NASA telescopes help solve ancient supernova mystery

ScienceDaily (Oct. 24, 2011) — A mystery that began nearly 2,000 years ago, when Chinese astronomers witnessed what would turn out to be an exploding star in the sky, has been solved. New infrared observations from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer, or WISE, reveal how the first supernova ever recorded occurred and how its shattered remains ultimately spread out to great distances.

The findings show that the stellar explosion took place in a hollowed-out cavity, allowing material expelled by the star to travel much faster and farther than it would have otherwise.

"This supernova remnant got really big, really fast," said Brian J. Williams, an astronomer at North Carolina State University in Raleigh. Williams is lead author of a new study detailing the findings online in the Astrophysical Journal. "It's two to three times bigger than we would expect for a supernova that was witnessed exploding nearly 2,000 years ago. Now, we've been able to finally pinpoint the cause."

A new image of the supernova, known as RCW 86, is online at http://go.nasa.gov/pnv6Oy .

In 185 A.D., Chinese astronomers noted a "guest star" that mysteriously appeared in the sky and stayed for about 8 months. By the 1960s, scientists had determined that the mysterious object was the first documented supernova. Later, they pinpointed RCW 86 as a supernova remnant located about 8,000 light-years away. But a puzzle persisted. The star's spherical remains are larger than expected. If they could be seen in the sky today in infrared light, they'd take up more space than our full moon.

The solution arrived through new infrared observations made with Spitzer and WISE, and previous data from NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory.

The findings reveal that the event is a "Type Ia" supernova, created by the relatively peaceful death of a star like our sun, which then shrank into a dense star called a white dwarf. The white dwarf is thought to have later blown up in a supernova after siphoning matter, or fuel, from a nearby star.

"A white dwarf is like a smoking cinder from a burnt-out fire," Williams said. "If you pour gasoline on it, it will explode."

The observations also show for the first time that a white dwarf can create a cavity around it before blowing up in a Type Ia event. A cavity would explain why the remains of RCW 86 are so big. When the explosion occurred, the ejected material would have traveled unimpeded by gas and dust and spread out quickly.

Spitzer and WISE allowed the team to measure the temperature of the dust making up the RCW 86 remnant at about minus 325 degrees Fahrenheit, or minus 200 degrees Celsius. They then calculated how much gas must be present within the remnant to heat the dust to those temperatures. The results point to a low-density environment for much of the life of the remnant, essentially a cavity.

Scientists initially suspected that RCW 86 was the result of a core-collapse supernova, the most powerful type of stellar blast. They had seen hints of a cavity around the remnant, and, at that time, such cavities were only associated with core-collapse supernovae. In those events, massive stars blow material away from them before they blow up, carving out holes around them.

But other evidence argued against a core-collapse supernova. X-ray data from Chandra and XMM-Newton indicated that the object consisted of high amounts of iron, a telltale sign of a Type Ia blast. Together with the infrared observations, a picture of a Type Ia explosion into a cavity emerged.

"Modern astronomers unveiled one secret of a two-millennia-old cosmic mystery only to reveal another," said Bill Danchi, Spitzer and WISE program scientist at NASA Headquarters in Washington. "Now, with multiple observatories extending our senses in space, we can fully appreciate the remarkable physics behind this star's death throes, yet still be as in awe of the cosmos as the ancient astronomers."

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer .

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Space telescopes reveal secrets of turbulent black hole

ScienceDaily (Sep. 30, 2011) — Supermassive black holes at the hearts of active galaxies swallow large amounts of gas. During this feast they spill a lot of their 'food', which is discharged in turbulent outbursts. An international team of astronomers has revealed some striking features of such an outburst around a supermassive black hole in a distant galaxy. They found a very hot 'convertor' corona hovering above the black hole and cold gas 'bullets' in hotter diffuse gas, speeding outwards with velocities up to 700 km/s.

Unlike popular belief, not all the matter around a black hole is swallowed up. A disc of infalling gas forms around the black hole. On the journey inwards the gas and dust emit large amounts of X-ray and UV radiation. This radiation can be so strong that it diverts a part of the gas inflow. It causes winds flowing outward with velocities up to several hundreds of km/s. An international team of astronomers led by Dr. Jelle Kaastra from the SRON Netherlands Institute for Space Research took the opportunity to observe and map such an extreme environment around one of the brightest supermassive black holes known to us. This 'monster' black hole -- in the distant galaxy Markarian 509 -- has a mass 300 million times that of the Sun.

