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Highlights in X-ray Astronomy

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artist's conception

Artist's conception of a black hole ejected from a galaxy

Image Credit: Illustration: MPE, optical image: HST

Superkick: Black hole expelled from its parent galaxy

Gravitational rocket propelled the monster at a speed of thousands of kilometres per second

By an enormous burst of gravitational waves that accompanies the merger of two black holes the newly formed black hole was ejected from its galaxy. This extreme ejection event, which had been predicted by theorists, has now been observed in nature for the first time. The team led by Stefanie Komossa from the Max Planck Institute for extraterrestrial Physics (MPE) thereby opened a new window into observational astrophysics. The discovery will have far-reaching consequences for our understanding of galaxy formation and evolution in the early Universe, and also provides observational confirmation of a key prediction from the General Theory of Relativity.

internal link MPE press release

Original paper:
external link ApJ Letters, 678, L81, 2008
external link preprint in astro-ph: 0804.4585
(April 29, 2008)
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light echo

The artistic view shows the light echo of a high-energy flash from a black hole

Credit: MPE/ESA

Black hole sheds light on a galaxy

Light echo of a high-energy flash from a black hole first observed in detail

For the first time, the light echo of a stellar tidal disruption could be observed in great detail. In doing so, an international team led by Stefanie Komossa from the MPE noticed the strongest iron emission ever observed in a galaxy and interpreted it as an evidence for a molecular torus. The light echo not only revealed the stellar disruption process, but it also provides a powerful new method for mapping galactic nuclei.

internal link MPE press release

Original paper:
external link ApJ Letters, 678, L13, 2008
external link Preprint: arXiv:0804.2670v1 [astro-ph]
(April 17, 2008)
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X-ray Binary

The artistic view shows a cataclysmic variable, the kind of close binary systems that host classical novae

Credit: Mark A. Garlick

Turbulent Disk

Asymmetric accretion disk causes X-ray flux variations in bright supersoft nova

A team led by Gloria Sala from the Max Planck Institute for extraterrestrial Physics has studied the Nova V5116 Sagittarii with the ESA X-ray observatory XMM-Newton and found abrupt decreases and increases of the flux, but an unchanged white dwarf atmosphere temperature both in the low- and the high-flux periods. A partial eclipse caused by an asymmetric accretion disk might explain the results.

internal link MPE press release
external link ESA news release

Original paper:
external link Astrophys. Journ. Letters, 675, L93 - L96, 2008
(April 3, 2008)
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On the trace of a supernova progenitor: the image shows a strong X-ray source detected by the Chandra observatory four years ago. The source is at the position of the Type Ia supernova SN 2007on.

Image: Chandra / Rasmus Voss, MPE

Possible Progenitor of Special Supernova Type Detected

Using data from NASA's Chandra X-ray Observatory, scientists have reported the possible detection of a binary star system that was later destroyed in a supernova explosion. The new method they used provides great future promise for finding the detailed origin of these important cosmic events.
In an article appearing in the February 14th issue of the journal Nature, Rasmus Voss of the MPE and Gijs Nelemans of Radboud University searched Chandra images for evidence of a much sought after, but as yet unobserved binary system - one that was about to go supernova. Near the position of a recently detected supernova, they discovered an object in Chandra images taken more than four years before the explosion. The supernova, known as SN 2007on, was identified as a Type Ia supernova. Astronomers generally agree that Type Ia supernovas are produced by the explosion of a white dwarf star in a binary star system. However, the exact configuration and trigger for the explosion is unclear.

external link MPG Press Release (in German language)
external link Chandra Press release
NASA / Chandra press release
Original Publication:
external link Nature 451, 802 - 804 (2008)
More articles:
external link Welt der Physik (in German language)
(February 13, 2008)
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The massive stellar black hole in M 33.

