Astronomers, using ESO’s Very Large Telescope, have for the first time made the link between an X-ray flash and a supernova. Such flashes are the little siblings of gamma-ray bursts (GRB) and this discovery suggests the existence of a population of events less luminous than ‘classical’ GRBs, but possibly much more numerous.
“This extends the GRB–supernova connection to X-ray flashes and fainter supernovae, implying a common origin”, said Elena Pian (INAF, Italy), lead-author of one of the four papers related to this event appearing in the 31 August issue of Nature.
The event began on 18 February 2006: the NASA/PPARC/ASI Swift satellite detected an unusual gamma-ray burst, about 25 times closer and 100 times longer than the typical gamma-ray burst. GRBs release in a few seconds more energy than that of the Sun during its entire lifetime of more than 10,000 million years. The GRBs are thus the most powerful events since the Big Bang known in the Universe.
The explosion, called GRB 060218 after the date it was discovered, originated in a star-forming galaxy about 440 million light-years away toward the constellation Aries. This is the second-closest gamma-ray burst ever detected. Moreover, the burst of gamma rays lasted for nearly 2,000 seconds; most bursts last a few milliseconds to tens of seconds. The explosion was surprisingly dim, however.
A team of astronomers has found hints of a budding supernova. Using, among others, ESO's Very Large Telescope (VLT) in Chile, the scientists have watched the afterglow of this burst grow brighter in optical light. This brightening, along with other telltale spectral characteristics in the light, strongly suggests that a supernova was unfolding. Within days, the supernova became apparent.
The observations with the VLT started on 21 February 2006, just three days after the discovery. Spectroscopy was then performed nearly daily for seventeen days, providing the astronomers with a large data set to document this new class of events.
The group led by Elena Pian indeed confirmed that the event was tied to a supernova called SN 2006aj a few days later. Remarkable details about the chemical composition of the star debris continue to be analysed.
The newly discovered supernova is dimmer than hypernovae associated with normal long gamma-ray bursts by about a factor of two, but it is still a factor of 2–3 more luminous than regular core-collapse supernovae.
All together, these facts point to a substantial diversity between supernovae associated with GRBs and supernovae associated with X-ray flashes. This diversity may be related to the masses of the exploding stars.
Whereas gamma-ray bursts probably mark the birth of a black hole, X-ray flashes appear to signal the type of star explosion that leaves behind a neutron star. Based on the VLT data, a team led by Paolo Mazzali of the Max Planck Institute for Astrophysics in Garching, Germany, postulate that the 18 February event might have led to a highly magnetic type of neutron star called a magnetar.
Mazzali and his team find indeed that the star that exploded had an initial mass of ‘only’ 20 times the mass of the Sun. This is smaller, by about a factor two at least, than those estimated for the typical GRB–supernovae.
“The properties of GRB 060218 suggest the existence of a population of events less luminous than ‘classical’ GRBs, but possibly much more numerous”, said Mazzali. “Indeed, these events may be the most abundant form of X- or gamma-ray bursts in the Universe, but instrumental limits allow us to detect them only locally”.
The astronomers find that the number of such events could be about 100 times more numerous than typical gamma-ray bursts.
Henri Boffin | alfa
A quantum spin liquid
24.10.2017 | Boston College
Single nanoparticle mapping paves the way for better nanotechnology
24.10.2017 | Chalmers University of Technology
Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
23.10.2017 | Event News
17.10.2017 | Event News
10.10.2017 | Event News
24.10.2017 | Life Sciences
24.10.2017 | Life Sciences
24.10.2017 | Materials Sciences