Convertor corona

The Markarian 509 black hole is surrounded by a disc of gas shining bright in ultraviolet light. This emission varies in a synchronised way with emissions observed at the low end of the X-ray band, some 100s of times higher in energy than visible light. "The only way to explain this is by having gas hotter than that in the disc, a so-called 'corona', hovering above the disc," Jelle Kaastra says. "This corona absorbs and reprocesses the ultraviolet light from the disc, energising it and converting it into X-ray light. It must have a temperature of a few million degrees. Using five space telescopes, which enabled us to observe the area in unprecedented detail, we actually discovered a very hot 'corona' of gas hovering above the disc. This discovery allows us to make sense of some of the observations of active galaxies that have been hard to explain so far."

Cold gas bullets

The X-ray spectrum obtained with the Reflection Grating Spectrometer (RGS) of the space telescope XMM-Newton is the best obtained so far of such a system. It reveals unprecedented details of its gaseous environment. For the first time it has been possible to show that the outflow consists of at least five distinct components with temperatures ranging between 20.000 to a million degrees. The superb ultraviolet spectrum obtained by the Cosmic Origins Spectrograph of the Hubble Space Telescope reveals that the coolest gas in the line of sight towards Markarian 509 has 14 different velocity components at various locations in the innermost parts of this galaxy. Thus far only seven velocity components were identified.

The combined X-ray and UV measurements demonstrate that most of the visible outflowing gas is blown off from a dusty gas torus surrounding the central region more than 15 light years away from the black hole. This outflow consists of dense, cold blobs or gas bullets embedded in hotter diffuse gas. "Even at a distance of 15 light years, the energy released near the black hole manages to blow off gas from the dusty torus that surrounds the disc of infalling gas," Kaastra says.

Signs of cosmic collision

Further outwards, the signatures of the interstellar gas of the host galaxy are seen. That gas is strongly ionised by the central X-ray source: atoms are stripped of some or most of their electrons when illuminated by the powerful flux of X-rays. Even further out, at hundred thousands of light years, the X-ray light shines through gas falling in towards Markarian 509 with speeds of 200 km/s. This gas may point at a collision with a smaller galaxy in the past, that may have triggered the activity of Markarian 509.

Space telescopes

Five large space telescopes were involved in this hundred days campaign that took place in late 2009. The heart of the campaign consisted of repeated visible, X-ray and gamma-ray observations with ESA's XMM-Newton and INTEGRAL satellites, which monitored Markarian 509 for six weeks. This was followed by long observations with NASA's Chandra X-ray satellite, using the Low Energy Transmission Grating, and the NASA/ESA Hubble Space Telescope using the new Cosmic Origins Spectrograph. Prior to these observations short snapshots to monitor the behaviour of the source at all wavelengths were taken with the Swift satellite.

The combined efforts of all these instruments and astronomers gave an unprecedented insight into the core of an active galaxy. Right in the middle of the campaign the source went into outburst. The physical changes due to this outburst could be followed over the electromagnetic spectrum from visible light to X-rays.

Papers

The international consortium responsible for this campaign consists of 26 astronomers from 21 institutes on 4 continents. The first results of this campaign will be published as a series of 7 papers in Astronomy and Astrophysics, titled Multiwavelength campaign on Mrk 509 (see below). More results are in preparation.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by SRON Netherlands Institute for Space Research.

Journal References:

