The Cosmic radio burst caught red-handed

A schematic illustration of CSIRO’s Parkes radio telescope receiving the polarised signal from the new ‘fast radio burst’. Credit: Swinburne Astronomy Productions.

Pasadena, CA— Fast radio bursts are quick, bright flashes of radio waves from an unknown source in space. They are a mysterious phenomenon that last only a few milliseconds, and until now they have not been observed in real time. An international team of astronomers, including three from the Carnegie Observatories, has for the first time observed a fast radio burst happening live. Their work is published in Monthly Notices of the Royal Astronomical Society.

There is a great deal of scientific interest in fast radio bursts, particularly in uncovering their origin.

“These events are one of the biggest mysteries in the Universe” noted Carnegie Observatories' Acting Director John Mulchaey. “Until now, astronomers were not able to catch one of these events in the act.”

Only seven fast radio bursts have previously been discovered, since the first one found in 2007. All were found retroactively by combing through data from the Parkes radio telescope in eastern Australia and the Arecibo telescope in Puerto Rico.

“These bursts were generally discovered weeks or months or even more than a decade after they happened! We’re the first to catch one in real time,” said Emily Petroff, a PhD candidate from Swinburne University of Technology in Melbourne, Australia and lead author of the publication.
Swinburne is a member institution of the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO).

In order to observe the fast radio burst in real time, the team mobilized 12 telescopes around the world and in space, including Carnegie’s Magellan and Swope telescopes. Each telescope followed-up on the original burst observation at different wavelengths.

Measurements of the interaction between previously detected fast radio burst’s flashes and the free electrons their signals encountered in space as they traveled to reach us had previously indicated that the bursts likely originated far outside of our galaxy. But the idea was controversial.

The team’s data indicates that the burst originated up to 5.5 billion light years away. This means that the sources of theses bursts are extremely bright and could perhaps be used as a cosmological tool for measuring and understanding our universe once we come to understand them better.

“Together, our observations allowed the team to rule out some of the previously proposed sources for the bursts, including nearby supernovae,” explained Carnegie’s Mansi Kasliwal who was on the team along with Mulchaey and colleague Yue Shen. “Short gamma-ray bursts are still a possibility, as are distant magnetic neutron stars called magnetars, but not long gamma ray bursts.”

Gamma ray bursts are high-energy explosions that form some of the brightest celestial events. Long bursts can signify energy released during a supernova and are followed by an afterglow, which emits lower wavelength radiation than the original explosion.

Another interesting piece of information the team was able to gather about the burst is its polarization. The orientation of the radio waves indicates that the burst likely originated near or passed through a magnetic field, information that can help narrow down potential sources going forward.

“As we continue to search for the source of fast radio bursts, Carnegie is well positioned to make big strides in the field,” Mulchaey said. “Quick access to big telescopes like Magellan may be the key to solving this mystery.”

Caption: A schematic illustration of CSIRO’s Parkes radio telescope receiving the polarised signal from the new fast radio burst. Image is credited to Swinburne Astronomy Productions.