Picture: Pietsch, MPE

Most massive stellar black hole found

MPE members were actively involved in the detection of an exceptionally massive black hole. This result has intriguing implications for the evolution and ultimate fate of massive stars. The black hole is part of a binary system in M 33. By combining data from NASA's Chandra X-ray Observatory and the Gemini telescope on Mauna Kea, Hawaii, the mass of the black hole, was determined to be 15.7 times that of the Sun.

exteral link MPG press release
(in German language)
external link Chandra press release

Original publication:
external link Nature 449, 872-875 (2007)

(October 18, 2007)
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2XMM logo

Logo of the new catalogue

Image: ESA

XMM-Newton releases the largest catalogue of X-ray sources

The largest catalogue of X-ray sources ever made has now been released. The catalogue, '2XMM', has been compiled from observations carried out with ESA's XMM-Newton space observatory over 6 years of operation.
The 2XMM Serendipitous EPIC Source Catalogue is the result of several years of development by the XMM-Newton Survey Science Centre (SSC), a consortium of European institutes including the MPE.

external link ESA press release
external link MPG press information   (in German)
link Information on XMM-Newton at MPE
external link Web page of the new catalogue "2XMM"

external link Web page of the previous catalogue "1XMM"
(September 7, 2007)
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M 31

Optical M 31 H-alpha image overplotted with contours from Chandra observations. The positions of 17 counterparts of optical novae detected in these images are indicated with circles and nova names.

Credits: W. Pietsch (MPE Garching, Germany), P. Massey (Lowell Observatory, USA), NASA/Chandra

X-rays provide a new way to investigate exploding stars

Using the X-ray observatories XMM-Newton (ESA) and Chandra (NASA) as well as optical monitoring observations, astronomers from the MPE have identified a new class of exploding stars where the X-ray emission "lives fast and dies young".

The identification of this particular class of explosions gives astronomers a valuable new constraint to help them model and understand stellar explosions.

link Special web page at MPE:
Optical Novae as X-ray Sources
exteral link Original paper:
Astronomy & Astrophysics, 465, 2007, pp.375-392
exteral link ESA Press Release
exteral link Chandra Press Release

(May 09, 2007)
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Artists concept of eRosita

Picture: MPE

eRosita Approved - The Search for Dark Energy Can Start

The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt (DLR)) has approved funding (21 million Euro) to build the eROSITA X-ray telescope for a launch in 2011. ROSKOSMOS and DLR signed a memorandum of understanding for the cooperation for this project.

exteral link MPG Press Release (in German Language)
interal link eRosita pages at MPE

(March 30, 2007)
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XMM: SN 1987A

Recent XMM-Newton view of supernova SN 1987A

Image: ESA

XMM-Newton's anniversary view of supernova SN 1987A

The supernova SN 1987A in the Large Magellanic Cloud is the nearest supernova detected since the invention of the telescope. Almost 20 years after its discovery on 23 February 1987, XMM-Newton observed the stellar remnant in X-rays on 17 January 2007. Continuously brightening since the first detection in X-rays by ROSAT in 1992, it now outshines all other X-ray sources in its immediate neighbourhood and it is more than ten times brighter as compared to the first-light observations of XMM-Newton in January 2000.

Frank Haberl of MPE is XMM-Newton's EPIC Principal Investigator.

external link ESA press release

(February 24, 2007)
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Distribution of the Dark Matter as revealed by the Hubble Space Telescope

Image: NASA, ESA and R. Massey (California Institute of Technology)

First 3D map of the Universe's Dark Matter scaffolding

An international team of scientists generated the yet most accurate map of the distribution of Dark Matter for a certain region of the universe. For details see the links below. MPE scientists contributed to the map of the visible (baryonic) matter, which helped to calibrate the method applied for revealing the distribution of the Dark matter. (Nature, January 7, 2007)

external link MPG press release (in German language)
external link NASA/ESA HST press release

(January 8, 2007)
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PSR B1929+10

An artist’s impression of the ‘lumininescent’ magnetosphere surrounding a pulsar.  The pulsar itself is invisible in this view and sits at the very centre of the image. Above the pulsar’s magnetic poles, charged particles are accelerated outwards along the magnetic field lines and produce intense beamed radiation that can be observed by XMM-Newton.

