Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Galaxy's gamma-ray flares erupted far from its black hole

08.01.2013
In 2011, a months-long blast of energy launched by an enormous black hole almost 11 billion years ago swept past Earth.

Using a combination of data from NASA's Fermi Gamma-ray Space Telescope and the National Science Foundation's Very Long Baseline Array (VLBA), the world's largest radio telescope, astronomers have zeroed in on the source of this ancient outburst.

Theorists expect gamma-ray outbursts occur only in close proximity to a galaxy's central black hole, the powerhouse ultimately responsible for the activity. A few rare observations suggested this is not the case.

The 2011 flares from a galaxy known as 4C +71.07 now give astronomers the clearest and most distant evidence that the theory still needs some work. The gamma-ray emission originated about 70 light-years away from the galaxy's central black hole.

The 4C +71.07 galaxy was discovered as a source of strong radio emission in the 1960s. NASA's Compton Gamma-Ray Observatory, which operated in the 1990s, detected high-energy flares, but the galaxy was quiet during Fermi's first two and a half years in orbit.

In early November 2011, at the height of the outburst, the galaxy was more than 10,000 times brighter than the combined luminosity of all of the stars in our Milky Way galaxy.

"This renewed activity came after a long slumber, and that's important because it allows us to explicitly link the gamma-ray flares to the rising emission observed by radio telescopes," said David Thompson, a Fermi deputy project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

Located in the constellation Ursa Major, 4C +71.07 is so far away that its light takes 10.6 billion years to reach Earth. Astronomers are seeing this galaxy as it existed when the universe was less than one-fourth of its present age.

At the galaxy's core lies a supersized black hole weighing 2.6 billion times the sun's mass. Some of the matter falling toward the black hole becomes accelerated outward at almost the speed of light, creating dual particle jets blasting in opposite directions. One jet happens to point almost directly toward Earth. This characteristic makes 4C +71.07 a blazar, a classification that includes some of the brightest gamma-ray sources in the sky.

Boston University astronomers Alan Marscher and Svetlana Jorstad routinely monitor 4C +71.07 along with dozens of other blazars using several facilities, including the VLBA.

The instrument's 10 radio telescopes span North America, from Hawaii to St. Croix in the U.S. Virgin Islands, and possess the resolving power of a single radio dish more than 5,300 miles across when their signals are combined. As a result, The VLBA resolves detail about a million times smaller than Fermi's Large Area Telescope (LAT) and 1,000 times smaller than NASA's Hubble Space Telescope.

In autumn 2011, the VLBA images revealed a bright knot that appeared to move outward at a speed 20 times faster than light.

"Although this apparent speed was an illusion caused by actual motion almost directly toward us at 99.87 percent the speed of light, this knot was the key to determining the location where the gamma-rays were produced in the black hole's jet," said Marscher, who presented the findings Monday at the American Astronomical Society meeting in Long Beach, Calif.

The knot passed through a bright stationary feature of the jet, which the astronomers refer to as its radio "core," on April 9, 2011. This occurred within days of Fermi's detection of renewed gamma-ray flaring in the blazar. Marscher and Jorstad noted that the blazar brightened at visible wavelengths in step with the higher-energy emission.

During the most intense period of flaring, from October 2011 to January 2012, the scientists found the polarization direction of the blazar's visible light rotated in the same manner as radio emissions from the knot. They concluded the knot was responsible for the visible and the gamma-ray light, which varied in sync.

This association allowed the researchers to pinpoint the location of the gamma-ray outburst to about 70 light-years from the black hole.

The astronomers think that the gamma rays were produced when electrons moving near the speed of light within the jet collided with visible and infrared light originating outside of the jet. Such a collision can kick the light up to much higher energies, a process known as inverse-Compton scattering.

The source of the lower-energy light is unclear at the moment. The researchers speculate the source may be an outer, slow-moving sheath that surrounds the jet. Nicholas MacDonald, a graduate student at Boston University, is investigating how the gamma-ray brightness should change in this scenario to compare with observations.

"The VLBA is the only instrument that can bring us images from so near the edge of a young supermassive black hole, and Fermi's LAT is the only instrument that can see the highest-energy light from the galaxy's jet," said Jorstad.

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

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

For images related to this finding and to learn more about Fermi, visit:
http://go.nasa.gov/TGwz3N

J. D. Harrington | EurekAlert!
Further information:
http://www.nasa.gov
http://go.nasa.gov/TGwz3N

More articles from Physics and Astronomy:

nachricht Study offers new theoretical approach to describing non-equilibrium phase transitions
27.04.2017 | DOE/Argonne National Laboratory

nachricht SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>