CDF-S Transient: Mysterious Cosmic Explosion Puzzles Astronomers

 

 CDF-S XT1

Credit X-ray: NASA/CXC/Universidad Católica de Chile/F.Bauer et al.

JPEG (274.8 kb) - Large JPEG (1.3 MB) - Tiff (5.6 MB) - More Images

 

 CDF-S Transient - Video 

Tour of CDF-S XT1
 

More Animations

Scientists have discovered a mysterious flash of X-rays using NASA's Chandra X-ray Observatory, in the deepest X-ray image ever obtained, as reported in our latest press release. The X-ray source is located in a region of the sky known as the Chandra Deep Field-South (CDF-S), which is shown in the main panel of this graphic. Over the 17 years Chandra has been operating, the telescope has observed this field many times, resulting in a total exposure time of 7 million seconds, equal to two and a half months. In this CDF-S image, the colors represent different bands of X-ray energy, where red, green, and blue show the low, medium, and high-energy X-rays that Chandra can detect.

The mysterious source that scientists discovered, shown in the inset box, has remarkable properties. 

Prior to October 2014, this source was not detected in X-rays, but then it erupted and became at least a factor of 1,000 brighter in a few hours. After about a day, the source had faded completely below the sensitivity of Chandra.

Thousands of hours of legacy data from the Hubble and Spitzer Space Telescopes helped determine that the event came from a faint, small galaxy about 10.7 billion light years from Earth. For a few minutes, the X-ray source produced a thousand times more energy than all the stars in this galaxy.

While scientists think this source likely comes from some sort of destructive event, its properties do not match any known phenomenon. This means this source may be of a variety that scientists have never seen before.

The researchers do, however, have some ideas of what this source could be. Two of the three main possibilities to explain the X-ray source invoke gamma-ray burst (GRB) events, which are jetted explosions triggered either by the collapse of a massive star or by the merger of a neutron star with another neutron star or a black hole. If the jet is pointing towards the Earth, a burst of gamma-rays is detected. As the jet expands, it loses energy and produces weaker, more isotropic radiation at X-ray and other wavelengths.

Possible explanations for the CDF-S X-ray source, according to the researchers, are a GRB that is not pointed toward Earth, or a GRB that lies beyond the small galaxy. A third possibility is that a medium-sized black hole shredded a white dwarf star.

Thousands of hours of legacy data from the Hubble and Spitzer Space Telescopes helped determine that the event came from a faint, small galaxy about 10.7 billion light years from Earth. For a few minutes, the X-ray source produced a thousand times more energy than all the stars in this galaxy.

The mysterious X-ray source was not seen at any other time during the two and a half months of exposure time Chandra has observed the CDF-S region. Moreover, no similar events have yet been found in Chandra observations of other parts of the sky.

This X-ray source in the CDF-S has different properties from the as yet unexplained variable X-ray sources discovered in the elliptical galaxies NGC 5128 and NGC 4636 by Jimmy Irwin and collaborators. In particular, the CDF-S source is likely associated with the complete destruction of a neutron star or white dwarf, and is roughly 100,000 times more luminous in X-rays. It is also located in a much smaller and younger host galaxy, and is only detected during a single, several-hour burst.

Additional highly targeted searches through the Chandra archive and those of ESA's XMM-Newton and NASA's Swift satellite may uncover more examples of this type of variable object that have until now gone unnoticed. Future X-ray observations by Chandra and other X-ray telescopes may also reveal the same phenomenon from other objects.

A paper describing this result appears in the June 2017 issue of the Monthly Notices of the Royal Astronomical Society and is available online. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations. 