J. S. Kaastra, P.-O. Petrucci, M. Cappi, N. Arav, E. Behar, S. Bianchi, J. Bloom, A. J. Blustin, G. Branduardi-Raymont, E. Costantini, M. Dadina, R. G. Detmers, J. Ebrero, P. G. Jonker, C. Klein, G. A. Kriss, P. Lubinski, J. Malzac, M. Mehdipour, S. Paltani, C. Pinto, G. Ponti, E. M. Ratti, R. A. N. Smith, K. C. Steenbrugge, C. P. de Vries. Multiwavelength campaign on Mrk 509: I. Variability and spectral energy distribution. Astronomy & Astrophysics, 2011; 534: A36 DOI: 10.1051/0004-6361/201116869J. S. Kaastra, C. P. de Vries, K. C. Steenbrugge, R. G. Detmers, J. Ebrero, E. Behar, S. Bianchi, E. Costantini, G. A. Kriss, M. Mehdipour, S. Paltani, P.-O. Petrucci, C. Pinto, G. Ponti. Multiwavelength campaign on Mrk 509: II. Analysis of high-quality Reflection Grating Spectrometer spectra. Astronomy & Astrophysics, 2011; 534: A37 DOI: 10.1051/0004-6361/201116870R. G. Detmers, J. S. Kaastra, K. C. Steenbrugge, J. Ebrero, G. A. Kriss, N. Arav, E. Behar, E. Costantini, G. Branduardi-Raymont, M. Mehdipour, S. Bianchi, M. Cappi, P. Petrucci, G. Ponti, C. Pinto, E. M. Ratti, T. Holczer. Multiwavelength campaign on Mrk 509: III. The 600 ks RGS spectrum: unravelling the inner region of an AGN. Astronomy & Astrophysics, 2011; 534: A38 DOI: 10.1051/0004-6361/201116899M. Mehdipour, G. Branduardi-Raymont, J. S. Kaastra, P. O. Petrucci, G. A. Kriss, G. Ponti, A. J. Blustin, S. Paltani, M. Cappi, R. G. Detmers, K. C. Steenbrugge. Multiwavelength campaign on Mrk 509: IV. Optical-UV-X-ray variability and the nature of the soft X-ray excess. Astronomy & Astrophysics, 2011; 534: A39 DOI: 10.1051/0004-6361/201116875J. Ebrero, G. A. Kriss, J. S. Kaastra, R. G. Detmers, K. C. Steenbrugge, E. Costantini, N. Arav, S. Bianchi, M. Cappi, G. Branduardi-Raymont, M. Mehdipour, P. O. Petrucci, C. Pinto, G. Ponti. Multiwavelength campaign on Mrk 509: V. Chandra-LETGS observation of the ionized absorber. Astronomy & Astrophysics, 2011; 534: A40 DOI: 10.1051/0004-6361/201117067G. A. Kriss, N. Arav, J. S. Kaastra, J. Ebrero, C. Pinto, B. Borguet, D. Edmonds, E. Costantini, K. C. Steenbrugge, R. G. Detmers, E. Behar, S. Bianchi, A. J. Blustin, G. Branduardi-Raymont, M. Cappi, M. Mehdipour, P. Petrucci, G. Ponti. Multiwavelength campaign on Mrk 509: VI. HST/COS observations of the far-ultraviolet spectrum. Astronomy & Astrophysics, 2011; 534: A41 DOI: 10.1051/0004-6361/201117123K. C. Steenbrugge, J. S. Kaastra, R. G. Detmers, J. Ebrero, G. Ponti, E. Costantini, G. A. Kriss, M. Mehdipour, C. Pinto, G. Branduardi-Raymont, E. Behar, N. Arav, M. Cappi, S. Bianchi, P.-O. Petrucci, E. M. Ratti, T. Holczer. Multiwavelength campaign on Mrk 509: VII. Relative abundances of the warm absorber. Astronomy & Astrophysics, 2011; 534: A42 DOI: 10.1051/0004-6361/201117304

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View the original article here

Space telescopes reveal secrets of turbulent black hole

ScienceDaily (Sep. 30, 2011) — Supermassive black holes at the hearts of active galaxies swallow large amounts of gas. During this feast they spill a lot of their 'food', which is discharged in turbulent outbursts. An international team of astronomers has revealed some striking features of such an outburst around a supermassive black hole in a distant galaxy. They found a very hot 'convertor' corona hovering above the black hole and cold gas 'bullets' in hotter diffuse gas, speeding outwards with velocities up to 700 km/s.

Unlike popular belief, not all the matter around a black hole is swallowed up. A disc of infalling gas forms around the black hole. On the journey inwards the gas and dust emit large amounts of X-ray and UV radiation. This radiation can be so strong that it diverts a part of the gas inflow. It causes winds flowing outward with velocities up to several hundreds of km/s. An international team of astronomers led by Dr. Jelle Kaastra from the SRON Netherlands Institute for Space Research took the opportunity to observe and map such an extreme environment around one of the brightest supermassive black holes known to us. This 'monster' black hole -- in the distant galaxy Markarian 509 -- has a mass 300 million times that of the Sun.

Convertor corona

The Markarian 509 black hole is surrounded by a disc of gas shining bright in ultraviolet light. This emission varies in a synchronised way with emissions observed at the low end of the X-ray band, some 100s of times higher in energy than visible light. "The only way to explain this is by having gas hotter than that in the disc, a so-called 'corona', hovering above the disc," Jelle Kaastra says. "This corona absorbs and reprocesses the ultraviolet light from the disc, energising it and converting it into X-ray light. It must have a temperature of a few million degrees. Using five space telescopes, which enabled us to observe the area in unprecedented detail, we actually discovered a very hot 'corona' of gas hovering above the disc. This discovery allows us to make sense of some of the observations of active galaxies that have been hard to explain so far."

