Max-Planck-Institut für extraterrestrische Physik
Highlights in X-ray Astronomy
Deutsche Version MPE High-Energy Astrophysics X-Ray Astronomy Highlights
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
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.
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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
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.
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The artistic view shows a cataclysmic variable, the kind of close binary systems that host classical novae Credit: Mark A. Garlick |
Turbulent Disk
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.
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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.
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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.
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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.
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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.
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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.
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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.
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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)
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Max-Planck-Scientists find new insights in the processes on how old pulsars generate X-rays: Old pulsars still have new tricks to teach usThe 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.
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XMM-Newton spots the greatest ball of fireUsing 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.
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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. |
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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. |
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| 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. |
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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 @ mpe.mpg.de), Roberto Turolla (University of Padua, Italy, roberto.turolla @ pd.infn.it), Cor P. De Vries (SRON, Netherlands Institute for Space Research, Utrecht, The Netherlands, C.P.de.Vries @ sron.nl), Silvia Zane (Mullard Space Science Laboratory, University College London, UK, sz @ mssl.ucl.ac.uk), Jacco Vink (University Utrecht, The Netherlands, j.vink @ astro.uu.nl), Mariano Méndez (SRON, mariano @ sron.nl) and Frank Verbunt (University Utrecht, F.W.M.Verbunt @ astro.uu.nl).
The paper appeared in Astronomy & Astrophysics, 451, L17 (2006) and is available at
ESA press release
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XMM-Newton
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ESA Press Release
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Astronomy & Astrophysics (in press) preprint in astro-ph |
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Black Holes in a radar trapUsing the X-ray Satellite XMM-Newton researchers measure velocities near the speed of light in the vicinity of cosmic mass monsters
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An international team of astronomers including members of the MPE detected the most powerful massive merger of galaxies on record.
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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.
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"1XMM"
derived from observations of XMM-Newton,
(April 10, 2003)
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Using the Chandra X-ray satellite, Two Supermassive Black Holes in Same Galaxy.
(November 19, 2002)
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(July 26, 2002)
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(July 8, 2002)
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(November 26, 2001)
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