Other co-authors are: M. Bailes (Swinburne University of Technology and ARC Centre of Excellence for All-sky Astrophysics); E.D. Barr (Swinburne University of Technology and ARC Centre of Excellence for All-sky Astrophysics); B. R. Barsdell (Harvard-Smithsonian Center for Astrophysics); N. D. R. Bhat (ARC Centre of Excellence for All-sky Astrophysics and Curtin University) ; F. Bian (Australian National University); S. Burke-Spolaor (Caltech); M. Caleb(Australian National University, Swinburne University of Technology, ARC Centre of Excellence for All-sky Astrophysics); D. Champion (Max Planck Institut für Radioastronomie); P. Chandra (Tata Institute of Fundamental Research Pune University Campus); G. Da Costa (Australian National University); C. Delvaux (Max-Planck-Institut für extraterrestrische Physik); C. Flynn (Swinburne University of Technology and ARC Centre of Excellence for All-sky Astrophysics); N. Gehrels (NASA Goddard Space Flight Center); J. Greiner (Max-Planck-Institut für extraterrestrische Physik); A. Jameson (Swinburne University of Technology and ARC Centre of Excellence for All-sky Astrophysics); S. Johnston (CSIRO Astronomy & Space Science Australia Telescope National Facility); E. F. Keane (Swinburne University of Technology and ARC Centre of Excellence for All-sky Astrophysics); S. Keller (Australian National University); J. Kocz (Harvard-Smithsonian Center for Astrophysics and Jet Propulsion Laboratory, Caltech); M. Kramer (Max Planck Institut für Radioastronomie and University of Manchester) G. Leloudas (University of Copenhagen and Weizmann Institute of Science); D. Malesani (University of Copenhagen); C. Ng (Max Planck Institut für Radioastronomie); E. O. Ofek (Weizmann Institute of Science); D. A. Perley (Caltech); A. Possenti (Osservatorio Astronomico di Cagliari); B. P. Schmidt (Australian National University and ARC Centre of Excellence for All-sky Astrophysics); B. Stappers (University of Manchester); P. Tisserand (Australian National University and ARC Centre of Excellence for All-sky Astrophysics); W. van Straten (Swinburne University of Technology and ARC Centre of Excellence for All-sky Astrophysics ); and C. Wolf (Australian National University and ARC Centre of Excellence for All-sky Astrophysics).

The Parkes radio telescope and the Australia Telescope Compact Array are part of the Australia Telescope National Facility, which is funded by the Commonwealth of Australia for operation as a National Facility and managed by CSIRO. Parts of this research were conducted by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO). GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. Research with the ANU SkyMapper telescope is supported in part through an ARC Discovery Grant. Part of the funding for GROND was granted from a Leibniz-Prize. The Dark Cosmology Centre is supported by the Danish National Research council. Other support came from Curtin Research Fellowship;, EXTraS, funded from the European Union's Seventh Framework Programme for research, technological development and demonstration; Hubble Fellowships; a Carnegie-Princeton Fellowship; the Arye Dissentshik career development; the Willner Family Leadership Institute Ilan Gluzman (Secaucus, N.J.), the Israeli Ministry of Science; Israel Science Foundation; Minerv;, Weizmann-UK; the I-CORE Program of the Planning and Budgeting Committee.

The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.

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Source: Royal Astronomical Society

Tremors of the Big Bang: First direct evidence of cosmic inflation

Gravitational waves from inflation generate a faint but distinctive twisting pattern in the polarization of the cosmic microwave background, known as a "curl" or B-mode pattern. For the density fluctuations that generate most of the polarization of the CMB, this part of the primordial pattern is exactly zero. Shown here is the actual B-mode pattern observed with the BICEP2 telescope, which is consistent with the pattern predicted for primordial gravitational waves. The line segments show the polarization strength and orientation at different spots on the sky. The red and blue shading shows the degree of clockwise and anti-clockwise twisting of this B-mode pattern. Credit: BICEP2 Collaboration

Almost 14 billion years ago, the universe we inhabit burst into existence in an extraordinary event that initiated the Big Bang. In the first fleeting fraction of a second, the universe expanded exponentially, stretching far beyond the view of our best telescopes. All this, of course, was just theory.

Researchers from the BICEP2 collaboration today announced the first direct evidence for this cosmic inflation. Their data also represent the first images of gravitational waves, or ripples in space-time. These waves have been described as the "first tremors of the Big Bang." Finally, the data confirm a deep connection between quantum mechanics and general relativity.

"Detecting this signal is one of the most important goals in cosmology today. A lot of work by a lot of people has led up to this point," said John Kovac (Harvard-Smithsonian Center for Astrophysics), leader of the BICEP2 collaboration.

These groundbreaking results came from observations by the BICEP2 telescope of the cosmic microwave background -- a faint glow left over from the Big Bang. Tiny fluctuations in this afterglow provide clues to conditions in the early universe. For example, small differences in temperature across the sky show where parts of the universe were denser, eventually condensing into galaxies and galactic clusters.

