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 Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT

nachricht Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>