An international team of astronomers, using data from several NASA and European Space Agency (ESA) space observatories, has discovered unexpected behavior from the supermassive black hole at the heart of the galaxy NGC 5548, located 244.6 million light-years from Earth. This behavior may provide new insights into how supermassive black holes interact with their host galaxies.
Immediately after NASA's Hubble Space Telescope observed NGC 5548 in June 2013, this international research team discovered unexpected features in the data. They detected a stream of gas flowing rapidly outward from the galaxy's supermassive black hole, blocking 90 percent of its emitted X-rays.
In this illustration, the position of a dark, absorbing cloud of material is located high above the supermassive black hole and accretion disk in the center of the active galaxy NGC 5548. Numerous other filaments twist around the black hole as they are swept away by a torrent of radiation "winds."
Image Credit: NASA, ESA, and A. Feild (STScI)
"The data represented dramatic changes since the last observation with Hubble in 2011," said Gerard Kriss of the Space Telescope Science Institute (STScI) in Baltimore, Maryland. "I saw signatures of much colder gas than was present before, indicating that the wind had cooled down due to a significant decrease in X-ray radiation from the galaxy's nucleus."
The discovery was made during an intensive observing campaign that also included data from NASA's Swift spacecraft, Nuclear Spectroscopic Telescope Array (NuSTAR) and Chandra X-ray Observatory, as well as ESA's X-ray Multi-Mirror Mission (XMM-Newton) and Integral gamma-ray observatory (INTEGRAL).
After combining and analyzing data from all six sources, the team was able to put together the pieces of the puzzle. Supermassive black holes in the nuclei of active galaxies, such as NGC 5548, expel large amounts of matter through powerful winds of ionized gas. For instance, the persistent wind of NGC 5548 reaches velocities exceeding 621 miles (approximately 1,000 kilometers) a second. But now a new wind has arisen, much stronger and faster than the persistent wind.
"These new winds reach speeds of up to 3,107 miles (5,000 kilometers) per second, but is much closer to the nucleus than the persistent wind," said lead scientist Jelle Kaastra of the SRON Netherlands Institute for Space Research. "The new gas outflow blocks 90 percent of the low-energy X-rays that come from very close to the black hole, and it obscures up to a third of the region that emits the ultraviolet radiation at a few light-days distance from the black hole."
The newly discovered gas stream in NGC 5548 -- one of the best-studied of the type of galaxy know as Type I Seyfert -- provides the first direct evidence of a shielding process that accelerates the powerful gas streams, or winds, to high speeds. These winds only occur if their starting point is shielded from X-rays.
It appears the shielding in NGC 5548 has been going on for at least three years, but just recently began crossing their line of sight.
"There are other galaxies with similar streams of gas flowing outward from the direction of its central black hole, but we've never before found evidence that the stream of gas changed its position as dramatically as this one has," said Kriss. "This is the first time we've seen a stream like this move into our line of sight. We got lucky."
Researchers also deduced that in more luminous quasars, the winds may be strong enough to blow off gas that otherwise would have become "food" for the black hole, thereby regulating both the growth of the black hole and that of its host galaxy.
These results are being published online in the Thursday issue of Science Express.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. STScI conducts Hubble science operations and is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.
For images and more information about Hubble, visit:
Ray Villard | Eurek Alert!
From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison
Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
24.02.2017 | Earth Sciences
24.02.2017 | Agricultural and Forestry Science
24.02.2017 | Life Sciences