Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Violent gamma-ray outbursts near supermassive black holes

22.05.2014

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.
http://mnras.oxfordjournals.org/content/441/3/1899.abstract
http://arxiv.org/abs/1403.4170

Contact:

Dr. Lars Fuhrmann,
Max-Planck-Institut für Radioastronomie.
Fon: +49(0)228-525-424
E-mail: lfuhrmann@mpifr-bonn.mpg.de

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
E-mail: azensus@mpifr-bonn.mpg.de

Dr. Emmanouil Angelakis,
Max-Planck-Institut für Radioastronomie.
Fon: +49(0)228-525-217
E-mail: eangelakis@mpifr-bonn.mpg.de

Dr. Norbert Junkes,
Press and Public Outreach,
Max-Planck-Institut für Radioastronomie.
Fon: +49(0)228-525-399
E-mail: njunkes@mpifr-bonn.mpg.de

Weitere Informationen:

http://www.mpifr-bonn.mpg.de/pressreleases/2014/5

Norbert Junkes | Max-Planck-Institut

More articles from Physics and Astronomy:

nachricht Down to the quantum dot
07.07.2015 | Forschungszentrum Juelich

nachricht Transition from 3 to 2 dimensions increases conduction, MIPT scientists discover
07.07.2015 | Moscow Institute of Physics and Technology

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: Surfing a wake of light

Researchers observe and control light wakes for the first time

When a duck paddles across a pond or a supersonic plane flies through the sky, it leaves a wake in its path. Wakes occur whenever something is traveling...

Im Focus: Light-induced Magnetic Waves in Materials Engineered at the Atomic Scale

Researchers explore ultrafast control of magnetism across interfaces: A new study discovers how the sudden excitation of lattice vibrations in a crystal can trigger a change of the magnetic properties of an atomically-thin layer that lies on its surface.

A research team, led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter at CFEL in Hamburg, the University of Oxford, and the...

Im Focus: Viaducts with wind turbines, the new renewable energy source

Wind turbines could be installed under some of the biggest bridges on the road network to produce electricity. So it is confirmed by calculations carried out by a European researchers team, that have taken a viaduct in the Canary Islands as a reference. This concept could be applied in heavily built-up territories or natural areas with new constructions limitations.

The Juncal Viaduct, in Gran Canaria, has served as a reference for Spanish and British researchers to verify that the wind blowing between the pillars on this...

Im Focus: X-rays and electrons join forces to map catalytic reactions in real-time

New technique combines electron microscopy and synchrotron X-rays to track chemical reactions under real operating conditions

A new technique pioneered at the U.S. Department of Energy's Brookhaven National Laboratory reveals atomic-scale changes during catalytic reactions in real...

Im Focus: Iron: A biological element?

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Conference on Regenerative Medicine in Leipzig: Last chance to submit abstracts until 2 July

25.06.2015 | Event News

World Conference on Regenerative Medicine: Abstract Submission has been extended to 24 June

16.06.2015 | Event News

MUSE hosting Europe’s largest science communication conference

11.06.2015 | Event News

 
Latest News

Down to the quantum dot

07.07.2015 | Physics and Astronomy

Tundra study uncovers impact of climate warming in the Arctic

07.07.2015 | Earth Sciences

Transition from 3 to 2 dimensions increases conduction, MIPT scientists discover

07.07.2015 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>