Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Integral expands our view of the gamma-ray sky

21.02.2007
Integral's latest survey of the gamma-ray universe continues to change the way astronomers think of the high-energy cosmos. With over seventy percent of the sky now observed by Integral, astronomers have been able to construct the largest catalogue yet of individual gamma-ray-emitting celestial objects. And there is no end in sight for the discoveries.

Integral is the European Space Agency's latest orbiting gamma-ray observatory. Ever since Integral began scientific operations in 2003, the project team has been devoting a substantial proportion of its observing time to a survey of the gamma-ray universe.

"The gamma-ray sky is notoriously variable and extremely unpredictable," says Anthony Dean, University of Southampton, UK, one of the original proposers of the Integral mission. Hence, the need for Integral's constant vigilance and an accurate catalogue of all gamma-ray sources. With this, astronomers can target individual gamma-ray objects for more detailed, study.

For the past three and a half years, Integral has been collecting survey data. At the end of every year, the data has been turned into a catalogue of sources.

During the first year, it concentrated on the regions close to the centre of our galaxy and found more than 120 sources. During the following year, Integral broadened its reach and found almost 100 more sources.

Now Integral has observed over 70 percent of the sky, with a total exposure time of 40 million seconds. A European team of astronomers led by Antony Bird, University of Southampton, UK, have turned all three years' worth of data into the third Integral catalogue of gamma-ray sources. It contains a total of 421 gamma-ray objects. Most have been identified as either binary stars in our Galaxy containing exotic objects such as black holes and neutron stars, or active galaxies, far away in space. But a puzzling quarter of sources remain unidentified so far.

"I think many of these will turn out to be either star systems enshrouded in dust and gas, or cataclysmic variable stars," says Dean. Integral observes in the gamma-ray band so it can see through the intervening material. It has demonstrated that it can discover sources obscured at other wavelengths.

One surprise has been the efficiency with which Integral has detected just one minor subclass of cataclysmic variable stars (CVs), the so-called intermediate polars. Initially astronomers were not sure that CVs would emit gamma rays. Indeed, Integral has already shown that only about one percent of them do. "At the moment, the reason why this should be is totally mysterious," says Dean.

As its surveys points further from our Galaxy, so Integral increasingly sees the active galaxies. These represent about a tenth of all galaxies and each one has some kind of extraordinary activity taking place in its core. It is widely accepted that this activity is driven by a gigantic black hole sucking matter out of existence.

Roman Krivonos, Max-Planck-Institute für Astrophysik, Germany, and colleagues have used the Integral survey to show that AGN are concentrated in the same places that ordinary galaxies are found. Whilst this is not an unexpected result, it is the first time such an AGN distribution has been seen at high-energies.

"Integral represents a milestone in gamma-ray astronomy," says Dean. Thirty years ago, NASA’s Einstein observatory produced a catalogue of X-ray sources that became the standard reference document for all X-ray observatories – including ESA's XMM-Newton. "Integral is doing the same for gamma-ray astronomy," says Dean.

"We are in a golden age of gamma-ray astronomy," agrees Bird. And ESA's Integral is at the forefront of this brave new universe.

Christoph Winkler | alfa
Further information:
http://www.esa.int/SPECIALS/Integral/SEM0HNBE8YE_0.html

More articles from Physics and Astronomy:

nachricht Protecting the power grid: Advanced plasma switch for more efficient transmission
17.08.2018 | DOE/Princeton Plasma Physics Laboratory

nachricht Unraveling the nature of 'whistlers' from space in the lab
15.08.2018 | American Institute of Physics

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: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Quantum material is promising 'ion conductor' for research, new technologies

17.08.2018 | Materials Sciences

Low bandwidth? Use more colors at once

17.08.2018 | Information Technology

Protecting the power grid: Advanced plasma switch for more efficient transmission

17.08.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>