Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Swift Observes An Unusual Bang In The Far Universe

05.04.2006


Almost 40 years have passed since top secret nuclear weapon warning satellites accidentally discovered bursts of high energy gamma rays coming from space. Although many thousands of gamma ray bursts (GRBs) have since been detected, the origin and nature of these bursts is still not well understood.



One example of an unusual gamma ray burst occurred on 1 August 2005, when instruments on board the NASA-UK-Italy Swift spacecraft detected a bizarre GRB, which displayed unprecedented behaviour. Results based on the Swift data are being presented today (Wednesday) at the RAS National Astronomy Meeting in Leicester by Massimiliano De Pasquale from Mullard Space Laboratory-UCL.

Gamma ray bursts take the form of a brilliant burst of radiation, followed by a slowly fading afterglow. This shallow decay in the X-ray and optical light curve usually lasts for several days after the high energy explosion.


Swift data have shown that, whatever the ‘central engine’ that powers the GRB may be, it does not switch off after a few seconds, but often produces fast flares of radiation and injects energy into the outflow for hours.

Scientists believe that most GRBs are thought to be the result of a black hole swallowing a large star. This process might take long enough to explain both the prompt emission of X-rays and gamma rays, the late flares and energy injection.

The remaining matter is launched outwards at a huge velocity, but the interstellar medium around the burst acts like a “brake” to this outflow, being heated in the process and producing the afterglow emission.

In the case of the August 2005 gamma ray burst, known as GRB050801 after its date of detection, there was a bright afterglow with a steady emission both in X-ray and optical wavelengths, without any initial, brilliant flare. This behaviour lasted for only 250 seconds after the end of the prompt emission, before the afterglow began the typical decline in brightness. This behaviour has never been observed before.

The flat emission both in X-ray and optical wavelengths gives some hints about the ‘central engine’ of this GRB.

“This feature might be explained if we assume that, rather than a black hole, the core of the star has shrunk its mass and its magnetic field into an object known as a magnetar,” said Massimiliano De Pasquale.

A magnetar is a form of neutron star, the remains of a collapsed star that was originally about 10 times more massive than the Sun. This extremely dense object typically has a radius of only 10 km but the same mass of the Sun.

Magnetars are thousands of times more magnetic than ordinary neutron stars, with a magnetic field 1,000 million million times stronger than the Earth’s. Only a few of these exotic objects are known.

“Such an object initially rotates very quickly, typically hundreds of times every second, but it slows down by irradiating its energy at the magnetic poles, like a lighthouse,” said De Pasquale. “This would keep the afterglow emission steady for a time scale similar to that observed for GRB 050801.

The joint analysis of data from the XRT and UVOT instruments on Swift has also allowed the team to determine the distance of GRB050801, which was previously unknown, by measuring the amount of light absorbed during its intergalactic travel en route to the Earth.

It turns out that the burst took place 9 billion light-years away, which means that the gamma rays, X-rays and light from the gamma ray burst were created and began their journey across the universe 4,500 million years before the Earth was born.

“The explosion produced the same amount of energy as the Sun produces during its entire lifetime of 10 billion years,” said Massimiliano De Pasquale.

Massimiliano De Pasquale | alfa
Further information:
http://www.nam2006.le.ac.uk/index.shtml
http://www.ras.org.uk

More articles from Physics and Astronomy:

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>