Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Flashes shed light on cosmic clashes

06.10.2005


ESO’s telescopes see afterglows of elusive short bursts



An international team of astronomers led by Danish astronomer Jens Hjorth [1] has for the first time observed the visible light from a short gamma-ray burst (GRB). Using the 1.5m Danish telescope at La Silla (Chile), they showed that these short, intense bursts of gamma-ray emission most likely originate from the violent collision of two merging neutron stars. The same team has also used ESO’s Very Large Telescope to constrain the birthplace of the first ever short burst whose position could be pinpointed with high precision, GRB 050509B. The results are being published in the October 6 issue of the journal Nature.

Gamma-ray bursts, the most powerful type of explosion known in the Universe, have been a mystery for three decades. They come in two different flavours, long and short ones. Over the past few years, international efforts have convincingly shown that long gamma-ray bursts are linked with the ultimate explosion of massive stars (hypernovae; see e.g. ESO PR 16/03).


"The breakthrough in our understanding of long-duration GRBs (those lasting more than about 2 seconds), which ultimately linked them with the energetic explosion of a massive star as it collapses into a black hole, came from the discovery of their long-lived X-ray and optical afterglows," says Jens Hjorth (Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Denmark). "Short duration GRBs have however evaded optical detection for more than 30 years," he adds.

Things changed recently. In the night of July 9 to 10, 2005, the NASA HETE-2 satellite detected a burst of only 70-millisecond duration and, based on the detection of X-rays, was able to determine its position in the sky. Thirty-three hours after, Jens Hjorth and his team obtained images of this region of the sky using the Danish 1.5m telescope at ESO La Silla. The images showed the presence of a fading source, sitting on the edge of a galaxy.

"We have thus discovered the first optical afterglow of a short gamma-ray burst", says co-author Kristian Pedersen, also from the Dark Cosmology Centre of the University of Copenhagen.

The burst, named GRB 050709, resides 11,000 light-years from the centre of a star-forming dwarf galaxy that is about 2,400 million light-years away and is quite young – about 400 million years old. From observations conducted until 20 days after the burst, the astronomers can rule out the occurrence of an energetic hypernova as found in most long GRBs. This supports the hypothesis that short GRBs are the consequence of the merging of two very compact stars.

The same conclusion comes forward from the study of another event, GRB 050509B. This 40-millisecond burst was detected on May 9 by the NASA/ASI/PPARC Swift satellite, which could, for the first time, determine its position. Images obtained with the FORS instruments on ESO’s Very Large Telescope allowed the astronomers to study the vicinity of the burst.

The GRB was found to sit very close to a luminous, non-star forming elliptical galaxy lying 2,700 million light-years away and belonging to a cluster of galaxies.

"It is striking that the two short bursts that have finally been localised appear in quite different environments", says Jesper Sollerman, a member of the team from Stockholm Observatory (Sweden) and Dark Cosmology Centre (Denmark). "The most important aspect of these discoveries is probably that we have finally shown that the short bursts are indeed cosmic explosions from far away in the Universe", he adds.

Because elliptical galaxies are generally devoid of very massive stars but rich in tight binary systems containing compact stars, the association of the burst with this kind of galaxy gives the merging hypothesis another boost.

Whilst Hjorth and his colleagues still caution not to jump too quickly to definitive conclusions, astronomers cannot but marvel at the new chapter in astronomy that has just been opened.

Henri Boffin | EurekAlert!
Further information:
http://www.eso.org

More articles from Physics and Astronomy:

nachricht SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

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: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>