Fast Facts for CDF-S Transient:

Scale: Main Image is 16 arcmin across; Inset Image is 3.7 arcsec across
Category: Cosmology/Deep Fields/X-ray Background, Black Holes
Coordinates (J2000): RA 03h 32m 39s | Dec -27° 51' 34"
Constellation: Fornax
Observation Date: Inset Image: October 2, 2014
Observation Time: Inset Image: 26 hours 7 minutes.
Obs. ID: Inset Image: 16454
Instrument: ACIS
References: Bauer, F. et al., 2017, MNRAS (in press); arXiv:1702.04422
Color Code: Inset Image: X-ray (Blue)
Distance Estimate: About 10.7 billion light years

Source: NASA’s Chandra X-ray Observatory

NGC 5128: Mysterious Cosmic Objects Erupting in X-rays Discovered

http://chandra.harvard.edu/photo/2016/ngc5128/

NGC 5128

Credit: NASA/CXC/UA/J.Irwin et al.  

 JPEG (929.8 kb) - Large JPEG (10.9 MB) - Tiff (96.3 MB) - More Images

A Tour of IC 2497

---

This image shows the location of a remarkable source that dramatically flares in X-rays unlike any ever seen. Along with another similar source found in a different galaxy, these objects may represent an entirely new phenomenon, as reported in our latest press release [link to PR].

These two objects were both found in elliptical galaxies, NGC 5128 (also known as Centaurus A) shown here and NGC 4636. In this Chandra X-ray Observatory image of NGC 5128, low, medium, and high-energy X-rays are colored red, green, and blue, and the location of the flaring source is outlined in the box to the lower left.

Both of these mysterious sources flare dramatically - becoming a hundred times brighter in X-rays in about a minute before steadily returning to their original X-ray levels about an hour later. At their X-ray peak, these objects qualify as ultraluminous X-ray sources (ULXs) that give off hundreds to thousands of times more X-rays than typical X-ray binary systems where a star is orbiting a black hole or neutron star.

Five flares were detected from the source located near NGC 5128, which is at a distance of about 12 million light years from Earth. A movie showing the average change in X-rays for the three flares with the most complete Chandra data, covering both the rise and fall, is shown in the inset.

The source associated with the elliptical galaxy NGC 4636, which is located about 47 million light years away, was observed to flare once.

The only other objects known to have such rapid, bright, repeated flares involve young neutron stars such as magnetars, which have extremely powerful magnetic fields. However, these newly flaring sources are found in populations of much older stars. Unlike magnetars, the new flaring sources are likely located in dense stellar environments, one in a globular cluster and the other in a small, compact galaxy.

When they are not flaring, these newly discovered sources appear to be normal binary systems where a black hole or neutron star is pulling material from a companion star similar to the Sun. This indicates that the flares do not significantly disrupt the binary system.

While the nature of these flares is unknown, the team has begun to search for answers. One idea is that the flares represent episodes when matter pulled away from a companion star falls rapidly onto a black hole or neutron star. This could happen when the companion makes its closest approach to the compact object in an eccentric orbit. Another explanation could involve matter falling onto an intermediate-mass black hole, with a mass of about 800 times that of the Sun for one source and 80 times that of the Sun for the other.

This result is describing in a paper appearing in the journal Nature on October 20, 2016. The authors are Jimmy Irwin (University of Alabama), Peter Maksym (Harvard-Smithsonian Center for Astrophysics), Gregory Sivakoff (University of Alberta), Aaron Romanowsky (San Jose State University), Dacheng Lin (University of New Hampshire), Tyler Speegle, Ian Prado, David Mildebrath (University of Alabama), Jay Strader (Michigan State University), Jifeng Lui (Chinese Academy of Sciences), and Jon Miller (University of Michigan).

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

---

Fast Facts for NGC 5128:

Scale: Main image is 16.7 arcmin across (about 58,000 light years); Inset image is 1 arcmin across (about 3,500 light years)
Category: Quasars & Active Galaxies
Coordinates (J2000): RA 13h 25m 52.7s | Dec -43° 05' 46.00"
Constellation: Centaurus
Observation Date: 21 pointings between 05 Dec 1999 and 29 Aug 2012
Observation Time: 229 hours 57 min (9 days 13 hours 57 min).
Obs. ID: 316, 962, 2978, 3965, 7797-7799, 7800, 8489, 8490, 10722, 10723, 10724-10726, 11846, 11847, 12155, 12156, 13303, 13304
Instrument: ACIS
Also Known As: Centaurus A, Cen A
References: Irwin, J. et al, 2016, Nature (in press)
Color Code: X-ray (Red, Green, Blue)
Distance Estimate: 12 million light years

