using "transit observations" (when the exoplanet passes between us and the host star, resulting in the star becoming slightly dimmer). In such observations, some characteristics of the exoplanet's atmosphere are revealed as host starlight passes through it. This is the same situation seen with Jupiter and its Galilean satellites, and makes studies of transmitted sunlight of the planets in our solar system essential for comparison.

The observations for this project were very challenging because the Galilean satellites (while eclipsed) are extremely faint and they are located next to the incredibly bright disk of Jupiter. In addition, the eclipses only happen at very specific times, and Jupiter and the satellites are continuously in motion during the observations. The complexity of the situation requires the observation procedure to be much more sophisticated. This new discovery required thorough preparations by the project team and conscientious support by the operations staff. (Figure 4)

Figure 4: Three-color (JHK) image of Jupiter and Ganymede obtained by Subaru Telescope. Because Ganymede moves with respect to Jupiter during the observations, it appears as three separately colored dots. Image taken at around 5 am, July 27, 2012 in Hawaii Time. Blue color is for J band (1.3 micrometer), green is for H band (1.6 micrometer), and red is for K band (2.2 micrometer), respectively. (Credit: NAOJ/JAXA/Tohoku University)

The results of this study will be published in The Astrophysical Journal in its July 10, 2014 issue (Tsumura et al. 2014 arXiv: 1405.5280). This research is supported by Japan Society for the Promotion of Science, KAKENHI (#24111717, #26800112), and NASA through a grant from Space Telescope Science Institute and Jet Propulsion Laboratory in U. S. A.

Notes:

1. Observations of Jupiter's upper atmosphere were conducted by the Galileo spacecraft, and by "occultation" of microwaves from field stars or spacecraft located behind Jupiter. However, opportunities to observe these events are rare and limited, thus the observations of the Galilean satellite eclipses are a unique method to study Jupiter's upper atmosphere.
2. Transmitted light through the planetary atmosphere was observed by the occultation methods described in (*1) and the Venus transit. However, they are very rare events, too.

Paper information:

To appear in the July 10, 2014 issue of the Astrophysical Journal, Volume 789.
"Near-infrared Brightness of the Galilean Satellites Eclipsed in Jovian Shadow: A New Technique to Investigate Jovian Upper Atmosphere"
K. Tsumura (1,2), K. Arimatsu (2,3), E. Egami (4), Y. Hayano (5), C. Honda (6), J. Kimura (7), K. Kuramoto (8), S. Matsuura (2), Y. Minowa (5), K. Nakajima (9), T. Nakamoto (10), M. Shirahata (2, 11), J. Surace (12), Y. Takahash i(8), and T. Wada (2)

¹Frontier Research Institute for Interdisciplinary Science, Tohoku University, Japan

²Department of Space Astronomy and Astrophysics, Institute of Space and Astronoutical Science, Japan Aerospace Exploration Agency, Japan

³Department of Astronomy, Graduate School of Science, The University of Tokyo, Japan

⁴Department of Astronomy, Arizona University, U. S. A.

⁵Subaru Telescope, National Astronomical Observatory of Japan, U. S. A.

⁶Research Center for Advanced Information Science and Technology, Aizu Research Cluster for Space Science, The University of Aizu, Japan

⁷Earth-Life Science Institute, Tokyo Institute of Technology, Japan

⁸Department of Cosmosciences, Graduate School of Science, Hokkaido University, Japan

⁹Department of Earth and Planetary Sciences, Kyushu University, Japan

¹⁰Department of Earth and Planetary Sciences, Graduate School of Science and Engineering, Tokyo Institute of Technology, Japan

¹¹National Astronomical Observatory of Japan, Japan

¹²Spitzer Science Center, California Institute of Technology, U. S. A.

Source: Subaru Telescope

Remarkable White Dwarf Star Possibly Coldest, Dimmest Ever Detected

Artist impression of a white dwarf star in orbit with pulsar PSR J2222-0137. It may be the coolest and dimmest white dwarf ever identified. Credit: B. Saxton (NRAO/AUI/NSF)

A team of astronomers has identified possibly the coldest, faintest white dwarf star ever detected. This ancient stellar remnant is so cool that its carbon has crystallized, forming -- in effect -- an Earth-size diamond in space.

