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 New Method of Characterizing Graphene
30.05.2017 | Universität Basel

nachricht NASA's SDO sees partial eclipse in space
29.05.2017 | NASA/Goddard Space Flight Center

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: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

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...

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

Reptile vocalization is surprisingly flexible

30.05.2017 | Life Sciences

EU research project DEMETER strives for innovation in enzyme production technology

30.05.2017 | Power and Electrical Engineering

New insights into the ancestors of all complex life

29.05.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>