Cold gas bullets

The X-ray spectrum obtained with the Reflection Grating Spectrometer (RGS) of the space telescope XMM-Newton is the best obtained so far of such a system. It reveals unprecedented details of its gaseous environment. For the first time it has been possible to show that the outflow consists of at least five distinct components with temperatures ranging between 20.000 to a million degrees. The superb ultraviolet spectrum obtained by the Cosmic Origins Spectrograph of the Hubble Space Telescope reveals that the coolest gas in the line of sight towards Markarian 509 has 14 different velocity components at various locations in the innermost parts of this galaxy. Thus far only seven velocity components were identified.

The combined X-ray and UV measurements demonstrate that most of the visible outflowing gas is blown off from a dusty gas torus surrounding the central region more than 15 light years away from the black hole. This outflow consists of dense, cold blobs or gas bullets embedded in hotter diffuse gas. "Even at a distance of 15 light years, the energy released near the black hole manages to blow off gas from the dusty torus that surrounds the disc of infalling gas," Kaastra says.

Signs of cosmic collision

Further outwards, the signatures of the interstellar gas of the host galaxy are seen. That gas is strongly ionised by the central X-ray source: atoms are stripped of some or most of their electrons when illuminated by the powerful flux of X-rays. Even further out, at hundred thousands of light years, the X-ray light shines through gas falling in towards Markarian 509 with speeds of 200 km/s. This gas may point at a collision with a smaller galaxy in the past, that may have triggered the activity of Markarian 509.

Space telescopes

Five large space telescopes were involved in this hundred days campaign that took place in late 2009. The heart of the campaign consisted of repeated visible, X-ray and gamma-ray observations with ESA's XMM-Newton and INTEGRAL satellites, which monitored Markarian 509 for six weeks. This was followed by long observations with NASA's Chandra X-ray satellite, using the Low Energy Transmission Grating, and the NASA/ESA Hubble Space Telescope using the new Cosmic Origins Spectrograph. Prior to these observations short snapshots to monitor the behaviour of the source at all wavelengths were taken with the Swift satellite.

The combined efforts of all these instruments and astronomers gave an unprecedented insight into the core of an active galaxy. Right in the middle of the campaign the source went into outburst. The physical changes due to this outburst could be followed over the electromagnetic spectrum from visible light to X-rays.

Papers

The international consortium responsible for this campaign consists of 26 astronomers from 21 institutes on 4 continents. The first results of this campaign will be published as a series of 7 papers in Astronomy and Astrophysics, titled Multiwavelength campaign on Mrk 509 (see below). More results are in preparation.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by SRON Netherlands Institute for Space Research.

Journal References:

