Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Possible Extragalactic Source of High-Energy Neutrinos

28.04.2016

Coincidence of a highly energetic outburst of an active galactic nucleus with a neutrino event at PeV energy

Nearly 10 billion years ago in a galaxy known as PKS B1424-418, a dramatic explosion occurred. Light from this blast began arriving at Earth in 2012. Now, an international team of astronomers, led by Prof. Matthias Kadler, professor for astrophysics at the university of Würzburg, and including other scientists from the new research cluster for astronomy and astroparticle physics at the universities of Würzburg and Erlangen-Nürnberg, have shown that a record-breaking neutrino seen around the same time likely was born in the same event. The results are published in "Nature Physics".


Fermi LAT images showing the gamma-ray sky around the blazar PKS B1424-418. Brighter colors indicate greater numbers of gamma rays. The arc marks part of the source region for the Big Bird neutrino

NASA/DOE/LAT Collaboration


These radio images from the TANAMI project reveal the 2012-2013 eruption of PKS B1424-418. The core of the blazar’s jet producing the most dramatic blazar outburst TANAMI has observed to date.

TANAMI

Neutrinos are the fastest, lightest, most unsociable and least understood fundamental particles, and scientists are just now capable of detecting high-energy ones arriving from deep space. The present work provides the first plausible association between a single extragalactic object and one of these cosmic neutrinos.

Although neutrinos far outnumber all the atoms in the universe, they rarely interact with matter, which makes detecting them quite a challenge. But this same property lets neutrinos make a fast exit from places where light cannot easily escape -- such as the core of a collapsing star -- and zip across the universe almost completely unimpeded. Neutrinos can provide information about processes and environments that simply aren't available through a study of light alone.

Recently, the IceCube Neutrino Observatory at the South Pole found first evidence for a flux of extraterrestrial neutrinos, which was named the Physics World breakthrough of the year 2013. To date, the science team of IceCube Neutrino has announced about a hundred very high-energy neutrinos and nicknamed the most extreme events after characters on the children's TV series "Sesame Street." On Dec. 4, 2012, IceCube detected an event known as Big Bird, a neutrino with an energy exceeding 2 quadrillion electron volts (PeV). To put that in perspective, it's more than a million million times greater than the energy of a dental X-ray packed into a single particle thought to possess less than a millionth the mass of an electron. Big Bird was the highest-energy neutrino ever detected at the time and still ranks second.

Where did it come from? The best IceCube position only narrowed the source to a patch of the southern sky about 32 degrees across, equivalent to the apparent size of 64 full moons. “It’s like a crime scene investigation”, says lead author Matthias Kadler, a professor of astrophysics at the University of Würzburg in Germany, “The case involves an explosion, a suspect, and various pieces of circumstantial evidence.”

Starting in the summer of 2012, NASA’s Fermi satellite witnessed a dramatic brightening of PKS B1424-418, an active galaxy classified as a gamma-ray blazar. An active galaxy is an otherwise typical galaxy with a compact and unusually bright core. The excess luminosity of the central region is produced by matter falling toward a supermassive black hole weighing millions of times the mass of our sun. As it approaches the black hole, some of the material becomes channeled into particle jets moving outward in opposite directions at nearly the speed of light. In blazars one of these jets happens to point almost directly toward Earth.

During the year-long outburst, PKS B1424-418 shone between 15 and 30 times brighter in gamma rays than its average before the eruption. The blazar is located within the Big Bird source region, but then so are many other active galaxies detected by Fermi.
The scientists searching for the neutrino source then turned to data from a long-term observing program named TANAMI. Since 2007, TANAMI has routinely monitored nearly 100 active galaxies in the southern sky, including many flaring sources detected by Fermi. Three radio observations between 2011 and 2013 cover the period of the Fermi outburst. They reveal that the core of the galaxy's jet had been brightening by about four times. No other galaxy observed by TANAMI over the life of the program has exhibited such a dramatic change.

“Within their jets, blazars are capable of accelerating protons to relativistic energies. Interactions of these protons with light in the central regions of the blazar can create pions. When these pions decay, both gamma rays and neutrinos are produced,“ explains Karl Mannheim, a coauthor of the study and astronomy professor in Würzburg, Germany. "We combed through the field where Big Bird must have originated looking for astrophysical objects capable of producing high-energy particles and light," adds coauthor Felicia Krauß, a doctoral student at the University of Erlangen-Nürnberg in Germany. "There was a moment of wonder and awe when we realized that the most dramatic outburst we had ever seen in a blazar happened in just the right place at just the right time."