Since the cosmic microwave background is a form of light, it exhibits all the properties of light, including polarization. On Earth, sunlight is scattered by the atmosphere and becomes polarized, which is why polarized sunglasses help reduce glare. In space, the cosmic microwave background was scattered by atoms and electrons and became polarized too.

"Our team hunted for a special type of polarization called 'B-modes,' which represents a twisting or 'curl' pattern in the polarized orientations of the ancient light," said co-leader Jamie Bock (Caltech/JPL).

Gravitational waves squeeze space as they travel, and this squeezing produces a distinct pattern in the cosmic microwave background. Gravitational waves have a "handedness," much like light waves, and can have left- and right-handed polarizations.

"The swirly B-mode pattern is a unique signature of gravitational waves because of their handedness. This is the first direct image of gravitational waves across the primordial sky," said co-leader Chao-Lin Kuo (Stanford/SLAC).

The team examined spatial scales on the sky spanning about one to five degrees (two to ten times the width of the full Moon). To do this, they traveled to the South Pole to take advantage of its cold, dry, stable air.

"The South Pole is the closest you can get to space and still be on the ground," said Kovac. "It's one of the driest and clearest locations on Earth, perfect for observing the faint microwaves from the Big Bang."

They were surprised to detect a B-mode polarization signal considerably stronger than many cosmologists expected. The team analyzed their data for more than three years in an effort to rule out any errors. They also considered whether dust in our galaxy could produce the observed pattern, but the data suggest this is highly unlikely.

"This has been like looking for a needle in a haystack, but instead we found a crowbar," said co-leader Clem Pryke (University of Minnesota).

When asked to comment on the implications of this discovery, Harvard theorist Avi Loeb said, "This work offers new insights into some of our most basic questions: Why do we exist? How did the universe begin? These results are not only a smoking gun for inflation, they also tell us when inflation took place and how powerful the process was."

BICEP2 is the second stage of a coordinated program, the BICEP and Keck Array experiments, which has a co-PI structure. The four PIs are John Kovac (Harvard), Clem Pryke (UMN), Jamie Bock (Caltech/JPL), and Chao-Lin Kuo (Stanford/SLAC). All have worked together on the present result, along with talented teams of students and scientists. Other major collaborating institutions for BICEP2 include the University of California at San Diego, the University of British Columbia, the National Institute of Standards and Technology, the University of Toronto, Cardiff University, Commissariat à l'Energie Atomique.

BICEP2 is funded by the National Science Foundation (NSF). NSF also runs the South Pole Station where BICEP2 and the other telescopes used in this work are located. The Keck Foundation also contributed major funding for the construction of the team's telescopes. NASA, JPL, and the Moore Foundation generously supported the development of the ultra-sensitive detector arrays that made these measurements possible.

Technical details and journal papers can be found on the BICEP2 release website: http://bicepkeck.org

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

Source: Harvard–Smithsonian Center for Astrophysics

Gravity may have saved the universe after the Big Bang, say researchers

Center of the Milky Way galaxy (stock image). Credit: © DR / Fotolia

New research by a team of European physicists could explain why the universe did not collapse immediately after the Big Bang.

Studies of the Higgs particle -- discovered at CERN in 2012 and responsible for giving mass to all particles -- have suggested that the production of Higgs particles during the accelerating expansion of the very early universe (inflation) should have led to instability and collapse.

Scientists have been trying to find out why this didn't happen, leading to theories that there must be some new physics that will help explain the origins of the universe that has not yet been discovered. Physicists from Imperial College London, and the Universities of Copenhagen and Helsinki, however, believe there is a simpler explanation.

In a new study in Physical Review Letters, the team describe how the spacetime curvature -- in effect, gravity -- provided the stability needed for the universe to survive expansion in that early period. The team investigated the interaction between the Higgs particles and gravity, taking into account how it would vary with energy.

They show that even a small interaction would have been enough to stabilise the universe against decay.