J. S. Kaastra, P.-O. Petrucci, M. Cappi, N. Arav, E. Behar, S. Bianchi, J. Bloom, A. J. Blustin, G. Branduardi-Raymont, E. Costantini, M. Dadina, R. G. Detmers, J. Ebrero, P. G. Jonker, C. Klein, G. A. Kriss, P. Lubinski, J. Malzac, M. Mehdipour, S. Paltani, C. Pinto, G. Ponti, E. M. Ratti, R. A. N. Smith, K. C. Steenbrugge, C. P. de Vries. Multiwavelength campaign on Mrk 509: I. Variability and spectral energy distribution. Astronomy & Astrophysics, 2011; 534: A36 DOI: 10.1051/0004-6361/201116869J. S. Kaastra, C. P. de Vries, K. C. Steenbrugge, R. G. Detmers, J. Ebrero, E. Behar, S. Bianchi, E. Costantini, G. A. Kriss, M. Mehdipour, S. Paltani, P.-O. Petrucci, C. Pinto, G. Ponti. Multiwavelength campaign on Mrk 509: II. Analysis of high-quality Reflection Grating Spectrometer spectra. Astronomy & Astrophysics, 2011; 534: A37 DOI: 10.1051/0004-6361/201116870R. G. Detmers, J. S. Kaastra, K. C. Steenbrugge, J. Ebrero, G. A. Kriss, N. Arav, E. Behar, E. Costantini, G. Branduardi-Raymont, M. Mehdipour, S. Bianchi, M. Cappi, P. Petrucci, G. Ponti, C. Pinto, E. M. Ratti, T. Holczer. Multiwavelength campaign on Mrk 509: III. The 600 ks RGS spectrum: unravelling the inner region of an AGN. Astronomy & Astrophysics, 2011; 534: A38 DOI: 10.1051/0004-6361/201116899M. Mehdipour, G. Branduardi-Raymont, J. S. Kaastra, P. O. Petrucci, G. A. Kriss, G. Ponti, A. J. Blustin, S. Paltani, M. Cappi, R. G. Detmers, K. C. Steenbrugge. Multiwavelength campaign on Mrk 509: IV. Optical-UV-X-ray variability and the nature of the soft X-ray excess. Astronomy & Astrophysics, 2011; 534: A39 DOI: 10.1051/0004-6361/201116875J. Ebrero, G. A. Kriss, J. S. Kaastra, R. G. Detmers, K. C. Steenbrugge, E. Costantini, N. Arav, S. Bianchi, M. Cappi, G. Branduardi-Raymont, M. Mehdipour, P. O. Petrucci, C. Pinto, G. Ponti. Multiwavelength campaign on Mrk 509: V. Chandra-LETGS observation of the ionized absorber. Astronomy & Astrophysics, 2011; 534: A40 DOI: 10.1051/0004-6361/201117067G. A. Kriss, N. Arav, J. S. Kaastra, J. Ebrero, C. Pinto, B. Borguet, D. Edmonds, E. Costantini, K. C. Steenbrugge, R. G. Detmers, E. Behar, S. Bianchi, A. J. Blustin, G. Branduardi-Raymont, M. Cappi, M. Mehdipour, P. Petrucci, G. Ponti. Multiwavelength campaign on Mrk 509: VI. HST/COS observations of the far-ultraviolet spectrum. Astronomy & Astrophysics, 2011; 534: A41 DOI: 10.1051/0004-6361/201117123K. C. Steenbrugge, J. S. Kaastra, R. G. Detmers, J. Ebrero, G. Ponti, E. Costantini, G. A. Kriss, M. Mehdipour, C. Pinto, G. Branduardi-Raymont, E. Behar, N. Arav, M. Cappi, S. Bianchi, P.-O. Petrucci, E. M. Ratti, T. Holczer. Multiwavelength campaign on Mrk 509: VII. Relative abundances of the warm absorber. Astronomy & Astrophysics, 2011; 534: A42 DOI: 10.1051/0004-6361/201117304

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Radio telescopes capture best-ever snapshot of black hole jets

ScienceDaily (May 20, 2011) — An international team, including NASA-funded researchers, using radio telescopes located throughout the Southern Hemisphere has produced the most detailed image of particle jets erupting from a supermassive black hole in a nearby galaxy.

"These jets arise as infalling matter approaches the black hole, but we don't yet know the details of how they form and maintain themselves," said Cornelia Mueller, the study's lead author and a doctoral student at the University of Erlangen-Nuremberg in Germany.

The new image shows a region less than 4.2 light-years across -- less than the distance between our sun and the nearest star. Radio-emitting features as small as 15 light-days can be seen, making this the highest-resolution view of galactic jets ever made. The study will appear in the June issue of Astronomy and Astrophysics and is available online.

Mueller and her team targeted Centaurus A (Cen A), a nearby galaxy with a supermassive black hole weighing 55 million times the sun's mass. Also known as NGC 5128, Cen A is located about 12 million light-years away in the constellation Centaurus and is one of the first celestial radio sources identified with a galaxy.

Seen in radio waves, Cen A is one of the biggest and brightest objects in the sky, nearly 20 times the apparent size of a full moon. This is because the visible galaxy lies nestled between a pair of giant radio-emitting lobes, each nearly a million light-years long.

These lobes are filled with matter streaming from particle jets near the galaxy's central black hole. Astronomers estimate that matter near the base of these jets races outward at about one-third the speed of light.

Using an intercontinental array of nine radio telescopes, researchers for the TANAMI (Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry) project were able to effectively zoom into the galaxy's innermost realm.

"Advanced computer techniques allow us to combine data from the individual telescopes to yield images with the sharpness of a single giant telescope, one nearly as large as Earth itself," said Roopesh Ojha at NASA's Goddard Space Flight Center in Greenbelt, Md.

The enormous energy output of galaxies like Cen A comes from gas falling toward a black hole weighing millions of times the sun's mass. Through processes not fully understood, some of this infalling matter is ejected in opposing jets at a substantial fraction of the speed of light. Detailed views of the jet's structure will help astronomers determine how they form.