Picture: W. Becker / MPE

Max-Planck-Scientists find new insights in the processes on how old pulsars generate X-rays:

Old pulsars still have new tricks to teach us

The super-sensitivity of ESA’s XMM-Newton X-ray observatory has shown that the prevailing theory of how stellar corpses, known as pulsars, generate their X-rays needs revising. In particular, the energy needed to generate the million-degree polar hotspots seen on cooling neutron stars may come predominately from inside the pulsar, not from outside. This is suggested by the investigation of five, several million years old rotation-powered pulsars using XMM-Newton.

external link ESA's XMM-Newton Science News
external link MPG press release
(in German language)
Relevant Publications:
external link Becker et al., ApJ 645, p. 1421 (2006)
external link Becker et al., ApJ 633, p. 367 (2005)
external link Becker et al., ApJ 615, p. 908 (2004)

(July 26, 2006)
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This X-ray image shows a comet-like blob of gas about 5 million light-years long hurling through a distant galaxy cluster with a velocity of over 500 miles per second (more than 750 km/s). The 'comet' is confined to the orange regions in the middle of this image. The head is to the lower right of center. The scale is 1 million light years.

Picture: ESA/XMM-Newton/Finoguenov et al.

XMM-Newton spots the greatest ball of fire

Using data from ESA's XMM-Newton X-ray observatory, a team of international scientists including members of MPE found a comet-like ball of gas over a thousand million times the mass of the sun hurling through the distant galaxy cluster Abell 3266 with a velocity of over 750 kilometres per second. This colossal 'ball of fire' is by far the largest object of this kind ever identified.

external link ESA press release
link detailed description
(in German language)
external link article in ""
external link article in ""
(in German language)
external link Original article in ApJ (access controlled)

(June 13, 2006)
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XMM-Newton reveals a tumbling neutron star

Spinning neutron stars, also known as pulsars, are generally known to be highly stable rotators. Their periodic signals, either in the radio or X-ray bands, can serve as very accurate clocks. Using ESA's XMM-Newton X-ray observatory, an international group of astrophysicists discovered that one such spinning neutron star, named RX J0720.4-3125, appears not as stable as expected. They found that over the past 4.5 years the temperature of this enigmatic object kept rising. Very recent observations have, however, shown that this trend reversed and the temperature is now decreasing. According to their recent publication, this effect is not due to a real variation in temperature, but instead to a changing viewing geometry. RX J0720.4-3125 is most probably precessing, i.e. there is a slow tumbling of the star, which exposes different areas of the surface over time. The X-ray observations promise to give new insights into the thermal evolution and finally the interior structure of neutron stars.
Artist's impression of XMM-Newton (credit: ESA)
XMM-Newton X-ray image of the sky around RX J0720.4-3125 which is the central bright object appearing in red (credit: Frank Haberl, MPE)
Neutron stars are one of the endpoints of stellar evolution. With a mass comparable to that of our Sun confined into a sphere of 20-40 km diameter, their density is even somewhat higher than that of an atomic nucleus, a billion tons per cubic centimeter. Soon after their birth in a supernova explosion their temperature is of the order of 1.000.000 degrees and the bulk of their thermal emission falls in the X-ray band of the electromagnetic spectrum. Young isolated neutron stars are slowly cooling down and it takes a Million years before they become too cold to be observable in X-rays.