"The Standard Model of particle physics, which scientists use to explain elementary particles and their interactions, has so far not provided an answer to why the universe did not collapse following the Big Bang," explains Professor Arttu Rajantie, from the Department of Physics at Imperial College London.

"Our research investigates the last unknown parameter in the Standard Model -- the interaction between the Higgs particle and gravity. This parameter cannot be measured in particle accelerator experiments, but it has a big effect on the Higgs instability during inflation. Even a relatively small value is enough to explain the survival of the universe without any new physics!"

The team plan to continue their research using cosmological observations to look at this interaction in more detail and explain what effect it would have had on the development of the early universe. In particular, they will use data from current and future European Space Agency missions measuring cosmic microwave background radiation and gravitational waves.

"Our aim is to measure the interaction between gravity and the Higgs field using cosmological data," says Professor Rajantie. "If we are able to do that, we will have supplied the last unknown number in the Standard Model of particle physics and be closer to answering fundamental questions about how we are all here."

The research is funded by the Science and Technology Facilities Council, along with the Villum Foundation, in Denmark, and the Academy of Finland.

Source: Imperial College London

Turning the Moon into a cosmic ray detector

Artists rendition of the SKA. Credit: SKA Organisation

Scientists from the University of Southampton are to turn the Moon into a giant particle detector to help understand the origin of Ultra-High-Energy (UHE) cosmic rays -- the most energetic particles in the Universe.

The origin of UHE cosmic rays is one of the great mysteries in astrophysics. Nobody knows where these extremely rare cosmic rays come from or how they get their enormous energies. Physicists detect them on Earth at a rate of less than one particle per square kilometre per century.

Dr Justin Bray, a Research Fellow in Cosmic Magnetism at the University of Southampton, is lead author of a proposal to use the Square Kilometre Array (SKA), set to become the largest and most sensitive radio telescope in the world, to detect vastly more UHE cosmic rays by using the Moon as a giant cosmic ray detector.

On Earth, physicists detect these high-energy particles when they hit the upper atmosphere triggering a cascade of secondary particles that generate a short and faint burst of radio waves only a few nanoseconds long.

It is this signal that astronomers hope to pick up from the Moon, but as these signals are so short and faint no radio telescope on Earth is currently capable of picking them up.
With its large collecting area and high sensitivity, the SKA will be able to detect these signals using the visible lunar surface -- millions of square kilometres -- giving the researchers access to more data about UHE cosmic rays than they have ever had before.

The current largest detector on Earth is the Pierre Auger Observatory in Argentina that covers an area of 3,000 square kilometres, about the size Luxembourg. The SKA will be more than 10 times larger (33,0000 square kilometres) and researchers hope to detect around 165 UHE cosmic rays a year from the Moon compared to the 15-a-year currently observed.

Dr Bray announced details of the project at a major SKA conference in Italy.. He says: "Cosmic rays at these energies are so rare that you need an enormous detector to collect a significant number of them -- but the moon dwarfs any particle detector that has been built so far. If we can make this work, it should give us our best chance yet to figure out where they're coming from."

Dr Bray is working with Professor Anna Scaife, also from Physics and Astronomy at the University of Southampton, who leads the development of the SKA's Imaging Pipeline as part of the Science Data Processor (SDP) work package consortium.

Professor Scaife says: "Defining science goals for the telescope is crucial for ensuring that the appropriate technical capabilities are considered during the design phase."

Using a network of radio antennas in the Southern hemisphere, the SKA will advance our understanding of how the Universe evolved and challenge Einstein's theory of relativity. With receivers across Australia and Africa, its dishes and antennas will provide detailed information on the large scale 3D structure of the Universe.

When operational in the early 2020's, the SKA radio telescope will produce more than 10 times the current global traffic of the Internet in its internal telecommunications system. To play back a single day's worth of SKA data on an MP3 player would take about two million years.

Source: University of Southampton

Physicists suggest new way to detect dark matter

This is associate professor Chris Kouvaris from the University of Southern Denmark. Credit: University of Southern Denmark

For years physicists have been looking for the universe's elusive dark matter, but so far no one has seen any trace of it. Maybe we are looking in the wrong place? Now physicists from University of Southern Denmark propose a new technique to detect dark matter.