Source: NASA’s Chandra X-ray Observatory

The Dark Side of Star Clusters

PR Image eso1519a

The giant elliptical galaxy Centaurus A (NGC 5128) and its strange globular clusters

PR Image eso1519b

The strange galaxy Centaurus A in the constellation of Centaurus 

PR Image eso1519c

Wide-field view of the giant galaxy Centaurus A

 Videos

PR Video eso1519a

Panning across the giant elliptical galaxy Centaurus A (NGC 5128) and its strange globular clusters 

---

VLT discovers new kind of globular star cluster

Observations with ESO’s Very Large Telescope in Chile have discovered a new class of “dark” globular star clusters around the giant galaxy Centaurus A. These mysterious objects look similar to normal clusters, but contain much more mass and may either harbour unexpected amounts of dark matter, or contain massive black holes — neither of which was expected nor is understood.

Globular star clusters are huge balls of thousands of stars that orbit most galaxies. They are among the oldest known stellar systems in the Universe and have survived through almost the entire span of galaxy growth and evolution.

Matt Taylor, a PhD student at the Pontificia Universidad Catolica de Chile, Santiago, Chile, and holder of an ESO Studentship, is lead author of the new study. He sets the scene: “Globular clusters and their constituent stars are keys to understanding the formation and evolution of galaxies. For decades, astronomers thought that the stars that made up a given globular cluster all shared the same ages and chemical compositions — but we now know that they are stranger and more complicated creatures.”

The elliptical galaxy Centaurus A (also known as NGC 5128) is the closest giant galaxy to the Milky Way and is suspected to harbour as many as 2000 globular clusters. Many of these globulars are brighter and more massive than the 150 or so orbiting the Milky Way.

Matt Taylor and his team have now made the most detailed studies so far of a sample of 125 globular star clusters around Centaurus A using the FLAMES instrument on ESO’s Very Large Telescope at the Paranal Observatory in northern Chile [1].

They used these observations to deduce the mass of the clusters [2] and compare this result with how brightly each of the clusters shines.

For most of the clusters in the new survey, the brighter ones had more mass in the way that was expected — if a cluster contains more stars it has greater total brightness and more total mass. But for some of the globulars something strange showed up: they were many times more massive than they looked. And even more strangely, the more massive these unusual clusters were, the greater the fraction of their material was dark. Something in these clusters was dark, hidden and massive. But what?

There were several possibilities. Perhaps the dark clusters contain black holes, or other dark stellar remnants in their cores? This may be a factor that explains some of the hidden mass, but the team concludes that it cannot be the whole story. What about dark matter? Globular clusters are normally considered to be almost devoid of this mysterious substance, but perhaps, for some unknown reason, some clusters have retained significant dark matter clumps in their cores. This would explain the observations but does not fit into conventional theory.

Co-author Thomas Puzia adds: “Our discovery of star clusters with unexpectedly high masses for the amount of stars they contain hints that there might be multiple families of globular clusters, with differing formation histories. Apparently some star clusters look like, walk like, and smell like run-of-the-mill globulars, but there may quite literally be more to them than meets the eye.”

These objects remain a mystery. The team is also engaged in a wider survey of other globular clusters in other galaxies and there are some intriguing hints that such dark clusters may also be found elsewhere.

Matt Taylor sums up the situation: “We have stumbled on a new and mysterious class of star cluster! This shows that we still have much to learn about all aspects of globular cluster formation. It’s an important result and we now need to find further examples of dark clusters around other galaxies.”

Notes

[1] Up to now astronomers have studied star clusters to this detail only in the Local Group. The relatively small distances make direct measurements of their masses possible. Looking at NGC 5128, which is an isolated, massive elliptical galaxy just outside the Local Group about 12 million light-years away, they were able to estimate masses of globular clusters in a completely different environment by pushing VLT/FLAMES to its limits.