Neutron stars are known to possess very strong magnetic fields, typically several trillion times stronger than that of the Earth. The field can be so strong that it influences the heat transport from the stellar interior through the crust leading to hot spots around the magnetic poles on the star surface. It is the emission from these hotter polar caps which dominates the X-ray spectrum. There are only a few isolated neutron stars known from which we can directly observe the thermal emission from the surface of the star. One of them is RX J0720.4-3125, rotating with a period of about 8.4 s. "Given the long cooling time scale it was therefore highly unexpected to see its X-ray spectrum changing over a couple of years," said Frank Haberl from the Max-Planck-Institut for extraterrestrial physics in Garching, Germany, who led the research group.

It is very unlikely that the global temperature of the neutron star changes that quickly, we rather watch different areas of the stellar surface at different times. This is also observed during the rotation period of the neutron star when the hot spots are moving in and out of our line of sight, i.e. their contribution to the total emission changes. A similar effect on a much longer time scale can be observed when the neutron star precesses (similar to a spinning top). In that case the rotation axis itself moves around a cone leading to a slow change of the viewing geometry over the years. Free precession can be caused by a slight deformation of the star from a perfect sphere which may have its origin in the very strong magnetic field.
Animation of a rotating and precessing neutron star with two hot polar caps (credit: Roberto Turolla, Univ. of Padova)
During the first XMM-Newton observation of RX J0720.4-3125 (May 2000), the observed temperature was at minimum and the cooler, larger spot was predominantly visible, while four years later (May 2004), precession brought into view mostly the second, hotter and smaller spot, increasing the observed temperature. This likely explains the observed temperature/emitting area variations and their anti-correlation.
Temperature variations observed from RX J0720.4-3125 (credit: Frank Haberl, MPE)
In their work Haberl et al. developped a model for RX J0720.4-3125 which can explain many of the peculiar characteristics which have been a challenge so far. In their scenario the long-term change in temperature is produced by the different fractions of the two hot polar caps which enter into view as the star precesses with a period of about 7-8 years. In order for such a model to work, the two emitting regions need to have different temperatures and sizes, as it has been recently proposed in the case of another member of the same class of isolated neutron stars. Learning more about the temperature distribution on the surface of a highly magnetized cooling neutron star will provide insights into the magnetic field geometry and its influence on the heat transport through the neutron star crust.

According to the team "RX J0720.4-3125 is probably the best case to study precession of a neutron star via its X-ray emission which we see directly from the stellar surface. Precession may be a powerful tool to probe the neutron star interior and learn about the state of matter under conditions which we can not produce in the laboratory. Additional XMM-Newton observations are planned to further monitor this intriguing object. We are continuing the theoretical modelling from which we hope to learn more about the thermal evolution, the magnetic field geometry of this particular star and the interior structure of neutron stars in general."

Notes to editors:

These results will appear in an article in the scientific journal Astronomy & Astrophysics. The article, ‘Evidence for precession of the isolated neutron star RX J0720.4-3125’, is by Frank Haberl (Max-Planck-Institut fur extraterrestrische Physik, Garching, Germany, email: fwh @, Roberto Turolla (University of Padua, Italy, roberto.turolla @, Cor P. De Vries (SRON, Netherlands Institute for Space Research, Utrecht, The Netherlands, @, Silvia Zane (Mullard Space Science Laboratory, University College London, UK, sz @, Jacco Vink (University Utrecht, The Netherlands, j.vink @, Mariano Méndez (SRON, mariano @ and Frank Verbunt (University Utrecht, F.W.M.Verbunt @

The paper appeared in Astronomy & Astrophysics, 451, L17 (2006) and is available at
Astronomy Abstract Service or Astrophysics abstracts, astro-ph/0603724

ESA press release
MPG press release (in German)
PPARC press release

(April 19, 2006)
(update May 24, 2006)
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galaxy cluster RXCJ0658.5-5556

X-ray image of RXCJ0658.5-5556, a violently merging cluster. The dark blue region near the centre is the core of a sub-cluster flying through the main cluster body at high "supersonic" speed, as indicated by a mach cone in front of this region and a very dramatic entropy enhancement (red arrow) which is the cluster gas heated by the shock front.