The universe consists of atoms and particles -- and a whole lot more that still needs to be detected. We can only speculate about the existence of this unknown matter and energy.

"We know that app. 5 pct. of the universe consists of the known matter we are all made of. 

The rest is unknown. This unknown matter is called dark matter, and we believe that it is all around us, including here on Earth," explains Chris Kouvaris, associate professor at the Centre for Cosmology and Particle Physics Phenomenology (CP3-Origins), Department of Physics, Chemistry and Pharmacy, University of Southern Denmark.

He and his colleague from CP3-Origins, postdoc Ian Shoemaker, now suggest a new way to detect the existence of the elusive dark matter.

Cosmic noise is a problem

Over the last years, physicists have placed detectors in underground sites app. a kilometer or more deep in order to detect dark matter. The idea is that dark matter is easier to detect in deep sites because there is less noise from cosmic or Earth-produced radiation that can potentially cover the dark matter signal. This approach of detecting dark matter makes sense provided that dark matter interacts only a bit with atoms as it goes underground. The scientific term for this is that dark matter is weakly interacting with its surroundings.

"But we don't know if dark matter is that weakly interacting. In principle dark matter particles can lose energy as they travel underground before they hit the detector due to interactions with regular atoms. And in that case they might not have enough energy left to trigger the detector once they arrive there," says Chris Kouvaris.

Signals are good 12 hours a day

In a new research paper, he and Shoemaker study the possibility that dark matter can indeed interact substantially with atoms. They claim that depending on the properties of the dark matter particles, deep placed detectors can be blind because particles might have lost most of their energy before reaching the detector.

"In such a case, it would make more sense to look for dark matter signals on the surface of the Earth or in shallow sites," Kouvaris argues.

Placing a detector in shallow sites or on the surface ensures small energy loss for the dark matter particles but it also means a big increase in the background noise. This was after all the reason why detectors were placed in deep sites in the first place. To overcome this problem Kouvaris and Shoemaker propose -- instead of trying to detect a single collision of a dark matter particle with the detector -- to look for a signal that varies periodically during the day.

Because dark matter particles approach the detector from various directions, as the Earth rotates, the flux of the particles reaching the detector can vary. This causes a signal that will go from maximum to minimum in 12 hours and back to maximum again after another 12 hours.

Such a pattern will make the signals from dark matter stand out clear even though the detectors also pick up cosmic noise.

"The best locations for the observation of such a modulation signal are places in the south hemisphere with latitude around 40 degrees, such as Argentina, Chile and New Zealand" says Chris Kouvaris.

What is dark matter and dark energy?

27 pct. of the universe is believed to consist of dark matter. Dark matter is believed to be the "glue" that holds galaxies together. Nobody knows what dark matter really is.

5 pct. of the universe consists of known matter such as atoms and subatomic particles.
The rest of the universe is believed to consist of dark energy. Dark energy is believed to make the universe expand.

Source: University of Southern Denmark

Unravelling the mystery of gamma-ray bursts with kilometer-scale microphones

This is an illustration of how a neutron star might orbit a black hole. Credit: NASA

A team of scientists hopes to trace the origins of gamma-ray bursts with the aid of giant space 'microphones'.

Researchers at Cardiff University are trying to work out the possible sounds scientists might expect to hear when the ultra-sensitive LIGO and Virgo detectors are switched on in 2015.
It's hoped the kilometre-scale microphones will detect gravitational waves created by black holes, and shed light on the origins of the Universe.

Researchers Dr Francesco Pannarale and Dr Frank Ohme, in Cardiff University's School of Physics and Astronomy, are exploring the potential of seeing and hearing events that astronomers know as short gamma-ray bursts.

These highly energetic bursts of hard radiation have been seen by gamma-ray satellites such as Fermi and Swift, but the exact origin of these quickly disappearing flashes of gamma-rays remains unknown.