[2] The FLAMES observations provide information about the motions of the stars in the clusters. This orbital information depends on the strength of the gravitational field and can hence be used to deduce the mass of the cluster — astronomers call such estimates dynamical masses. The light gathering power of a 8.2-metre VLT Unit Telescope mirror and FLAMES’s ability to observe more than 100 clusters simultaneously was the key to collecting the data necessary for the study.

More Information

This research was presented in a paper entitled “Observational evidence for a dark side to NGC 5128’s globular cluster system”, by M. Taylor et al., to appear in the Astrophysical Journal.

The team is composed of Matthew A. Taylor (Pontificia Universidad Catolica de Chile, Santiago, Chile; ESO, Santiago, Chile), Thomas H. Puzia (Pontificia Universidad Catolica de Chile), Matias Gomez (Universidad Andres Bello, Santiago, Chile) and Kristin A. Woodley (University of California, Santa Cruz, California, USA).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links

• Science paper
• Images of the VLT

Contact

Matthew A. Taylor
Pontificia Universidad Catolica de Chile
Santiago, Chile
Tel: +56-9-91912386
Email: mataylor5128@gmail.com

Thomas H. Puzia
Pontificia Universidad Catolica de Chile
Santiago, Chile
Tel: +56-9-89010007
Email: tpuzia@gmail.com

Richard Hook
ESO, Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org

Source: ESO

Hubble traces the halo of a galaxy more accurately than ever before

PR Image heic1415a

Centaurus A halo

PR Image heic1415b

Centaurus A halo annotated

PR Image heic1415c

Area of Centaurus A halo probed by Hubble

PR Image heic1415d

Area of Centaurus A halo probed by Hubble

An in-depth look at the giant elliptical galaxy Centaurus A

Astronomers using the NASA/ESA Hubble Space Telescope have probed the extreme outskirts of the stunning elliptical galaxy Centaurus A. The galaxy’s halo of stars has been found to extend much further from the galaxy’s centre than expected and the stars within this halo seem to be surprisingly rich in heavy elements. This is the most remote portion of an elliptical galaxy ever to have been explored.

There is more to a galaxy than first meets the eye. Extending far beyond the bright glow of a galaxy's centre, the swirling spiral arms, or the elliptical fuzz, is an extra component: a dim halo of stars sprawling into space.

These expansive haloes are important components of a galaxy. The halo of our own galaxy, the Milky Way, preserves signatures of both its formation and evolution. Yet, we know very little about the haloes of galaxies beyond our own as their faint and spread-out nature makes exploring them more difficult. Astronomers have so far managed to detect very few starry haloes around other galaxies.

Now, by utilising the unique space-based location of the NASA/ESA Hubble Space Telescope and its sensitive Advanced Camera for Surveys and Wide Field Camera 3, a team of astronomers has probed the halo surrounding the prominent giant elliptical galaxy Centaurus A [1], also known as NGC 5128, to unprecedented distances. They have found that its halo spreads far further into space than expected and does so in an unexpected form.

"Tracing this much of a galaxy's halo gives us surprising insights into a galaxy's formation, evolution, and composition," says Marina Rejkuba of the European Southern Observatory in Garching, Germany, lead author of the new Hubble study. "We found more stars scattered in one direction than the other, giving the halo a lopsided shape — which we hadn't expected!" 

Along the galaxy's length the astronomers probed out 25 times further than the galaxy's radius — mapping a region some 450 000 light-years across. For the width they explored along 295 000 light-years, 16 times further than its "effective radius" [2]. These are large distances if you consider that the main visible component of the Milky Way is around 120 000 light-years in diameter. In fact, the diameter of the halo probed by this team extends across 4 degrees in the sky — equivalent to eight times the apparent width of the Moon.

Alongside their unexpected uneven distribution, the stars within the halo also showed surprising properties relating to the proportion of elements heavier than hydrogen and helium found in the gas that makes up the stars. While the stars within the haloes of the Milky Way and other nearby spirals are generally low in heavy elements, the stars within Centaurus A's halo appear to be rich in heavy elements, even at the outermost locations explored.