Image credit: ESA

probes the
formation of galaxy clusters

An international team of astronomers,
including members of the MPE,
detected the first direct X-ray evidence of shock heating in merging clusters.

external link ESA Press Release
external link Astronomy & Astrophysics (in press)
preprint in astro-ph

(September 06, 2005)
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rotating Black Hole

Artist's concept of the relativistic flow of matter around a fast rotating Black Hole in the centre on an accretion disk.

Image: MPE

Black Holes in a radar trap

Using the X-ray Satellite XMM-Newton researchers measure velocities near the speed of light in the vicinity of cosmic mass monsters

external link Press Release of the Max Planck Society
external link A&A article for Press Release (pdf)

(February 23, 2005)
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projected pressure map of Abell 754

Projected pressure map of Abell 754.

(Image credit: Alexis Finoguenov, MPE)

An international team of astronomers including members of the MPE detected the

most powerful massive merger of galaxies

on record.

external link Massive merger of galaxies is the most powerful on record
(ESA Space Science News)
external link Massive merger of galaxies is the most powerful on record
(Goddard Space Flight Center Top Story)
external link Massive Merger of Galaxies is the Most Powerful on Record
(NASA News)
external link Titanic merger of galaxy clusters revealed
(New Scientist)
external link Großer Knall im Weltall
(ZDF; in German)

(September 28, 2004)
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Black Hole disrupts star

A star is ripped apart by the tidal forces of a massive black hole. Part of the stellar debris is then accreted by the black hole. This causes a luminous flare of radiation which fades away as more and more of the matter disappears into the black hole.

(Credit: Illustration: NASA/CXC/M.Weiss)

Combining data from the X-ray satellites Chandra and XMM-Newton, the Hubble Space telescope and earlier data from the X-ray mission ROSAT, an international group of astronomers lead by Stefanie Komossa from MPE now have found

the first strong evidence of a giant supermassive black hole ripping apart a star at the center of a distant galaxy,

a process long predicted by theory.

link MPE background information
external link Chandra Press Release (04-061)
external link Chandra photo album
external link ESA Press Release (PR 12-2004)
external link MPG Pressemitteilung
(in German)
external link The full article:
Astrophysical Journal Letters, 603, L17 (2004).

(February 18, 2004)
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new X-ray map of the sky


derived from observations of XMM-Newton,
has been constructed with the help of MPE
and is now released on behalf of ESA.

external link MPG press information
(in German)
external link ESA News
link Informationon XMM-Newton at MPE
external link Article in
external link Web page of catalogue

(April 10, 2003)
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Using the Chandra X-ray satellite,
scientists from the MPE find

Two Supermassive Black Holes in Same Galaxy.

link Detailed Information (MPE)
external link Paper in Astrophysical Journal Letters 582, L15-L19, 2003.
external link MPG Research News
external link Chandra Press Releases from Harvard
external link NASA News Release

(November 19, 2002)
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Analyzing data from the X-ray satellite Chandra
Konrad Dennerl from MPE finds:

Planet Mars is glowing in X-rays
(text in German)

pdf-File of the MPG press information (in German)

article in the journal "Sky and Telescope"

(July 26, 2002)
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Analyzing data from the X-ray satellite XMM-Newton
scientists from MPE and ESA find a

Mysterious iron factory in the Early Universe .

Paper in ApJ 573
(link to ADS)
Cosmos could be much older than thought
( - report: July 10)

(July 8, 2002)
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A team from the MPI für extraterrestrische Physik made the first

observations of the planet Venus in X-rays

using the NASA satellite Chandra.

MPG press information (in German)

article in astronews (in German)

(November 26, 2001)
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link Highlights of the ROSAT Mission Excellent Research Results of the X-Ray Group

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© X-Ray Group at MPE (group)
last update:01-12-2008, editor of this page:Frank Haberl

up © Max-Planck-Institut für extraterrestrische Physik