Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Violent gamma-ray outbursts near supermassive black holes


Where in powerful jets of distant active galaxies are outbursts of high energy gamma-ray emission produced?

A team led by Lars Fuhrmann from MPIfR Bonn, performed intensive, multi-frequency radio observations with some of the best single-dish radio telescopes in combination with NASA's Fermi Telescope, to study the place where the high energy outbursts occur.

An artist's view of the nuclear region of an active galaxy with a disk of accreting material (brown/yellow) and a powerful, collimated radio jet perpendicular t o the disk.

Credit: NASA JPL/CalTech

Telescopes utilized for the data acquisition in the radio and y-ray regime. Clockwise from upper left: Effelsberg 100m, APEX 12m, Fermi -ray observatory and IRAM 30m.

Credit: MPIfR/N. Junkes (100m), APEX-Team (12m), NASA E/PO, Sonoma State University, Aurore Simonnet (Fermi), MPIfR (30m).

For the first time a connection between outbursts of high energy gamma-ray emission and their counterparts at many radio frequencies has been established for a large sample of galaxies. Measuring delays in time between these events finally produced better constraints on the exact location where the gamma-ray outbursts take place.

Special types of distant active galaxies and their innermost central regions show extreme physical processes. In the vicinity of a spinning supermassive black hole (billions of times heavier than our Sun) an enormous amount of energy is released, often in the most energetic form of light: high energy gamma-ray photons at mega- or even gigaelectronvolt (MeV/GeV) energies. This energy output is produced by feeding the black hole from surrounding stars, gas and dust.

Matter is spiraling in onto the black hole and strong magnetic fields channel some of the infalling gas into two powerful, well collimated "jets" of plasma accelerating away from the center with velocities approaching the speed of light. Many of the connected physical processes are not understood in detail so far, for example the production of high-energy gamma-ray photons and their place of origin inside the jet, or the origin of strong outbursts of emission across the whole electromagnetic spectrum. New instruments and observing programs covering a large fraction of the whole energy spectrum nearly simultaneously allow new insights into the extreme physics of these objects to be obtained.

Using a combination of three of the world’s most advanced single-dish radio observatories, namely the Effelsberg 100-m, IRAM 30-m and APEX 12-m telescopes covering quasi-simultaneously 11 radio frequency bands (the so-called Fermi-GST AGN Multi-frequency Monitoring Alliance, F-GAMMA programme), the team of scientists was able to monitor the frequently occurring radio outbursts of about 60 powerful active galaxies over many years.

"Since the era of the EGRET instrument on the Compton Gamma-ray Observatory in the 1990s, it has been discussed whether outbursts of radio emission are physically connected to similar events occurring at gamma rays" says Anton Zensus, Director at the Max Planck Institute for Radio Astronomy (MPIfR) and Fermi Affiliated Scientist. "Now with the combination of F-GAMMA radio and Fermi gamma-ray long-term data, and thanks to special analysis techniques, we finally know it!"

In addition to radio data within the F-GAMMA programme, the research team used gamma-ray observations of NASA’s Fermi Gamma-ray Space Telescope (launched in 2008), and a new statistical method to add up many radio and gamma-ray events. "It was illuminating to see the statistical noise going down and the average correlation popping up" explains Stefan Larsson, from Stockholm University.

"This finally demonstrates that a significant connection exists, even when using different radio frequencies" he continues. The study furthermore shows that the radio outbursts arrived at the telescopes later in time than their gamma-ray counterparts, with mean delays between 10 and 80 days. "For the first time we see that the radio delays become smoothly smaller towards higher radio frequencies", adds Emmanouil Angelakis from MPIfR. "Towards higher frequencies we are looking deeper into the jet. The gamma-ray photons are thus coming from the innermost radio emitting jet regions."

Using the measured time delays the team was finally able to estimate distances of a few ten light years or less between the radio and gamma-ray outburst regions. "Based on our delay measurements we could estimate for one of the brightest gamma-ray emitting active galaxies in the sky, 3C 454.3, how far away from the supermassive black hole most of the gamma-ray photons must have been produced. We are talking about only a few light year distances – very close to the footpoint of the jet and the black hole itself!" proudly reports Lars Fuhrmann from MPIfR, the lead author of the paper. "This has serious implications for the physical processes producing the gamma-ray photons!" he adds. In the meantime the team is continuing to use the "Joint Eye" on the universe to collect more data and more events for detailed follow-up studies.

Original paper:

Detection of significant cm to sub-mm band radio and γ-ray correlated variability in Fermi bright blazars, L. Fuhrmann, S. Larsson, J. Chiang, E. Angelakis, J. A. Zensus, I. Nestoras, T. P. Krichbaum, H. Ungerechts, A. Sievers, V. Pavlidou, A. C. S. Readhead, W. Max-Moerbeck, and T. J. Pearson, 2014, MNRAS, 441, 1899-1909.


Dr. Lars Fuhrmann,
Max-Planck-Institut für Radioastronomie.
Fon: +49(0)228-525-424

Prof. Dr. J. Anton Zensus,
Director and Head of Research Group „Radio Astronomy / VLBI“
Max-Planck-Institut für Radioastronomie.
Fon: +49(0)228-525-298

Dr. Emmanouil Angelakis,
Max-Planck-Institut für Radioastronomie.
Fon: +49(0)228-525-217

Dr. Norbert Junkes,
Press and Public Outreach,
Max-Planck-Institut für Radioastronomie.
Fon: +49(0)228-525-399

Weitere Informationen:

Norbert Junkes | Max-Planck-Institut

More articles from Physics and Astronomy:

nachricht Ground-breaking research could challenge underlying principles of physics
23.11.2015 | University of Southampton

nachricht Quantum Simulation: A Better Understanding of Magnetism
20.11.2015 | Ruprecht-Karls-Universität Heidelberg

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: Lactate for Brain Energy

Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.

In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...

Im Focus: Laser process simulation available as app for first time

In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.

Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...

Im Focus: Quantum Simulation: A Better Understanding of Magnetism

Heidelberg physicists use ultracold atoms to imitate the behaviour of electrons in a solid

Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...

Im Focus: Climate Change: Warm water is mixing up life in the Arctic

AWI researchers’ unique 15-year observation series reveals how sensitive marine ecosystems in polar regions are to change

The warming of arctic waters in the wake of climate change is likely to produce radical changes in the marine habitats of the High North. This is indicated by...

Im Focus: Nanocarriers may carry new hope for brain cancer therapy

Berkeley Lab researchers develop nanoparticles that can carry therapeutics across the brain blood barrier

Glioblastoma multiforme, a cancer of the brain also known as "octopus tumors" because of the manner in which the cancer cells extend their tendrils into...

All Focus news of the innovation-report >>>



Event News

Gluten oder nicht Gluten? Überempfindlichkeit auf Weizen kann unterschiedliche Ursachen haben

17.11.2015 | Event News

Art Collection Deutsche Börse zeigt Ausstellung „Traces of Disorder“

21.10.2015 | Event News

Siemens Healthcare introduces the Cios family of mobile C-arms

20.10.2015 | Event News

Latest News

Siemens offers concrete solution portfolio for Industrie 4.0 with Digital Enterprise

24.11.2015 | Trade Fair News

Compact, rugged, three-phase power supplies for worldwide use

24.11.2015 | Trade Fair News

Sensor sees nerve action as it happens

24.11.2015 | Life Sciences

More VideoLinks >>>