"Even at these extreme distances, we still haven't reached the edge of Centaurus A's halo, nor have we detected the very oldest generation of stars," adds co-author Laura Greggio of INAF, Italy. "This aged generation is very important. The larger stars from it are responsible for manufacturing the heavy elements now found in the bulk of the galaxy's stars. And even though the large stars are long dead, the smaller stars of the generation still live on and could tell us a great deal."

The small quantity of heavy elements in the stellar haloes of large spiral galaxies like the Milky Way, is thought to originate from the way that the galaxies formed and evolved, slowly pulling in numerous small satellite galaxies and taking on their stars. For Centaurus A, the presence of stars rich in heavy elements in such remote locations suggests a single past merger with a large spiral galaxy. This event would have ejected stars from the spiral galaxy's disc and these are now seen as part of Centaurus A's outer halo.

"Measuring the amount of heavy elements in individual stars in a giant elliptical galaxy such as Centaurus A is uniquely the province of Hubble — we couldn't do it with any other telescope, and certainly not yet from the ground," adds Rejkuba. "These kinds of observations are fundamentally important to understanding the galaxies in the Universe around us."

These results are being published online in Astrophysical Journal on the 22 July and will appear in the 10 August 2014 issue.

Notes

[1] As it is relatively near to Earth, Centaurus A is prominent in our night sky and is well known for its striking and beautiful appearance (heic1110, opo9814e). To see more about this galaxy, see Hubblecast 46: A tour of Centaurus A.

[2] The effective radius of a galaxy, as referenced here, is the radius of the area in which half of the galaxy’s light is emitted. Astronomers use this effective radius rather than the full radius because the galaxy becomes faint and undefined at its outskirts.

Notes for editors

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The international team of astronomers in this study consists of M. Rejkuba (European Southern Observatory, Germany; Excellence Cluster Universe, Germany), W. E. Harris (McMaster University, Canada), L. Greggio (INAF, Italy), G. L. H. Harris (University of Waterloo, Canada), H. Jerjen (Australian National University, Australia), O. A. Gonzalez (European Southern Observatory, Chile).

More information

Image credit: NASA, ESA & M. Rejkuba (European Southern Observatory)

Links

• Images of Hubble
• More on Centaurus A: heic1110, opo9814e and Hubblecast 46: A tour of Centaurus A.
• Research paper online in Astrophysical Journal.

Contacts

Marina Rejkuba
European Southern Observatory
Garching bei München, Germany
Tel: +49 89 3200 6453
Email: mrejkuba@eso.org

Laura Greggio
INAF, Osservatorio Astronomico di Padova
Padova, Italy
Tel: +39 049 8293463
Cell: +39 347 73189089
Email: laura.greggio@oapd.inaf.it

Georgia Bladon
ESA/Hubble, Public Information Officer
Garching bei München, Germany
Cell: +44 7816291261
Email: gbladon@partner.eso.org

Source:  ESA/HUBBLE - Space Telescope

A Deeper Look at Centaurus A

PR Image eso1221a
A deep look at the strange galaxy Centaurus A

PR Image eso1221b
The strange galaxy Centaurus A in the constellation of Centaurus

Videos

PR Video eso1221a

Zooming in on the strange galaxy Centaurus A

PR Video eso1221b

Panning over a deep view at the strange galaxy Centaurus A

The strange galaxy Centaurus A is pictured in a new image from the European Southern Observatory. With a total exposure time of more than 50 hours this is probably the deepest view of this peculiar and spectacular object ever created. The image was produced by the Wide Field Imager of the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile.

Centaurus A, also known as NGC 5128 [1], is a peculiar massive elliptical galaxy with a supermassive black hole at its heart. It lies about 12 million light-years away in the southern constellation of Centaurus (The Centaur) and has the distinction of being the most prominent radio galaxy in the sky. Astronomers think that the bright nucleus, strong radio emission and jet features of Centaurus A are produced by a central black hole with a mass of about 100 million times that of the Sun. Matter from the dense central parts of the galaxy releases vast amounts of energy as it falls towards the black hole.