“It’s a really remarkable object,” said David Kaplan, a professor at the University of Wisconsin-Milwaukee. “These things should be out there, but because they are so dim they are very hard to find.”

Kaplan and his colleagues found this stellar gem using the National Radio Astronomy Observatory’s (NRAO) Green Bank Telescope (GBT) and Very Long Baseline Array (VLBA), as well as other observatories.

White dwarfs are the extremely dense end-states of stars like our Sun that have collapsed to form an object approximately the size of the Earth. Composed mostly of carbon and oxygen, white dwarfs slowly cool and fade over billions of years. The object in this new study is likely the same age as the Milky Way, approximately 11 billion years old.

Pulsars are rapidly spinning neutron stars, the superdense remains of massive stars that have exploded as supernovas. As neutron stars spin, lighthouse-like beams of radio waves, streaming from the poles of its powerful magnetic field, sweep through space. When one of these beams sweeps across the Earth, radio telescopes can capture the pulse of radio waves.

The pulsar companion to this white dwarf, dubbed PSR J2222-0137, was the first object in this system to be detected. It was found using the GBT by Jason Boyles, then a graduate student at West Virginia University in Morgantown.

These first observations revealed that the pulsar was spinning more than 30 times each second and was gravitationally bound to a companion star, which was initially identified as either another neutron star or, more likely, an uncommonly cool white dwarf. The two were calculated to orbit each other once every 2.45 days.

The pulsar was then observed over a two-year period with the VLBA by Adam Deller, an astronomer at the Netherlands Institute for Radio Astronomy (ASTRON). These observations pinpointed its location and distance from the Earth -- approximately 900 light-years away in the direction of the constellation Aquarius. This information was critical in refining the model used to time the arrival of the pulses at the Earth with the GBT.

By applying Einstein's theory of relativity, the researchers studied how the gravity of the companion warped space, causing delays in the radio signal as the pulsar passed behind it. These delayed travel times helped the researchers determine the orientation of their orbit and the individual masses of the two stars. The pulsar has a mass 1.2 times that of the Sun and the companion a mass 1.05 times that of the Sun.

These data strongly indicated that the pulsar companion could not have been a second neutron star; the orbits were too orderly for a second supernova to have taken place.

Knowing its location with such high precision and how bright a white dwarf should appear at that distance, the astronomers believed they should have been able to observe it in optical and infrared light.

Remarkably, neither the Southern Astrophysical Research (SOAR) telescope in Chile nor the 10-meter Keck telescope in Hawaii was able to detect it.

“Our final image should show us a companion 100 times fainter than any other white dwarf orbiting a neutron star and about 10 times fainter than any known white dwarf, but we don’t see a thing,” said Bart Dunlap, a graduate student at the University of North Carolina at Chapel Hill and one of the team members. “If there’s a white dwarf there, and there almost certainly is, it must be extremely cold.”

The researchers calculated that the white dwarf would be no more than a comparatively cool 3,000 degrees Kelvin (2,700 degrees Celsius). Our Sun at its center is about 5,000 times hotter.

Astronomers believe that such a cool, collapsed star would be largely crystallized carbon, not unlike a diamond. Other such stars have been identified and they are theoretically not that rare, but with a low intrinsic brightness, they can be deucedly difficult to detect. Its fortuitous location in a binary system with a neutron star enabled the team to identify this one.

A paper describing these results is published in the Astrophysical Journal.

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

Contacts:

Charles Blue, Public Information Officer
National Radio Astronomy Observatory
+1 434-296-0314; cblue@nrao.edu

Dr. Katy Garmany, Deputy Press Officer
National Optical Astronomy Observatory
+1 520-318-8526; kgarmany@noao.edu

David Kaplan
Asst. Professor
Dept. of Physics, UW-Milwaukee
+1-414-229-4971; kaplan@uwm.edu

**********

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