Nav: Home

A new view of the X-ray sky

March 24, 2016

Scientists at the Max Planck Institute for Extraterrestrial Physics (MPE) have revisited the all-sky survey carried out by the ROSAT satellite, to create a new image of the sky in at X-ray wavelengths. Along with this a revised and extended version of the catalogue of bright and faint point-like sources will be released. The now published "2RXS catalogue" provides the deepest and cleanest X-ray all-sky survey to date, which will only be superseded with the launch of the next generation X-ray survey satellite, eROSITA, currently being completed at MPE.

In the 1990s, the ROSAT X-ray satellite performed the first deep all-sky survey with an imaging telescope in the 0.1-2.4 keV energy band, increasing the number of known X-ray sources by a factor of approximately 100. The intention of the new analysis was to improve the reliability of the catalogue, by re-analysing the original photon event files, using an advanced detection algorithm and a complete screening process.

An important feature of the new catalogue is a statistical assessment of the reliability of the sources. Because of the extreme sensitivity and low background of the ROSAT PSPC instrument, cosmic X-ray sources can be identified with the detection of just a few photons. These are sometimes difficult to distinguish from random fluctuations, and the new catalogue provides an assessment of this effect, based on simulated data.

The catalogue contains more than just a list of sources, for example X-ray images and overlaid X-ray contour lines for each of the detections are provided. For many sources, X-ray light curves were created to shows how the sources vary in brightness on intra-day timescales. For the brightest sources X-ray spectral fits were performed based on three basic spectral models, a power law, a thermal-plasma and a black-body emission model. This is important because it can distinguish what kind of cosmic source produces the X-rays. These include powerful accreting black holes, giant clusters of galaxies, active stars and the remnants of stars that exploded in supernova explosions.

With the new catalogue, the astrophysical community will now be able to explore these objects in the X-ray sky with more confidence, and with considerably more information.

Additionally, the experience gained by the high-energy group at MPE in creating the new ROSAT all-sky survey X-ray source catalogue will be integrated in the data reduction analysis and scientific exploration of the forthcoming eROSITA all-sky survey. The eROSITA X-ray survey telescope currently built by MPE will be launched in 2017 to scan the whole sky with even higher precision than ROSAT, reaching 30 times deeper into the universe. One of its main goals is to measure the distribution of about 100,000 galaxy clusters, containing thousands of galaxies each. The 2RXS catalogue is the deepest and most reliable X-ray all-sky survey before eROSITA.
Original publication:

Boller, Th., Freyberg, M., Trümper, J., Haberl, F., Voges, W., Nandra, K.
Second ROSAT all-sky survey (2RXS) source catalogue
A&A volume 588 (April 2016), id. A103
Online publication March 24, 2016


Related Stars Articles:

New evidence that all stars are born in pairs
Though astronomers have long known that many if not most stars are binaries, the question has always been, Were they born that way, or did one star capture another?
A planet hotter than most stars
A newly discovered Jupiter-like world is so hot that it's stretching the definition of the word 'planet.'
Finding inspiration in the stars
Lars Bildsten, director of the Kavli Institute for Theoretical Physics, wins the 2017 Dannie Heineman Prize for Astrophysics.
Astrophysicists release new study of one of the first stars
Timothy Beers, the Notre Dame Chair in Astrophysics, is part of a team that has used the Cosmic Origins Spectrograph on the Hubble Space Telescope to study key regions of the ultraviolet spectrum of a star thought to have been enriched by elements from one of the first generation of stars.
Deadly stars
Every now and then large sun storms strike the Earth where they cause aurora and in rare cases power cuts.
A new way to determine the age of stars?
Researchers have developed a new conceptual framework for understanding how stars similar to our Sun evolve.
Hubble unveils monster stars
Astronomers using the unique ultraviolet capabilities of the NASA/ESA Hubble Space Telescope have identified nine monster stars with masses over 100 times the mass of the Sun in the star cluster R136.
'Cannibalism' between stars
Stars do not accumulate their final mass steadily, but in a series of violent events manifesting themselves as sharp stellar brightening.
Turbulent times: When stars approach
Using new methods, astrophysicists from the Heidelberg Institute for Theoretical Studies (HITS), Germany, simulate the common-envelope phase of binary stars, discovering dynamic irregularities that may help to explain how supernovae evolve.
Rotational clock for stars needs recalibration
New work from a team of astronomers indicates that one recently developed method for determining a star's age needs to be recalibrated for stars older than our sun.

Related Stars Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...