This Wide Field Imager (WFI) picture allows us to appreciate the galaxy’s elliptical nature, which shows up as the elongated shape of the fainter outer parts. The glow that fills much of the picture comes from hundreds of billions of cooler and older stars. Unlike most elliptical galaxies, however, Centaurus A’s smooth shape is disturbed by a broad and patchy band of dark material that obscures the galaxy’s centre.

The dark band harbours large amounts of gas, dust and young stars. Bright young star clusters appear at the upper-right and lower-left edges of the band along with the red glow of star-forming clouds of hydrogen, whilst some isolated dust clouds are silhouetted against the stellar background. These features, and the prominent radio emission, are strong evidence that Centaurus A is the result of a merger between two galaxies. The dusty band is probably the mangled remains of a spiral galaxy in the process of being ripped apart by the gravitational pull of the giant elliptical galaxy.

The new set of images from WFI include long exposures through red, green and blue filters as well as filters specially designed to isolate the light from glowing hydrogen and oxygen. The latter help us to spot the known optical jet features around Centaurus A, which were barely visible in a previous image from the Wide Field Imager (eso0315a).

Extending from the galaxy to the upper left corner of the image are two groups of reddish filaments, which are roughly lined up with the huge jets that are prominent in radio images. Both sets of filaments are stellar nurseries, containing hot young stars [2]. Above the left side of the dusty band, we find the inner filaments, lying about 30 000 light-years away of the nucleus. Further out, around 65 000 light-years away from the galaxy’s nucleus and close to the upper left corner of the image, the outer filaments are visible. There is also possibly a very much fainter trace of a counter jet extending to the lower right.

Centaurus A has been extensively studied at wavelengths ranging from radio all the way to gamma-rays. In particular, radio and X-ray observations have been crucial for studying the interaction between the energetic output of the central supermassive black hole and its surroundings, see eso0903. Studies of Centaurus A with ALMA are just beginning.

Many of the observations of Centaurus A used to make this image were taken to see whether it was possible to use ground-based surveys to detect and study variable stars in galaxies like Centaurus A outside the local group [3]. More than 200 new variable stars in Centaurus A were discovered.

Notes

[1] The galaxy was first documented by British astronomer James Dunlop at the Parramatta observatory in Australia on August 4, 1826. This galaxy is often called Centaurus A because was the first major source of radio waves discovered in the constellation of Centaurus back in the 1950s.

[2] The origin of both filaments is not clear and astronomers still debate whether they are the result of the ionisation produced by radiation from the nucleus or the result of shocks within the gas clumps.

[3] More information is presented in the paper by J.T.A. de Jong et al. 2008.

More information

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links
Photos of the MPG/ESO 2.2-metre Telescope
Other photos taken with the MPG/ESO 2.2-metre Telescope
Photos of La Silla

Contacts

Richard Hook
ESO, La Silla, Paranal, E-ELT and Survey Telescopes Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 15 37 35 91
Email: rhook@eso.org

Spectacular Hubble View of Centaurus A

PR Image heic1110a

Spectacular Hubble view of Centaurus A

PR Video heic1110a
Hubblecast 46: A tour of Centaurus A

PR Video heic1110b
Pan across Centaurus A

The NASA/ESA Hubble Space Telescope has produced a close-up view of the galaxy Centaurus A. Hubble’s out-of-this-world location and world-class Wide Field Camera 3 instrument reveal a dramatic picture of a dynamic galaxy in flux.

Centaurus A, also known as NGC 5128, is well known for its dramatic dusty lanes of dark material. Hubble’s observations, using its most advanced instrument, the Wide Field Camera 3, are the most detailed ever made of this galaxy. They have been combined here in a multi-wavelength image that reveals never-before-seen detail in the dusty portion of the galaxy.

As well as features in the visible spectrum, this composite shows ultraviolet light from young stars, and near-infrared light, which lets us glimpse some of the detail otherwise obscured by the dust.

