Classified as an ultraluminous X-ray source (ULX), the object is only the second ever seen in M31 and became the target of an intense observing campaign by orbiting X-ray telescopes -- including NASA's Swift -- and radio observatories on the ground. These efforts resulted in the first detection of radio-emitting jets from a stellar-mass black hole outside our own galaxy.
A ULX is thought to be a binary system containing a black hole that is rapidly accreting gas from its stellar companion. However, to account for the brilliant high-energy output, gas must be flowing into the black hole at a rate very near a theoretical maximum, a feeding frenzy that astronomers do not yet fully understand.
"There are four black hole binaries within our own galaxy that have been observed accreting at these extreme rates," said Matthew Middleton, an astronomer at the Anton Pannekoek Astronomical Institute in Amsterdam. "Gas and dust in our own galaxy interfere with our ability to probe how matter flows into ULXs, so our best glimpse of these processes comes from sources located out of the plane of our galaxy, such as those in M31."
As gas spirals toward a black hole, it becomes compressed and heated, eventually reaching temperatures where it emits X-rays. As the rate of matter ingested by the black hole increases, so does the X-ray brightness of the gas. At some point, the X-ray emission becomes so intense that it pushes back on the inflowing gas, theoretically capping any further increase in the black hole's accretion rate. Astronomers refer to this as the Eddington limit, after Sir Arthur Eddington, the British astrophysicist who first recognized a similar cutoff to the maximum luminosity of a star.
"Black-hole binaries in our galaxy that show accretion at the Eddington limit also exhibit powerful radio-emitting jets that move near the speed of light," Middleton said. Although astronomers know little about the physical nature of these jets, detecting them at all would confirm that the ULX is accreting at the limit and identify it as a stellar mass black hole.
The European Space Agency's XMM-Newton observatory first detected the ULX, dubbed XMMU J004243.6+412519 after its astronomical coordinates, on Jan. 15. Middleton and a large international team then began monitoring it at X-ray energies using XMM-Newton and NASA's Swift satellite and Chandra X-ray Observatory. The scientists conducted radio observations using the Karl G. Jansky Very Large Array (VLA) and the continent-spanning Very Long Baseline Array, both operated by the National Science Foundation in Socorro, N.M., and the Arcminute Microkelvin Imager Large Array located at the Mullard Radio Astronomy Observatory near Cambridge, England.
In a paper published online by the journal Nature on Wednesday, Dec. 12, the scientists reveal their successful detection of intense radio emission associated with a jet moving at more than 85 percent the speed of light. VLA data reveal that the radio emission was quite variable, in one instance decreasing by a factor of two in just half an hour.
"This tells us that the region producing radio waves is extremely small in size -- no farther across than the distance between Jupiter and the sun," explained team member James Miller-Jones, a research fellow at the Curtin University node of the International Centre for Radio Astronomy Research in Perth, Western Australia.
Black holes have been conclusively detected in two varieties: "lightweight" ones created by stars and containing up to a few dozen times the sun's mass, and supermassive "heavyweights" of millions to billions of solar masses found at the centers of most big galaxies. Astronomers have debated whether many ULXs represent hard-to-find "middleweight" versions, containing hundreds to thousands of solar masses.
"The discovery of jets tells us that this particular ULX is a typical stellar remnant about 10 times the mass of the sun, swallowing as much material as it possibly can," Middleton said. "We may well find jets in ULXs with similar X-ray properties in other nearby galaxies, which will help us better understand the nature of these incredible outflows."
Commenting on the findings on behalf of the Swift team, Stefan Immler at NASA's Goddard Space Flight Center in Greenbelt, Md., noted that it was almost exciting enough for astronomers to witness a new ULX so close to home, even if "close" is a few million light-years away. "But detecting the jets is a real triumph, one that will allow us to study the accretion process of these elusive black hole candidates in never-before-seen detail," he said.
NASA's Goddard Space Flight Center, Greenbelt, Md.
Francis Reddy | Source: EurekAlert!
Further information: www.nasa.gov
Further Reports about: Astronomers > Astronomy > binge-eating > black hole > black populations > Goddard Space Flight Center > Large Hadron Collider > radio emission > solar masses > Space > speed of light > speed|scan atlineCT-System > ULX > VLA > X-ray microscopy > XMM-Newton
More articles from Physics and Astronomy:
Three-dimensional view helps laser in building new molecules
06.12.2013 | Max-Planck-Institut für Quantenoptik
NASA Goddard Planetary Instruments Score a Hat Trick
06.12.2013 | NASA/Goddard Space Flight Center
International team of scientists develops new feedback method for optimizing the laser pulse shapes used in the control of chemical reactions
In many ways, traditional chemical synthesis is similar to cooking. To alter the final product, you can change the ingredients or their ratio, change the method of mixing ingredients, or change the temperature or pressure of the environment of the ingredients.
Like an accomplished chef, chemists have become very skilled ...
A genetic defect protects mice from infection with influenza viruses
A new study published in the scientific journal PLOS Pathogens points out that mice lacking a protein called Tmprss2 are no longer affected by certain flu viruses.
The discovery was made by researchers from the Helmholtz Centre for Infection Research (HZI) in Braunschweig in collaboration with colleagues from Göttingen and ...
The Light: Global study gets underway with online user survey
Light has a fundamental impact on our sense of well-being and performance. In cooperation with Zumtobel, a supplier of lighting solutions, Fraunhofer IAO has launched a global user survey of lighting quality in offices. The objective is to identify the best lighting conditions for a variety of spaces and lighting ...
Quantum entanglement, a perplexing phenomenon of quantum mechanics that Albert Einstein once referred to as “spooky action at a distance,” could be even spookier than Einstein perceived.
Physicists at the University of Washington and Stony Brook University in New York believe the phenomenon might be intrinsically linked with wormholes, hypothetical features of space-time that in popular science fiction can provide a much-faster-than-light shortcut from one part of the universe to another.
But here’s the catch: One couldn’t actually ...
A star is formed when a large cloud of gas and dust condenses and eventually becomes so dense that it collapses into a ball of gas, where the pressure heats the matter, creating a glowing gas ball – a star is born.
New research from the Niels Bohr Institute, among others, shows that a young, newly formed star in the Milky Way had such an explosive growth, that it was initially about 100 times brighter than it is now. The results are published in the scientific journal, Astrophysical Journal Letters.
The young ...
06.12.2013 | Materials Sciences
06.12.2013 | Life Sciences
06.12.2013 | Life Sciences
05.12.2013 | Event News
04.12.2013 | Event News
12.11.2013 | Event News