The jets strongly interact with surrounding gas, at times possibly changing a galaxy's rate of star formation. Jets play an important but poorly understood role in the formation and evolution of galaxies.

NASA's Fermi Gamma-ray Space Telescope has detected much higher-energy radiation from Cen A's central region. "This radiation is billions of times more energetic than the radio waves we detect, and exactly where it originates remains a mystery," said Matthias Kadler at the University of Wuerzburg in Germany and a collaborator of Ojha. "With TANAMI, we hope to probe the galaxy's innermost depths to find out."

Ojha is funded through a Fermi investigation on multiwavelength studies of Active Galactic Nuclei.

The astronomers credit continuing improvements in the Australian Long Baseline Array (LBA) with TANAMI's enormously increased image quality and resolution. The project augments the LBA with telescopes in South Africa, Chile and Antarctica to explore the brightest galactic jets in the southern sky.

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the U.S. The Australia Long Baseline Array is part of the Australia Telescope National Facility, which is funded by the Commonwealth of Australia for operation as a National Facility managed by the Commonwealth Scientific and Industrial Research Organization.

For related multimedia, visit: http://svs.gsfc.nasa.gov/goto?10770

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by NASA/Goddard Space Flight Center.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Radio telescopes capture best-ever snapshot of black hole jets

ScienceDaily (May 20, 2011) — An international team, including NASA-funded researchers, using radio telescopes located throughout the Southern Hemisphere has produced the most detailed image of particle jets erupting from a supermassive black hole in a nearby galaxy.

"These jets arise as infalling matter approaches the black hole, but we don't yet know the details of how they form and maintain themselves," said Cornelia Mueller, the study's lead author and a doctoral student at the University of Erlangen-Nuremberg in Germany.

The new image shows a region less than 4.2 light-years across -- less than the distance between our sun and the nearest star. Radio-emitting features as small as 15 light-days can be seen, making this the highest-resolution view of galactic jets ever made. The study will appear in the June issue of Astronomy and Astrophysics and is available online.

Mueller and her team targeted Centaurus A (Cen A), a nearby galaxy with a supermassive black hole weighing 55 million times the sun's mass. Also known as NGC 5128, Cen A is located about 12 million light-years away in the constellation Centaurus and is one of the first celestial radio sources identified with a galaxy.

Seen in radio waves, Cen A is one of the biggest and brightest objects in the sky, nearly 20 times the apparent size of a full moon. This is because the visible galaxy lies nestled between a pair of giant radio-emitting lobes, each nearly a million light-years long.

These lobes are filled with matter streaming from particle jets near the galaxy's central black hole. Astronomers estimate that matter near the base of these jets races outward at about one-third the speed of light.

Using an intercontinental array of nine radio telescopes, researchers for the TANAMI (Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry) project were able to effectively zoom into the galaxy's innermost realm.

"Advanced computer techniques allow us to combine data from the individual telescopes to yield images with the sharpness of a single giant telescope, one nearly as large as Earth itself," said Roopesh Ojha at NASA's Goddard Space Flight Center in Greenbelt, Md.

The enormous energy output of galaxies like Cen A comes from gas falling toward a black hole weighing millions of times the sun's mass. Through processes not fully understood, some of this infalling matter is ejected in opposing jets at a substantial fraction of the speed of light. Detailed views of the jet's structure will help astronomers determine how they form.

The jets strongly interact with surrounding gas, at times possibly changing a galaxy's rate of star formation. Jets play an important but poorly understood role in the formation and evolution of galaxies.

NASA's Fermi Gamma-ray Space Telescope has detected much higher-energy radiation from Cen A's central region. "This radiation is billions of times more energetic than the radio waves we detect, and exactly where it originates remains a mystery," said Matthias Kadler at the University of Wuerzburg in Germany and a collaborator of Ojha. "With TANAMI, we hope to probe the galaxy's innermost depths to find out."

Ojha is funded through a Fermi investigation on multiwavelength studies of Active Galactic Nuclei.

The astronomers credit continuing improvements in the Australian Long Baseline Array (LBA) with TANAMI's enormously increased image quality and resolution. The project augments the LBA with telescopes in South Africa, Chile and Antarctica to explore the brightest galactic jets in the southern sky.

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the U.S. The Australia Long Baseline Array is part of the Australia Telescope National Facility, which is funded by the Commonwealth of Australia for operation as a National Facility managed by the Commonwealth Scientific and Industrial Research Organization.

For related multimedia, visit: http://svs.gsfc.nasa.gov/goto?10770

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by NASA/Goddard Space Flight Center.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here