In a paper published Monday, April 18, in Nature Physics, the team suggests the PKS B1424-418 outburst and Big Bird are linked, calculating only a 5-percent probability the two events occurred by chance alone. Using data from Fermi, NASA’s Swift and WISE satellites, the LBA and other facilities, the researchers determined how the energy of the eruption was distributed across the electromagnetic spectrum and showed that it was sufficiently powerful to produce a neutrino at PeV energies.

"Taking into account all of the observations, the blazar seems to have had means, motive and opportunity to fire off the Big Bird neutrino, which makes it our prime suspect," explains Matthias Kadler.

Francis Halzen, the principal investigator of IceCube at the University of Wisconsin–Madison, and not involved in this study, thinks the result is an exciting hint of things to come. "IceCube is about to send out real-time alerts when it records a neutrino that can be localized to an area a little more than half a degree across, or slightly larger than the apparent size of a full moon," he concludes. "We're slowly opening a neutrino window onto the cosmos."

But this study also demonstrates the vital importance of classical astronomical observations in an era when new detection methods like neutrino observatories and gravitational-wave detectors open new but unknown skies.

TANAMI (Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry) is a multiwavelength monitoring program of active galaxies in the Southern sky. It includes regular radio observations using the Australian Long Baseline Array (LBA) and associated telescopes in Chile, South Africa, New Zealand and Antarctica. When networked together, they operate as a single radio telescope more than 6,000 miles across and provide a unique high-resolution look into the jets of active galaxies.

The IceCube Neutrino Observatory, built into a cubic kilometer of clear glacial ice at the South Pole, detects neutrinos when they interact with atoms in the ice. This triggers a cascade of fast-moving charged particles that emit a faint glow, called Cerenkov light, as they travel, which is picked up by thousands of optical sensors strung throughout IceCube. Scientists determine the energy of an incoming neutrino by the amount of light its particle cascade emits.

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

Original Paper:

Coincidence of a high-fluence blazar outburst with a PeV-energy neutrino event. Kadler, M.; Krauß, F.; Mannheim, K.; Ojha, R.; Müller, C.; Schulz, R.; Anton, G.; Baumgartner, W.; Beuchert, T.; Buson, S.; Carpenter, B.; Eberl, T.; Edwards, P. G.; Eisenacher Glawion, D.; Elsässer, D.; Gehrels, N.; Gräfe, C.; Hase, H.; Horiuchi, S.; James, C. W.; Kappes, A.; Kappes, A.; Katz, U.; Kreikenbohm, A.; Kreter, M.; Kreykenbohm, I.; Langejahn, M.; Leiter, K.; Litzinger, E.; Longo, F.; Lovell, J. E. J.; McEnery, J.; Phillips, C.; Plötz, C.; Quick, J.; Ros, E.; Stecker, F. W.; Steinbring, T.; Stevens, J.; Thompson, D. J.; Trüstedt, J.; Tzioumis, A. K.; Wilms, J.; Zensus, J. A. 2016, Nature Physics, DOI 10.1038/nphys3715.

Local Contact:
Prof. Dr. Matthias Kadler,
Lehrstuhl für Astronomie, Institut für Theoretische Physik und Astrophysik, Universität Würzburg.
Fon: +49 931 31-85138
E-mail: matthias.kadler@astro.uni-wuerzburg.de

Prof. Dr. Karl Mannheim,
Lehrstuhl für Astronomie, Institut für Theoretische Physik und Astrophysik, Universität Würzburg.
Fon: +49 931 31-85030
E-mail: mannheim@astro.uni-wuerzburg.de

Weitere Informationen:

http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3715.html Original Paper

Gunnar Bartsch | Julius-Maximilians-Universität Würzburg

More articles from Physics and Astronomy:

nachricht Two dimensional circuit with magnetic quasi-particles
22.01.2018 | Technische Universität Kaiserslautern

nachricht Meteoritic stardust unlocks timing of supernova dust formation
19.01.2018 | Carnegie Institution for Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Thanks for the memory: NIST takes a deep look at memristors

22.01.2018 | Materials Sciences

Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments

22.01.2018 | Earth Sciences

Saarland University bioinformaticians compute gene sequences inherited from each parent

22.01.2018 | Life Sciences

VideoLinks Wissenschaft & Forschung
Overview of more VideoLinks >>>