"By picking up the gravitational waves associated with these events, we will be able to access precious information that was previously hidden, such as whether the collision of a star and a black hole has ignited the burst and roughly how massive these objects were before the impact," explained Dr Ohme, who has focused his research on predicting the exact shape of the gravitational wave signals scientists are expecting to see.

Dr Pannarale added: "A possible scenario that could produce gamma-ray bursts involves a neutron star, the most compact star in the Universe, being ripped apart by a black hole while orbiting it. The remaining matter would be accelerated so much it could cause the energy bursts we are observing today.

"In some cases, by observing both electro-magnetic and gravitational wave signatures of the same event, we will be able to better understand the behaviour of material in the highest density region we know in our Universe, so that we will start to rule out various theoretical models that have been proposed but cannot be tested otherwise."

Source: Cardiff University

'Eye of Sauron' provides new way of measuring distances to galaxies

This image shows the spiral galaxy NGC 4151. Credit: X-ray: NASA/CXC/CfA/J.Wang et al.; Optical: Isaac Newton Group of Telescopes, La Palma/Jacobus Kapteyn Telescope; Radio: NSF/NRAO/VLA.

A team of scientists, led by Dr Sebastian Hoenig from the University of Southampton, have developed a new way of measuring precise distances to galaxies tens of millions of light years away, using the W. M. Keck Observatory near the summit of Mauna Kea in Hawaii.

The method is similar to what land surveyors use on Earth, by measuring the physical and angular, or 'apparent', size of a standard ruler in the galaxy, to calibrate the distance from this information.

The research, which is published in the journal Nature, was used to identify the accurate distance of the nearby NGC4151 galaxy, which wasn't previously available. The galaxy NGC 4151, which is dubbed the 'Eye of Sauron' by astronomers for its similarity to the film depiction of the eye of the character in The Lord of the Rings, is important for accurately measuring black hole masses.

Recently reported distances range from 4 to 29 megaparsecs, but using this new method the researchers calculated the distance of 19 megaparsecs to the supermassive black hole.
Indeed, as in the famous saga, a ring plays a crucial role in this new measurement. All big galaxies in the universe host a supermassive black hole in their centre and in about a tenth of all galaxies, these supermassive black holes are growing by swallowing huge amounts of gas and dust from their surrounding environments. In this process, the material heats up and becomes very bright -- becoming the most energetic sources of emission in the universe known as active galactic nuclei (AGN).

The hot dust forms a ring around the supermassive black hole and emits infrared radiation, which the researchers used as the ruler. However, the apparent size of this ring is so small that the observations were carried out using infrared interferometry to combine W. M. Keck Observatory's twin 10-meter telescopes, to achieve the resolution power of an 85m telescope.

To measure the physical size of the dusty ring, the researchers measured the time delay between the emission of light from very close to the black hole and the infrared emission. This delay is the distance the light has to travel (at the speed-of-light) from close to the black hole out to the hot dust.

By combining this physical size of the dust ring with the apparent size measured with the data from the Keck interferometer, the researchers were able to determine a distance to the galaxy NGC 4151.

Dr Hoenig says: "One of the key findings is that the distance determined in this new fashion is quite precise -- with only about 10 per cent uncertainty. In fact, if the current result for NGC 4151 holds for other objects, it can potentially beat any other current methods to reach the same precision to determine distances for remote galaxies directly based on simple geometrical principles. Moreover, it can be readily used on many more sources than the current most precise method."

"Such distances are key in pinning down the cosmological parameters that characterise our universe or for accurately measuring black hole masses. Indeed, NGC 4151 is a crucial anchor to calibrate various techniques to estimate black hole masses. Our new distance implies that these masses may have been systematically underestimated by 40 per cent."

Dr Hoenig, together with colleagues in Denmark and Japan, is currently setting up a new program to extend their work to many more AGN. The goal is to establish precise distances to a dozen galaxies in this new way and use them to constrain cosmological parameters to within a few per cent. In combination with other measurements, this will provide a better understanding of the history of expansion of our universe.

Source: University of Southampton