The dark dust lane that crosses Centaurus A does not show an absence of stars, but rather a relative lack of starlight, as the opaque clouds block the visible light from reaching us. Hubble’s Wide Field Camera 3 has focussed on these dusty regions, which span from corner to corner in this image. Wider views from ground-based telescopes show this stripe crossing the entire galaxy.

Interesting features such as the warped shape of its disc of gas and dust (outside the view) hint that at some point in the past, Centaurus A collided and merged with another galaxy. The shockwaves of this event caused hydrogen gas to coalesce and sparked intense areas of star formation, as seen in its outlying regions and in red patches visible in this Hubble close-up.

The galaxy’s compact nucleus contains a highly active supermassive black hole at its centre. Powerful relativistic jets release vast amounts of radio and X-ray radiation — although these are invisible here as Hubble’s instruments are designed to study optical, ultraviolet and infrared wavelengths.

At just over 11 million light-years distant, Centaurus A is relatively nearby in astronomical terms. However, it is not only close, it is also bright. This makes it a very attractive target for amateur astronomers in the southern hemisphere, where it is visible. Stargazers can see the galaxy through binoculars, while larger amateur telescopes begin to unveil the distinctive dusty lanes.

However it is only with the capabilities of the Hubble Space Telescope that many of the features in this image become visible: as well as providing unparalleled clarity and resolution, Hubble’s position in orbit means that it can see ultraviolet wavelengths which are blocked by the atmosphere and so invisible from the ground.
Notes

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Image credit: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration. Acknowledgment: R. O’Connell (University of Virginia) and the WFC3 Scientific Oversight Committee

Links
Images of Hubble
Wide-field image of Centaurus A from the European Southern Observatory
NASA press release

Contacts
Oli Usher
Hubble/ESA Garching, Germany
Tel: +49-89-3200-6855
Email: ousher@eso.org

Radio Telescopes Capture Best-Ever Snapshot of Black Hole Jets

Centaurus A is a giant elliptical active galaxy 12 million light-years away. At its heart lies a black hole with a mass of 55 million suns. Now, the TANAMI project has provided the best-ever image of particle jets powered by the black hole, revealing features as small as 15 light-days across. The jets feed vast lobes of radio-emitting gas that reach far beyond the visible galaxy.

Merging X-ray data (blue) from NASA’s Chandra X-ray Observatory with microwave (orange) and visible images reveals the jets and radio-emitting lobes emanating from Centaurus A's central black hole. Credit: ESO/WFI (visible); MPIfR/ESO/APEX/A.Weiss et al. (microwave); NASA/CXC/CfA/R.Kraft et al. (X-ray) . Larger image

Left: The giant elliptical galaxy NGC 5128 is the radio source known as Centaurus A. Vast radio-emitting lobes (shown as orange in this optical/radio composite) extend nearly a million light-years from the galaxy. Credit: Capella Observatory (optical), with radio data from Ilana Feain, Tim Cornwell, and Ron Ekers (CSIRO/ATNF), R. Morganti (ASTRON), and N. Junkes (MPIfR). Right: The radio image from the TANAMI project provides the sharpest-ever view of a supermassive black hole's jets. This view reveals the inner 4.16 light-years of the jet and counterjet, a span less than the distance between our sun and the nearest star. The image resolves details as small as 15 light-days across. Undetected between the jets is the galaxy's 55-million-solar-mass black hole. Credit: NASA/TANAMI/Müller et al. Larger image | Larger image with captions

The elliptical galaxy NGC 5128, host of the Centaurus A radio source, as it appears in visible light. The galaxy is located about 12 million light-years away and is one of the closest that sports an active supermassive black hole. Credit: Capella Observatory. Larger image

The TANAMI array consists of nine radio telescopes located on four continents. By combining data from the individual telescopes, astronomers can acquire images with the sharpness of a single telescope some 6,200 miles (10,000 km) across -- about 80 percent of Earth's diameter. Credit: Matthias Kadler (Univ. of Würzburg) and J. Wilms (Univ. of Erlangen-Nuremberg). Larger image

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

Francis Reddy
NASA's Goddard Space Flight Center, Greenbelt, Md.