Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

XMM-Newton ’spare-time’ provides impressive sky survey

04.05.2006


For the past four years, while ESA’s XMM-Newton X-ray observatory has been slewing between different targets ready for the next observation, it has kept its cameras open and used this spare time to quietly look at the heavens. The result is a ’free-of-charge’ mission spin-off – a survey that has now covered an impressive 25 percent of the sky.



The rapid slewing of the satellite across the sky means that a star or a galaxy passes in the field of view of the telescope for ten seconds only. However, the great collecting area of the XMM-Newton mirrors, coupled with the efficiency of its image sensors, is allowing thousands of sources to be detected.
Furthermore, XMM-Newton can pinpoint the position of X-rays coming from the sky with a resolution far superior to that available for most previous all-sky surveys. This is sufficient to allow the source of these X-rays to be found in many cases.

By comparing XMM-Newton survey’s data with those obtained over a decade ago by the international ROSAT mission, which also performed an all-sky survey, scientists can now check the long-term stability, or the evolution, of about two thousand objects in the sky.



An initial look shows that some sources have changed their brightness level by an incredible amount. The most extreme of these are variable stars and more surprisingly galaxies, whose unusual volatility may be due to large quantities of matter being consumed by an otherwise dormant central black hole.

The slew survey is particularly sensitive to active galactic nuclei (AGN) - galaxies with an unusually bright nucleus – which can be traced out to a distance of ten thousand million light years.

While most stars and galaxies look like points in the sky, about 15 percent of the sources catalogued by XMM-Newton have an extended X-ray emission. Most of these are clusters of galaxies - gigantic conglomerations of galaxies which trap hot gas that emit X-rays over scales of a million light years.

Eighty-one of these clusters are already famous from earlier work but many other clusters, previously unknown, appear in this new XMM-Newton sky catalogue.
Scientists hope that the newly detected sources of this kind also include very distant clusters which are highly luminous in X-rays, as these objects are invaluable for investigating the evolution of the Universe. Follow-up observations by large optical telescopes are now needed to determine the distances of the individual galaxies in the newly discovered clusters.

Using traditional pointed observations, it takes huge amounts of telescope-time to image very large sky features, such as old supernova remnants, in their entirety. The slewing mechanism provides a very efficient method of mapping these objects, and several have been imaged including the 20 000 year-old Vela supernova remnant, which occupies a sky area 150 times larger than the full moon.

Extraordinarily bright, low-mass X-ray binary systems of stars (called ’LMXB’) – either powered by matter pulled from a normal star, or exploding onto the surface of a neutron star, or being consumed by a black hole - are observed with sufficient sensitivity to record their detailed light spectrum. Passes across these intense X-ray sources can help astronomers to understand the long-term physics of the interaction between the two stars of the binary system.

Many areas of astronomy are expected to be influenced by the XMM-Newton sky survey. Today, 3 May 2006, the XMM-Newton scientist have released a part of the catalogue resulting from the initial processing of the highest quality data obtained so far.

Such data correspond to a sky coverage of about 15 percent, and include more than 2700 very bright sources and a further 2000 sources of lower significance. Currently, about 55 percent of the catalogue entries have been identified with known stars, galaxies, quasars and clusters of galaxies.

A faster turn-around of slew-data processing is now planned to catch interesting transient (or temporary) targets in the act, before they have a chance to fade. This will give access to rare, energetic events, which only a sensitive wide-angle survey such as XMM-Newton’s can achieve.

It is planned to continually update the catalogue as XMM-Newton charts its way through the stars. This will cover at least 80 percent of the sky, leaving a tremendous legacy for the future.

Norbert Schartel | alfa
Further information:
http://www.esa.int/esaSC/SEMA7OOFGLE_index_0.html

More articles from Physics and Astronomy:

nachricht First Juno science results supported by University of Leicester's Jupiter 'forecast'
26.05.2017 | University of Leicester

nachricht Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>